ERGONOMÍA OCUPACIONAL - SOCIEDAD DE ERGONOMISTAS ...

ERGONOMÍA OCUPACIONAL 

INVESTIGACIONES Y APLICACIONES 

VOL. 3

SOCIEDAD DE ERGONOMISTAS DE MÉXICO A.C. (SEMAC) 

2010

ERGONOMÍA OCUPACIONAL 

INVESTIGACIONES Y APLICACIONES 

VOL. 3 

EDITADO POR: 

CARLOS ESPEJO GUASCO 

Presidente Fundador SEMAC 

ENRIQUE DE LA VEGA BUSTILLOS 

Presidente SEMAC 2002-2004 

VICTORIO MARTINEZ CASTRO 

Presidente SEMAC 2008-2010

2010 Sociedad de Ergonomistas de México A.C. (SEMAC) 

ISBN 978-0-578-05757-6

Prefacio 

La Sociedad de Ergonomistas de México A.C. (SEMAC), como parte relevante de su 

actividad e interés en la difusión, promoción y apoyo a la ergonomía, ha organizado 

desde 1999 y de forma anual, su Congreso Internacional de Ergonomía. En Mayo de 

2010, el XII Congreso Internacional de Ergonomía tiene lugar en CD. Juárez, Chih., con 

la participación de ergonomistas profesionales e interesados en esta área. 

Aunque este último año ha sido, económicamente, muy difícil, eso no ha disminuido la 

calidad de los trabajos que se presentan este año. Se reúnen en este libro una selección 

de los trabajos, presentados en este congreso, más representativos de las diversas 

áreas que participan en la ergonomía, aportando diferentes investigaciones y soluciones 

a problemas específicos, con la finalidad de contribuir a la difusión, apoyo en la 

educación e investigación, de temas de interés para la ergonomía. 

Los editores, árbitros y comité académico, a nombre de la Sociedad de Ergonomistas de 

México, A.C., agradecemos a los autores de los trabajos aquí presentados su esfuerzo, 

e interés por participar y compartir su trabajo y conocimientos en el XII Congreso 

Internacional de Ergonomía de SEMAC. También agradecemos a los participantes y 

asistentes, provenientes de muy diversos lugares y formaciones, así como a todo el 

equipo de organización de este congreso, su valiosa aportación que estamos seguros 

derivará en el avance de la ergonomía en las Instituciones de Educación Superior y en 

la planta productiva nacional y mundial. 

Enrique de la Vega Bustillos 

Presidente SEMAC 2002 – 2004 

SOCIEDAD DE ERGONOMISTAS DE MÉXICO A.C. 

“Trabajo para optimizar el trabajo” 

Cd. Juárez, Chih. Mayo de 2010

ANTHROPOMETRY 

Ergonomía Ocupacional. Investigaciones y aplicaciones:. Vol 3 

CONTENT 

ANTHROPOMETRIC DATA OF STUDENTS OF THE UNIVERSITY 

OF SONORA, SONORA, MEXICO 

Martina Elisa Platt Borbón, Amina Marín Martínez, María Magdalena 

Ayala, Rafael Castillo Ortega and Félix Montaño Valle 

ANTHROPOMETRY AND FACILITIES DESIGN VERIFICATION 

OF NEW DEVELOPED PRESCHOOL LEVEL BUILDINGS IN THE 

EDUCATIONAL SECTOR OF HERMOSILLO, SONORA. 

Hiram Jesús Higuera Valenzuela, Manuel Sandoval Delgado 

DESIGN ANTHROPOMETRIC REFERENCED LETTERS TO THE 

LABOR POPULATION OF CABORCA CITY IN SONORA 

MEXICO. 

Joaquín Vásquez Quiroga, Jesús 

1 

Rodolfo Guzmán Hernández, 

Enrique Javier de la Vega Bustillos. 

BIOMECHANICAL 

BIOMECHANICAL MODEL TO ESTIMATE RECOVERY TIME ON 

HIGHLY REPETITIVE WORK IN MAQUILA OPERATIONS 

Fco. Octavio López Millán, Enrique Javier de la Vega Bustillos, 

Manuel Arnoldo Rodríguez Medina, Armando Ayala Corona 

VERIFICATION OF MAXIMUM ACCEPTABLE WEIGHT OF LIFT, 

TABULATED IN LIBERTY MUTUAL TABLES, IN WOMEN OF 

CABORCA 

Jesús Rodolfo Guzmán Hernández, Joaquín Vásquez Quiroga, 

Enrique Javier De La Vega Bustillos 

FORCE ANALYSIS IN HANDS ON HIGHLY REPETITIVE WORK 

IN MAQUILA OPERATIONS 

Fco. Octavio López Millán, Enrique Javier de la Vega Bustillos, 

MaríaJesúsTéllez Moroyoqui, LodevarPavlovichOviedo, 

Bertha Leticia Ortiz Navar 

DESIGN AND WORK ANALYSIS 

ADVANTAGES OF THE ORTHOGONAL ARRANGEMENTS OF 

THE METHOD TAGUCHI IN THE DESIGN OF EXPERIMENTS IN 

ERGONOMIC 

Alois Fabiani-Bello, Humberto García-Castellanos, Rosa Maria 

Reyes Martinez 

Page 

1 

14 

20 

35 

46 

55 

76

ERGONOMICS AND EDUCATION 


ACADEMIC ASSAYS FOR ERGONOMICS. 

Zoe Madai Cruz Purata, María del Sagrario Medina Rodríguez, Julio 

Gerardo Lorenzo Palomera 

OCCUPATIONAL ERGONICS 

ANALYSIS OF CORRELATION BETWEEN THE VARIABLES OF 

TEMPERATURE, STRENGTH AND CYCLES PER MINUTE TO 

PERFORM HORIZONTAL REPETITIVE MOVEMENTS OF THE 

WRIST 

Camargo Wilson Claudia, Rivera Valerio Abril A., 

Rubio Martinez Jesus R., de la Vega Bustillos Enrique J., 

López Bonilla Oscar R., Olguín Tiznado Jesús E., 

Báez López Yolanda A. 

TEMPERATURE ANALYSIS ON WRIST SURFACE DUE 

REPETITIVE MOVEMENT TASKS USING SENSORIAL 

THERMOGRAPHY TO FIND OUT A POSSIBLE PATHOLOGY 

FOR A CTD 

Ordorica Villalvazo Javier, Camargo Wilson Claudia, De la Vega 

Bustillos Enrique, Olguín Tiznado Jesús E., López Bonilla Oscar R., 

Limón Romero Jorge 

VIBRATION STUDY TO IMPROVE STRIPPING OPERATION 

IN A LITOGRAPHICS COMPANY 

Mario Ramírez Barrera, Jorge Valenzuela Corral, Athenea Núñez 

Sifuentes 

A DESCRIPTIVE STUDY ABOUT THE INTEGRATION OF 

ERGONOMIC ATTRIBUTES ON THE SELECTION OF 

ADVANCED MANUFACTURING TECHNOLOGY -AMT- 

Aidé Maldonado Macías, Arturo Reallyvázquez, Guadalupe Ramírez, 

Jorge Garcia-Alcaraz, Salvador Noriega 

WORK EVALUATION 

REMOTE ERGONOMICS EVALUATIONS IN THE OFFICE 

Jeffrey E. Fernandez, Gabriel Ibarra-Mejia , and Brandy F. Ware 

COMPARATIVE ANALYSIS BETWEEN AN ERGONOMIC 

EVALUATION AND THE USERS' SATISFACTION OF NEW 

EDUCATIONAL CENTERS 

Martín Daniel Del Sol Rangel, Manuel Sandoval Delgado 

DESIGN AND IMPLEMENTATION OF MANUFACTURING CELL 

WITH ERGONOMIC SUPPORT ANALYSIS 

Rigoberto Zamora Alarcón, Manuel Enrique Alcaráz Ayala, 

Julio César Romero González 

86 

98 

114 

128 

137 

151 

156 

163

ROSA MARIA REYES 

MARTINEZ 

Instituto Tecnologico de Cd. 

Juarez 

AIDE ARACELY MALDONADO 

MACIAS 

Universidad Autonoma de Cd. 

Juarez 

MA. ANTONIA BARRAZA 

Createc Cd. Juarez 

JEAN PAUL BECKER 

Ergon, Guadalajara, Jal. 

GABRIEL IBARRA MEJIA 

Universidad Autonoma de Cd. 

Juarez 

MIGUEL BALDERRAMA 

CHACON 

Valeo, Cd. Juarez 


COMITÉ ACADÉMICO 

MONICA AIDE BARRERA 

Delphi, Cd. Juarez 

ELISA CHACON MARINEZ 

Nchmarketing, Cd. Juarez 

CARLOS ESPEJO GUASCO 

Visteon, Cd. Juarez 

FRANCISCO OCTAVIO 

LOPEZ MILLAN 

Instituto Tecnologico de 

Hermosillo 

VICTORIO MARTINEZ 

CASTRO 

MABE

Ergonomía Ocupacional. Investigaciones y Aplicaciones. Vol 3 2010 

"ANTHROPOMETRIC DATA OF STUDENTS OF THE 

UNIVERSITY OF SONORA, SONORA, MEXICO" 

Martina Elisa Platt Borbón, Amina Marín Martínez, María Magdalena Ayala, 

Rafael Castillo Ortega and Félix Montaño Valle 

Industrial Engineering Department, Universidad de Sonora, Sonora, México 

1 mplatt@industrial.uson.mx, 2 amarin@industrial.uson.mx, 3 magdar@industrial.uson.mx, 4 rcastillo@industrial. 

RESUMEN 

uson.mx, 5 felixm@industrial.uson.mx 

Las cartas antropométricas dan la información acerca de las dimensiones de una población determinada y 

son muy utilizadas por los diseñadores. Los expertos en diseño afirman que una ayuda física diseñada 

para una población especifica, no es óptima para cualquier otra; ésto parece lógico, pero en nuestro país, 

no es posible ratificar o rectificar esta afirmación debido a que desconocemos las Cartas Antropométricas 

Mexicanas. 

La antropometría es la determinante de las condiciones ergonómicas; por tanto, los estudios 

antropométricos deben referirse a una población específica y de ahí nuestro interés por conocer las 

medidas de los estudiantes de la Universidad de Sonora. 

Se incluye un ejemplo de las tablas antropométricas por edad y por sexo de un estudio realizado a 227 

estudiantes de la Universidad de Sonora, Unidad regional Centro y se describe la metodología utilizada. 

ABSTRACT 

Anthropometric data gives information about the dimensions of a certain population and it is used by 

designers. Design experts affirm that physical equipment and facilities designed for a specific population, 

are not good for any other one; this seems logical, but, in our country, it is not possible to ratify or to rectify 

this statement because many of us ignore the Mexican Anthropometric data. 

Sociedad de Ergonomistas de México, A.C. 1


In order to design ergonomic living and working conditions, anthropometric principles must be applied; 

therefore anthropometric studies should refer to a specific population and it is our interest to know the 

dimensions and some physical features of the students of the University of Sonora. 

This research contains data collected in a sample of 227 students of the University of Sonora, Sonora, 

Mexico, from January to December, 2009; their body dimensions by age and sex, are depicted in figures 1 

and 2, and the methodology used is also described. 

INTRODUCTION 

Nowadays, men have reached an unusual development. Tools, equipment, machines and all kind of 

technology that are available aim for comfort and well-being in our daily life, as well as effectiveness, 

adaptability, prevention and for safety at work. These advances always arrive of the hand with new models 

of equipment, machines, tools or vehicles, which more dissimilar, force men to adapt themselves inside of 

or outside of them, implying possible risks, mainly at work places (McCormick, 1982). 

In all men’s activities, some or a lot of physical effort is needed, and they need and will continue needing 

physical assistance to reduce fatigue, to improve manufactured items or to produce them more quickly; 

some examples are: pincers or a hammer in a shop, a typewriter in an office, a pan in the kitchen or a 

stairway and its handrails in a building, etc. 

New scientific approaches and technological advances are key elements in designing to achieve higher 

productivity with almost perfect equipment and machinery. These items should eliminate the sources of 

risks and injuries. Designs should also take into account men’s physical characteristics, limitations and 

capabilities who will use them; designs must adapt physical tools to users and should avoid unnecessary 

efforts, tasks must be performed quickly, easily and safely, since individuals are more productive being 

comfortable at work. 



Adapting tools to users or workers should not only be bounded to the operator, but to all persons that will 

work with them, such it is the case of the maintenance personnel. Any internal part of equipment or 

machine should be accessible and be able to provide the necessary space to make any repair (Flores, 

2001). 

Mexican workers also have to adapt themselves to working tools and conditions, mainly for three 

circumstances: there is a great quantity of equipment and machinery that were bought in foreign countries, 

which were not designed to be operated by the Mexican population; Mexican manufacturers produce their 

items erroneously, they design them as they were designed in other countries and the most dramatic 

situation is that they don't know the physical characteristics (anthropometric data) of the Mexican 

population, or perhaps they have not been published. 

The Mexican anthropometric data found in the literature, up to now, have little information and they were 

collected from certain regions. 

a. The Yucatan population's anthropometric data is a research carried out by George Dee Williams in 

1927 and published in 1931 by the Bureau of International Research of Harvard University and 

Radcliffe College under the name of "Mayan-Spanish Crosses in Yucatan". 

b. Anthropometric measurements of some selected world populations, were presented as a report by 

Robert M. White during the International Symposium of Engineering of Human Factors in 1972. This 

report presents the dimensions of the military Air Forces of eighteen (18) Latin American countries 

on the whole, but the reference of the source of information is not shown. 

c. Datos antropométricos de la población de Ciudad Juárez, is a study carried out in 1986 and 1987 

by the Center of Graduates of the Technological Institute of Ciudad Juárez. This investigation 

presents 50 anthropometric data of 987 adults, mainly from the maquiladora industry. 

d. “Estudio de ergonomía estática en una empresa textil Mexicana” was published in the journal 

Condiciones de Trabajo, in 1979. 



e. Anthropometry of female maquila workers, is a research published in the International Journal of 

Industrial Ergonomics in 1999 by Victor Liu, David Sanchez Monroy and Guillermo Parga. It 

presents twelve body dimensions of women workers in the maquiladora industry. 

f. Cartas antropométricas para la población laboral de la maquila de Ciudad Obregón, is a research 

conducted by Claudia Elena Mungarro Ibarra, in 2009. 

g. Cartas antropométricas de adultos con enanismo de 18 a 45 años de edad para el diseño de 

mobiliario, this survey was carried out in Mexico City, by Rubén Baptista Balderas, an Industrial 

Design graduate student at Centro Universitario UAEMéx Zumpango, who took body dimensions of 

adults with dwarfism among 18 to 45 years old to design different furniture. 

h. Cartas antropométricas de la población laboral del estado de Sonora, área serrana, this study 

gathered body dimensions of workers in the northeastern region of the state of Sonora, Mexico and 

it was performed by students of the Universidad de la Sierra in the state of Sonora in 2008. 

i. Cartas antropométricas de la población laboral de la República Mexicana, a research published by 

the Instituto Tecnológico of Hermosillo. 

Some employers may perceive that since tasks are designed or redesigned, whatever the operator will 

need may be, carefully, taken into account, but it may increase their investment, but in the long run, 

investment will be recovered and the gains will be financially enlarged. 

On the other hand, if an employee works comfortably when he/she is sitting down, he/she will not feel tired, 

will not feel any pain, and will be able to work easily and relaxed, and his/hers items quality will increase, 

as well as effectiveness and efficiency. In such scenario, health care costs will decrease and the 

employee’s moral will improve. 

Ergonomics principles can avoid injuries or painful illnesses that can handicap workers and make work 

places more comfortably safe in productive environments (McCormick, 1982). 

Anthropometric data`s main utilization is objects designed for human use, such as tools, furniture, work 

stations, facilities, etc. which optimize working and living conditions. 



As it can be seen, designing for human use is a wide objective, and to achieve good results it is necessary 

to keep in mind that who is or will be a product’s customer. That is the main reason that anthropometric 

data is necessary as another tool for work designers, and its gathering takes time and it is quite expensive. 

OBJECTIVES 

To gather anthropometric data of students of the University of Sonora, in Hermosillo, Sonora, México, for 

different population strata, for: 

a) Age range (3), and 

b) Sex (2) 

METHODOLOGY 

A group of four trained people got the anthropometric data of 227 students. Three of the investigators (M. 

E. P. B. and A. M. M.) trained this group; they covered techniques, devices to use; and the required 

theoretical and practical knowledge to carry out the necessary activities. 

The trained group carried out the project with students of the University of Sonora in Hermosillo, Sonora, 

México. Students were asked to wear light clothing and to take off their shoes during the study. 

An anthropometer, a graduated scale in kilograms, and a survey of anthropometric data to register 

measurements were used. 

Measurements were taken by the students’ right side posture, when they were standing straight up, and 

also sitting down, in an erect position. 

1. Standing straight up. The individual remains standing straight, seeing toward the front, with the 

ankles together, the weight distributed equally in both feet and with his arms hanging naturally to his 

sides. 

2. Sitting down straight. The individual remains sitting down and straight, with his/her view toward the 

front, the arms relaxed and hanging, forearms and hands extended forward, thighs were horizontal, 

and his/her feet resting in an adjusted surface so that the knees were in an angle of 90 degrees. 



Data were gathered and processed in Excel software, and percentiles were later determined. 

Data were grouped by sex, age and geographical regions, in the following way: 

a. for sex: women and men, 

b. for age, from 17 to 20, from 21 to 23 and from 24 years old and up. 

c. Birthplace, the Mexican Republic was divided by several areas: 

North zone, for the States of Chihuahua, Coahuila, Durango, New León and Zacatecas. 

Centered area that includes the States of Aguascalientes, Mexico, Guanajuato, Hidalgo, Morelos, Puebla, 

Querétaro, San Luis Potosí', besides Mexico Federal District. 

Northern Pacific area: The states of the Northwestern area such as Sonora, Baja California, Sinaloa and 

Nayarit. 

Center Pacific area, for the states of Jalisco, Michoacán and Colima. 

South Pacific area: for the states of Guerrero, Oaxaca and Chiapas. 

Gulf of Mexico area, includes the states of Tamaulipas and Veracruz. 

The different areas were settled down, arbitrarily, following the approach of their geographical proximity. 

In figures 1 and 2, are shown the codes used, their description and the individual's position. This code was 

taken from a study carried out by the NASA. 



UNIVERSIDAD DE SONORA. Carta Antropométrica 

Edad: 15-20 21-30 31-40 41-50 51-60 Sexo: F M 

Lugar de Nacimiento (Estado): _______________________________________ Ocupación: ____________________________________ 

Lugar de Nacimiento (Estado): Padre: _____________________________ Madre: ______________________________________ 

Analista: _________________________________________________________ (Usar ropa ligera y ajustada al cuerpo) 

920 Peso (Kg) 122 Ancho de hombros 

805 Estatura 223 Ancho de pecho 

328 Altura al ojo 457 Ancho de cadera (parado) 

23 Altura al hombro 32 Largo de brazo 

309 Altura al codo 67 Profundidad del pecho 

949 Altura a la cintura (ombligo) 430 Circunferencia de la cabeza 

398 Altura al glúteo 639 Circunferencia del cuello 

973 Altura a la muñeca 230 Circunferencia del pecho 

66 Altura a los nudillos 931 Circunferencia de la cintura 

265 Altura al dedo medio 68 Circunferencia del brazo 

797 Ancho de brazos extendidos 

lateralmente 

798 Ancho de codos con las manos 

al centro del pecho 

178 Circunferencia de la cadera 

69 Circunferencia de la pantorrilla 

80 Distancia de la pared al dedo medio 144 Distancia de oído a oído sobre la 

cabeza 



752 Distancia de la pared al nudillo 165 Ancho de la cara a la altura de las 

patillas 

Figure 1. Codes used, their description, and the individual's position. 

427 Ancho de la cabeza 912 Altura del asiento a los nudillos con los 

brazos extendidos hacia arriba 

595 Altura de la barbilla a la parte superior 

de la cabeza 

200 Longitud desde el respaldo del asiento a 

la parte posterior de la rodilla 

441 Longitud de la cabeza 194 Longitud desde el respaldo del asiento al 

frente de la rodilla 

420 Longitud de la mano 2fgm Altura desde el suelo a la cabeza 

(sentado) 

656 Longitud de la palma de la mano 4fgm Altura desde el suelo al asiento 

411 Ancho de la palma de la mano 529 Altura desde el suelo a la rodilla 

(sentado) 

859 Ancho de muslos con las rodillas juntas 

(sentado) 

678 Altura desde el suelo a la parte posterior 

de la rodilla (sentado) 

758 Altura del asiento a la cabeza 70 Longitud desde el codo al dedo medio 

330 Altura del asiento al ojo 507 Ancho de la espalda con los brazos 

extendidos hacia el frente 

25 Altura del asiento al hombro 459 Ancho de la cadera (sentado) 

Sociedad de Ergonomistas de México, A.C. 8 

Elaboró: GF y SM


312 Altura del asiento al codo a 90° 775 Longitud del pie 

856 Altura al muslo 776 Alto del pie 

914 Altura del asiento al dedo medio con 

brazos extendidos hacia arriba 

777 Ancho del pie 

Figure 2. Codes used, their description, and the individual's position. 


Elaboró: GF y SM


RESULTS 

Six anthropometric data were obtained from a sample of 227 students, for women and men, for three group 

of ages from 17 to 20, from 21 to 23 and from 24 to 54 years old. 

Hereby are presented two anthropometric surveys where body dimensions are described, measurements are 

in centimeters and weight is shown in kilograms for 5 th , 50 th and 95 th percentiles of a women’s sample 

(figure 3) and for a masculine sample (figure 4), both, from 17 to 20 years old. In figure 5 data shows a 

sample size of 227 masculine and feminine students by age range and sex. 

Measurement’s Desription 5% 50% 95% Measurement’s Description 5% 50% 95% 

Weight 37.17 66.6 96.02 Length of head 17.042 19.241 21.441 

Stature 151.77 165.54 179.3 Length of hand 15.828 17.594 19.36 

Length of palm of hand 7.831 9.8366 11.842 

Height standing Width of palm of hand 4.5519 7.8598 11.168 

Eye 139.97 153.73 167.5 Diameter of grabs (interior) 36.064 45.146 54.228 

Shoulder 123.24 136.02 148.8 

Elbow 86.196 107.4 128.6 Heights sitting 

Waist 91.871 101.94 112 Height to head from seat 71.443 85.524 99.605 

Buttock 65.34 74.432 83.52 Height to eye from seat 

Height to shoulder from 

67.182 75.012 82.842 

Wrist 53.194 82.124 111.1 seat 

Height to elbow from seat, 

50.45 59.456 68.462 

Middle finger 54.842 63.695 72.55 90 degrees 20.364 24.951 29.538 

Width of extended arms 151.27 166.63 182 Height to thigh from seat 10.891 14.046 17.202 

Width of elbows to the 

Height to Middle finger 

center of chest 70.412 85.588 100.8 from seat, arms up 117.5 129.26 141.01 

Length of arm extended 

Height to center of fist, arms 

from the wall 64.072 81.687 99.3 up 100.41 122.3 144.2 

Length to the center of the 

Height to head from floor 

fist from the wall 51.492 73.712 95.93 sitting 

Hight to seat from floor 

121.12 131.11 141.1 

Width of shoulders standing 34.828 42.038 49.25 sitting 23.215 49.154 75.092 

Width of chest standing 24.719 30.34 35.96 Popliteal to buttocks 

Length from knees to 

39.537 47.641 55.746 

Width of hips standing 

Circumferencia of neck 

26.245 33.701 41.16 buttocks 48.308 59.027 69.745 

standing 

Circumferencia fo chest 

23.618 35.539 47.46 Height from floor to popliteal 35.818 43.388 50.958 

standing 73.352 90.66 108 Height from floor to knee 40.054 52.266 64.477 

Circumferencia of waist 

Length from elbow to 

standing 55.12 79.619 104.1 middle finger 

Width of back with arms 

40.634 44.907 49.18 

Circumference of hips 

extended forward –forward 

standing 81.893 99.361 116.8 reach 34.85 40.587 46.323 

Circumference of head 46.695 54.395 62.1 Width of hips, sitting 32.447 38.468 44.489 

Distance from ear to ear 

Width of thighs with knees 

over head 

Width of face to the height 

26.672 34.971 43.27 meeting 30.701 37.212 43.723 

of sideburns 11.977 13.563 15.15 Length of foot 21.381 24.137 26.892 

Width of head 

Height of chin to superior 

13.645 14.973 16.3 Width of foot 6.4972 8.4366 10.376 

part of head 18.517 22.146 25.78 Height of instep 4.3354 6.2829 8.2305 

Figure 3. Body dimensions for a femenine sample from 17 to 20 years old. 



Measurement’s description 5% 50% 95% Measurement’s description 5% 50% 95% 

Weight 42.488 71.49375 100.49 Length of head 16.075 19.574 23.073 

Stature 159.93 171.5791 183.23 Length of hand 15.673 18.054 20.435 

Length of palm of hand 8.6763 10.373 12.07 

Height standing Width of palm of hand 6.6558 8.1094 9.5629 

Eye 146.22 158.5875 170.955 Diameter of grabs (interior) 41.309 47.465 53.621 

Shoulder 130.06 141.2395 152.41 

Elbow 92.509 109.3958 126.28 Heights sitting 

Waist 95.292 105.0958 114.9 Height to head from seat 68.123 86.91 105.7 

Buttock 54.349 79.39791 104.44 Height to eye from seat 67.85 77.194 86.538 

Wrist 59.077 85.08333 111.08 Height to shoulder from seat 

Height to elbow from seat, 

51.535 61.767 71.998 

Middle finger 57.349 65.675 74.000 90 degrees 20.315 25.654 30.993 

Width of extended arms 160.06 173.7833 187.50 Height to thigh from seat 11.199 14.198 17.196 

Width of elbows to the center 

Height to Middle finger from 

of chest 80.408 88.92812 97.448 seat, arms up 123.05 135.74 148.43 

Length of arm extended 

Height to center of fist, arms 

from the wall 74.883 84.65416 94.425 up 113.39 126.16 138.93 

Length to the center of the 

Height to head from floor 

fist from the wall 65.872 74.74166 83.6111 sitting 

Hight to seat from floor 

122.9 132.74 142.57 

Width of shoulders standing 35.141 44.8 54.458 sitting 25.36 49.129 72.899 

Width of chest standing 26.262 31.33333 36.4043 Popliteal to buttocks 

Length from knees to 

41.01 48.425 55.84 

Width of hips standing 

Circumferencia of neck 

29.324 35.1 40.876 buttocks 51.866 59.494 67.121 

standing 

Circumferencia fo chest 

18.107 38.59791 59.088 Height from floor to popliteal 37.174 43.798 50.422 

standing 75.157 92.11041 109.06 Height from floor to knee 45.236 52.631 60.026 

Circumferencia of waist 

Length from elbow to middle 

standing 62.925 84.41458 105.90 finger 

Width of back with arms 

40.184 46.278 52.372 

Circumference of hips 

extended forward –forward 

standing 81.922 97.05833 112.19 reach 38.252 43.581 48.911 

Circumference of head 46.276 56.28666 66.297 Width of hips, sitting 31.955 38.346 44.737 

Distance from ear to ear over 

Width of thighs with knees 

head 

Width of face to the height of 

25.215 35.57708 45.939 meeting 29.586 36.777 43.969 

sideburns 12.364 14.04375 15.723 Length of foot 22.467 25.502 28.537 

Width of head 

Height of chin to superior 

13.581 15.52604 17.471 Width of foot 6.2461 8.6625 11.079 

part of head 19.43 22.74375 26.057 Height of instep 4.812 6.5781 8.3443 

Figure 4. Body dimensions of a masculine sample from 17 to 20 years old. 


Estratum by age 

17-20 

21-23 

24-54 

TOTALS 


Masculine 

Feminine 


48 

85 

3 

136 

Figure 5. Sample size, grouped by age and sex of students of the Universidad de Sonora. 

CONCLUSIONS AND SUGGESTIONS 

Ergonomics emerged exclusively to increase worker's productivity, with time, it has become into a 

multidiscipline, it looks forward to make tools more functional and spaces habitable, to improve aspects like 

the men’s safe, comfort and health. 

At present times, muscular – skeletal problems are often found in workers, "in such situations applied 

Ergonomics is useful because it improves adaptability of physical persons’ limitations to environmental 

conditions and to work tools, avoiding the development of pathologies like tendinitis, cervical and lumbar 

injuries, among others." 

Products, tools, machines, work places and furniture should be designed thinking of the activity or activities 

that people will carry out on them. A work place can have more than one worker and its design should be 

adjustable, that is why sometimes, it is necessary to build products of several sizes in such a way that 

someone would have the possibility to choose the one that better adapts to the user's necessities, the other 

one, would be to create products that are adjustable in a certain range of body dimensions, making necessary 

to know the benefits and costs in such a way that decisions that are taken are the correct ones. 

41 

47 

3 

91


As it can be seen, everything that is manufactured, elaborated to interrelate with man should use their 

dimensions, it is necessary to know human anthropometry. 

The anthropometric data gathered in this research is one more effort added to those that were made 

previously in Mexico. Body dimensions of students of the University of Sonora, in Hermosillo, Sonora, 

Mexico includes male and female from 17 to 20, 21 and from 23 to 24 years old and older students; natives 

and non natives from Hermosillo. These sample is build of 60.87% men and 39.83% women, 100% belong 

to the North Pacific area and 93.52% were born in the state of Sonora. 

Suggestions that can be made are: to invite researchers, education institutions and companies to develop 

anthropometric data of Mexican populations, aiming to design production systems that will fulfill their main 

goals: to increase productivity and to produce high product quality, optimizing workers’ safe and comfort at 

the same time, so that they would allow them to compete in today’s global business. 

REFERENCES 

1. McCormick, Ernest and Sanders, Mark. (1982). Human Factors in Engineering and Design. United 

States of America. McGraw-Hill Book Company. 

2. Neufert, Ernest. (1977). The Art of Projecting in Architecture. Barcelona, Spain. Editorial Gustavo 

Gil, S. A. 

3. Instituto Mexicano del Seguro Social (1982). Lecturas en materia de seguridad social. Ergonomía. 

México. 

4. Flores, Cecilia. (2001). Ergonomía para el diseño. Designio. 

5. Mondelo, Gregori, de Pedro Gómez. (2002). Ergonomía 4. El trabajo en oficinas. Editotial 

Alfaomega. 

6. Murrell, K. F. H. (1979). Ergonomics. London, England. Chapman & Hall. 

7. Konz, Stephan. (2004) Work Design. Columbus, Unites States. Grid Publishing. 

8. Unites States of America. NASA. (1987). Anthropometric Source Book, Vol 2: A Handbook of 

Anthropometric Dates. 



ANTHROPOMETRY AND FACILITIES DESIGN VERIFICATION OF NEW 

DEVELOPED PRESCHOOL LEVEL BUILDINGS IN THE EDUCATIONAL 

SECTOR OF HERMOSILLO, SONORA. 

Hiram Jesús Higuera Valenzuela 1 , Manuel Sandoval Delgado 1 

1 Departamento de Investigación y Posgrado 

Instituto Tecnológico de Hermosillo 

Ave. Tecnológico S/N Colonia Sahuaro 

Hermosillo, Sonora 83170 

Corresponding author’s e-mail: hiram.higuera@gmail.com, msandoval@ith.mx 

Resumen: Esta investigación nace de la problemática de la no existencia de tablas 

antropométricas de la población infantil principalmente en la edad de preescolar en México, las 

utilizadas por el Instituto Nacional de la Infraestructura Física Nacional no incluyen datos 

pertenecientes a infantes en edad de preescolar, las cuales se utilizan para la elaboración de 

mobiliario y dimensionamiento en el diseño de las instalaciones educativas (INIFED). 

Antropometría infantil. 

Abstract: This research comes from the lack of anthropometric charts for Mexican children in preschool 

level, the charts used by the Instituto Nacional de la Infraestructura Física Nacional 

(National Institute for Educational Facilities) do not include data from pre-school level children; 

those charts are used to build furnishing and to determine the right size of the facilities (INIFED). 

Children’s Anthropometry 

1. INTRODUCTION 

Current situation in developing countries and economic growth, lack of in-house technologies and 

economic and technological dependence favor the use of models designed by other cultures 

(Oborne, 2007). 

2. OBJETIVES 

Check if design is within measurements found in the anthropometry charts in new pre-school level 

buildings in Hermosillo, Sonora during 2007 and 2008, since previously built schools show a lot of 

mistakes regarding the facilities’ size and the furnishing causing a lot of discontents and troubles 

in teachers and family parents in pre-school level buildings. 

3. METHODOLOGY 


3.1 Programming stage 


a) The aim of this anthropometric research must be very clear, specifying if data collected will 

be used for a new design, redesign or to create a general purpose database. 

b) It is necessary to define the kind of anthropometric technique that will be applied, which can 

be “Static Anthropometry” or “Dynamic Anthropometry”. (Flores G., 1997). 

Static anthropometry measures the body still. It measures the skeleton between specific 

anatomic points. Dynamic or functional anthropometry it’s the one which measures the body in 

motion, acknowledging that the actual reach of a person’s arm it’s not equal to the length of the 

arm itself, but it takes into consideration the additional reach provided by the movement of the 

shoulder and torso when a person is working (Ergocupacional). 

c) Once that the kind of anthropometric technique has been chosen, all the measures that will 

be used need to be specified and for this we need to keep in mind our final goal. In order to 

choose the measures we need to take, we must refer to the general anthropometric set 

(static or dynamic), taking into account the name and standard reference points in order to 

keep the techniques systematization. 

d) Once that the measures to be taken have been defined, the anthropometric chart to be 

used needs to be designed. A copy of the chart for each subject needs to be built. 

e) Besides the good quality and accuracy of the measuring equipment, portability it’s 

important, since most of the time it will be necessary to go where people who will be 

measured is. The most basic equipment must include anthropometric chart, portable 

anthropometer, flexometer, and tape measure. (Flores G., 1997). 

Figure 1. Anthropometric chart and portable anthropometer. 

3.2 Sampling 

In this stage it’s when individuals in new facilities start to be measured in order to collect 

raw data; this is 32 measures by each individual. 

3.3 Statistics Analysis 

Once that the data is collected, it is analyzed and an anthropometric chart is built; 

percentiles 95, 50, 5 come from this chart, those are used to build facilities and furnishing. 



The impossibility to make a design for the whole population forces us to pick a segment 

which includes the data in between. Thus, highest and lowest values are left out and focus on the 

90% of the population. As a norm, the practical totality of anthropometric data is expressed in 

percentiles. In order to make this research more effective, population is broken into percentages 

categories, sorted from lowest to highest according to a specific body measure. For example, the 

first height percentile indicates that 99% of the individuals measured would be above this 

dimension. In the same way, a percentile of 95% in height would state that only 5% of the 

individuals measured would be over it, since the remaining 95% would be just as tall or shorter. 

(Panero, 1993). 

3.4 Steps to get percentiles 

1. Summation of raw data is calculated In a spreadsheet (total of measures), mean or 

average is calculated using the following formula: 

= Data mean or average 

ΣX = Summation of the values of all the measures. 

n = Number of elements of the sample. 

2. Standard deviation it’s calculated, which defines the individual deviation of each 

measure regarding to the mean. 

s 2 = Variation of the sample. 

s = Standard variation of the sample. 

x = Value of the measures. 

= Mean of the sample. 

n - 1 = Number of measures of the sample -1 

3. Standard deviation of the unit it’s calculated, which is called “z”, where z equals to: 

x = Random variable value 

= Average distribution of the random variable. 

s = Standard variation of this distribution. 

z = Number of standard deviations of x regarding the mean of this distribution. 

(Navidi, 2006). 


(1) 

2 

3 

(4)

(DINBelg) 

4. Percentiles are calculated 

4. RESULTS 


Since this is an ongoing research, some of the necessary measures are still missing in order to 

conduct a full test of the facilities and furnishing, however, there is an anthropometric chart with 

the data collected so far and it is possible to get preliminary results in order to get the dimensions 

for facilities and furnishing. 

In this example the dimensions of the sink and classroom chairs will be used. 

In order to calculate height and width for the sink measures 949 (height to the waist) and 752 

(distance from the wall to the center of the fist) 

Results for 949 

X = 61.55 

S = 4.88 

5 % = 61.55 – (4.88 x 1.65) = 53.498 cm (9) 


X = 46.26 

S = 3.66 

5 % = 46.26 – (3.66 x 1.65) = 40.221 cm (10) 


5 

6 

7 

(8)


Figure 2. Sink dimensions 

In order for most of the children to be able to use the sink without any problems percentile 5 

from mean 949 and 752 was used. 

Measures 200 (length from the back of the knee to the back of the chair), 678 (height from 

the ground to the back side of the knee), 459 (width of hips, sitting down), 25 (height from the seat 

to the shoulder) are used in order to get the dimensions of the chair. 


X = 28.82 

S = 2.13 

5 % = 28.82 – (2.13 x 1.65) = 25.3055 cm (11) 


X = 28.98 

S = 2.38 

5 % = 28.98 – (2.38 x 1.65) = 25.053 cm (12) 


X = 22.09 

S = 1.95 

5 % = 22.09 + (1.95 x 1.65) = 25.3075 cm (13) 


X = 37.56 

S = 2.54 

5 % = 37.56 – (2.54 x 1.65) = 33.369 cm (14) 


5. CONCLUSIONS 


Figure 3. Chair dimensions 

This research is extremely important since there are no anthropometric charts for pre-school level 

children in Mexico. These charts are used to build furnishing and determine the size of new 

schools buildings. This project aims to get the necessary information in order to build these charts. 

6. REFERENCES 

Flores G., Cecilia (1997) Antropometría Aplicada, Primer Encuentro Internacional de Ergonomía, 

Instituto Tecnológico de Mérida, Mérida Yucatán. 

Oborne, David J. (1990 reimpresión 2001), Ergonomía en acción la adaptación del medio de 

trabajo al hombre. – 2ª edición – México: Trillas. 

INIFED (Instituto Nacional de la Infraestructura Física Educativa 2008), Normas y 

Especificaciones para Estudios, Proyectos, Construcción e Instalaciones, Volumen 3 

Habitabilidad y Funcionamiento, Tomo III Diseño de Mobiliario. 

http://www.inifed.gob.mx/templates/normas%20t%C3%A9cnicas.asp (Visited on May 15, 

2009). 

ERGOCUPACIONAL Uso de tablas antropométricas en ergonomía, 

http://www.ergocupacional.com/4910/35922.html (Visited on March 8, 2010). 

Panero Julios (1993) Las dimensiones humanas en los espacios interiores. Ed. G. Gili, S.A. 

México, D.F. 

Navidi William (2006) Estadística para ingenieros y científicos. McGraw-Hill Interamericana. 

México, D.F. 

DINBelg Body dimensions of the Belgian population Formulas, 

http://www.dinbelg.be/formulas.htm (Visited on March 8, 2010). 



1 

M.C. Joaquín Vásquez Quiroga 1 , M.C. Jesús Rodolfo Guzmán Hernández 2 , Dr. Enrique Javier de 

la Vega Bustillos 3 . 

1 

2 

3 

DESIGN ANTHROPOMETRIC REFERENCED LETTERS TO THE LABOR 

POPULATION OF CABORCA CITY IN SONORA MEXICO. 

Program Coordinator and Professor, Department of Physics, Mathematics and Engineering, 

Universidad de Sonora, Caborca Sonora, México. 

jovaqui@caborca.uson.mx 

Professor and Researcher at the Instituto Tecnológico de Hermosillo, Mexico 

e_delavega_mx@yahoo.com 

Professor, Department of Physics, Mathematics and Engineering 

Universidad de Sonora, Caborca, Sonora, México. 

rguz@caborca.uson.mx 

RESUMEN 

Esta investigación es el resultado de las mediciones de 50 variables antropométricas de 200 

personas en edad laboral de la Ciudad de Caborca Sonoro México, con el objetivo de poder 

hacer una aportación importante a la creación de cartas antropométricas para la población 

mexicana. En la actualidad son pocos los datos que se tienen de las medidas antropométricas de 

la población mexicana, haciéndose necesario utilizar las medidas de otros países en donde las 

condiciones y complexión física son diferentes. 

Las cartas antropométricas que aquí se obtuvieron están distribuidas por grupos de edad, sexo y 

lugar de origen. Este trabajo puede ser el inicio de investigaciones similares en otras poblaciones 

de México y llegar a tener un registro antropométrico del total de la población mexicana, para 

poder desarrollar estaciones o espacios de trabajo que se adapten a la población, herramientas, 

ropa, equipo de protección personal como cascos y guantes, calzado, lo mismo que lugares de 

descanso. 

Palabras claves: Cartas Antropométricas, Antropometría y Ergonomía. 

ABSTRACT 

This research is the result of 50 anthropometric measurements of 200 people of working age of 

Caborca Sonora Mexico City, in order to be able to make a significant contribution to creating 

cards for the Mexican population anthropometric. At present there are few data have 

anthropometric measurements of the Mexican population, making it necessary to use measures 

other countries where conditions and physique are different. 

The anthropometric letters were obtained here are divided by age, sex and place of origin. This 

work may be the beginning of similar investigations in other populations of Mexico and get to have 

a record of all anthropometric Mexican population, to develop stations or workspaces that are 

tailored to the people, tools, clothing, protective equipment personal as helmets and gloves, 

footwear, as well as resting places. 

Keywords: Anthropometric Letters, Anthropometry and Ergonomics. 




It is now of vital importance to take into account the design and the anatomic structure of 

individuals to understand and develop all those areas in which performance involves human 

beings, this is not new and has been studied before in different countries and not with measures 

aimed at the Mexicans. The purpose of a study of this type is able to physically help the worker in 

all areas where it is involved, such as designing work spaces suitable for each person, the design 

of tools, safety equipment and personal protection clothing, and have references dimensional 

population. 

With all the technological advances that have occurred, you can have a better life, as 

studies have been developed in several areas, one of them is the anthropometry, with which they 

determine the dimensions of the human body, in this area there are some studies in developed 

countries, but very few of the Mexican population. Hence the interest start recording 

anthropometric data, thinking about making a contribution to the creation of anthropometric cards 

to this population. The creation of these cards is essential to have a population register, in order 

to make designs of stations, the design of tools and equipment, etc.., Always trying the user is 

comfortable and without risk of injury by position not normal. This is important to understand their 

measurement and to determine the field of development or dimensional capabilities that people 

have. For this reason the study will focus to working anthropometric cards of population of H. 

Caborca, Sonora, and this is an important input to record anthropometric measurements of the 

Mexican population. 

Throughout history, many investigations that have been developed in the area of 

anthropometry. In more current times these investigations have risen to be an important support 

for ergonomics, this is the case: 

Annis (1996) did an analysis of anthropometric changes the size and body shapes as they 

get older people, to see the implications of these changes in the dimensions of workspaces. 

Gosseens (1998) studied the dimensions of the seats of five different types of civil aircraft. 

The results were compared with existing standards and biomechanical criteria. It was evident that 

these seats failed to meet requirements of depth, slope, height of lumbar support and armrests. 

Therefore, none of these seats allow the pilot was in a comfortable sitting posture. In comparison 

with aviation standards, the anthropometric dimensions were not satisfactory. 

Panagiotopoulou (2003) developed a study for the purpose of comparing the size of 

primary school students, with the dimensions of the desks, to determine if the dimensions of the 

furniture is well designed and see if they promote good posture sitting considering the dimensions 

of children. 

Jung (2005) developed a prototype of an adjustable chair for educational institutions, where 

they assess their suitability according to international standards. His research began with simple 

mechanisms for adjusting the height of chair legs and backrest height and seat depth. 

In Mexico, these investigations have increased due to the recommendations made in the 

Federal Regulation on Safety, Hygiene and Environment Working in Article 102 and as SEMAC 

associations (Society of ergonomic Mexicana AC), which organizes conferences in presented 

research papers such as: 

Ergonomic design for computer work stations, presented by Martinez (2000). 

Implementation of an ergonomic process for the industry for control musculoskeletal 

injuries, presented by Sánchez (2002). 

Research and Ergonomics in Mexico, presented by de la Vega (2004). 



In developing this work is clearly important that represents the human resources within an 

organization, since this depends on the effectiveness of the production process. Therefore, the 

objective of the development of this research is the creation of letters of the anthropometric 

measurements of the working population of the City of Caborca, by age group, sex and place of 

origin. 

Obtaining anthropometric cards may be made designs for the population, helping 

businesses and people in general. Currently there are very few reliable records of the 

anthropometric dimensions of these people, so it is taken as the measures of other countries 

where physique is different and the conditions too. 

When designing industrial products is important to provide who are the users to succeed in 

the product, taking into account different body sizes, safety and human comfort, it is here that 

involves anthropometry (Reeder 2003). 

Hence the great importance of anthropometric data to researchers from the human factor, 

for practical use with these, such as would be the design of clothing, tools, to provide statistical 

guidelines for product design and build models biomechanical. (Park, Kim 1997). 

According Cavassa (2004) there are two types of anthropometrics: anthropometry static or 

structural, which refers to the dimensions in which the body is in static state, for example, height, 

weight, etc. 

The other type is the dynamic anthropometry: it refers to taking action where the body is 

operating, for example stretching one arm to reach something. 

At the time of wanting to design, there are some factors that influence the anatomical 

structure of the human body are: age (until maturity), sex (male, female), race, occupation, 

clothing (especially in cold weather ) and even the time of day (in the morning the people are 

measuring 6 mm more, because the spinal discs are not compressed (Konz 1999). 

When will develop designs for a group of people is important to take into account some 

principles such as: 

1. Design principle to extremes: this design takes the maximum and minimum value of the 

characteristics of user populations. 

2. Adjustable design principle: it is used for facilities and equipment that can be adapted to various 

individuals. 

3. Design principle for the average: this approach is less expensive but less used, since it is 

difficult to get the design that fits 50% of the population (Niebel 2001) 

The anthropometric cards is to develop a record of human body stockings for people to 

have a higher confidence level to develop a design such as a workstation, machinery, equipment, 

clothing, etc. such is the case study by Mohammad (2005) which record some measures of hand. 

There are an infinite number of steps you can take the human body as recommended by the 

manual of procedures (Secretariat 2002). For the case study of this work, selected 50 of them, 

according to the definitions used in similar anthropometric examinations conducted by the 

National Aeronautics and Space Administration (NASA 1978). 

2. MATERIALS AND METHODS 

For the development of the research team used the following: 

• three anthropometer model 01140, 01290 and 01291 marks Lafayette. 

• One stadimeter marks Seca. 

• One analog scale marks Seca. 



• Two measuring tape marks Powerlock Stanley. 

• Two flexible tapes. 

• Two calibrators marks Chicago Brand. 

• Two chairs designed with a height adjustment system. 

• One calibrated cone diameter grip. 

• One computer for recording information. 

The methodology for taking the measures was as follows: 

It had a special area for training and standardization process of the four assistants in order to 

achieve uniformity in the way of measuring. 

The measurements were conducted in a private room and quiet, being present only the 

individual, the analyst and an assistant. 

People who were measured were treated with respect and care, trying to earn their trust. 

Before the measurement was given a brief explanation of the steps, procedures and 

requirements for measurement. 

Was prepared and calibrated all equipment necessary to make anthropometric measurements, 

ensuring that all necessary materials are available. 

To begin with the taking of measures, the person must wear few clothes, nothing in the head 

or feet, the surface of the floor, seat or platform must be flat, horizontal and non-compressible, 

measure the right side of the person. At the time of the measures breathing should be light. 

The 50 measures that were recorded for each person are: 

Code Name of the measure 

N920 Weight 

N805 Stature 

N328 Standing eye height to 

N23 Standing shoulder height 

N309 The standing elbow height 

N949 Standing waist height 

N398 Height standing gluteus 

N973 Standing tall on the wrist 

N265 Standing height to the middle finger 

N797 Width arms outstretched 

N798 Width at center chest elbows 

N80 Arm length from the wall 

N752 Distance from wall to the center of the fist 

N122 Standing shoulder width 

N223 Standing chest width 

N457 Standing Hip Width 

N639 Standing neck circumference 

N230 Standing chest circumference 

N931 Waist circumference stands 

N178 Standing hip circumference 

N430 Head circumference 

N144 Distance from ear to ear on the head 

N165 Face width to the height of the pins 

N427 Head width 

N595 Height of the chin to the top of head 

N441 Head length 

N420 Length of hand 



N656 Length of the palm 

N411 Width of palm 

N402 Grip diameter 

N758 Seat height sitting at the head 

N330 Seat height sitting in the eye 

N25 Seat height sitting shoulder 

N312 Seat height to seated elbow to 90 

N856 Sitting thigh-high 

N914 Seat height to the middle finger sitting 

N912 Height to the center of the cuff arms up 

N2FGM Height of sitting down 

N4FGM Seat height from floor to sit 

N200 Back of the knee to the back of chair 

N194 Length from knee to back of chair 

N678 Height from floor to knee back 

N529 Height from floor to knee 

N381 Length from elbow to middle finger 

N507 Back Width arms outstretched in front 

N459 Seated hip width 

N859 Width thighs with knees together 

N775 Leg length 

N777 Foot width 

N776 High instep 

Was measured at 200 and will be an analysis of data from the 200 people using the 

spreadsheet Excel, the result will reflect the percentiles 5%, 50% and 95%, the maximum and 

minimum of each measurements. 

3. ANALYSIS OF RESULTS 

The results of research carried out in each of the measurements are shown in the tables or charts 

anthropometric working population of Caborca, Sonora, as follows: 

Table 1 shows the total data by age group and sex in years, in tables 2, 3, 4, 5, 6, 7 and 8 

shows the results of the analysis of the 50 measures anthropometric research by age, sex and 

place of origin. 

The tables show the calculation of the percentiles 5, 50 and 95%, and the maximum and 

minimum measurements. The calculations were analyzed in the Excel spreadsheet. The weight 

calculation is given in kilograms, the other measures are in centimeters. 

Table 1 Distribution of data by age group and sex. 

SEX 

AGE MEN WOMEN TOTALS 

18-20 69 24 93 

21-23 49 26 75 

24-27 24 8 32 

TOTALS 142 58 200 



Table 2 Results of analysis of measures for the age ranges of 18-20 years. 

Percentile 

Code Name of the measure 5% 50% 95% MIN MAX 

N920 Weight 48.6 68 93.4 40 105 

N805 Stature 156.8 170.5 183.4 151.1 194 

N328 Standing eye height to 145.3 160.2 173.6 140.5 182.4 

N23 Standing shoulder height 130.6 142.8 153.3 126 167.5 

N309 The standing elbow height 98.8 108.2 117.3 95.6 129.2 

N949 Standing waist height 93.6 102.5 110.4 92 121.7 

N398 Height standing gluteus 68.1 74 86.1 62 96.4 

N973 Standing tall on the wrist 75.4 83.6 90.3 71 105 

N265 Standing height to the middle finger 59.1 64.9 71.1 56 78.1 

N797 Width arms outstretched 156.6 175.1 187.2 150.7 200.7 

N798 Width at center chest elbows 79.3 91.5 97.2 68.3 99.4 

N80 Arm length from the wall 76.9 89.3 115 68.5 118 

N752 Distance from wall to the center of the fist 66.5 75.7 106.5 64.8 111 

N122 Standing shoulder width 37 43.3 48.1 34.5 54 

N223 Standing chest width 26.4 30.4 35 24.3 38.4 

N457 Standing Hip Width 31 35.4 39.8 30.3 46.7 

N639 Standing neck circumference 31.3 37 41.6 29.7 44 

N230 Standing chest circumference 81 94.5 110.2 77 117 

N931 Waist circumference stands 67.1 85 105.2 64.5 115.2 

N178 Standing hip circumference 90.3 102 117.9 84.7 127 

N430 Head circumference 54 57 60.5 52.5 98.4 

N144 Distance from ear to ear on the head 34.5 37 39.8 32.3 55 

N165 Face width to the height of the pins 12.9 14.4 15.7 11.7 15.9 

N427 Head width 14.5 15.5 16.9 12 17.9 

N595 Height of the chin to the top of head 20 23 25.2 18.5 25.7 

N441 Head length 17.5 19 20.3 16.4 20.9 

N420 Length of hand 16.4 18.5 19.8 16.1 21.2 

N656 Length of the palm 9.4 10.6 11.4 9.2 12.3 

N411 Width of palm 7.3 8.4 9.3 6.9 9.8 

N402 Grip diameter 4.2 4.8 5.6 3.5 6.5 

N758 Seat height sitting at the head 82 88.8 95.5 79 100.5 

N330 Seat height sitting in the eye 71.5 78 84.2 64.6 90.2 

N25 Seat height sitting shoulder 57 61.5 66.6 54.3 68.5 

N312 Seat height to seated elbow to 90 22 26 29 19.4 38 

N856 Sitting thigh-high 13.5 16 18.8 12 21 

N914 Seat height to the middle finger sitting 119.5 132.3 145.7 114 148.5 

N912 Height to the center of the cuff arms up 110.2 121.3 133.7 104.2 136.3 

N2FGM Height of sitting down 121.9 130 139.2 115.5 143.4 

N4FGM Seat height from floor to sit 37.8 42 45.6 36 47.2 

N200 Back of the knee to the back of chair 41 45.4 51 39.1 56.7 

N194 Length from knee to back of chair 53.2 59.2 66.5 48.4 72.3 

N678 Height from floor to knee back 37 42.3 45.4 33.5 49 

N529 Height from floor to knee 48.4 54.3 58.9 30.4 64.2 

N381 Length from elbow to middle finger 42.3 48 51.5 41.1 53 

N507 Back Width arms outstretched in front 37.2 42 46.9 32.7 49.9 

N459 Seated hip width 35.5 39.1 46.2 32 49.3 

N859 Width thighs with knees together 29.8 33.3 40 26.1 49.8 



N775 Leg length 22.8 26 28.5 21.6 30.4 

N777 Foot width 8.6 9.7 10.7 8 11.2 

N776 High instep 6.2 8.3 10 5 12.3 


Percentile 


N920 Weight 51.7 68 106.3 47 132 

N805 Stature 153.5 168 181.3 148 184 

N328 Standing eye height to 142.2 157.5 169.8 138 174.2 

N23 Standing shoulder height 128 140.6 152 126 185.5 

N309 The standing elbow height 97 106.3 116.2 90.8 123.8 

N949 Standing waist height 93 100 111.3 91 116 


N973 Standing tall on the wrist 73.6 82 92.2 69 95.3 

N265 Standing height to the middle finger 56.9 65 72.4 55 75.8 

N797 Width arms outstretched 153.7 172 186.3 152 189.6 

N798 Width at center chest elbows 77.9 89.2 95.6 64 98.2 

N80 Arm length from the wall 77.5 98 115.7 73.3 128.7 

N752 Distance from wall to the center of the fist 68 92 105.4 61.7 112 

N122 Standing shoulder width 37.4 42.8 48.3 35.5 51.1 

N223 Standing chest width 27.1 30.2 35.9 25.5 40 

N457 Standing Hip Width 32.4 35.7 43.2 30.5 45.2 

N639 Standing neck circumference 31 36.9 41.7 29.5 46 

N230 Standing chest circumference 85.9 96 118.2 83 124.5 

N931 Waist circumference stands 70 85 115.3 56 125.4 

N178 Standing hip circumference 93.9 104 125.7 91 135.5 

N430 Head circumference 54 56.8 59.2 53.5 61 

N144 Distance from ear to ear on the head 34 37 39.6 33.5 41 

N165 Face width to the height of the pins 12.9 14 15.8 12 16.7 

N427 Head width 14.1 15.5 16.5 12 16.8 

N595 Height of the chin to the top of head 19.5 22.2 24.8 19 25.8 

N441 Head length 17.4 18.9 20.5 17 24.6 



N411 Width of palm 7.2 8.4 9.3 6.5 9.5 

N402 Grip diameter 4 4.7 5.4 3.4 5.6 

N758 Seat height sitting at the head 80.6 88 93.8 79 95 

N330 Seat height sitting in the eye 70.9 77.2 82.4 66.7 84 

N25 Seat height sitting shoulder 56 60.9 70.3 53.5 83 

N312 Seat height to seated elbow to 90 22 26 30.7 19.2 39 

N856 Sitting thigh-high 13.1 16 19.9 12 21.5 

N914 Seat height to the middle finger sitting 118.3 132.2 141 113.4 145 

N912 Height to the center of the cuff arms up 110 122.4 129.8 103.3 140.5 

N2FGM Height of sitting down 119 130 137 115.4 140 

N4FGM Seat height from floor to sit 37.3 41 45 36 46.5 

N200 Back of the knee to the back of chair 40.1 46 50.1 39.7 55 

N194 Length from knee to back of chair 52.7 59 64.4 51 70.5 

N678 Height from floor to knee back 36.6 42 46 35.5 50.9 



N529 Height from floor to knee 47.3 54 58.6 43.4 65.5 

N381 Length from elbow to middle finger 40.9 46.6 51 40 54 

N507 Back Width arms outstretched in front 36.7 41.6 46.1 34 47.7 

N459 Seated hip width 35.5 39 46 29 54.7 

N859 Width thighs with knees together 30 33.5 40.2 28.4 46.8 

N775 Leg length 22.7 25.5 27.8 22 28.6 

N777 Foot width 8.4 9.8 11 8 12 

N776 High instep 5.9 8 9.2 5 10.5 


Percentile 


N920 Weight 57.6 74.5 108.4 50 138 

N805 Stature 158.9 171 183.3 156 187 

N328 Standing eye height to 147.3 161 169.7 132 177.6 

N23 Standing shoulder height 132 142.5 153.8 131 159.3 

N309 The standing elbow height 102.3 107.5 117.5 100.5 119 

N949 Standing waist height 91.3 101 109 85 113 

N398 Height standing gluteus 65 73 80.7 62 89 

N973 Standing tall on the wrist 76.1 81 92.2 68.5 92.8 

N265 Standing height to the middle finger 59.8 65.1 72.9 58.5 74 

N797 Width arms outstretched 160 174 188.2 155 193 

N798 Width at center chest elbows 85 91 96.3 83 99 

N80 Arm length from the wall 81.3 95.2 116.3 77 122.5 

N752 Distance from wall to the center of the fist 62.8 87.2 106.7 60 107 

N122 Standing shoulder width 38 44.7 49.5 36.2 52.9 

N223 Standing chest width 27.6 32 37.3 26.2 41.4 

N457 Standing Hip Width 31.6 36 44.2 31.5 76.5 

N639 Standing neck circumference 32.6 38 44 31 44.8 

N230 Standing chest circumference 86.6 98.4 117.5 85.5 150 

N931 Waist circumference stands 74.8 90 120 70 151.8 

N178 Standing hip circumference 94.6 107.2 122.9 93 149.5 

N430 Head circumference 54.8 57.5 60 54 60 

N144 Distance from ear to ear on the head 34.6 36.8 40 34 40 


N427 Head width 14.4 15.3 16.7 12.4 17 

N595 Height of the chin to the top of head 20.9 23 27.1 20 29 

N441 Head length 17 19 20.2 16 20.6 

N420 Length of hand 17 18.6 20 17 20.1 

N656 Length of the palm 9.6 10.7 11.3 9.5 22 

N411 Width of palm 7.3 8.7 9.1 7 9.3 


N758 Seat height sitting at the head 84.3 88.2 93.2 83 98 

N330 Seat height sitting in the eye 72.9 77.1 83 70 84.5 

N25 Seat height sitting shoulder 58 61 68.1 57 83 

N312 Seat height to seated elbow to 90 21.8 27.2 29.8 21 32 

N856 Sitting thigh-high 13.7 16.3 18.9 13 20 

N914 Seat height to the middle finger sitting 122.4 131.8 140.8 117.4 150 

N912 Height to the center of the cuff arms up 111.7 122 129.7 109.4 138 



N2FGM Height of sitting down 123.6 130 137.8 121.5 139 

N4FGM Seat height from floor to sit 37.6 41.8 46.2 37 47 

N200 Back of the knee to the back of chair 41.4 45.3 49.1 40 53.5 

N194 Length from knee to back of chair 55.4 58.2 65 53 67.2 

N678 Height from floor to knee back 37.8 42.7 46.3 36 48.5 

N529 Height from floor to knee 50.4 55.3 61 49.5 63.2 

N381 Length from elbow to middle finger 43.6 47 49.5 41 50.3 

N507 Back Width arms outstretched in front 37.2 43 47.8 35 49.7 


N859 Width thighs with knees together 29.3 34.6 43.8 27.5 52.6 

N775 Leg length 23.1 26 28.3 23 30 

N777 Foot width 9 9.7 11 8.7 11 

N776 High instep 6.1 8 10 6 10 

Table 5 Results of analysis of measures for female. 

Percentile 


N920 Weight 46.9 57.5 95 40 138 

N805 Stature 151 160 172 148 172.8 


N23 Standing shoulder height 126.9 133 142.4 126 147 

N309 The standing elbow height 96.8 102.9 109.9 94 114 

N949 Standing waist height 92.6 98.5 106.5 85 109 

N398 Height standing gluteus 66.3 72.4 80.1 61.5 82.7 

N973 Standing tall on the wrist 73 79.4 85.8 71 87 

N265 Standing height to the middle finger 56.4 62.1 68.1 56 69.9 

N797 Width arms outstretched 152.4 160.4 176.5 150.7 177 

N798 Width at center chest elbows 73.9 83.5 89.6 64 93.7 

N80 Arm length from the wall 75.5 81.8 106.5 73.3 114 

N752 Distance from wall to the center of the fist 64.7 71.7 98.9 61.7 104.5 


N223 Standing chest width 26 29 35.4 24.3 41.4 

N457 Standing Hip Width 32.6 35.6 45 30.3 46.7 

N639 Standing neck circumference 30 33 38.2 29.5 44.8 

N230 Standing chest circumference 82.8 92.5 118.5 79.8 150 

N931 Waist circumference stands 66 77.5 112.2 64.5 151.8 

N178 Standing hip circumference 92.7 99.2 127.2 84.7 149.5 

N430 Head circumference 53.5 56 58.2 53 98.4 

N144 Distance from ear to ear on the head 33.9 36 38.7 33 39 


N427 Head width 14.2 15.1 16.2 12 17.9 

N595 Height of the chin to the top of head 19 22 24.2 18.5 29 

N441 Head length 17.1 18.5 20 16.4 20.3 


N656 Length of the palm 9 9.7 11.2 7.8 19.2 

N411 Width of palm 7 7.5 8.5 6.5 9.3 

N402 Grip diameter 3.9 4.5 5 3.5 5.6 

N758 Seat height sitting at the head 79.5 85 89.4 79 93 

N330 Seat height sitting in the eye 69.8 74.1 78.3 66.3 81.7 



N25 Seat height sitting shoulder 55.8 59 63.5 53.5 69 

N312 Seat height to seated elbow to 90 22 26.6 29.6 20.5 39 

N856 Sitting thigh-high 12.6 15.2 18.7 12 21.5 

N914 Seat height to the middle finger sitting 114.9 123.7 133.1 113.4 135 

N912 Height to the center of the cuff arms up 108 115 122.5 103.3 127.7 

N2FGM Height of sitting down 117 124.8 131.1 115.4 134.1 

N4FGM Seat height from floor to sit 37 39.2 44 36 45.1 

N200 Back of the knee to the back of chair 40 44 49 39.1 49.2 

N194 Length from knee to back of chair 51 56.9 61.4 48.4 65.4 

N678 Height from floor to knee back 36 38.9 43.1 35.5 44 

N529 Height from floor to knee 46.6 51.1 55.3 30.4 56 

N381 Length from elbow to middle finger 40.7 44 47 40 49.1 

N507 Back Width arms outstretched in front 35.5 39.9 43.6 33 48.6 

N459 Seated hip width 35.1 39 49.2 32.7 56.4 

N859 Width thighs with knees together 30 33.7 42.8 28.5 52.6 

N775 Leg length 22 23.8 25.1 21.6 27.2 

N777 Foot width 8.1 9 10 8 10.3 

N776 High instep 6 7.7 9 5 9.7 

Table 6 Results of analysis of measures for male. 

Percentile 


N920 Weight 57.1 73 100.9 49 132 

N805 Stature 163 172 183.8 156.7 194 

N328 Standing eye height to 151 161.5 174 132 182.4 


N309 The standing elbow height 102 109.7 118 90.8 129.2 

N949 Standing waist height 94.1 103 111.4 91 121.7 

N398 Height standing gluteus 65 74.7 88.6 59 106.8 

N973 Standing tall on the wrist 76 84 92.5 68.5 105 

N265 Standing height to the middle finger 59 66 73.4 55 78.1 

N797 Width arms outstretched 166 177.4 189.2 160.5 200.7 


N80 Arm length from the wall 84.2 93 116.6 68.5 128.7 

N752 Distance from wall to the center of the fist 72 79.8 107 60 112 


N223 Standing chest width 28 31 36.4 25.7 40 


N639 Standing neck circumference 34 37.9 42.5 32.8 46 

N230 Standing chest circumference 85.1 96.5 116.3 77 124.4 

N931 Waist circumference stands 73.1 87 111.4 56 126 

N178 Standing hip circumference 94 104 117.8 87 135.5 

N430 Head circumference 54 57 60 52.5 86.5 

N144 Distance from ear to ear on the head 34.5 37 40 32.3 55 

N165 Face width to the height of the pins 13 14.5 16 12.5 16.7 

N427 Head width 14.5 15.6 16.6 12.4 17.7 

N595 Height of the chin to the top of head 20.5 23 25.4 18.9 28.8 

N441 Head length 17.5 19 20.6 16 24.6 

N420 Length of hand 17.4 18.8 20 17 21.2 

N656 Length of the palm 10 10.7 11.4 9.5 22 



N411 Width of palm 7.9 8.7 9.3 7.5 9.8 


N758 Seat height sitting at the head 84 89.6 95.1 81 100.5 

N330 Seat height sitting in the eye 73 79 84 64.6 90.2 

N25 Seat height sitting shoulder 58 62 67.5 56 83 

N312 Seat height to seated elbow to 90 22 26 29.5 19.2 32 

N856 Sitting thigh-high 14 16.4 19.4 12.4 21 

N914 Seat height to the middle finger sitting 127.2 134.3 145 119 150 

N912 Height to the center of the cuff arms up 117 124 134 111.5 140.5 

N2FGM Height of sitting down 123.6 131.5 139 120.4 143.4 

N4FGM Seat height from floor to sit 38.5 42.3 46 36.5 47.2 

N200 Back of the knee to the back of chair 42 46 51.2 40 56.7 

N194 Length from knee to back of chair 55.7 60 66 52 72.3 

N678 Height from floor to knee back 39.2 43 46.7 33.5 50.9 


N381 Length from elbow to middle finger 45 48 51.5 41.6 54 

N507 Back Width arms outstretched in front 38.4 43 47.2 32.7 49.9 

N459 Seated hip width 35.7 39.2 46 29 54.7 


N775 Leg length 24.7 26.4 28.6 24 30.4 

N777 Foot width 9 10 11 8.5 12 

N776 High instep 6 8.3 10 5 12.3 

Table 7 Results of analysis of measures for Caborca people 

Percentile 


N920 Weight 50 69 100.9 40 138 

N805 Stature 155.1 169.1 183 148 194 



N309 The standing elbow height 98 107.1 117.4 90.8 129.2 

N949 Standing waist height 93 101.5 110.5 85 121.7 


N973 Standing tall on the wrist 75 82.5 92 68.5 105 

N265 Standing height to the middle finger 58 64.9 72.6 55 78.1 

N797 Width arms outstretched 155.1 174 187.6 150.7 200.7 

N798 Width at center chest elbows 79 90.2 97.3 64 99.4 

N80 Arm length from the wall 77.3 91.3 115.2 68.5 128.7 

N752 Distance from wall to the center of the fist 66.2 78.9 106.7 60 112 


N223 Standing chest width 26.8 30.7 36.8 24.3 41.4 


N639 Standing neck circumference 31 37 42 29.5 46 

N230 Standing chest circumference 84 95.9 117 77 150 

N931 Waist circumference stands 68.1 85.2 112 56 151.8 

N178 Standing hip circumference 93 103.3 121 84.7 149.5 

N430 Head circumference 54 57 60 52.5 98.4 

N144 Distance from ear to ear on the head 34 37 40 32.3 55 


N427 Head width 14.5 15.4 16.6 12 17.9 

N595 Height of the chin to the top of head 19.6 22.8 25.4 18.5 29 



N441 Head length 17.3 19 20.4 16 24.6 


N656 Length of the palm 9.3 10.5 11.4 7.8 22 

N411 Width of palm 7.2 8.5 9.3 6.5 9.8 


N758 Seat height sitting at the head 82 88.3 95 79 100.5 

N330 Seat height sitting in the eye 71 77.4 83.7 64.6 90.2 

N25 Seat height sitting shoulder 56.8 61 67.3 54.3 83 

N312 Seat height to seated elbow to 90 22 26.3 29.5 19.2 39 

N856 Sitting thigh-high 13.1 16 19.4 12 21.5 

N914 Seat height to the middle finger sitting 119 132 142.4 113.4 150 

N912 Height to the center of the cuff arms up 110 121.8 131.9 103.3 140.5 

N2FGM Height of sitting down 121 130 138.9 115.4 143.4 

N4FGM Seat height from floor to sit 37.6 41.6 46 36 47.2 

N200 Back of the knee to the back of chair 40.5 45.3 51 39.1 56.7 

N194 Length from knee to back of chair 53 59 65.5 48.4 72.3 

N678 Height from floor to knee back 36.7 42.1 46 33.5 50.9 


N381 Length from elbow to middle finger 42 47 51.4 40 54 

N507 Back Width arms outstretched in front 37 42 47.1 32.7 49.9 



N775 Leg length 22.9 25.9 28.4 21.6 30.4 

N777 Foot width 8.5 9.8 11 8 12 

N776 High instep 6 8 10 5 12.3 

Table 8 Results of analysis of measures for Caborca not native people. 

Percentile 


N920 Weight 50.3 68.0 89.7 46.0 105.0 

N805 Stature 154.2 171.7 180.2 150.6 184.2 

N328 Standing eye height to 144.3 161.0 170.8 143.0 175.0 

N23 Standing shoulder height 128.6 144.2 152.5 128.1 155.0 

N309 The standing elbow height 97.3 111.5 114.5 97.0 117.0 

N949 Standing waist height 92.6 101.8 111.5 92.4 114.0 

N398 Height standing gluteus 66.9 73.1 83.2 61.5 84.0 

N973 Standing tall on the wrist 75.0 84.7 89.2 73.0 90.0 

N265 Standing height to the middle finger 58.1 65.4 70.6 58.0 71.0 

N797 Width arms outstretched 153.7 174.3 186.2 152.0 187.0 


N80 Arm length from the wall 76.0 92.7 116.2 73.3 117.0 

N752 Distance from wall to the center of the fist 66.2 78.3 105.3 63.1 107.0 


N223 Standing chest width 27.0 29.9 35.2 26.6 36.4 


N639 Standing neck circumference 31.9 36.5 39.8 31.0 44.0 

N230 Standing chest circumference 86.6 95.0 113.6 84.0 117.0 

N931 Waist circumference stands 73.8 85.2 109.1 70.0 115.2 

N178 Standing hip circumference 94.4 101.8 112.9 91.0 117.8 



N430 Head circumference 53.9 56.0 57.7 53.5 59.0 

N144 Distance from ear to ear on the head 33.9 36.0 39.2 33.5 40.0 


N427 Head width 14.2 15.7 16.6 14.0 17.3 

N595 Height of the chin to the top of head 19.9 23.0 25.0 19.4 25.3 

N441 Head length 17.3 18.2 19.1 17.0 19.2 



N411 Width of palm 7.4 8.5 9.3 7.3 9.3 


N758 Seat height sitting at the head 82.0 89.0 92.7 79.0 95.2 

N330 Seat height sitting in the eye 72.7 78.5 82.1 69.0 82.6 

N25 Seat height sitting shoulder 57.3 61.7 68.6 53.5 83.0 

N312 Seat height to seated elbow to 90 22.2 25.5 28.7 22.0 29.6 

N856 Sitting thigh-high 14.2 16.2 18.3 13.7 19.8 

N914 Seat height to the middle finger sitting 119.5 132.6 141.0 116.6 146.5 

N912 Height to the center of the cuff arms up 112.9 122.8 130.1 107.8 136.3 

N2FGM Height of sitting down 120.5 130.0 137.7 117.5 141.4 

N4FGM Seat height from floor to sit 37.1 41.0 45.3 36.5 45.3 

N200 Back of the knee to the back of chair 41.9 46.1 49.0 41.0 49.2 

N194 Length from knee to back of chair 54.3 60.9 63.2 52.5 64.0 

N678 Height from floor to knee back 36.9 41.9 45.0 36.6 45.0 


N381 Length from elbow to middle finger 41.5 46.5 49.7 40.7 50.6 

N507 Back Width arms outstretched in front 36.9 42.9 45.1 36.1 45.3 

N459 Seated hip width 36.9 38.2 45.2 36.6 46.2 


N775 Leg length 22.5 25.7 28.0 21.8 28.3 

N777 Foot width 8.4 9.8 10.7 8.3 11.0 

N776 High instep 6.9 8.1 9.4 6.3 9.9 

4. CONCLUSIONS AND RECOMMENDATIONS 

Working conditions are an important issue, so it should be taken into account when 

designing a workspace, thereby, the worker will feel more comfortable and secure and will result 

in higher productivity, lower absenteeism, fewer accidents, lower turnover, etc. To achieve this it is 

necessary to design each station or place of work according to the needs of the population that 

will occupy this space, this implies knowing the dimensions of the population, if not known, it can 

hardly meet the target, however when known, can have an assurance that the highest percentage 

of people who use the work area, will have no problems in terms of size and awkward postures. 

By creating a product would be recommended to be used without problem by the largest 

number of users. The reality is that many products do not have the ability to adapt to 100% of 

users. For this you can follow two paths, the first would make products of various sizes in such a 

way that takes the opportunity to choose the one that best suits the needs of the user, the other 

would be to create products that are adjustable over a range measures, making it necessary to 

know the cost-benefits so that decision making is correct. The selection of some of the 

alternatives mentioned above would be facilitated if known anthropometric dimensions of the 

population that is expected to address. From the above highlights the importance of the results of 

this research. 



From this research were obtained anthropometric records or letters of the working 

population of the city of Caborca, Sonora, Mexico, in the age ranges from 18 to 20, 21 to 23 and 

24 to 27 years, and the letter Anthropometric women and men, those from Caborca and not 

originating in Caborca. These letters reflect the measures of the population having an age range 

from 18 to 27 years, within which 71% are men and 29% are women, 91% are from Caborca and 

9% do not originate in Caborca. 

It is hoped that this research is another step towards the creation of anthropometric letters 

of the Mexican population, as currently there are very few records are. 

At the end of the investigation we can see the importance of the study of ergonomics 

and especially one of its branches which is the anthropometry, which is responsible for examining 

each of the different measures that make up the human body. Knowing these measures can be 

designed with a higher degree of reliability workstations, tools and equipment, safety equipment, 

clothing, etc. so we can give each user a more convenient and comfortable life. 

The recommendations can be made once this investigation is that it would be very 

interesting and important to continue to obtain anthropometric records of the total Mexican 

population, in order to develop equipment, workstations, tools and equipment as well as 

everything that needs dimensions of people, especially for the Mexican people and not have to 

take the actions of other countries and make adjustments later. 

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Biomechanical model to estimate recovery time on highly repetitive work in 

maquila operations 

Fco. Octavio López Millán 1 , Enrique Javier de la Vega Bustillos 1 , 

Manuel Arnoldo Rodríguez Medina 2 , Armando Ayala Corona 3 

1 Departamento de Ingeniería Industrial. 

Instituto Tecnológico de Hermosillo. Ave. Tecnológico S.N. 

Hermosillo, Sonora, Mx. 83170 

Author’s e-mail: lopezoctavio@yahoo.com.mx 


Instituto Tecnológico de Cd. Juárez. Ave. Tecnológico 1340 

Cd. JuárezChih, Sonora, Mx. 32500 

3 Departamento de Ingeniería Industrial y de Sistemas 

Universidad del Valle de México. Blvd. Enrique Mazón No. 617. 


Resumen: El propósito de este trabajo es desarrollar un modelo biomecánico que permita hacer 

estimaciones de los tiempos de recuperación, basado en un número importante de variables 

obtenidas de condiciones de trabajo reales, donde, el mismo grupo de músculos está expuestoal 

trabajo repetitivo y a bajos esfuerzos. Las variables independientes están relacionadas con las 

características de los trabajadores y del trabajo. Las variables de respuesta son el tiempo de 

recuperación y la fatiga percibida. Los datos se obtuvieron de industrias maquiladoras del 

noroeste de México. 

Palabras clave: Modelo biomecánico, trabajo repetitivo, maquiladora 

Abstract: The purpose of this research is development a biomechanical model allowing 

estimating the recovery time based on an important number of variables, obtained from real work 

conditions, where the same muscle group is exposed to repetitive work and low efforts. 

Independent variables are related to personal characteristics and work characteristics. Response 

variable are recovery time and perceived fatigue. Data were obtained from workers and work 

stations from Maquila industries in northwest Mexico. The research is based on considerations 

about anthropometrics from a Mexican population, genre and hour of work. 

Keywords: Biomechanical modeling, repetitive work, cumulative effect of force, maquila 

1. Introduction. 

Assessment of human work has been a fundamental element on the ergonomics evolution, 

actually there is a wide variety of methods for the ergonomics assessment of work stations, 

however, at the moment that the ergonomist needs a tool, sometimes there is the constraint which 



results usually shows the most risky condition, in terms of a work muscle skeletal disorder, it 

means that shows a value qualifying a single moment of work, while the work remains continuous 

along the journey. 

The work doing by the hands has been a very important factor on manufacturing industries, 

especially on development countries, but the human being and its physical characteristics at 

service of material transformation trough industrial process it is not an endless power supply, 

while time pass away, physical performance could be affected and modified. 

As a result of frequent exposure to work there is a risk of musculoskeletal injuries, Bernard et al 

(1997) refers that it´s “were recognized as having occupational etiologic factors as early as the 

beginning of the 18th century. However, it was not until the 1970s that occupational factors were 

examined using epidemiologic methods, and the work-relatedness of these conditions began 

appearing regularly in the international scientific literature. Since then the literature has increased 

dramatically; more than six thousand scientific articles addressing ergonomics in the workplace 

have been published. Yet, the relationship between MSDs and work-related factors remains the 

subject of considerable debate.” 

Continuous and repetitive tasks could lead to disorders on the soft tissues on joints. The tissues 

that frequently get injured as a result of exposure to occupational biomechanical hazards are 

ligaments, tendons and muscles. Other structures affected less frequently are cartilage and 

bones. All biological tissues are visco-elastic; hence, their mechanical properties are time- and 

strain rate-dependent. The tissue visco-elastic property determines the duration required for 

complete mechanical recovery, Kumar (2001). 

Disorders on the soft tissues are well known as cumulative trauma disorders (CTD´s), it´s 

basically a combination of factors or occupational activities that leads to these injuries, Keyserling 

et al (1993) includes repetitive motions, forceful exertions, and awkward postures. Bernard et al 

(1997) presents an evaluation and summary of the epidemiologic evidence focuses on disorders 

affecting the neck and the upper extremity; including tension neck syndrome, shoulder tendinitis, 

epicondylitis, carpal tunnel syndrome, and hand-arm vibration syndrome, which have been the 

most extensivelystudied in the epidemiologic literature. Combination of these risk factors on the 

same activities increases the possibility of injuries in wrist and shoulder while neck disorders are 

related to awkward posture, for instance. 



CTD´s cost days and money so there are relevant, the BLS (2005) reports 1,234,700 workdays 

lost in USA. In the same year there were 270,890 reported injuries in low back. Bernard et al 

(1997) reports 32% of injuries were due to excessive efforts or repetitive tasks. In specific, 65% of 

cases were caused by effort to lifts objects or materials, affecting low back, 52% were caused by 

pushing or pulling. But it´s not only low back injuries, the report includes 47,681 shoulder injuries 

and 92,576 injuries associated to repetitive movements, 55% of that affected wrist. 

Muggleton et al (1999) refers to injuries related to work as typical injuries on XX century and 

consider it´s as the bigger of problems on occupational wealth. On United Kingdom, upper limb 

musculoskeletal disorders are the most frequent just below low back pain injuries. CTD external 

causes says, are related with the pressure on industry business for increasing productivity. In 

consequence, costs for; medical attention, incapacities days, lost workdays, employs rotation, 

absenteeism costs, have been increased too. 

Viikari-Juntura (1997), notes the need of programs and strategies to prevent occupational 

injurieswhile lost days increases on industrial countries, as well as development countries. The 

European Union is working on rules and laws about occupational injuries, focusing in harmonizing 

it´s legislation. 

In México, according to the IMSS (Mexican Institute for the Social Safety) in 2006 were reported 

138,700 work injuries in hand-wrist and low back area. The Mexican legislation and rules doesn´t 

make any difference between accident and occupational injuries. 

In northern México, in Border States the data are the follows: 

Table 1. Work related injuries in Nothern Mexico.. 

State Injuries Hand-wrist Low back 

Nuevo León 29054 10425 3264 

Baja California 16308 6025 2041 

Sonora 12074 3678 2127 

Tamaulipas 11823 3691 1734 

Chihuahua 1762 453 239 

Coahuila 1425 358 149 



1.1 Occupational injuries. The risk factors are related with injuries in joints and soft tissues. 

There are several terms to name it, Grieco et al (1998) defines as “Work Musculoskeletal 

Disorders; WMSD”, but frequently is used as a synonymous “Cumulative Trauma Disorders 

(CTD´s)” or “Repetitive Strain Injuries (RSI)”. Grieco et al (1998) associate as characteristics of 

these injuries the follows: Its origin is due to several factors (occupational and personal), it take 

long time to develop the disorder, recovery are used to be slow and probably never at 100%, 

frequently involves groups of tendons and muscles and that one’s caused by nerves pressed are 

de lesser frequents but the painful and costly. 

1.2 Ergonomic Risk Factors. To understand the musculoskeletal disorders problem, is required 

to identify the risk factors associated to these kinds of injuries. There is a wide literature about it 

and its don´t surprise, the problem has been studied for years and many point of views and results 

of research converge on the causes or risk factors, Colombini (1998) recognize mainly four risk 

factors; repetitive movements (frequency), force applied to the task, awkward postures and lack of 

enough recovery time on each work cycle. Muggleton (1999) includes vibration as a risk factor for 

the hand-wrist. McAtamney y Corlet (1973) refers to the risk factors as external factors, including 

a consideration for static work load on muscles. Furthermore, highly repetitive work may directly 

damage tendons through repeated stretching and elongation, as well as increase the likelihood of 

fatigue and decrease the opportunity for tissues to recover Keyserlin et al (1993). 

The focus of this project is on the repetitive effect on recovery time based on manufacturing 

activities at high level of repetition which is the most of the tasks that operators perform on 

maquila industries in basically all Northern of México. 

Is well known the wide ergonomics assessment techniques available in present, Liand Buckle 

(1999) mentioned that exposure to risks for potential work-related musculoskeletal injuries has 

been assessed using a variety of methods, including pen and paper based observation methods, 

videotaping and computer-aided analysis, direct or instrumental techniques, and various 

approaches to self-report assessment. 



The purpose of this research is develop a model to describe the effect of repetitive task and 

predict the recovery time for continuous task and includes subjective factors as perceived fatigue, 

this last factor in order to explain the presence of tape on finger tips or wrist protections. 

2. Method. 

It is very relevant to the success of this project obtain the data from real conditions, that means 

going to the assembly production lines on maquilas and get the data. The first step consists 

tochoose the work stations, video recorder it, get data: anthropometric and operational and 

perceived fatigue. 

We appreciate the support from the maquila, they let Us to see the process, mostly of it is 

confidential, for the first step 23 workstations were analyzed, the variables included are; height, 

weight, angle on shoulder (RH) to perform a sustained effort and the time on that posture. 

Additionally, a perceived fatigue questionnaire was ask to answer for, it qualifies from 0 to 3 

presences of any symptoms like numbness, pain or stiffness, were 0 means no symptom at the 

end of the work shift, 1 means seldom times remember any symptom, 2 is related to occasionally 

feels any symptom and 3 are related to frequent symptoms. For each workstation were 

considered two activities involving shoulder posture. 

On second step data were analyzed using 3D SSPP© and Rohmert formula to estimate 

recuperation time for each operator. The third step involves the linear regression analysis and the 

Bayesian approach to optimize the time recuperation model. WinBUGS is the tool for Bayesian. 

3. Results 

All collected data are at the end, summarizing, 46 data were analyzed for the 23 operators; it’s 

due to the use of two different exertion times. On each job the angle on shoulder was measured 

and every workstation was modeled using the 3D SSPP© software to obtain the moment on the 

shoulder. Moment and sustained effort time on seconds were used to introduce as data to 

Rohmert formula, the result is the recovery time for the shoulder, expressed on seconds on 

different posture, for every 60 seconds of work. 

3.1 Statistical analysis. The analysis was made using SPSS© software. In the beginning, the 

moment on shoulder was considered as a variable, it’s give an excellent correlation r = .918 with 



an adjust r = .819 which means a high explanation to the variability of the data, but moment on the 

practice is not an easy data to calculate, that´s why we optioned a less efficient model but easy to 

use and understand. 

Subtracting the moment the model summary is: 

The linear regression model obtained is shown as follows: 

Coefficients a 

Model 

UnstandardizedCoefficients 

B Std. Error Beta 

StandardizedCo 

efficients 

t Sig. 

1 (Constant) -28.025 29.563 -.948 .348 

Estatura .220 19.919 .001 .011 .991 

Peso -.115 .079 -.133 -1.454 .153 

Angulo .466 .082 .436 5.684 .000 

FatPer 1.068 1.097 .077 .974 .335 

TESF 1.208 .128 .716 9.451 .000 

a. Dependent Variable: TREC 

Expressed on the mathematical form, the model is: 

Recovery Time= -28.025 + .22*Height - .115*Weight + .466*Angle + 1.068*Perceived Fatigue 

+ 1.208*Sustained effort time 

3.2 Bayesian Analysis.The Bayesian analysis is included in order to optimize the linear 

regression model coefficients, on this approach; coefficients leave the parameter condition in the 

model becoming a variable on the model. WinBUGS is a tool developed to perform Bayesian, 

based on Markov Chain and Monte Carlo methods the software allows simulate a great number of 

repetitions. 



There are some additional considerations to made; variables fit a normal distribution. On every 

variable the software run more than 10,000 iterations. 

The linear regression model has change as follows: 

Recovery Time= -44.13+ 5.22*Height -0.1227*Weight + 0.5464*Angle -0.02*Perceived Fatigue 

+ 1.534*Sustained effort time 

The resulting model is based on the original linear regression model but coefficients become 

variables with its own statistical distribution. 

Bayesian analysis is a very useful tool when experiments are limited and especially when the data 

come from human characteristics and a cross functional approach are used on the research. 

4. Discussion 

The linear regression model optimized can now be used to estimate recovery times on repetitive 

operations but is necessary draw some limitations; to verify the accuracy of the model it was run 

with different exertion times, the model result on negative values for recovery time when the 

exertion timeis below 10 seconds and for exertion times higher than 30 seconds results are 

considerably greater that could made efficient on process get on low values, so it has and impact 

on costs. 

In test stage, when exertion times are below 10 seconds, recovery time calculated by Rohmert 

formula result on values around 2 seconds or lower, that could be interpreted like low risk 

operations due to repetitiveness and classifieds on green codes. On the other hand exertion time 

over 30 seconds results on high repetition rates having an effect on sustain effort and 

consequently on a high risk for an occurrence of occupational injuries. 

The application of the model is not complicated, the input variables are the predictors variables; 

the height is expressed on meters, the weight is in kilograms, the angle on the shoulder can be 

measured using a goniometer, perceived fatigue could be get asking to the operators for the 

presence of any symptom described before and exertion time can be measured by a chronometer 

or analyzing the video time counter. Once the data are collected, introduce it in the formula and 

the results are expressed on how many seconds per every 60 seconds cycle are needed to 

recover a group of muscles from fatigue due to the job. 

The application of the model could be extensive on a future to other groups of muscles, for 

instance low back muscles or wrist articulation, increasing the focus of the research, increasing 



the analysis of different jobs when those are repetitive. At the end the final purpose is bringing a 

little more on safety on daily performance allowing to people return home with a little bit more 

energy to share with the family. 

References 

Bernard, B. (1997). “Musculoskeletal Disorders and Workplace Factors; A Critical Review of 

Epidemiologic Evidence for Work-Related Musculoskeletal Disorders of the Neck, Upper 

Extremity, and Low Back”.Centers for Disease Control and Prevention, National Institute for 

Occupational Safety and Health (NIOSH). 

Bureau of Labor Statistics (2007).“Injuries, Illnesses, and Fatalities (IIF) program”.www.bls.gov. 

Colombini, D. (1998) 'An observational method for classifying exposure to repetitive movements 

of the upper limbs', Ergonomics, 41:9, 1261 – 1289. 

Grieco, A. (1998). “Application of the concise exposure index (OCRA) to tasks involving repetitive 

movements of the upper limbs in a variety of manufacturing industries: preliminary validations”, 

Ergonomics, 41:9, 1347 - 1356 

Instituto Mexicano del Seguro Social, (2006). “Información estadística en salud; accidentes de 

trabajo (1). www.imss.gob.mx 

Keyserling, W. M., Stetson, D. S., Silverstein, B. A. and Brouwer, M. L. (1993) “A checklist for 

evaluating ergonomic risk factors associated with upper extremity cumulative trauma disorders”, 

Ergonomics, 36:7, 807 – 831. 

Kumar, Shrawan (2001) 'Theories of musculoskeletal injury causation', Ergonomics, 44:1, 17 – 

47 

Li G., Buckle P. (1999).“ Current techniques for assessing physical exposure to work-related 

musculoskeletal risks, with emphasis on posture-based methods”. Ergonomics, 42; 5, 674 – 695. 

McAtamney, L. Corlet, N., (1973).“RULA; A survey method for the investigation of work-related 

upper limb disorders”. Applied Ergonomics; 24(2), 91-99. 

Muggleton, J. M., Allen, R. and Chappell, P. H.,(1999.) “Hand and arm injuries associated with 

repetitive manual work in industry: a review of disorders, risk factors and preventive measures”, 

Ergonomics, 42:5, 714 – 739. 

Rohmert Walter (1973). “Problems in determining rest allowances”. Applied Ergonomics, 4.2 91- 

95. 



Viikari-Juntura, Eira R. A. (1997) 'The scientific basis for making guidelines and standards to 

prevent work-related musculoskeletal disorders', Ergonomics, 40:10, 1097 – 1117 

DATA 

Height Weight 

Shoulder 

Angle 

Perceived 

Fatigue 

T exer T rec 

1.62 64 60 3 15 9.84 

1.61 59 45 2 14 5.23 

1.53 61 45 0 12 3.39 

1.56 60 40 1 18 7.72 

1.61 55 40 2 17 6.53 

1.61 65 45 3 10 2.73 

1.58 61 40 3 15 5.3 

1.54 58 35 2 20 7.19 

1.60 66 55 3 15 9.51 

1.65 58 35 3 19 8.35 

1.64 67 65 2 13 8.39 

1.56 57 55 3 16 8.01 

1.58 56 60 3 21 17.25 

1.62 65 40 2 18 9.99 



1.61 67 46 2 15 1.33 

1.72 86 40 2 16 2.54 

1.62 74 40 2 14 0.91 

1.58 81 55 3 19 12.41 

1.58 54 30 3 21 6.82 

1.63 56 50 2 25 24.98 

1.62 64 60 3 21 22.05 

1.61 59 45 2 26 23.11 

1.53 61 45 0 24 17.88 

1.56 60 40 1 29 24.27 

1.61 55 40 2 27 19.82 

1.56 52 30 2 26 9.62 

1.61 65 45 3 24 35.11 

1.58 61 40 3 26 19.83 

1.54 58 35 2 29 17.54 

1.60 66 55 3 23 26.52 

1.60 53 35 2 22 9.04 

1.55 50 40 2 23 9.95 

1.65 58 35 3 27 19.4 



1.64 67 65 2 21 26.51 

1.56 57 55 3 29 33.39 

1.58 56 60 3 25 26.22 

1.62 65 40 2 28 28.84 

1.68 102 45 3 22 14.33 

1.67 77 30 3 24 2.05 

1.72 86 40 2 28 9.75 

1.52 75 39 3 22 0.86 

1.62 74 40 2 21 2.42 

1.58 81 55 3 30 37.15 



VERIFICATION OF MAXIMUM ACCEPTABLE WEIGHT OF LIFT, TABULATED IN 

LIBERTY MUTUAL TABLES, IN WOMEN OF CABORCA 

Jesús Rodolfo Guzmán Hernández 1 , Joaquín Vásquez Quiroga 1 , 

Enrique Javier De La Vega Bustillos 2 

1 Grupo disciplinar de Ergonomía, Programa de Ingeniería Industrial, 

Universidad de Sonora Unidad Regional Norte, campus Caborca. 

Caborca, Sonora, México, 

rguzman@caborca.uson.mx, jovaqui@caborca.uson.mx 

2Maestría en Sistemas Industriales 

Instituto Tecnológico de Hermosillo 

Hermosillo, Sonora, México 

en_vega@ith.mx 

RESUMEN: Esta investigación se realizo con la intención de verificar la aplicación de los datos, 

de peso máximo de levantamiento (MLW), tabulados en las Tablas Liberty mutual, en la 

población laboral femenina de Caborca, Sonora, México. El experimento se limito a tareas de 

levantamiento vertical, frecuencia de uno por minuto, cajas de 34 cm de ancho (distancia desde el 

cuerpo), distancia de movimiento 51 cm, en tres niveles de levantamiento, bajo, que corresponde 

a levantamientos entre el suelo y la altura de nudillos, medio, de altura de nudillos a altura de 

hombros y alto, de altura de hombros a brazo extendido. Ésta fue realizada con alumnas 

estudiantes del programa de Ingeniería Industrial y de Sistemas adoptando el supuesto de que 

ellas pudieran estar formando parte de la fuerza laboral de las empresas establecidas en la 

región. Como resultado de este experimento se observo que los peso máximos tabulados en la 

Tabla Liberty Mutual para tareas similares a las de este experimento, son cuantitativamente 

mayores y existe evidencia estadística suficiente para rechazar que se pueden aplicar a la 

población laboral bajo estudio. 

Palabra clave: levantamiento de carga mujeres, tareas de levantamiento mujeres, máxima 

peso aceptable 

ABSTACT: The intention of this investigation was verify the application of maximum lifting weight 

data tabulated in the Liberty Mutual Tables (MLW), on the female labor population of Caborca, 

Sonora, Mexico. The experiment was limited to vertical lifting tasks, frequency of one per minute, 

boxes of 34 cm of wide (distance since the body), distance of movement 51 cm, in three levels of 



lifting, low, that corresponds to lifting among the floor and the height of knuckles, medium, of 

height of knuckles to height of shoulders and high, of height of shoulders to arm extended. This 

investigation was done with 14 students, female gender, of the program Industrial and Systems 

Engineering, with the assumption that they could be part of the workforce of firms established in 

the region. As a result of this experiment was observed that the information of maximum 

acceptable weight tabulated in liberty mutual tables for similar tasks this experiment are 

quantitatively greater and there is sufficient statistical evidence to reject that we can apply it to 

working population under study. 

Keyword: women lifting weight, women lifting tasks, maximum acceptable weight 


Webster et al (1994) suggest that low back pain, associated with manual handling of loads, 

has been recognized as a major problem worldwide is the most costly injury in the industrial world. 

De la Vega (2006), citing The National Institute for Occupational Safety and Health (NIOSH) 1991, 

indicates the factors that directly influence the risk of lower back injuries are the weight and 

dimensions of the object, the distance is raised, lowered, pulled or pushed, and the repetition rate, 

as well as indirect factors such as age and physical condition of the worker. The consequences of 

ignoring the weight limit on the repetitive handling of loads can result in decreased performance at 

work and presents a risk of back pain that can become a cumulative trauma disorder (CTD) Putz- 

Anderson (1994). There are some studies about amount of weight that an individual is capable of 

lifting and about task design of the handling manual of loads with minimal risk of injury considering 

their characteristics and physical abilities. The reports of these studies represent guides to the 

industry which requires manually moving loads repeatedly. Among the most widely used guides 

include the NIOSH equation and the Liberty Mutual tables. The first is a tool through which, 

considering 7 factors involved in a lifting task, calculate the recommended weight limit (LPR) and, 

once known, is calculated the Lifting index that he is the ratio between the load weight and the 

recommended weight limit. The values that can take this index may fall into three risk zones, 

namely: limited risk (lifting index


3), this type of task is unacceptable from an ergonomic standpoint and should be changed. 

Moreover, the Liberty Mutual Company has developed the Liberty Mutual tables or tables of 

Snook which are a collection of tables which sets the maximum acceptable weight for help to 

control the risk of injury in the lower back in activities of manual handling of loads. In particular for 

lifting load, use the frequency of the task, the distance of movement of the load, the height at 

which the movement is placed, the size of the object and its grips and the horizontal distance 

(distance from the body) like parameters. With these parameters, the maximum acceptable weight 

it is tabulated in 10, 25, 50, 75 and 90 percentiles for male and female peoples. These studies 

and the respective conclusions were generated from the experimental data obtained of developed 

workers populations countries and the findings and their recommendations they are apply in 

Mexico without considering that data were obtained without including the characteristics and 

physical abilities of the Mexican population. 

In the Mexican Republic from 1992 to 2002 the Mexican Social Security Institute reported 

cases of 191.639 spine injuries, including back pain, accounting for 4.7% of total workplace 

injuries. Likewise, there is 42.422 dorsopatias with total disability in the period reported, including 

low back pain associated with lifting loads, representing 18.98% of total disability (Review IMSS 

2004), which indicates the relevance of the lesions of the spine. From the above, born the need to 

conduct this study which seeks to identify injury risks in applying the criteria of acceptable loads in 

the female population in Caborca, Sonora, Mexico, on grounds that it may be a cause for lower 

back pain that result of the manual materials handling, a problem that is occurring more often in 

companies. This raises the question "The maximum acceptable weight, reported by the Liberty 

Mutual tables for women, applies to women workers of Caborca? About this question the present 

investigation was made and it focuses only on tasks of vertical lift in frequency of one per minute, 

boxes width 34 cm, (distance from the body), movements 51 cm distance and three levels lifting: 

low , corresponding to uprisings between the ground and knuckle height, medium level, from 

height to knuckle to shoulder height and from shoulder height to arm's length. 

2. OBJETIVE 

The objective of this study is to identify risks in applying the criteria of maximum acceptable 

charges Liberty Mutual tabulated in Tables in the female working population Caborca, Sonora, 



Mexico, because it can be one of the causes of lower back pain , resulting from manual material 

handling, is a problem that is occurring more often in business. This led to pose the question "The 

maximum acceptable weight women, the tables set by Liberty Mutual, is applicable to workers in 

Caborca? 

3. MATERIALS AND METHODS 

Details of the experiment, from where the Liberty Mutual Tables were made, it is found in the 

publications of Ciriello et al 1983, 1990 and 1991. The experiment was conducted using 

psychophysical approach. This approach requires that the subject is motivated by an incentive, 

and He,based on the perceived sensations, select the maximum load that it considers may sustain 

for a working day of 8 hr. According to Shoaf (1997), the major hypothesis of the psychophysical 

approach is that: at a given time, adjusted to 40 minutes, a person is able to predict the maximum 

weight or force that could be manipulated during a period of 8 hr; Mital (1983) states, people can 

estimate the amount of weight that can lift comfortably in 8 hr, based on experiencing fatigue in 25 

min and, hopefully, the weight selected by the subject is the same whether the person continues 

lifting it for 8 hr; Additionally, he states: there is no literature evidence to validate this claim. 

Under these criteria, basically, the subject is given control of the weight of the load, the participant 

monitors their own sensations of fatigue and adjusts the weight which he believes could bear. All 

other variables such as task frequency, load weight, distance of movement, etc.. are controlled by 

the experimenter. The participants in this experiment were 14 young female between 19 and 22 

years, they were university-level students they could be part of the workforce in the Caborca 

region. All signed in writing that they were free of lower back injury and had no cardiovascular 

disease. They used casual clothing and tennis shoes, jeans and loose shirts. 

To all participant in the experiment and for verify that the heights and distances of 

movement of loads in lifting tasks was be according to the experiment of Snook, were taken the 

anthropometric measures of weight, height, knuckle height, acromial height and extended arm 

height. Given the limited experience of the participants in manual handling of loads were given a 

belt to help keep your lower back straight. The participants were given training equal to the 

training done it in Ciriello et al (1983) experiment, to familiarize them with the activities to 

performed and gain experience in adjusting the load, increase or decrease according to their own 



perceptions, they doing efforts themselves but without reaching a state of extreme tiredness, 

weakness, overheating or running out of breath, this, doing movements of vertically lifting , at a 

distance of 51 cm, with bending the knees and keeping your back straight, no turns or twists, 

without pull or push the load. For four consecutive days of tasks were performed lifting low (floor 

knuckle hight), increasing gradually the time. During first and second day were made a task for 10 

min with light load and heavy load respectively, the third day two tasks of 10 minutes each with 

light and heavy load respectively, without resting, the fourth day two tasks of 15 minutes with light 

load and heavy load respectively, without resting. The fifth, sixth and seventh days were for do the 

data collection. The daily tasks were made with duration of 40 minutes divided into two periods of 

20 minutes each one, without rest between periods, in the first period it gave them a heavy load 

and in the second light load, all randomly selected. 

Each day were made only the task for each level indicated for in the lifting Liberty Mutual 

tables, namely between floor level and knuckle height ( lifting low), between knuckle height and 

acromial height (lifting medium) and between airmail height and arm extended length (lifting 

height). For the experiment were used rigid polypropylene boxes with length of 55 cm (distance 

between hands), 34 cm wide (distance from the body) and 17 cm in height. The handgrips were 

located at half of the distance from the body and 15 cm from the floor of the box. The box 

contained a false bottom in which was placed a burden whose weight was randomly selected as in 

the experiment of Ciriello and Snook (1990). This hidden weight was not known by the participant 

in an attempt to minimize the visual effect. The load management was welding rods and it was 

used a balance T31P Ohaus, a decimal minute chronometer, a bell and shelves height-adjustable. 

For each level of uprising were select, at random, 14 heavy load values, between 32 and 45 kg, 

then was decreased in 3 kg each, which corresponds to the box weight, and the lid of the double 

bottom, the resulting value were divides random, to place the burden in the hidden compartment 

and the visible, subsequently the same procedure was performed for 14 light loads between 2 and 

18 kg, Snook (1990). These two procedures were repeated for each of the three levels of lifting 

the experiment. In the collection of field data were given in the first period a heavy load and the 

second period a light load., Participants adjusted the load in each period, they decreased or 

increased it according to their own perceptions until it represented the maximum they could lift in 8 

hr of task, if the load of the second period was between 15% of the first, the average of the two 



loads is registered as the maximum acceptable load of the participant, otherwise the information is 

removed and a new test was performed. 

4. RESULTS AND DISCUSSION 

According to the working hypothesis raised in this investigation, if the maximum acceptable weight 

(MAW) of Table Liberty Mutual is applicable to the female population of the Caborca region, then 

the percentile distribution of the maximum load obtained from the participants, must statistically to 

exist a matching with the distribution of the liberty mutual table percentiles. Under this approach 

was performed the analysis for low level lifting. The results of the analysis are show in Table No 1 

Table 1 Analysis of field data, low level 

From the above table it is seen that for the 10th percentile there is not sufficient evidence to 

liberty mutual tabla data Hypotesis test 

MAW Null 

standard 

percentile (Kg) hypothesis statistical test desviation t α decisión 

90 11 P0 = 0.90 p= 0.79 0.08 -1.38 0.10 No rechazar Ho 

75 14 P0 = 0.75 p= 0.36 0.12 -3.25 0.00 Rechazar Ho 

50 16 P0 = 0.50 p= 0.21 0.13 -2.23 0.02 Rechazar Ho 

25 19 P0 = 0.25 p= 0.00 0.12 -2.08 0.03 Rechazar Ho 


reject the null hypothesis. For 75, 50 and 25 percentile the significance levels of the test statistic 

permit reject the null hypothesis. The 10th percentile, has significance level to accept Ho but, is 

not feasible to accept the hypothesis that it applies the maximum load in the female working 

population Caborca because there is no real data to the percentiles 25 and 10, for what there is 

certainty to make the decision that both hypotheses may be rejected. 

For mid level lifting was performed an analysis similar to the previous data, the obtained 

information shown in Table No 2 



Table 2 Analysis of field data, medium level 

liberty mutual tabla 

data Hypotesis test 

MAW Null 

standard 


90 10 P0 = 0.90 p= 0.64 0.08 -3.25 0.00 Rechazar Ho 

75 12 P0 = 0.75 p= 0.50 0.12 -2.08 0.03 Rechazar Ho 

50 14 P0 = 0.50 p= 0.07 0.13 -3.31 0.00 Rechazar Ho 

25 16 P0 = 0.25 p=0.00 0.12 -2.08 0.03 Rechazar Ho 


In the analysis can be seen that, for the 90, 75, 50 and 25 percentiles, the levels of significance of 

the test statistic are able to reject the null hypothesis. The 10th percentile has a high significance 

level to not accept H0 but there is not feasible to accept it because, there is not real evidence. 

For high lifting, was performed the analysis data that it is show in table3. 

Table 3 Analysis of field data, hight level 

liberty mutual tabla Hypotesis test 

MAW Null 

standard 



75 11 P0 = 0.75 p= 0.31 0.12 -3.67 0.00 rechazar Ho 

50 12 P0 = 0.50 p= 0.08 0.14 -3.00 0.01 rechazar Ho 

25 14 P0 = 0.25 p= 0.00 0.12 -2.08 0.03 rechazar Ho 


datos correspondientes a 13 participantes 

In this last analysis presents a situation similar to the results for lifting low, one can see that 

for the 90th percentile there is no sufficient evidence to reject that, at this level, we can apply the 

maximum weight indicated by the table, for the percentiles 75, 50 and 25 the level of significance 

of the test statistic is at able to reject the null hypothesis. For the 10th and 25th percentiles, same 



that in previous analysis is not feasible to accept the hypothesis Ho because there is no real 

evidence. 


With the results and analysis of the data above we can accept that, in general, there is not 

sufficient evidence to accept that the maximum weight recommended in Liberty Mutual Table for 

lifting in women, in vertical lifting for frequency of one per minute, boxes of 34 cm wide (distance 

from the body), movement distance of 51 cm, at the three levels of survey, can be applied to the 

female workforce of the Caborca region without running the risk of injury. Given this information 

we can conclude that, it is not appropriate to apply the recommendations in Table Liberty Mutual 

in the female working population in the Caborca region since it is possible that this population has 

a lower lifting capacity or possibly with a less dispersion in capacity lifting. As a result of this 

research we recommend that define the acceptable maximum weights in lifting burdens on women 

in different regions of our country since there are no recommendations in this regard and are a 

cause of interest public health 

6.REFERENCES 

Ciriello, VM and Snook, SH 1990., Ergonomy 1990, vol 33, no.3 ,187-200, "The effects of 

container size, frequency and extended horizontal reach on maximum acceptable weights of lifting 

for female industrial workers." 

Ciriello, VM and Snook, SH 1991, Ergonomy 1991, Vol 34, No 9,1194-1213, "The design of 

manual handing tasks: revised tables of maximum acceptable weights and forces". 

De La Vega Bustillos, Enrique 2005, "checklists, methods and mathematical models for ergonomic 

evaluation of work environments", Technological Institute of Hermosillo 

http://www.estrucplan.com.ar/articulos/verarticulo.asp?IDArticulo=982 visited in June 2009 

Mital, Anil (1983), Human Factors, 1983, 25 (5), 488-49, The Psychophysical approach in manual 

lifting, a verification study. 

National Institute for Occupational and healt (NIOSH), 1991, "Scientific support documentation for 

revised 1991 NIOSH lifting equation". 

Putz Anderson, V (1994) "Cumulative Trauma Disorders. A Manual for Musculoskeletal Diseases 

of the Upper Limbs. Taylor & Francis, London. 



Snook, SH and Ciriello, VM 1983, Human Factors, 1983.25 (5), 473-483, "A study of size, 

distance, Height and Frequency Effects of manual handling tasks 



Force analysis in hands on highly repetitive work in maquila operations 

Fco. Octavio López Millán 1 , Enrique Javier de la Vega Bustillos 2 , MaríaJesúsTéllez Moroyoqui 1 , 

LodevarPavlovichOviedo 2 , Bertha Leticia Ortiz Navar 3 




Author’s e-mail: lopezoctavio@yahoo.com.mx 

2 División de Estudios de Posgrado e Investigación. 




Instituto Tecnológico de Nogales. Ave. Instituto Tecnológico #911. 

Nogales, Sonora, Mx. 84065 

Resumen: Esta investigación se enfoca a analizar la fuerza como una función de tiempo en datos 

obtenidos en condiciones reales, considerando trabajo altamente repetitivo, donde las manos y 

dedos están expuestos a trabajo repetitivo y bajos esfuerzos. Se utilizo el diseño genera de 

medidas repetidas para analizar el comportamiento de la fuerza para ambas manos y pulgares. 

La hora, el turno y el día de trabajo fueron considerados como factores. La fuerza fue medida de 

la sexta a la octava hora en un intervalo de una hora, mientras que la semana empezó el lunes; 

el monitoreo fue de una semana. Los datos fueron obtenidos de plantas maquiladoras de las 

ciudades de Hermosillo y Nogales Sonora. 

Palabras Calve: Fuerza en manos, fuerza en pulgares, trabajo repetitivo, efecto acumulado 

de la fuerza, maquila. 

Abstract: The focus of this research is analyze how force is going as a function of time in data 

obtained from real work conditions, considering highly repetitive work, where the hands and 

fingers are exposed to repetitive work and low efforts. The repetitive measurement general design 

was used to analyze force behavior for both hands and both thumbs. The hour on the shift and the 

day week are the factors. Force was measured from the sixth hour to the eight hour on one hour 

interval, while the week day starts on Monday; the monitor is for a week. Data were obtained on 

maquila plants in Hermosillo and Nogales Sonora. 

Keywords: Hands force, thumbs force, repetitive work, cumulative effect of force, maquila. 



1. Introduction 

The work doing by the hands has been a very important factor on manufacturing industries, 

especially on development countries, but the human being and its physical characteristics at 

service of material transformation on industrial process it is not an endless power supply, while 

time passthrough the day, physical performance could be affected and modified. 

As a result of frequent exposure to work there is a risk of musculoskeletal injuries, Bernard et al 

(1997) refers that it´s “were recognized as having occupational etiologic factors as early as the 

beginning of the 18th century,however, it was not until the 1970s that occupational factors were 

examined using epidemiologic methods, and the work-relatedness of these conditions began 

appearing regularly in the international scientific literature. Since then the literature has increased 

dramatically; more than six thousand scientific articles addressing ergonomics in the workplace 

have been published. Yet, the relationship between MSDs and work-related factors remains the 

subject of considerable debate.” 

To understand the musculoskeletal disorders problem, is required to identify the risk factors 

associated to these kinds of injuries. There is a wide literature about it and its don´t surprise, the 

problem has been studied for years and many point of views and results of research converge on 

the causes or risk factors, Colombini (1998) recognize mainly four risk factors; repetitive 

movements (frequency), force applied to the task, awkward postures and lack of enough recovery 

time on each work cycle. Muggleton (1999) includes vibration as a risk factor for the hand-wrist. 

McAtamney y Corlet (1973) refers to the risk factors as external factors, including a consideration 

for static work load on muscles. Furthermore, highly repetitive work may directly damage tendons 

through repeated stretching and elongation, as well as increase the likelihood of fatigue and 

decrease the opportunity for tissues to recover Keyserlin et al (1993). 

This work is focused in finding the relationship between frequency and the force that people can 

exert as a function of time and some anthropometric characteristics, the approach is; on the latest 

hours of the shift work, force become to decrease significant, at least statistically and there is a 

relationship between force and anthropometrics. 

2. Method 

One objective was collect data in working conditions, so the “experiment” was planned as follows: 



• Find a process with highly repetitive operations; it is more than 300 units per hour. 

• The job involves extensive use of the hands and the fingers. 

• The anthropometrics measurements are for the hands and some generals: 

o Length of the hand. 

o Width of the hand. 

o Height of the hand. 

o Width of the wrist 

o Height of the wrist 

o Height of the thumb 

o Width of the thumb 

o Height of the middle finger 

o Width of the middle finger 

• The force on handgrip and thumb grip is measure with a Jamar© hand dynamometer and 

finger dynamometer. Every day 3 measurements are made every half hour from the sixth 

hour for the handgrip and finger grip for each side of the hands. 

• All data is collected and analyzed on statistical software (SPSS©) 

• Multiple linear regression is the tool to analyze the relationship between force and 

anthropometrics. 

• The repetitive measurements general model is used to analyze the force within hours and 

within days. 

• The data are from maquilas on Hermosillo and Nogales, Sonora, Mex. 

3. Results 

Is relevant to mention, again, how important get data from working conditions is, there was about 

50 operators who they were asked for to participate with the measurements for anthropometrics 

and force exertions, we appreciate that very much as well the maquila support to achieve the 

purpose of the research. Once data were collected and organized on worksheets next step is 

proceed to statistical analysis. 

The first part is finding the relationship between anthropometrics and force for each side on the 

hands, before the linear regression analysis, principal components was run to discriminate and 



group variables, the next tables show it:The first iteration includes all variables resulting on seven 

groups and .717 acceptable KMO value, results are: 

Table 1. Total variance explained 

. 

The first rotated component matrix shows how variables are grouped in the seven groups: 

Table 2 Rotated Component Matrix 



After several iterations, the target is find two groups; this final rotated matrix is next: 

Table 3 Final Rotated Component Matrix 

As values are shown on the table 4.3 the groups are formed with the higher coefficients; a first 

group is for; gender, height, weight and hand force. The second group are formed with; hand 

length, hand width, thumb width, thumb length and wrist width. 

Once groups are formed the next is linear regression analysis, the purpose here is just to found 

some kind of statistical relationship between variables or personal and force, next table shows the 

better relationship: 

Table 4 Linear Regression Model 

Predictor variables were; height, weight, thumb width, wrist width and hand length. Response 

variable is hand force. 

Linear regression shows a relationship between variables and force, that in general conditions, so 

next step is the analysis of force as a function of time. 



Force behavior was tested using repetitive measurements general model for each hand. 

Additionally some extra test was run in order to probe variances and differences between hours 

and days. Results are in next tables. The first test is for right hand and the hour of the shift, table 5 

shows descriptive and table 6 shows Mauchy´s sphericity test. 

. 

. 

Table 5.Descriptive statistics for right hand and hour 

Table 6.Mauchy´ssphericity test 

Significance on Mauchy´s test is 0.00 that means differences between variances are not equals, 

so is necessary run the Bonferronistest for multiple comparisons, this test shows in what hour are 

a difference in average exerted force on right hand, table 7 shows it. 

Same proceed is for the left hand and next tables shows results for descriptive statistics, 

significance on Mauchy´s test is 0.00 that means differences between variances are not equals, 

so is necessary again run the Bonferronis test for multiple comparisons, this test shows in what 

hour are a difference in average exerted force on left hand. 

All statistical tests are for a 95% confidence level. 


. 

. 


Table 7.Bonferroni´s pair comparisons for right hand 

Table 8.Descriptive for left hand 

Table 9.Mauchy´s test for left hand. 



Table 10.Bonferroni´s pair comparison for left hand. 

Same proceed is for both hands but the analysis is now within week days. Next tables shows 

results for descriptive statistics, significance on Mauchy´s test is 0.00 that means differences 

between variances are not equals, so is necessary again run the Bonferronis test for multiple 

comparisons, this test shows in what day are a difference in average exerted force the hand. 

. 

Right hand force descriptive are: 

Table 11.Mauchy´s test for day and right hand 


. 

Table 12.Descriptive statistics for right hand and day. 


Table 13.Bonferroni´s comparison pair test 



Table 14.Mauchy´s test for day and left hand 

Table 15. Descriptive statistics for left hand and day 

Table 15.Bonferroni´s comparison pair test for left hand and day. 



4. Discussion 

In an implicit form the purpose of this research was to show how force depend on anthropometric 

characteristics and how force is related with fatigue with a clear decrease pattern on force 

behavior trough hours and days. 

The first part tested by principal components and linear regression is positive; a statistical 

relationship does exist between hand and finger anthropometrics and force, in detail table 3 shows 

that, all values on above .600 on second group are related with the explanation of variance. 

In the second part the expected was that the greater values for hand forces were on the early hour 

and Monday, but results are not in that direction, for right hand force within hours, table 7 shows a 

difference only between the first hour of the test and 2.5 hours later. For left hand there is not 

statistical evidence that shows how force decrease in function of time. 

For hand force behavior related to day week, due to more than 90% of people are right-handed, 

the expected force behavior is that on Monday are the greater averages while on Friday should be 

the smaller averages. Table 12 shows that there is not any significative difference on right hand 

force average. For left hand force average, respect to Monday is valid a decreasing force behavior 

but statistically is valid only to Friday, on Tuesday the difference on average is only respect to 

Friday. The other days remain the same. 

As a final conclusion on this research the findings is that force has not a decreasing behavior due 

to hours or days, it makes necessary to increase the number of measurements and run a test for 

the thumb force. 

This fact, no decreasing force behavior should be not assumed as a fatigue free operations, while 

data were collected people says how at the end of the day they are with symptoms of pain and 

numbness on fingers, wrist, shoulder, neck and low back. Highly repetitive operations may have 

not an effect on force but that does not means that is an easy job. 

In maquilas, there is a lot of situations that should be improved, beyond manufacturing and quality 

is the human being, it is not only manpower, they are people and deserve a good place to 

workon. 

References 

Bernard, B. (1997). “Musculoskeletal Disorders and Workplace Factors; A Critical Review of 

Epidemiologic Evidence for Work-Related Musculoskeletal Disorders of the Neck, Upper 

Extremity, and Low Back”.Centers for Disease Control and Prevention, National Institute for 

Occupational Safety and Health (NIOSH). 



Colombini, D. (1998) 'An observational method for classifying exposure to repetitive movements 

of the upper limbs', Ergonomics, 41:9, 1261 – 1289. 

McAtamney, L. Corlet, N., (1973).“RULA; A survey method for the investigation of work-related 

upper limb disorders”. Applied Ergonomics; 24(2), 91-99. 

Muggleton, J. M., Allen, R. and Chappell, P. H.,(1999.) “Hand and arm injuries associated with 

repetitive manual work in industry: a review of disorders, risk factors and preventive measures”, 

Ergonomics, 42:5, 714 – 739. 

Keyserling, W. M., Stetson, D. S., Silverstein, B. A. and Brouwer, M. L. (1993) “A checklist for 

evaluating ergonomic risk factors associated with upper extremity cumulative trauma disorders”, 

Ergonomics, 36:7, 807 – 831. 



ENVIRONMENTAL CONDITIONS VERIFICATION IN FACILITIES DESIGNED 

FOR NEW DEVELOPED PRE-SCHOOL LEVEL BUILDINGS IN THE 

EDUCATIONAL SECTOR IN HERMOSILLO, SONORA DURING 2007-2008. 

Francis María Quintero Díaz 1 , Manuel Sandoval Delgado 1 

1 Departamento de Investigación y Posgrado 

Instituto Tecnológico de Hermosillo. 

Ave. Tecnológico y Periférico Poniente S/N Colonia Sahuaro. 

Hermosillo, Sonora 83170 

Corresponding author’s e-mail: francis_mquinterod@hotmail.com, msandoval@ith.mx 

RESUMEN: Alrededor de todo el mundo, en el seno de toda clase de comunidades, con 

independencia de condiciones económicas, u otras características físicas, existen escuelas en 

condiciones precarias que se constituyen en barreras, a veces infranqueables, para que tanto los 

estudiantes, como profesores y personal técnico y administrativo desarrollen sus actividades 

normales dentro de los planteles con éxito. Tales condiciones pueden ser los niveles de ruido, 

iluminación, temperatura y ventilación a los que están expuestos diariamente, es por eso que 

hace dos años en la ciudad de Hermosillo sonora se empezaron a construir escuelas de nivel 

preescolar diseñadas para que estas condiciones no afecten las actividades de las personas que 

laboran en ellas. 

El propósito de esta investigación es realizar un estudio comparativo entre la normatividad 

correspondiente que rige el diseño y construcción del salón de clases donde laboran los niños y 

el personal de las instalaciones de los edificios de nueva creación del nivel preescolar en el 

sector educativo, en cuanto a medio ambiente se refiere; tales como ruido, iluminación y 

temperatura, con los parámetros realmente encontrados en dichas instalaciones. 

ABSTRACT: Around the world, within all kind of communities, regardless of the economic 

condition or any other physical characteristic there are schools in such poor conditions that create, 

sometimes insurmountable, barriers for students, teachers, as well as technical and administrative 

staff to successfully develop their diary activities within school. Such conditions are related with: 

noise level, lighting, temperature and ventilation which users are daily exposed to. As a response 

to this situation, the pre-school level facilities that were designed so that the environmental 



conditions could not affect the daily activities of their users, started to be constructed two years 

ago in Hermosillo Sonora. 

The aim of this research is compare the corresponding regulations ruling the design and 

construction of classroom where children work and the personnel of pre-school level new facilities 

in the educational sector in terms of environment such as: noise, light and temperature with 

parameters actually found in these facilities. 


From the very moment of our birth we find ourselves immerse in a physical environment essential 

for life; however, if that environment degrades, it might become an enemy of our health that would 

chase us until the end (González, 1990). 

According to the Instituto de Infraestructura Física Educativa (INIFED) (Institute of Educational 

Physical Infrastructure), the classroom is where children and young people can reach through 

knowledge a great number of better opportunities; therefore, it is necessary that all Mexican 

students have access to quality education and schools that inspire and motivate the learning 

(INIFED, 2008). 

2. OBJECTIVE 

Decide if the design of facilities for new developed pre-school level buildings in the educational 

sector meets criteria established by the official standards regarding the design of the working 

environment (noise, lighting, temperature and ventilation). 


The methodology carried out in this research is accordance with the Official Standards ruling the 

design of working environment, such as: 

3.1 Federal Regulation of Security, Hygiene, and Working Environment. 



This regulation establishes the necessary measures to prevent accidents and illness of work, 

trying to get the work done under safe, health and appropriate environmental conditions for 

workers, in accordance with the Federal Labor Law and the International Trade held and ratified 

by the United Mexican States related to these matters (Federal Regulation of Security, Hygiene, 

and Working Environment), (1997) 

3.2 Mexican Official Standards. 

3.2.1 Mexican Official Standard NOM-011-STPS-2001, security and health conditions in 

workplaces where noise is produced. 

Data collected in Appendix B evaluation of the level of exposure to noise tells the following: 

To evaluate noise in a permanent workplace the previous rule recommends that measuring spot 

must be located in the place the worker usually takes (in this particular case, the child) otherwise, 

as close as possible to it without hinder his/her work. In the same way, when a person works 

seated, the microphone has to be placed at the workers head average level. Measurements were 

taken as recommended. 

Measurements were taken to the following conditions: 

Children singing. 

Children performing current activities (NOM-011-STPS-2001), (1994). 

3.2.2 Mexican Official Standard NOM-015-STPS-1994, regarding to the labor exposure of high or 

low thermal conditions in workplaces. 

This rule makes some recommendations to take measurements, among them: 

The position of the measuring spots depends on needs and characteristic of each area 

and/or workplace. In this case, measurements were taken in the classroom central spot. 

The height of the measurement equipment was set in accordance with the height of the 

children’s work area (table): 60 cm. 



The evaluation must be made at least three times during the 8 hour working day. Since 

children work day lasts 3 hours, it was decided to take measurements every hour, starting 

from the time they get in until the time they get of (NOM-015-STPS-1994), (1994). 

3.2.3 The Mexican Official Standard NOM-025-STPS-1999, lighting conditions in workplaces. 

The following activities were carried out according to law recommendations mentioned before: 

Workplace reconnaissance. 

Since sunlight and electric light are used, both conditions’ measurements were taken. For 

the electric light, lamps were turned on 20 minutes before. 

Measurement spots were set in accordance with the working area by the following formula: 

Where: 

Working area index/rate. 

Working area dimensions (length and width) in meters. 

Lamps height regarding the working surface, in meters. 

In this case: 

The number above is placed in the following table: 

Index of 

area 

Table 1. Proportion between the working area index and the number of measurement areas 

Minimum number of areas Number of areas to be considered 

to be evaluated 

by the limitation 

4 6 

9 12 



16 20 

25 30 

Therefore, 9 areas were evaluated. Once the measurements were obtained, the % of Reflection 

Factor was calculated (to compare information later on) by the following method: 

Measurement spots must be the same as those set in the previous item. 

Calculation of the surface’s reflection factor: 

1. A first measurement (E1) is taken, with the luxmeter’s photocell facing the surface, at 10 

cm ± 2 cm distance, until the reading remains constant; 

2. In order to measure the incident light, the second measurement (E2) is taken with the 

photocell on the surface facing the opposite direction; 

3. The surface Reflection Factor (Kf ) is calculated with the following equation: 

(NOM-025-STPS-1999), (1999). 

3.3 Instituto Nacional de la Infraestructura Física Educativa (INIFED). (Institute of Educational 

Physical Infrastructure) The INIFED (2009) is the organization of the Federal Public Administration 

responsible for the construction, restoration, maintenance and equipment of the national 

educational physical infrastructure. It is important to mention that this institution does not say how 

to take measurements, it only provides parameters that must be met regarding the working 

environment; in addition to that it is based on the Mexican Official Standards. 

4. RESULTS 

Results shown below were collected in three classrooms during summer time. 

4.1 Noise: 


(2 

)


Table 2. Results of the Noise Factor’s (Lux) measurements. 

1 2 3 

Max Min Max Min Max Min 

Children singing 89 47.5 85 51.3 86.4 45.6 

Current activity 87.5 43.8 75.6 42.6 8 43.8 

4.2 Temperature. 

Table 3. Result of the Temperature Factor’s (Lux) measurements. 

1 2 3 

09:30 a.m. 

Min 24.5 22.8 24.7 

Average 25.9 24.8 26.6 

Max 27.3 26.7 28.4 

Min 28.9 28.4 29.8 

10:30 a.m. Average 29.5 29 29.7 

Max 30.2 29.7 29.7 

Min 33.3 32.4 34.2 

11:30 a.m. Average 33.7 33.2 34.7 

Max 34.1 34 35.2 

4.3 Lighting. 

Classroom 

Table 4. Results of the Lighting Factor’s measurements, classroom 1. 

LIGHTING (Lux) % REFLECTION FACTOR 

Natural Lighting Electric Lighting 

Natural 

Lighting 

Electric 

Lighting 

Max Min Max Min Max Min Max Min 

Measurement #1 264.7 233.3 640 590 40.0075 30.7758 28.5762 27.5937 

Measurement #2 534 486 748 716 26.7790 27.8600 29.2647 28.3798 

Measurement #3 547 478 947 756 27.7879 30.9205 29.2647 28.8359 

Measurement #4 912 892 1285 1234 24.4517 24.0022 25.0405 24.7081 

Measurement #5 1113 1070 1389 1373 29.3800 22.6168 26.3570 24.4136 

Measurement #6 1181 1139 1439 1434 22.5402 22.8709 23.3009 21.9456 

Measurement #7 494 398 918 891 30.6072 26.4070 27.1132 23.1986 

Measurement # 8 632 483 980 726 30.8723 26.2456 25.5478 21.6591 


Classroom 





Natural 

Lighting 

Electric 

Lighting 


Measurement #1 318 299 525 506 32.7044 33.7792 36.1904 36.5612 

Measurement #2 347 323 614 607 39.7694 41.7956 32.8990 32.1252 

Measurement #3 735 712 651 636 27.4829 26.1235 37.6344 27.9874 

Measurement #4 668 654 812 803 38.4730 36.5443 36.8226 33.7484 

Measurement #5 597 557 955 814 38.3584 39.1382 42.1989 39.9262 

Measurement #6 606 591 787 761 40.4290 32.4873 39.7712 40.3416 

Measurement #7 395 347 758 682 40.5063 44.6685 37.2031 39.8826 

Measurement # 8 465 446 872 832 38.9247 39.4618 37.2706 30.8894 

Classroom 




Natural 

Lighting 

Electric 

Lighting 


Measurement #1 290 276 535 518 35.5172 36.5942 35.3271 35.9073 

Measurement #2 325 305 624 607 39.3846 43.9344 32.0512 32.1252 

Measurement #3 680 677 635 628 29.5588 28.0649 36.2204 27.0700 

Measurement #4 670 655 821 807 29.5522 28.5496 35.3227 31.7224 

Measurement #5 620 598 859 851 28.8709 26.7558 46.5657 38.0728 

Measurement #6 586 580 789 771 29.0102 28.2758 39.5437 39.6887 

Measurement #7 405 398 759 682 35.3086 35.4271 36.8906 39.8826 

Measurement # 8 486 476 921 897 26.3374 25.8403 35.1791 28.6510 


4.4 Ventilation. 


Figure 1. Windows view. 

5. CONCLUSIONS. 

The Mexican Official Standard number 011 concerning to noise indicates that a hazardous 

situation occurs when dBs number surpasses 90. In this case the noise did not exceed the limit, at 

least not when children were there. 

The INIFED states that the advisable environmental conditions for working in a comfortable area, 

in the case of classrooms, are 18 to 25 Celsius, noticing that this condition is not fulfilled since 

most measurement exceeded 25 Celsius. 

According to the prevoiusly analized NOM 025, the lowest lighting level must be 300 (lux) for older 

people. As is noticed in the prevoius measurements, this parameter is not met, so that we can 

infer that light is not well distributed. The reflection on the furniture where kids work was another 

important issue that was evaluated and according to INIFED standards, the reflection highest 

value should be 50%, and as it is noticed in the previous measurements, does not exceed such 

level. 



6. REFERENCES. 

González Gallego Santiago (1990). La ergonomía y el ordenador. Primera edición, Editorial 

Marcombo, S. A. Barcelona España. 

Instituto Nacional de la Infraestructura Física Educativa (INIFED), (2008). 

http://www.inifed.gob.mx/templates/objetivos.asp. Página visitada el 13 de agosto de 2009. 

INIFED, (2009). Volumen 3. Habitabilidad y funcionamiento. Tomo I. Diseño Arquitectónico. 

http://www.inifed.gob.mx/templates/normas%20t%C3%A9cnicas.asp. Página visitada el 12 de 

marzo de 2009. 

(NOM-011-STPS-2001), (1994). Publicada en el Diario Oficial de la Federación el 06 de julio de 

1994. México, D.F. http://www.stps.gob.mx/DGSST/normatividad/noms/Nom-011.pdf. Recopilada 

en la página el 6 de mayo de 2009. 

(NOM-015-STPS-1994), (1994). Publicada en el Diario Oficial de la Federación el 19 de julio de 

1993. México D.F. http://www.stps.gob.mx/DGSST/normatividad/noms/NOM-015.pdf. Recopilada 

en pagina el 6 de mayo de 2009. 

(NOM-025-STPS-1999), (1999). Publicada en el Diario Oficial de la Federación el 27 de 

septiembre de 2005, México, D.F. 

http://www.stps.gob.mx/DGSST/normatividad/noms/Nom-025.pdf. Recopilada en la página el 6 de 

mayo de 2009. 

(Reglamento Federal de seguridad, higiene y medio ambiente de trabajo), (1997). Publicado 

en el Diario Oficial de la Federación el 21 de enero de 1997. México, D.F. 

http://www.stps.gob.mx/marcojuridico/vinculos_juridico/reglamentos_marco/r_seguridad.pdf. 

Recopilada en la página el 6 de mayo de 2009. 



ADVANTAGES OF THE ORTHOGONAL ARRANGEMENTS OF THE METHOD 

TAGUCHI IN THE DESIGN OF EXPERIMENTS IN ERGONOMIC 

Alois Fabiani-Bello 1 , Humberto García-Castellanos 2 , and Rosa M. Reyes 2 

1 Programa de Doctorado en Ciencias de la Ingeniería (DOCI) 

Universidad Autónoma de Ciudad Juárez 

Ave. Del Charro 450N, C.P. 32190 

Cd. Juárez, Chihuahua, México. 

e-mail: fides.sde@gmail.com 

2 Departamento de Ingeniería Industrial 

Instituto Tecnológico de Ciudad Juárez 

Av. Tecnológico Nro. 1340 

Cd. Juárez, Chihuahua, México. 

Resumen: Los métodos estadísticos basados en la función Chi-Cuadrada son frecuentemente 

utilizados por los ergónomos y estas técnicas por su naturaleza no paramétrica usualmente 

requieren de una gran cantidad de datos experimentales con el correspondiente uso de recursos 

y contienen una importante dosis de subjetividad basada en la experiencia del experimentador. 

Las metodologías de experimentación podrían ser más rápidas y más económicas para tomar 

decisiones con la mejor información estadística posible utilizando técnicas apropiadas del Diseño 

de Experimentos. El autor Fabiani-Bello et.al. (Conergo, 2008) expone un método conceptual 

basado en simulación Monte Carlo y experimentos sin réplicas que fueron utilizados para planear 

la experimentación en ergonomía al categorizar la fatiga visual o astenopia. En base a la misma 

línea de trabajo Reyes-Martínez et.al. (Conergo, 2009) muestra los primeros resultados del 

método caracterizando la fatiga visual según publicaciones recientes dando a lugar la 

identificación clara de los factores que influyen en la astenopia y pone a prueba los métodos 

estadísticos tradicionales. Después de dos años de investigar las ventajas y limitaciones del 

método Taguchi en varias aplicaciones experimentales se propone en este artículo el método 

validado del diseño experimental basado en arreglos ortogonales del Método Taguchi que podría 

ser usado en los experimentos de la ergonomía donde, según el ajuste de niveles factoriales de 

diseño, es posible medir el impacto de estos arreglos en alguna variable de interés retomando las 

conclusiones obtenidas hasta la fecha sobre el tema. 

Palabras Clave: Metodo Taguchi, Arreglos Ortogonales, Diseño de Experimentos 



2 

Abstract: The statistical methods based on the Chi-square of test ( χ ) are much used by the 

ergonomics and these need from a significant and big size of the sample with the corresponding 

use of resources and it contains an important dose of the subjectivity. Due to the cost of 

opportunity the methodologies must be more rapid in the treatment of the information, must be 

more economic and to take decisions with the best statistical information. Fabiani (2008) proposes 

a conceptual method based on simulation Monte Carlo that was used to plan the experimentation 

in ergonomics to the categorizer the visual fatigue. Based on the same line of work Reyes- 

Martínez et.al. (2009) it shows the first results of the method characterizing the visual fatigue as 

recent publications. The authoress identifies in a clear way the factors that influence the astenopia 

and it puts to test the statistical traditional methods. After two years of investigating the 

advantages and limitations of the method Taguchi in several experimental applications there is 

proposed in this article the validated method of the experimental design based on orthogonal 

arrangements of the Method Taguchi. The method that might be used in the experiments of the 

ergonomics where according to the level adjustment factorials of design it is possible to measure 

the impact of these arrangements in some variable of interest recapturing the conclusions 

obtained up to the date on the topic. 

. 

Key words: Taguchi Methods, Orthogonal Array, Experimental Design. 


The visual system is one of the principal organs of the human being since 80% of the emotions 

are perceived across the sight. The sciences that study the system of the sight begin to be 

interested in the labor matters at the end of the XIXth century turning into a more and more 

specializing professional activity and into a world more industrialized (Reyes-Martinez et.al, 2005). 

The new places and forms of work, the beginning of the automation and the systems of industrial 

production based on the competition for the quality (De la Vara, 2002) give place to a symptom 

that starts attracting attention of some specialists and especially of the companies because they 

realize that sometimes his workpeople can suffer a serious damage: The most common 

complaint, as for visual inconveniences, is vaguely described as " tired sight ". Other symptoms 



indicate blurry sight or the difficulty to focus objects closely or of far, the unsteady vision and the 

double image. The headache is the most common general symptom, but not always it must be 

related to the visual weariness. Specifically, the symptoms of weariness or visual fatigue can be 

aggravated by diverse factors. On the other hand, the sight deteriorates gradually in the adults 

and this decrease is marked especially between 30 and 50 years (Reyes-Martinez et.al. 2005). 

The system of vision of the human being perceives the reality across the eyes, by means of these 

the brain perceives the signs and processes them; these signs are received in an environment 

with lighting, the color, the moisture between others they generate changeability in the system of 

vision. With the time, the visual system deteriorates for the rhythm of industrial repetitive work. 

The signs of Visual Fatigue as the frequency of blinking might be abstracted as exits of the effort 

of the system to face his fatigue (Okada, 2002). 

The relation between the Engineering of Quality and the Ergonomics is real because both want to 

improve the yield of a system, in the first case the experimentation has an important role in new 

products design, in developing manufacturing processes and in the improvement of processes 

and in the second case the characterization of factors so that the health is not damaged in the 

persons. With regard to the experimentation one of the most used methodologies and recognized 

for its efficiency is the one proposed by Dr. Genichi Taguchi. In Quality Engineering, it is 

mandatory to select the operative levels of the control factors that affect to critical characteristic of 

quality, and then abstracting the Visual Fatigue as a "characteristic of quality" it is necessary to 

minimize it. 

2. METHODOLOGY FOR SELECTING THE PARAMETERS 

To understand and to talk about the interaction between the persons and his environment implies 

respecting many methodological, statistical restrictions and even of anthropology; the experience 

says to us that these models that to the moment can be only theoretical, help to understand the 

behavior of the system more they do not allow to manipulate it. Our methodology is designed only 

for knowledge of relations cause - effect between the factors and the variable of exit of the 



system. In this sense the method Taguchi for the prophecy of the output variable in the process is 

most adapted for our case; the process can be divided into five stages summarized in Table 1. 

N 

o. 

1 Preparation 

2. 

Table 1. Stages for the experimental design 

Stage Activity Content 

Determination of 

factors and levels 

1.1 Determine the experimental objective and targetcharacteristic 

values. 

1.2 Determine whether it is worthwhile to carry out the 

experiment under the current conditions. 

2.1 List all factors that relate to the objective (more 

than 50) with a Focus Group 

2.2 Select and determine factors and levels to be 

tested. 

3. Assignment 3.1 Assign factors and levels to the orthogonal array. 

4. Experiment 

5. Data analysis 

4.1 Eliminate the obstacles hindering the experiment. 

4.2 To continued the process of randomized 

experimentation generating only an experimental reply. 

4.3 With the simulation Monte Carlo all the possible 

outputs will be obtained 

5.1 To construct the correlogram and to interpret the 

coefficient of Pearson to characterize the incidental 

factors. 

5.3 Determine the optimum condition and to confirm 

them with the existing norms in the legal environment 

of Occupational Health. 

The sequence of the methodology and the recommendations of his application are based on the 

interpretation that the Dr. Teuro Mori does to the method Taguchi in his work titled originally " 

Taguchi Mesoddo or tsukatta yasashii shinjikken keikakuho nyumon " (1946). 



2.1. Experimental Design Application: First and Second Stage – Preparation and 

Determination of factors y levels. 

The target of the experimentation applied to the ergonomics will have to maximize or minimize an 

effect and it is clear that to maximize a variable sometimes implies minimizing his complement. 

The clear identification of the variable of exit of the interaction between the man and the system is 

important. The scope of the experiment is to know the factors that they affect in the awaited result 

and to arrange them according to his contribution to the changeability of the system. 

At first more than 50 potential factors must be put in a list and to obtain this number it is necessary 

to ask medical specialists that have worked with the topic, it is key to confirm points of view of the 

participants and to assume a position based on the nature of the industry at which one is 

employed. The information will be better if it is investigated in the arbitrated publications, 

catalogues and tests previous. 

Another key of the ergonomic experimental process is to classify the factors and to define the 

levels of the experimentation, for this activity it is necessary to identify clearly the class of factor 

(Mori, 1946). As well as to classify to the factors in the function to his relation with the studied 

effect and to avoid the strong interaction between them, this is important for the complexity of the 

system in study. We cannot experiment with all the factors but the target here is to consider all the 

important factors. In this stage of the experimentation the people can have different opinions, in 

such a situation, we do not have to classify rigorously the factors and that's why we make use of 

orthogonal series to confirm his effect. 

After defining the factors, we determine his levels. The number of levels should be two, three, or 

four. The use of three levels is recommended in particular (G.Taguchi, 1986). The works of the 

theoretical investigation demonstrated that this type of level determination they generate 

quadratic’s terms in the model (Fabiani-Bello, 2008). 



2.2. Experimental Design Application: Third Stage – Assignment. 

It is known that the most usual criterion to select the experimental design is the reduction of the 

variance of the regression coefficients. The key element to select a design that diminishes the 

variance is the orthogonality concept used by Taguchi in experimental designs. In fact, the 

complete factorial designs of two levels and the fractions of resolution III are orthogonal. 

In the ergonomic experimentation is possible to separate main effects and interactions using 

either of the following methods: (1) assign the main effect to the points to the linear graph 

assuming that interactions between three factors does not exist; (2) use a special orthogonal array 

where interactions confound equally with every level of the main effects. The first method uses the 

columns corresponding to the points on the linear graph en orthogonal arrays L 8 , L16, 

L32, 

L9 

and L 27 . For the second method L 12, L18 

and 36 

L orthogonal arrays are used which are of practical 

use in the industry for their effectiveness and reduction of costs (Wu, 1992). 

If we cannot anticipate possible interactions between factors, we can obtain quite a lot of 

information from past experience. But, if we cannot anticipate interactions, we can take any of the 

following approaches: (1) Assign the interaction between two factors. (2) Use orthogonal arrays 

12 , L18 

L or 36 

assign factors. 

L that does not generate interaction information. (3)Ignore interactions when you 

For experiments in ergonomics it is of interest principally to know the principal effects of factors, 

from what the second option is most recommended since it uses three levels and does not need 

to stop in the study of interactions that might be subjective in this stage of the process although 

the ability to anticipate is a part of technological know-how (G.Taguchi, 1986). For this reason the 

Taguchi methods for the case of study have been programmed in spreadsheets because these 

allow flexibility of programming for this type of algorithms. In fact, it contains statistical tools. 



2.3. Experimental Design Application: Fourth Stage – Experimentation. 

In the industry the resources are in general limited it is very probable that the number of 

experiments is limited to the available budget, in this case a design factorial finished and with only 

one experimental response can be used, nevertheless the principal effects can contain an error 

generated by the external noise (Montgomery, 2006). The principal disability of this method 

consists of the fact that is known that to certain number of factors this process is expensive. 

The methodology Taguchi usually guarantees less experimental tests and makes use of the big 

advantage of the orthogonal arrangements then to construct a reliable model to know the value of 

the average of the process with the following equation: 

ˆ = y + ( A − y) 

+ ( B − y) 

+ ... + ( N − y) 

(1) 

y k 

r 

s 

Where: 

yˆ = theoretical average of the process. 

y = real average of the process. 

A , B,... 

N Are the experimental factors. 

k , r,... 

s Are the levels of the experimental factors. 

In this way, the Monte Carlo method is used to simulate all possible iterations in a predictive 

model of values of the average. This means that in our methodology there will be randomized the 

order of the capture of information to only one reply and later to obtain the theoretical model of the 

average based on the contribution of the principal effects, with the equation (1) there will be 

generated all the possible values of the average making use of the Simulation Monte Carlo. In 

studies realized with regard to the MAPE of the theoretical model his value is usually 4 % 

(Fabiani, 2008). 

With regard to the person chosen for the experiment, the International Organization of the Work 

tells that the "average" worker does not exist in the reality, but based on the requests of the 



industrial work for which is experienced it is known that the profile of the person who executes the 

task and the Ergonomist jointly with the Engineer can suggest the conditions of an operator 

qualified for the position, this is that person who has necessary fitness, with required intelligence 

and instruction and who has acquired the workmanship and necessary knowledge to carry out the 

current work as norms of quality, quantity, health and safety (OIT, 1986). 

2.4 Application of experimental Design: Fifth Stage – Analysis of the information. 

Changing the levels of the factors, it is possible to know the interrelation between variables of 

entry and variables of exit to the system, the distributions of frequency for every variable and to 

the simulation of the experiment. Finally, the simulated population is validated comparing the 

levels of interrelation between variables and the percentage of obtained contribution of the 

ANOVA. 

The method allows to obtain a graphic report of different iterations to select the best combination 

of parameters. The relationship between the response variable and the independent variables is 

obtained based on the experience in previous investigations, which has found a narrow relation 

between coefficient of Pearson with the ANOVA (García-Castellanos and Fabiani-Bello, 2007). 

The following step is to verify the law with regard to the important factors in the response of the 

model and if norms do not exist on this matter it is necessary to choose the most appropriate 

levels of operation that maximize or minimize the response. 


It has been demonstrated that Taguchi methods are an important tool. Due to its simplicity, the 

use of these methods has become frequent in different areas and different productive processes. 

After the statistical experimentation, the Taguchi methodology allows to predict the performance of 

a process by means. The implementation of this methodology is simple and practical and it does 

not require of advanced statistical knowledge. Also, the validation of the method presented here 

could be by means of a case of study. 



4. REFERENCES 

Ross, Phillip J. (1996). Taguchi Techniques for Quality Engineering. McGraw-Hill Co., United 

States of America. 

Wu, Yuin, and Wu Alan (1997) Diseño Robusto utilizando los métodos Taguchi. Díaz de Santos 

S.A. Ed, Madrid, Spain. 

Suart P. Glen (1993), Taguchi Methods: a hands-on approach Addison-Wesley Co, Inc., United 

States of America. 

American Supplier Institute, Inc. (1987) Introduction to Quality Engineering: Course Manual. 

Center for Taguchi Methods, United States of America. 

Terou Mori (1946). The New Experimental Design, ASI Press, United States of America. 

Nelson Rodríguez (1999), Aplicación del Diseño de Experimentos para determinar el máximo 

peso aceptable en el manejo manual de materiales, Departamento de Ingeniería 

Industrial, Universidad de los Andes, Colombia. 

Tames Gonzalez S, Mart'nez-Alcántara S., Use of personal computers and health damages in 

newspaper industry workers. Salud Publica Mex 1993;35:177-185, Mexico. 

Rosa María Reyes Martínez M.C et al. (2005), Ergoftalmología: Análisis de los Factores que 

Inciden Astenopía de los Trabajadores de Inspección Visual Industria Electrónica de 

Ciudad Juárez, Memorias del VII Congreso Internacional de Ergonomía, Nuevo León, 

México, 3 al 5 de noviembre del 2005. 

Akira Okada (2001), Medición de la "Fatiga Visual", Universidad de Osaka, Panasonic Services 

(Central), Sancho de Ávila, 54, 1ª planta, Barcelona, Spain. 

Guillermo Martínez de la Teja, Diseño ergonómico para estaciones de trabajo con 

computadoras, Memorias del II Congreso Internacional de Ergonomía, Ciudad Juárez, 

México, Mayo 2000. 

Victor García-Castellanos, Alois C. Fabiani-Bello, and Humberto Hijar-Rivera (2007), A 

Computing Approach Based On The Taguchi Methods To Optimize The Selection Of 

Factors For The Nominal-The-Best Characteristics, Proceedings Of The 12th Annual, 

International Conference On Industrial Engineering, Theory, Applications and Practice, 

Cancun, Mexico, November 4-7, 2007. 



Fabiani-Bello, Alois (2008), Aportación Metodológica al Diseño de Productos Robustos según la 

filosofía de Genichi Taguchi, División de Estudios de Posgrado e Investigación, Instituto 

Tecnológico de Ciudad Juárez, México. 

Reyes-Martinez, Rosa (2009), Categorization of factors causing asthenopia en research 

professors at the itcj by Reading wit vdt: a shared experience, SEMAC 2009, pp. 154-166 



ACADEMIC ASSAYS FOR ERGONOMICS. 

LDI Zoe Madai Cruz Purata 1 , LDI María del Sagrario Medina Rodríguez 2 , Arq. Julio Gerardo 

Lorenzo Palomera 3 

1 Coordinadora de la Carrera de Diseño de Interiores. 

2 3 Facultad de Arquitectura, Diseño y Urbanismo. 

Universidad Autónoma de Tamaulipas. 

Campus Tampico – Madero. 

zoemadai@hotmail.com 

RESUMEN. Se presentan dos ensayos realizados en la Facultad de Arquitectura, Diseño y 

Urbanismo (FADU). En el contexto interactivo de las carreras de Arquitectura y Diseño de 

Interiores, se desarrolló un estudio básico del ambiente acústico que incide en el aula, por otro 

lado se hace una aproximación de análisis antropométrico de nuevo mobiliario para los talleres de 

diseño. 

El estudio acústico tiene como finalidad que el alumno se sensibilice con la noción ergonómica y 

se familiarice con herramientas elementales, como el decibelímetro, para diagnosticar y controlar 

el ambiente sonoro, ahora a nivel escolar, pensando en su aplicación en entornos reales. Se 

sigue un método de medición simple, en una secuencia predeterminada de espacios. Se 

obtienen indicadores no del todo adecuados para un óptimo ambiente de aprendizaje. 

El diagnóstico de mobiliario se aplica en un juego de restiradores “gemelos”, con dimensiones 

establecidas por el fabricante. Se aplica una técnica de observación de postura relacionada con 

el alcance y la holgura, de usuarios en interacción con el mueble, de una muestra de la población 

estudiantil en la FADU. Los resultados llevan a la reflexión de cómo la aparente comodidad puede 

ser realmente una lastimosa costumbre, a ser cultivada en los años de carrera universitaria. 

Palabras clave: Interiorismo. Bienestar. Ergonomía. Acústica. Antropometría. 

ABSTRACT. We present two tests conducted at the Faculty of Architecture, Design and Urbanism 

(FADU). In the interactive context of careers in Architecture and Interior Design, it was developed 



a basic study of acoustic environment impact in the classroom. Then it was applied an simple 

anthropometric analysis on new design workshops furniture. 

The acoustic study aim was to sensitize students about ergonomic notion and become familiar 

with basic tools such as decibelímetro, diagnose and control the sound environment, now at 

school, thinking about its application in real environments. It was followed a simple measurement 

method, in a predetermined sequence of spaces. Obtained indicators were not entirely 

appropriate for optimum learning environment. 

The diagnosis of furniture applies drawing board in a game of "twins", with dimensions specified 

by the manufacturer. It was applied an observational technique of scope and slack related 

posture. User - furniture interaction was observed of a sample of the student population. The 

results lead to the reflection of how the apparent comfort can be really a pitiful habit to be 

cultivated in the years of college. 

Keywords: Interiorism. Welfare. Ergonomics. Acoustics. Anthropometry. 

PROLOGUE. 

We present two academic assays conducted at the Faculty of Architecture, Design and Urbanism 

(FADU) 

In the interactive context of Architecture and Interior Design careers, it was developed a basic 

study of acoustic environment impact in the classroom, besides an approximation of 

anthropometric analysis of new furniture for the design workshops. Both exercises are strategies 

to reduce the gap between design activities and ergonomics, as well as linking quality as a daily 

practice. 

Ergonomics as inherent quality factor should be fully present in the field of design. In practice it is 

found that various educational trends, not necessarily provide consumers welfare in their models. 



The environmental experience as part of the learning process is student-way reference in its 

professional life. Hence the need to reorient educational objectives in design. 

Exercise 1: Acoustic study of a learning environment. 

1.1. INTRODUCTION. Conceptual Framework. 

As part of the exercise was revised conceptual framework based on Mapfre Foundation 

Ergonomics Handbook 

Ergonomics deals with the study of any physical environment from three sources: the 

measurable factors of the environment that are susceptible to modification, the physiological 

effects produced by these factors and also how the employee feels that environment. The sound 

from the physical point of view is a mechanical vibration transmitted through the air, capable of 

being perceived by the auditory organ. 

1.1.1. Sound effects in people. 

The sound effects can occur in people from three aspects: perception, extra-auditory effects, 

auditory effects. 

Perception. 

The inner ear acts as a transducer, transforming the physical signal (mechanical) in 

physiological signal (nervous), which is transmitted through the auditory nerve to auditory cortex, 

which produces the integration and interpretation of those signals. 

Extra-auditory effects. 

The fact that noise can cause physiological reactions of "stress" seems widely accepted, but has 



not yet established that these reactions can produce pathological effects. However, an analysis of 

more than one hundred relevant literature indicates that the most important are: 

Modification of the cardiovascular system: blood and heart rate. 

Influence on muscle tone. 

Digestive disorders. 

Visual function alterations. 

Alterations on metabolism. 

Auditory effects. 

The auditory effects are: injury to the ear and difficulty in language comprehension. For the scope 

of the study, was only considered the first. In an environment where understanding of the word 

difficult, is very likely that there are difficulties that will lead to discomfort for the worker and work 

impairment. The spoken word is a sonic element with high information content, so the process of 

perception is determined by various acoustic phenomena and the special interpretation of the 

message conveyed by the word. 

1.1.2. Acoustic comfort. 

The type of noise that bothers more in an office environment, is produced by the talks. Each 

type of activity will be treated differently. Can be generalized in terms of noise levels, noise in 

manual labor began to be troublesome from 80-90 dB, matching the levels from which they can 

and assume the risk of deafness. 

1.1.3. Effectiveness. 

Noise can alter a person's efficiency decreased performance and increased errors and 

accidents. Rates were determined for intellectual work discomfort, for example Beranek (1969) 

and Wisner, setting graphic curves correlated noise level in decibels and octaves center 

frequencies. The scope of this assay was limited to a simple sequence of measurement, but 

checking on the charts for better understanding by students. (Mapfre Ergonomics Manual) 


1.2. OBJECTIVES. 


Sensitize Interior Design students on the need to adapt the environmental conditions for human 

activity, in this case, learning. To learn the use of simple measuring sound tools, to diagnose and 

monitor a sound environment. 

1.3. METHOD. 

It was simplified to an academic exercise, the procedure established in the Mexican Official Norm 

for the security about noise sources. So, establishing six significant locations in the FADU 

campus, the sound pressure was measured. It was used a type 1 sound level meter, with a range 

of 50 to 120 dB, for capturing only the sound pressure. 

The group of 15 students made measurements in the selected areas thus obtained 90 

different indicators. For practical reasons the group was subdivided into two: seven people were 

devoted to three sites, and 8 to the other three areas. It was registered measurements taken in 

each area for a period of five minutes, for each student. 

1.4. RESULTS. 

The entire series averages were obtained, performing a table summarizing the average of the 

measurements (see Table 1). The teacher previously presented in the classroom as an 

introduction to the exercise and how to do it, including a concise explanation of the sound level 

meter use. 

Table 1. Sound Pressure measurementes. 

Site. Sound Pressure. dB 

Exterior environment (far away site) 40 

Class room 67 

Library. 64 


We compare the results: 


Laboratories (under construction) 71 

Patio. 66 

Cafeteria. 73 

a) With the recommended values in the corresponding official Mexican standard, which is 68 dB 

from 6:00 to 22:00 and 65 dB from 22:00 to 6:00. 

b) With the levels recommended by the ILO (OIT). 

c) It was showed the graph produced by Beranek. Although not conducted a detailed acoustic 

study to develop positions on the curves plotted, the models allow students to view individual 

cases. 

It is noted that approximately 55-90 dB levels for intellectual labor, it is extremely painful, 

depending on sound frequency. 

Table 2. Sound Pressure levels. OIT (ILO). 

Effect on humans Sound Level dB. Sound source. 

Extremely harmful. 

Harmful. 

140 Jet engine unit. 

130 Riveter. 

120 

110 

100 Truck. 

90 

Pain threshold. 

Propeller aircraft. 

Rock drill. 

Chainsaw. 

Metalworking shop. 

dangerous. 80 Busy street (car traffic) 

Prevents talk. 70 Passenger car. 

60 Normal conversation. 



Irritant. 50 Talk quietly. 

1.5. CONCLUSIONS. 

40 

30 Whispers. 

Music played on radio at low 

volume. 

20 City quiet floor. 

10 

Whisper 

(vegetation). 

of leaves 

0 Hearing threshold. 

It was expressed by the group the distinction of sounds within the classroom and outside, the 

habit of perceiving external sounds as part of the learning environment, like a sound 

accompaniment. Especially noticed some discomfort because the dominant noise abroad, is to 

talk out loud. 

Regarding the Library, a combination of whispers, voices, noise from air conditioning 

equipment, produce anxiety and stress in the interior. Inside the cafeteria, conversation is difficult 

because of the noise. 

It was found that the materials used in buildings are not insulated or sound-absorbing. They 

are generally flat surfaces finished in painted cement, windows aluminum bearing. Also it was 

noted the classrooms air conditioners, as sources of noise. 

The exercise participants were sensitized on to consider ergonomics to achieve acoustic 

comfort in the spaces. 



2. ANALYSIS OF NEW DESIGN WORKSHOPS FUNITURE. 

2.1. INTRODUCTION. 

In Design learning, we consider the experience as a key factor. Since the products generated will 

be used by users, which we seeks to satisfy. Considering as example the model of Kolb (1984), 

the traditional tendency is to exercise the conceptualization phase mostly in institutions. Taking a 

side step, we invited a group of students to think about their academic work. Leaving aside the 

conceptualization only about ergonomics, was experienced and observed the use of furniture for 

design: a drawing desk prototype. 

2.2. OBJECTIVES. 

The student through observation, conceptualization and experimentation known anthropometric 

parameters. 

2.3. METHOD. 

Concepts were presented using anthropometry concepts and anthropometric tables, considering 

the scope and parameters of clearance, 



It was conducted a simple anthropometric prototype drawing board "Twins." Continued as a 

methodology: analytical observation of the furniture in situ and photographs, analysis of simulated 

activity in furniture-user interaction, considering heights from 1.65 to 1.83 meters, in both sexes. 

The positions were static. It took anthropometric reference tables published by Prado-Ávila (2007). 

Observations were made of the furniture itself and users interacting with the furniture. There were 

registered users feelings about. 

It was made a physical survey of the furniture. It consists of two drawing tables linked by a metal 

structure made with angles of different caliber and length. Among these was placed additional 

shelf. The seat is circular, wood, supported on a rotating structure, a wheel support flange at the 

base, allows translation moves, subject to a pivot (see Figure 1). At first glance it seemed 

interesting. 

Figure 1. “Twins” Drawing Board Prototype 

They were invited to use the furniture first requesting suit as they liked it. Later they went in static 

postures leading to experience and visualize the scope and clearance parameters, comparing 

dimensions between the object and the person. 


2.4. RESULTS. 

Discoveries: 


The table surface measures 70 x 80 cm which is insufficient to work in a drawing paper sheet, in 

addition, there is no support for the drawing tools on the table and they could slip. Other coating is 

also recommended as this would prevent the tape off the ground especially because the climate 

humidity. 

It is needed an convenient adjustable board angle; it was fixed. Since the scope distances ratio 

from the user's fingertips on the furniture, creates an awkward bend in the lower back and also 

high tension in the shoulders and neck. Raise the height floor-edge of the table (0.91 mts.) would 

help to correct posture, facilitating work with the spine erect. For 95th percentile person said he 

felt comfortable until he was told to straighten the back (see Figure 2). 

Figure 2. Working posture: "comfortable" and erect. Percentile 95. 

It is suggested that in addition to the intermediate table support, useful for holding backpacks or 

bags, adding a drawer along the front edge of the table in each module for drawing and painting 

tools at hand. It is recommended to add a table with pen holders, whose support is articulated, at 

least one of the vertical bars of the support desk, and free rotation adaptable to the scope of the 

user. This little shelf complement the user's work when to laptop use is needed. 



Regarding the seat, it was noted the absence of lumbar support (lower back), plus the hard, flat 

surface is uncomfortable after a while of use, is proposed to be padded, in a broader measure 

even for obese people, as default timber is still important to be configured curves of the buttocks 

and knee. It would be advisable to consider a footrest support tube in the bank, and the swivel 

seat is height adjustment screw. People in 5th percentile needed to rely on tip toes on the ground 

(see Figure 3). 

2.5. CONCLUSIONS. 

Figure 3. Sitting posture Percentile 5. 

Continuing the efforts to sensitize the academic population at the Faculty of Architecture, Design 

and Urbanism of the UAT, to update the application of ergonomics, we believe these tests 

successful. The training process needs to adapt to the dynamic professional. In the field of design, 

experience is gained from learning in workshops and classrooms. 

In the second exercise, underwent an apparent "comfort" in the use of furniture design from the 

anthropometric point of view, and recognized awkward postures. The experience generated 

improvement ideas. 


5. REFERENCES. 


Ávila Ch. R.- Prado L., L. – González M., L (2007). Dimensiones antropométricas. Población 

Latinoamericana. Universidad de Guadalajara. Centro Universitario de Arte, Arquitectura y 

Diseño. Centro de Investigaciones en Ergonomía. México. 

Beranek, Leo L. (1969). Acústica. Editorial Hispanoamericana. Buenos Aires. 

Fundación Mapfre (1997). Manual de Ergonomía. Editorial Mapfre. Madrd. 

NORMA Oficial Mexicana NOM-081-ECOL-1994. Límites máximos permisibles de emisión de 

ruido de las fuentes fijas y su método de medición. 

http://www.sma.df.gob.mx/tsai/archivos/pdf/12nom-081-ecol-1994.pdf 



ANALYSIS OF CORRELATION BETWEEN THE VARIABLES OF 

TEMPERATURE, STRENGTH AND CYCLES PER MINUTE TO 

PERFORM HORIZONTAL REPETITIVE MOVEMENTS OF THE WRIST 

Camargo Wilson Claudia 1, 2 , Rivera Valerio Abril A. 1 , 

Rubio Martinez Jesus R. 1 , de la Vega Bustillos Enrique J. 3 , 

López Bonilla Oscar R. 2 , Olguín Tiznado Jesús E. 1, 2 , 

1, 2 

Báez López Yolanda A. 

1 Department of Industrial Engineering - Engineering Faculty Ensenada. 

Autonomous University of Baja California. 

Km. 103 Highway Tijuana-Ensenada S/N 

Ensenada, Baja California. Zip code 22760 

ccamargo@uabc.edu.mx, abrilriva@hotmail.com, rodolforubio@yahoo.com 

2 Division of Posgrade and Research MyDCI- Engineering Faculty Ensenada. 



Ensenada, Baja California. 22760 

olopez@uabc.edu.mx, jeol79@uabc.edu.mx, yolanda@uabc.edu.mx 

3 Division of Postgraduate Studies and Research 

Technological Institute of Hermosillo 

Technological Avenue S/N 

Hermosillo, Sonora. 83170 


RESUMEN. La necesidad de proteger a los trabajadores contra las causas que provocan tanto 

enfermedades profesionales como accidentes de trabajo es una cuestión indudable. De ahí el 

interés de analizar el comportamiento que tienen las variables de temperatura en el área de la 

muñeca, la fuerza y los ciclos por minuto ello al llevar a cabo movimientos repetitivos horizontales 

de la muñeca, los cuales son comúnmente encontrados en los lugares de trabajo. Objetivos: 

Correlacionar las variables de temperatura, fuerza y cantidad de movimientos por minuto cuando 

se trabaja con el movimiento repetitivo horizontal en el área de la muñeca. Delimitación del 

problema: Se simuló la jornada laboral de ocho horas con dos operadores (hombre y mujer) 

ejerciendo los movimientos horizontales, en las instalaciones de la Facultad de Ingeniería 

Ensenada de la Universidad Autónoma de Baja California. Metodología: Se simuló la jornada 

laboral con dos operadores ejerciendo los movimientos horizontales, para ello se realizó el 

registro de la temperatura en el área de la muñeca derecha (termógrafo sensorial Sköll), la fuerza 

del individuo (dinamómetro de torsión de muñeca Baseline) y los ciclos por minuto, los tres 



registros mencionados anteriormente se realizaban cada diez minutos. Resultados: Los 

resultados obtenidos fueron los siguientes: en el operador 1, se encontró correlación en los ciclos 

por minuto contra temperatura y contra fuerza; además el máximo en: la temperatura fue 

35.93°C, la fuerza 82 kg y los ciclos por minuto fue de 138 movimientos y el mínimo en: la 

temperatura fue 28.11°C, la fuerza 36 kg y los ciclos por minuto fue de 93 movimientos; en el 

operador 2 la correlación que se manifestó fue la de ciclos por minuto contra temperatura; 

además el máximo en: la temperatura fue 34.87°C, la fuerza 63 kg y los ciclos por minuto fue de 

140 movimientos; y el mínimo en: la temperatura fue 29.38°C, la fuerza 32 kg y los ciclos por 

minuto fue de 100 movimientos. Conclusiones: En base a este estudio se concluye que: existe 

correlación entre temperatura contra los ciclos por minuto y entre la fuerza contra ciclos por 

minuto; asimismo que no existe correlación entre temperatura y fuerza. 

Palabras clave: Temperatura, Fuerza, Ciclos por minuto. 

ABSTRACT. The need to protect workers against the causes of occupational diseases and accidents 

is a no doubt question. Hence the interest to analyze the behavior with variables in temperature in 

the area of the wrist, strength and cycles per minute, that to perform horizontal repetitive 

movements of the wrist, which are commonly found in workplaces. Objective: The objective was to 

correlate the variables of temperature, strength and number of movements per minute when working 

with horizontal repetitive movement of the right hand wrist area. Delimitation of the problem: It was 

simulated a working day of 8 hours with 2 operators (man and women) exerting horizontal 

movements, on the installations of the Faculty of Engineering Ensenada of the Autonomous 

University of Baja California. Methodology: It was simulated a working day with two operators 

exerting horizontal movements, and for this making the temperature recorder in the area of the 

right hand wrist (sensorial thermograph Sköll), the strength of the operator (dynamometer wrist- 

twisting Baseline) and cycles per minute, the three mentioned records were made every ten 

minutes. Results: The obtained results were: in the operator 1 ,there was a correlation in cycles 

per minute against temperature and against strength, besides the maximum in: temperature was 

35.93°C, strength was 82 kg and cycles per minute was 138 movements and the minimum in: 

temperature was 28.11°C, strength was 36 kg and cycles per minute was 93 movements; in the 

operator 2: there was a correlation in cycles per minute, besides the maximum in: temperature 



was 34.87°C, strength was 63 kg and cycles per minute was 140 movements and the minimum in: 

temperature was 29.38°C, strength was 32 kg and cycles per minute was 100 movements. 

Conclusion: On based on this study the conclusion was: correlation exists between temperature 

against cycles per minute and strength against cycles per minute; and there is no correlation 

between temperature and strength. 

Keywords: Temperature, Strength, Cycles per minute. 


The need to protect workers against the causes of occupational diseases and accidents is a 

question no doubt. All sources of work should carry out activities aimed at the prevention of 

occupational hazards, with consequent advantages in production and productivity, achieving 

greater social welfare, which is reflected in the economy of the company. The ergonomic 

approach is to design products and work to adapt them to the people and not vice versa. The logic 

that uses the ergonomics is based on the principle that people are more important than the 

objects or production processes; and therefore, cases where it arises any conflict of interest 

between people and things, should prevail people (Tortosa et al., 1999). 

Ergonomic hazards have been an issue to consider, for injuries caused to workers in work areas. 

For industry it is always important the health of the workers, because by avoiding the DTA's in it 

reduces their costs for disabilities, absenteeism and more importantly for investors. 

Musculoskeletal injuries are disorders characterized by an abnormal condition of muscle, tendons, 

nerves, vessels, joints, bones or ligaments, which results in impairment of motor or sensory 

function caused by exposure to risk factors: repetition, strength, inappropriate postures, contact 

stress and vibration (Sinclair, 2001). For example, some of the injuries and illnesses common in 

the wrist area causing repetitive or poorly designed work are: 

• Tenosynovitis: is an inflammation of the synovial capsule, this is the sheath that covers 

tendons. Tenosynovitis can occur in any tendon with a synovial sheath. However, most often 



occurs in the hand, wrist or foot. Most cases of tenosynovitis are caused by injury, infection, 

twisting, repetitive movement as: operate a computer, working on an assembly line, the cashier of 

a bank, sewing, playing musical instruments like violin or guitar 

(http://nlmnih.gov/medlineplus/ency/article/001242.htm) 

• Ganglia: it is a cyst in a joint or tendon sheath, usually in the back of the hand or wrist. 

(http://www.itcilo.it/actrav/osh_es/módulos/ergo/ergoa.htm) 

• Epicondylitis: is an inflammation of muscle attachments at the epicondyle of the elbow, the 

pain may appear in the muscles of the forearm and wrist. The causes that provoke are: Task force 

loading and repeatability, often in stressful jobs such as carpentry, plastering or bricklaying. 

(http://www.tiroriojano.com/lesiones/EPICONDILITIS.htm) 

• Crimping finger: is an inflammation of the tendons and / or tendon sheaths of the fingers. 

By use of air guns or staplers (International Labor Organization, 2004). 

• Carpal Tunnel Syndrome: presented by the type of horizontal repetitive movement and the 

disease that affects people. It is a Repetitive Strain Injury better documented, currently classified 

as compensable occupational disease in many countries. This syndrome affects the median nerve 

(one of the principal nerve in the wrist). Extreme cases can lead to permanent disability due to the 

absolute inability to flex the wrist to perform tasks as simple as operating a computer or holding an 

object in the hand. Affects workers who process meat or poultry, supermarket cashiers who use 

electronic scanners, the use of vibrating hand tools. 

In the United States with this syndrome each worker loses more than 30 working days, a figure 

higher than absenteeism from amputations and fractures. It has been estimated annual cost of 

these lesions in more than 100 million dollars (International Labor Organization, 2004). 

These injuries and illnesses caused by workplace tools and poorly designed or inappropriate 

usually develop slowly over months or years. However, a worker wills usually signs and symptoms 

for a long time to indicate that something is wrong. For example, the worker will be uncomfortable 

while doing their work or feel pain in muscles or joints once home after work. You can also have 

small muscle twitches for some time. It is important to investigate the problems of this kind, 

because what may begin with a mere inconvenience in some cases can end in injury or disease 

that severely incapacitated workers. 



Employees often have no choice and are forced to adapt to poorly designed work conditions that 

can seriously injure the hands, wrists, joints, back or other body parts. In particular, injuries can 

occur due to: 

• The repeated use over time vibrating tools and equipment, 

• Tools and tasks that require turning the hand movements of the joints, for example the work 

performed by many mechanics; 

• The application of strength in a forced position; 

• The application of excessive pressure on parts of the hand, back, wrists or joints. 

All of them will generate absenteeism and each day of absenteeism for health reasons is a cost. A 

day lost disability implies a direct cost and indirect. (Beevis, 2003; Derango, 2002; Hendrick, 

2003). 

This study aims to correlate the variables of temperature, strength and cycles per minute all this 

by repetitive horizontal movements, applied to a man and a woman which are commonly found in 

workplaces. 

The benefit of this study is that it will have social impact, economic and scientific: 

• The social impact, achieving avoid injury to the worker and it will be productive in your work area 

and have better social welfare. 

• The economic impact, because if the DTA's are avoided in work areas will reduce annual costs 

by the company. 

• The scientific impact, because it is a sensorial thermography technique actually not used. 

1.1 Related Articles 

Gold et. al., (2004) in the article entitled "Infrared Thermography for Examination of skin 

temperature in the dorsal hand office workers", identified differences between skin temperatures 

between 3 groups of office workers through dynamic thermography, we have the experiment when 

writing computer keyboard for 9 minutes at a time. It highlights the temperature of testing room as 

an important factor. 



Ming, et. al., (2005) in the article entitled "Sympathetic pathology evidence by hand thermal 

anomalies in carpal tunnel syndrome", the aim of this study was to classify the pathology 

compassionate in carpal tunnel syndrome and the use of infrared thermography. Exercise was 

conducted in which subjects were kept at room temperature between 22 and 25˚C for 15 minutes 

at room temperature are highlighted in the testing room as an important factor. 

Zontak, et. al., (1998) in the article entitled "Dynamic Thermography: Analysis of hand 

temperature During exercise", the aim of this study was to characterize the effect of exercise and 

responses in the skin temperatures due to controlled levels of exercise temperature conditions, 

making a ergonomics bicycle. 

Tchou, et. al., (1991) in the article entitled "Thermographic observations in unilateral carpal tunnel 

syndrome: Report of 61 cases", its purpose was to characterize the effect of exercise and 

responses in the skin temperatures, as an exercise the balance of hands for 15. 

Kyeong-Seop, et. al., (2006) in the article entitled "Infrared Thermography in Human Hand" 

estimated temperature conditions that could cause mental stress. Dipping both hands in a 

container of water at a temperature of 3˚C. 

Ferreira, et. al., (2007) in the article titled "Exercise-Associated Thermographic Changes in Young 

and Elderly Subjects", determined thermographic temperature changes associated in elderly and 

young people, doing knee bends with a weight of 1 kilogram added to the same for 3 minutes. 

This study presents the following objectives: 

2. OBJECTIVE 

• To correlate the variables of temperature, strength and number of movements per minute when 

working with horizontal repetitive movement of the right hand wrist area. 

• To show the application of sensorial thermography. 

• To develop preliminary test emulating a manufacturing industry repetitive operation. 




This study was performed at the facilities of the Autonomous University of Baja California from 5 

to September 11, 2009. The study involved a man and a woman using the dominant hand (both 

being right-handed), which are healthy people with age 24 being the average age of the 

economically active population, students in undergraduate and in unskilled industrial manual 

material handling. 

To achieve the objective of this study, was simulated eight-hour workday to exercise horizontal 

repetitive movements as shown in Figure 1. 

Figure 1: Horizontal repetitive movement 

The record was made to register the temperature in the area of the wrist with a sensorial 

thermograph Sköll for each operator placed at the height of the wrist in the right hand figure 2, the 

strength of the individual with a dynamometer wrist-twisting Baseline (Figure 3) and cycles per 

minute. 

Figure 2: Sensorial Thermograph Sköll 



Figure 3: Dynamometer wrist-twisting Baseline 

It is noteworthy that the three records mentioned above were made with a timer (Figure 4) every 

ten minutes. 

Figure 4: Timer 

4. RESULTS 

The table 1 and 2 are shown in the data from the experiment with horizontal repetitive movement 

of the operator 1 and the operator 2 within 7 days. In the second line of the both tables: 1 means 

cycles per minute, 2 means strength and 3 means temperature. 



Table 1. Data concentrate of the operator 1 in the 7 days. 



Table 2. Data Concentrate of the operator 2 in the 7 days. 


4.1 Analysis of correlation. 


In the figure 1 is shown the correlation between temperature and strength in the 7 days, where r is 

0.041. As r is 0.041 and 0.119 which is lower than the critical value we conclude that H0 is not 

rejected as there is insufficient evidence to conclude that there is a significant linear correlation. 

Figure 1: Correlation between Temperature (°C) and 

Strength (Kg) of the operator 1 in the 7 days. 

In the figure 2 is shown the correlation between cycles per minute and temperature in the 7 

days, where r is 0.292. As r is 0.292 and 0.119 which is greater than the critical value we conclude 

that there is a significant linear correlation, and H0 is rejected. 

Figure 2: Correlation between cycles per minute and 

temperature (°C) of the operator 1 in the 7 days. 



In the figure 3 is shown the correlation between cycles per minute and Power in the 7 days, with r 

of 0.266. As r is 0.266 and 0.119 which is greater than the critical value we conclude that there is 

a significant linear correlation, and H0 is rejected. 


strength (Kg) of the operator 1 in the 7 days. 

The table 3 is shown the results obtained from the variables of the operator 1 in the 7 days. 

Table 3: Results of the Operator 1 variables in the 7 days. 

The table 4 is shown the maximum and minimum values of the variables of temperature, strength 

and cycles per minute generated by day to perform horizontal repetitive movement of the operator 

1. 



Table 4: Results of the operation range of the operator 1 per day. 

In the figure 4 is shown the correlation between temperature and strength in the 7 days, being r - 

0.072. As r is -0.072 and 0.119 which is lower than the critical value we conclude that H0 is not 

rejected as there is insufficient evidence to conclude that there is a significant linear correlation. 

Figure 4: Correlation between Temperature (°C) and 

Strength (Kg) of the operator 2 in the 7days. 

In the figure 5 is shown the correlation between cycles per minute and temperature in the 7 days, 

with r -0.172. As r is -0.172 and its absolute value is 0.172 and 0.119 which is greater than the 

critical value we conclude that there is a significant linear correlation, and H0 is rejected. 




temperature (°C) of the operator 2 in the 7 days. 

In the figure 6 is shown the correlation between cycles per minute and Strength in the 7 days, 

being r -0.002 As r -0.002. and 0.119 which is lower than the critical value we conclude that H0 is 

not rejected as there is insufficient evidence to conclude that there is a significant linear 

correlation. 


Strength (Kg) of the operator 2 in the 7 days. 



The table 5 is shown the results obtained from the operator 2 variables in the 7 days. 

Table 5: Results of the operator 2 variables in the 7 days. 

The table 6 is shown the maximum and minimum values of the variables of temperature, strength and 

cycles per minute generated by day to perform horizontal repetitive movement in the operator 2. 

Table 6: Results of the operating range of the operator 2 per day. 


In the present study fulfilled the objective of correlating the variables temperature, strength, and 

cycles per minute that are manifested in the wrist area of the dominant hand (in this case the 

operators was the right hand) with horizontal repetitive movements during working day within a 

week. 

On based on this study the results were as follows: the operator 1 ,there was a correlation in 

cycles per minute against temperature and against strength, besides the maximum in: 

temperature was 35.93°C, strength was 82 kg and cycles per minute was 138 movements and the 

minimum in: temperature was 28.11°C, strength was 36 kg and cycles per minute was 93 

movements; the operator 2: there was a correlation in cycles per minute, besides the maximum in: 

temperature was 34.87°C, strength was 63 kg and cycles per minute was 140 movements and the 

minimum in: temperature was 29.38°C, strength was 32 kg and cycles per minute was 100 

movements. 



The conclusion was: correlation exists between temperature against cycles per minute and 

strength against cycles per minute; and there is no correlation between temperature and strength. 

6. REFERENCES 

Beevis, D., (2003). Ergonomics-Costs and Benefits Revisited. Applied Ergonomics 34: 491-496. 

Derango, K. and Franzini, L., (2002). Economic Evaluations of Workplace Health Interventions: 

Theory and Literature Review. In Handbook of Occupational Health Psychology, Ed 

Washington D.C. American Psychological Association. 

Ferreira, J., Mendonça, L.C., Nunez, L.A., Andrade, A.C., Rebelatto J.R., and Salvini, T. (2007). 

Exercise-Associated Thermographic Changes in Young and Elderly Subjects, Federal 

University of Saint Carlos. Physics’ Institute of Saint Carlos, Sao Paulo University, Brazil. 

Gold E. J., Cherniack M., Buchholz B., (2004). Infrared Thermography for examination of skin 

temperature in the dorsal hand office workers, Eur J. Apply Physiol 93: 245-251. 

Hendrick, H.W., (2003). Determining the Cost-Benefits of Ergonomics Projects and Factors that 

lead to their Success. Applied Ergonomics 34: 419-427. 

International Training Center of the International Labor Organization. ITCILO: Home page. 

http://www.itcilo.it/actrav/osh_es/módulos/ergo/ergoa.htm 

Kyeong-Seop, K., Shin, S.W., Yoon, T.H., Kim, E.J., Lee, J.W. and Kim, I.Y. (2006). Infrared 

Thermography in Human Hand”, School of Biomedical Engineering, Chungju, Korea. 

Ming, Z., Zaproudina, N., Siivola, J., Nousiainen, U., Pietikainen S., (2005). Sympathetic 

pathology evidenced by hand thermal anomalies in carpal tunnel syndrome, ISP 

Pathophysiology: 137-141. 

International Labor Organization (2004). Labor Productivity in Latin America, is the same as 20 years 

ago, Magazine of occupational panorama of the OIT. 

Sinclair, D.T. and Graves, R.J. (2001). Feasibility of Developing a Simple Prototype Decision Aid 

for the Initial Medical Assessment of Work Related Upper Limb Disorders. University of 

Aberdeen. Department of Environmental & Occupational Medicine. Hse Books. 

Shooting Sport Club La Rioja, Shooting Sport Club La Rioja Home page: 

http://www.tiroriojano.com/lesiones/EPICONDILITIS.htm 

Tchou, S.F., Costich, J.C. Burguess, R., Lexington, K.Y. and Wexler C. (1992). Thermographic 

observations in unilateral Carpal Tunnel Syndrome: Report of 61 cases, The Journal of the 

hand surgery 17A: 631-637. 

Tortosa, L. and Garcia, C., Page, A. and Ferreras, A. (1999). Ergonomics and disability. Institute 

of Biomechanics of Valencia (IBV), Valencia. ISBN 84-923974-8-9. 

U.S. National Library of Medicine and National Institutes of Health. Medical Encyclopedia: Home 

page. http://nlm.nih.gov/medlineplus/ency/article/001242.htm 

Zontak, A., Sideman, S, Verbitsky, O. and Beyar, R., (1998). Dynamic Thermography: Analysis of 

hand temperature, Annals of Biomedical Engineering, Vol. 26, 988-993. 



Temperature analysis on wrist surface due repetitive movement tasks using 

Sensorial Thermography to find out a possible pathology for a CTD 

Ordorica Villalvazo Javier 1,2 , Camargo Wilson Claudia 1,2 , De la Vega Bustillos Enrique 3 , 

Olguín Tiznado Jesús E. 1, 2 , López Bonilla Oscar R. 2 , Limón Romero Jorge 1, 2 . 

1 Department of Industrial Engineering - Engineering Faculty Ensenada. 




villalvazo@uabc.edu.mx, ccamargo@uabc.edu.mx 

2 Division of Posgrade and Research MyDCI- Engineering Faculty Ensenada. 




jeol79@uabc.edu.mx, olopez@uabc.edu.mx, j.limon@uabc.edu.mx 

3 Division of Postgraduate Studies and Research. 

Technological Institute of Hermosillo. 

Technological Avenue S/N 

Hermosillo, Sonora. 83170 


Resumen: A través de la historia se puede observar como la temperatura ha sido un indicador 

importante para determinar cambios importantes en los ecosistemas del planeta, en la resistencia 

de materiales para el diseño de nuevos productos, y también en el campo de la medicina 

analizando por ejemplo, fiebres ocasionadas por infecciones provocadas por nuevas 

enfermedades. A través de este estudio de las variaciones de temperatura corporales provocadas 

en los nervios del área de la muñeca generando la reducción en la habilidad muscular para 

realizar el trabajo debido a movimientos repetitivos, lo cual nos puede llevar a entender la 

patología de un Desorden de Trauma Acumulado (DTA), tomando en cuenta la termografía 

sensorial, ya que no es invasiva para el ser humano, que facilita la recolección y manipulación de 

los datos. Objetivos: Analizar cambios en los patrones de temperatura generados en el área de la 

muñeca. Mostrar la factibilidad de la aplicación de la termografía sensorial. Recabar información 

acerca de las variables no laborales (edad, género, peso, entre otras) y laborales (repetitividad, 

temperatura del área de trabajo). Desarrollar las pruebas preliminares emulando la operación 

ejecutada en la industria y que involucra los movimientos repetitivos. Identificar los puntos de 

estrés máximo alcanzados durante un periodo de operación describiendo síntomas detectados. 



Delimitación del problema: Este estudio se realizó con sólo un estudiante de la Facultad de 

Ingeniería Ensenada de la UABC. Metodología: Se seleccionó a un estudiante en condiciones 

físicas normales, quien realizó pruebas en un laboratorio aplicando el protocolo para el 

experimento haciendo uso de la termografía sensorial. Resultados: Las temperaturas máximas 

alcanzadas en ambas muñecas fueron en periodos de operación en tiempos muy similares. Se 

detectaron molestias en el hombro derecho en el rango donde se identifican las temperaturas 

más altas durante el proceso de la operación para ambas muñecas. A través del ajuste de una 

ecuación de tercer orden fue posible explicar el comportamiento de las temperaturas. 

Conclusiones: Por medio de la termografía sensorial es posible analizar patrones de temperatura, 

ligarlos a una estadística creando la posible patología de un DTA y que pudieran servir en futuras 

investigaciones. 

Palabras clave: Termografía sensorial, DTA, temperatura. 

Abstract: Through history we have observed how temperature has been an important factor to 

take in account in order to detect many several climatic changes in planet. This factor has been 

deeply studied in weather changes, material resistance for the designing of new products, and 

also, in the medicine field obtaining remarkable results studying fiber causes in multiple diseases, 

most of them related to infections. This research aimed at evaluating body temperature variations 

on wrist surface that can cause muscle disability and weakness due repetitive movement tasks. 

The work contributes to discover a possible Cumulative Trauma Disorder (CTD) pathology using 

sensorial Thermography as an innovative and dynamic tool, since this is not a non-invasive 

technique it means that can not cause any damage on humans. It is a powerful tool also, because 

allow investigators to manipulate data and import or export them to statistics programs. 

Objectives: Analyze temperature pattern changes and show up the feasibility of the sensorial 

thermography. Collect information about different kind of variables that may affect the study, like 

age, gender, weight, height, and others like repetitiveness and work area temperature. Perform 

preliminary test emulating an operation highly repetitive in the textile industry. Identify maximum 

stress points while preliminary test is taking place, and at the same moment detect key symptoms. 

Methodology: An Industrial engineering student in good shape was selected to perform the 

repetitive task in a lab by following the experiment protocol and using sensorial thermography. 



Results: Maximum temperatures in both wrists were detected in similar periods of time. The 

student showed pain symptoms in right shoulder while doing the task. It was detected while the 

maximum temperature range was reached in both wrists. By adjusting a third order equation it 

was possible to explain the temperature behavior. Conclusions: Through sensorial thermography 

is possible to analyze temperature pattern and link them to statistics creating a possible CTD 

pathology that could help in future researches. 

Keywords: Sensorial thermography, CTD, temperature. 


The highly repetitive activities are a disease that in nowadays affect thousands of people 

developing several cumulative trauma disorders. In many times this kind of disorders are confused 

with other kind of diseases. The cumulative trauma disorders cause damages on body tissues due 

to excess motion periods. It can be developed through pass of the time. Furthermore, today, the 

DTA’S are well known as an industrial epidemic causing a periodic disability. The experimentation 

was based on temperature analysis generated on wrist area of one subject, which is the area 

where the carpal tunnel syndrome begins. A repetitive movement simulation consisted in an 

operation emulated from a local textile industry. The study was taken using sensorial 

thermography. 

The thermography is a non invasive technique without biologic hazard. It detects, measures, and 

converts invisible, surface body heat into visible display which is the photographed or videotaped 

as a permanent record. This type of thermography it is the one we call infrared thermography 

(Feldman al., 1991). The digital sensorial thermography it is different from the infrared one, 

because it is widely used to look for temperature patterns on skin surface through sensor contact 

(Zontak et al., 1998). 



This technology was born while the submarine thermographs a long time ago were developed to 

measure underwater temperatures. It has many applications such as oceanography, marine 

ecology, industry, and many others (Lopez, 1992). 

This study arose from three important questions, what is the subject temperature behavior during 

the motion? What is the relationship between pain symptoms and temperature data? What are the 

max stress points? A close examination of the literature shoes that no study has been devoted to 

these problems emulating a motion executed in the textile industry in order to analyze cutaneous 

temperatures. 

However a swimming study was carried out with a professional swimmer in a pool where the 

swimmer practiced several swimming styles, so researchers could analyze the temperatures after 

each swimming style (Zaidi et al., 2007). 

The Study was carried out in a closed room where the temperature was a relevant parameter. We 

use a home heater to try to control the temperature, because according with the literature, the 

most useful temperature parameter in experimentations of this kind is between 20 and 25 degrees 

(E.Y.K, N.G. et al., 2005). 

It is advisable to specify that the present work is not a statistical study. The results obtained in this 

study cannot be considered to have a universal character since only one subject was taken into 

account for our experimentation. However we are doing many test with more subjects at the 

campus to make temperature behavior inferences. The objectives in this preliminary 

experimentation were to show the applications of the sensorial thermography on one hand, and on 

the other hand, to show the maximum temperature stress points. 

This Study presents the following objectives: 

2. OBJETIVES 

• To analyze temperature pattern changes generated on wrist area. 



• To show the application of sensorial thermography. 

• To collect information about subject gender, age, mass and others. 

• To collect information about repetitive cycles and temperature working area. 

• To develop preliminary test emulating a textile industry repetitive operation. 

• To identify maximum stress points during the operation period and to describe symptoms 

detected. 

3.1 The subject 

3. METHODOLOGHY 

The subject taking in part in this study is a subject in good shape. The principal anthropometric 

characteristics of the subject are summarized in table 1. 

Table 1. Anthropometric data for the subject 

Age Height 

Mass 

(m) 

(Kg) 

Subject 29 1.63 60 

3.2 Equipment and data analysis 

All the cutaneous temperatures were taken using a sensorial thermograph Sköll with a 

temperature range of 0˚C – 40˚C, a precision of ±.3˚C, and a resolution of 1 degree, a 

microporous tape (Lopez, 1992), a laptop (COMPAQ Intel Pentium Dual Core), a home heater. 

Programming the thermographs was possible using a program called Akela. Also a statistical 

program was used for data analysis (Minitab 15) and Microsoft Excel 2007. 

3.3 Protocol 

Subjects were asked to refrain from intense exercise, caffeine, smoking, alcohol and smoking for 

20 minutes prior to the experiment (Gold et al., 2004) and (Gold et al., 2009) because smoking 



could produce a massive reduction of body temperature and alcohol a raise of body temperature. 

Previous studies have demonstrated that the corporal temperature stabilization takes about 20 

minutes due to a reduction on body metabolism (E.Y.K NG y Sim en E.Y.NG et al., 2008). 

Having the opportunity to use a home heater we warmed up the room temperature for the 

experiment between 20-25 degrees (E.Y.K NG et al., 2005), Once we warmed up the room, the 

participant was seated in an ergonomic chair with arm rest and then stick the sensorial 

thermographs in both wrist, close to the median nerve region. After that, the subject was asked to 

rest both arms in a flatbed at the ribs height (Kroemer et al., 2001) for about twenty minutes. The 

next step in the experiment protocol was to simulate a highly repetitive operation executed in the 

textile industry for about 3.5 hours, this period of time representing the longest period of the 

workday. The operation involved several movements like reach, take, place and many others. 

Several pain symptoms were identified during the experiment. Finally, the sensor thermographs 

were removed from both wrist and then analyze the results. 

4. RESULTS 

The results of all pain symptoms detected during the experiment developed are shown in table 2. 

These anomalies were given off by the subject while he was doing the repetitive task. It was so 

important to write down the hour, minute and second, so we could link this info to the 

temperatures. 

Preliminary 

1 

Preliminary 

2 

Preliminary 

3 

Preliminary 

4 

Table 2. Anomalies detected in the operator 

Right 

shoulder 

pain 

x 

Left 

shoulder 

pain 

Lower 

back 

pain 

Upper 

back 

pain 

Right 

wrist 

pain 

x x x x x 

x x 

x x x x 

Right 

palm 

pain 


4.1 Preliminary test 1 


The corresponding temperature behavior is shown in Figure 1 and 2. If we compare both figures 

we can see that both temperature behaviors in both wrists are very but very similar. Three similar 

characteristics were identified as a result: 

• The temperatures in both writs (maximum stress points) were 33.44˚C and 32.921˚C, and were 

reached at similar periods of time, 11:41:14 and 11:49:28 (h:m:s). 

• The anomalies in right shoulder started to being shown by the person at the range where were 

the highest temperature levels, while doing the operation using both wrists. 

• The most aggressive projection of the temperature was approximately at 11:30 and 12:00 in 

both wrists. 

In both cases the subject beated the pain symptoms on right shoulder, this happened when the 

most aggressive projection began to appear, approximately at 11:40. Then at the same time the 

temperature projection became less aggressive and began a tendency of decrease. 

On the other hand, by adjusting a third order equation it was possible to explain the temperatures 

of the person with a coefficient of determination of 91.1% for the left hand wrist and 87.7% for the 

right hand wrist. 

Figure 1. Adjustment of the curve of left hand wrist 



Figure 2. Adjustment of the curve of right hand wrist 



we can see that both temperature behaviors in both wrists are very similar has shown in the 

previous preliminary test. The maximum time of stress of the hands was to similar one from each 

other, and based on this we could say the following important points: 

The maximum stress points were reached in similar times in both wrists. On left hand wrist at 

12:48:24 and the temperature was 34.276˚C and on right hand wrist was 12:48:39 and the 

temperature was 34.154˚C. Factors like temperature and time were similar. 

Many anomalies were detected on right wrist around 12:33:30 and after one hour on right 

palm, and at the same time on lower back. 

Anomalies on right shoulder were detected when the maximum temperature stress point was 

reached. 

On the other hand it was possible to adjust a polinomial third order equation that represents the 

subject temperature behavior and as a result a coefficient of determination of 80.5% for the left 

hand wrist and 86.8% for right hand wrist. 







we can see that both temperature behaviors in both wrists are very similar has shown in the 

previous preliminary test and. The maximum time of stress of the hands was similar one from 

each other, and based on this we could say the following important points: 



The maximum stress points were reached in similar times in both wrists. On left hand wrist 

at 14:11:40 and the temperature was 33.481˚C and on right hand wrist was 14:13:22 and 

the temperature was 33.313 ˚C. Factors like temperature and time were similar. 

A lower back pain was identified around 12:55:35 and close to the end of the 

experimentation a pain on right hand wrist around 14:54:10. 

Anomalies on right shoulder were detected when the maximum temperature stress point 

was reached. 

On the other hand it was possible to adjust a polinomial third order equation that represents the 

subject temperature behavior and as a result a coefficient of determination of 90.8% for the left 

hand wrist and 94.5% for right hand wrist. 







we can see that both temperature behaviors in both wrists are similar has shown in the previous 

preliminary test and. The maximum time of stress of the hands was to similar one from each other, 

and based on this we could say the following important points: 

The maximum stress points were reached in similar times in both wrists. On left hand wrist 

at 12:52:14 and the temperature was 33.686˚C and on right hand wrist was 13:03:53 and 

the temperature was 33.114˚C. Factors like temperature and time were similar. 

A lower back pain was identified around 12:55:35 and close to the end of the 

experimentation a pain on right hand wrist around 14:54:10. 

Anomalies on right shoulder were detected during the period when the temperature began 

to decrease around 13:42:52. Also a pain on right palm was identified around 14:13:43. 

At the end of the test a pain on left shoulder was identified around 3:52:40 and also the 

pain on right shoulder increased in a several way, this occurred around 3:56:36. 

On the other hand it was possible to adjust a polinomial third order equation that represents 

the subject temperature behavior and as a result a coefficient of determination of 97.3% for 

the left hand wrist and 95.6% for right hand wrist. 


4.5 Averages 




Taking in account the maximum temperatures reached in the experiment stress points of all the 

preliminary test of both hand wrists, we obtained averages for each hand wrist, and the equation 1 

shows how to calculate the averages: 


y 

n 

∑ 

i= 

= 1 

n 

y 

i 


We found out, and based on having similar temperature patterns and stress point periods that 

averages were similar too. The average temperature for left hand wrist was y = 33. 

72 ˚C and 

y = 33. 

38˚C 

for the right hand wrist. 


A preliminary experimental test was undertaken on one hand, for studying the feasibility of using 

sensorial thermography on the analysis of repetitive tasks, and on the other hand to identify the 

maximum stress point, behavior and temperature patterns as a result of the activity. In particular, 

this study shows that the use of the sensorial thermography is appropriate in order to detect 

temperature patterns. It is remarkable to mention that in all the test the temperature patterns were 

very similar in both hand wrists, independently of the dominant hand of the subject. The 

temperature patters were similar for all the tests, but changing its behavior during the days. The 

same conditions were taking in account for the entire tests, including the room temperature as the 

main element. 

On the other hand it was possible to adjust a polinomial third order equation for each test that 

represents the subject temperature data behavior and as a result a coefficient of determination to 

represent the level of the curve adjustment to data. 

6. RECOMENDATIONS 

One should recall to this conclusions cannot be considered as universal as far as only one 

subject, a subject in good shape, took part in this study. Nevertheless, the conclusions make us 


(1)


think of considering a statistical study taking in part more subjects (men and women), to verify if 

the temperature patters of several subjects are linked in same way. 

7. REFERENCES 

E.Y.K, N.G. and E.C., K.E.E., (2008). Advanced integrated technique in breast cancer 

Thermography, Journal of Medical Engineering & Technology, Vol. 32, 103-114. 

Feldman, F., (1991). Thermography of the hand and wrist: Practical applications, Hand Clinics, 

Vol. 7, No.1. 

Gold, J., Cherniack, M., Hanlon, A., Dennerlein, T., Dropkin, J., (2009). Skin temperature in 

dorsal hand of office workers and severity of upper extremity musculoskeletal disorders, Int. 

Arch. Occup. Envior. Health, 82: 1281-1292. 

Gold, J., Cherniack, M., Buchholz, B., (2004). Infrared Thermography for examination of skin 

temperature in the dorsal hand office workers, Eur J. Apply Physiol 93: 245-251. 

Kroemer, E., Kroemer, H., Kroemer. K., (2001). “Ergonomics: How to design for ease and 

efficiency”, second edition, Prentice Hall, ISBN 0-13-725478-1, 97-113. 

Lopez, R., (1992). Oceanologic Research Institute, Autonomous University of Baja California. 

Submarine digital thermograph, Develop and instrumentation, Vol. 3 No.2, 1992 

Puig A.A., (1993). Smoking influence in the variations of biochemical, physiological and 

performance parameters, Barcelona, Spain. 

Zaidi H., TaÏar R., Fohanno S., Polidori G., (2007). The influence of swimming type on the skintemperature 

maps of a competitive swimmer from infrared Thermography, Acta of 

Bioengineering and Biomechanics, Vol. 9, No.1. 

Zontak Alla, Sideman Samuel, Verbitsky Oleg, Beyar Rafael, (1998). Dynamic Thermography: 

Analysis of hand temperature, Annals of Biomedical Engineering, Vol. 26, 988-993. 



VIBRATION STUDY TO IMPROVE STRIPPING OPERATION 

IN A LITOGRAPHICS COMPANY 

Mario Ramírez Barrera ¹, Jorge Valenzuela Corral ¹ 

Athenea Núñez Sifuentes ˚ 

¹ Industrial and Manufacturing Engineering Department 

˚ Student from Institute of Engineering and Technology 

Universidad Autónoma de Ciudad Juárez 

mramirez@uacj.mx , jvalenzu@uacj.mx 

vain8109@gmail.com 

RESUMEN: En una empresa dedicada a la impresión y elaboración de cajas y precisamente en 

la operación de striping. o desbarbe que es donde se cortan los excesos o sobrantes de las cajas 

después del proceso de sauje (marcado o preformando por medio de prensas), nos encontramos 

que en esta operación los trabajadores se encuentran expuestos a los mas importantes factores 

de riesgo ocupacional como son frecuencia, esfuerzo energético y mala postura, pero sobre todo 

a una sobreexposición de vibración producida por un roto martillo neumático utilizado para quitar 

el cartón sobrante o la rebaba de las cajas durante la operación de striping, y es por esto que en 

esta investigación se analizo el uso de dicha herramienta y se vio que al utilizar un aislante 

adecuado en el mango del roto martillo neumático y los guantes ergonómicos anitimpacto y 

antivibración en vez de los de algodón que actualmente proporciona la empresa se reduce al 

máximo el estrés de trabajo producido por la vibración, así como también al utilizar el equipo de 

protección personal consistente en tapones auditivos, mascarillas y zapatos de seguridad se 

mejora considerablemente el entorno del operador y así se podrá reducir considerablemente el 

riesgo de adquirir una enfermedad profesional generada por el tipo de trabajo requerido por el 

proceso de fabricación del producto. 

Palabras Clave: Vibracion, Equipo de protecion personal. 

ABSTRACT:The comparative study was made in a company dedicated to fabricate and print 

carton boxes. After the carton press forming process there is an operation that removes carton 

excess and leftovers which was found that workers are exposed to an occupational risk 



conditions like frequency, body stress and bad postures besides of an overexposure vibrations 

condition originated from a pneumatic roto-hammer utilized to remove carton leftovers during the 

stripping operation , and that is why this investigation was focused in the use of this pneumatic 

tool. After a close analisys of the situation it was found that by adding the proper insulation to the 

tool handle and by using anti-impact / anti-vibration ergonomic gloves instead of the normal cotton 

gloves provided by the company, the stress condition due to the tool vibrations was drastically 

reduced, in addition to this the personal protection equipment was improved by utilizing ear plugs, 

mask and safety shoes, and as a result of these actions the work environment conditions were 

improved thus reducing the probability of getting a body trauma due to the fabrication process 

needs. 

Key words: Vibrations, Personnel Protection Equipment. 


After the carton Fabrication and Printing process there is a stripping operation which consists of 

two steps: carton preforming by utilizing a pneumatic roto-hammer and manual removal of 

leftovers from cartons located on pallets, figures 1.1 and 1.2 below show the fabrication process 

sequence. 

Figure 1.1 Preforming of boxes using Figure 1.2 Manual carton leftovers 

the pneumatic roto- hammer removal. 



In the operation mentioned above it was found that the workers were exposed to significant 

occupational risk conditions such as frequency, body stress and anti-ergonomic postures and also 

an overexposure to vibrations for extended periods of time affecting arms and hands due to the 

use of this roto-hammer tool, the workers were just using normal cotton gloves, also a survey was 

made finding that workers suffer from chronic back ache, weakness sensation of hand grasping 

ability known as Accumulative Trauma Disorder (ATD) in tendons and nerves which was 

developed due to this working condition for an extended period of time. 

2. INVESTIGATION METHODOLOGY 

Investigating carefully to get the proper analyzing data in order to improve this workstation, a 

Vibrations meter was used ( Bruel & kkjaer”s model vibrotest 60 shown in figure 2.1 ). Vibrations 

readings were taken using just regular cotton gloves as shown in figure 2.2 to make the 

comparisson against utilizing anti-impact / anti-vibrations ergonomic gloves and also an insulator 

material was installed on the roto-hammer handle to help improving this situation. Finally the 

readings were taken on both conditions and they are shown on the following tables . 

Figure 2.1 Vibrations Analyzer Figure 2.2 Vibrations readings taken at 

Utilized in the study Stripping work station. 



The data was carefully analyzed and charts were obtained to compare before and after conditions 

(1 µm = .001 mm = 1 x 10 ¯³ mm measuring units were used ) , without cotton gloves, with cotton 

gloves, with anti-impact / anti-vibtations gloves and last the insulation on the tool handle.was 

added. Chart figure 2.3 shows this data. 

Figure 2.3 This chart shows the average of vibration readings using this analyzer . without gloves 

(blue), with cotton gloves (purple), With ergonomic gloves (green), with both ergonomic gloves 

and handle insulation (red). 







3. RESULTS 

Based on the detailed ergonomic analysis made and considering the vibrations condition that the 

regular worker is exposed to during extended periods of time , It is strongly recommended to redesign 

and relocate this work station to make it safer and easier to handle the material used , and 

also it is suggested to break-down this operation in two steps physically separated from each 

other (pre forming and manual leftovers removal as shown in figure 3.1) in order to rotate 

operators every two hours in each step of the operation , place an anti-fatigue floor mat and at the 

same time insulating the handle of the roto-hammer pneumatic tool ( figure 3.2) and also utilizing 

anti-vibrations / anti-impact ergonomic cotton gloves / spandex and with akton material on the 

hand palm area to reduce the vibrations impact (figure 3.3), in addition to that , safety shoes with 

steel must be used at all times , as well ear plugs, and mouth mask to avoid contact with the 

carton dusts. 

. BEFORE AFTER 

ANTES 

DESPUES 

Figure 3.1 Layout of the stripping operation before and after the improvement showing the 

operation separated in two steps and physically separated also. 



Figure 3.2 Insulation of tool handle Figure 3.3 Anti-vibration/impact gloves 


The level of vibration due to the use of certain tools can be reduced to avoid a higher 

damage to the human body by taking several actions like rotation of workers (Administrative 

controls) more often , proper maintenance of tools to prevent malfunctioning, Installation of 

anti fatigue floor mats to isolate vibrations from human body,Anti-vibration devices like 

plastics or foams adapted to the tools or machines (Engineering controls). And also the use 

of personnel protection equipment like anti-vibration / anti-impact gloves. The lesson learned 

from this study , most important from all this, is to change or improve Company’s safety 

practices culture to protect workers by meeting Official Mexican Safety Norms (nom 017 and 

nom 024) at the workplace, and to train , and implement awareness programs aim to 

employees through visual and verbal communications medias to make them aware of the 

possible body damage due to long exposure of vibration conditions resulting in possible 

traumas. (Human administrative controls).* 

* Mario Ramirez Barrera (UACJ 2010) 



5. BIBLIOGRAPHY 

• Asfahl C ,R. Industrial Safety and Health managment ( 1995) 3ª Edition 

editorial Prentice Hall. 

• Bailey R. Human Performance Engineering. ( 1989) Prentice Hall. 

• International Organization for Standarization (2004) ISO 2631.5.2004 Mechanical vibration 

- Evaluation of human exposure to whole body vibration. ISO Switzerland 

• Normas Oficiales Mexicanas ( nom 017 y nom 024) 



A Descriptive Study about the Integration of Ergonomic Attributes on the 

Selection of Advanced Manufacturing Technology -AMT- 

Aidé Maldonado Macías 1, 2 , Arturo Reallyvázquez 1 , Guadalupe Ramírez 1 , Jorge Garcia- 

Alcaraz 1 , Salvador Noriega 1 

1 Department of Industrial and Manufacturing Engineering 

Ciudad Juárez Autonomous University 

Ave. del Charro 450 Norte, C.P. 32310 

Cd. Juárez, Chihuahua, México 

amaldona@uacj.mx 

2 Division of Graduate Studies and Research 

Ciudad Juárez Institute of Technology 

Ave. Tecnológico No. 4090 

Cd. Juárez, Chihuahua, México 

Resumen: Este artículo presenta un estudio descriptivo sobre la integración de la Ergonomía de 

compatibilidad de atributos (ECA) en la selección de la Tecnologia de Manufactura Avanzada 

(TMA) entre 30 personas que toman decisiones (TD) de las empresas del sector metal-mecánico 

situado en la zona fronteriza de Ciudad Juárez, México. La intención es aumentar el conocimiento 

sobre la consideración e importancia de los atributos ergonómicos en la adquisición de TMA. 

Además, fueron investigadas algunas de las características del personal que participa en su 

funcionamiento, la gestión y la toma de decisiones. Adicionalmente, se identificaron los 

procedimientos comunes de evaluación y selección de TMA; se da una clasificación de los 

equipos utilizados en estas empresas de acuerdo con el propósito de manufactura. 

La metodología expone la ECA en un modelo de atributos múltiples y describe la ECA aplicada 

para recabar información sobre las características de la selección de la TMA, selección de 

proocesos utilizados en estas empresas. Los resultados muestran que la mayoría de las 

empresas realizan algún tipo de diagnóstico para la selección de AMT, pero frecuentemente se 

omiten o descuidan los atributos ergonómicos. Sin embargo, los TM reconocen que al tomar en 

consideracion los atributos ergonomicos en la selección de TMA puede proporcionar una ventaja 

estratégica al facilitar y promover condiciones operativas más seguras en estos lugares de trabajo 

y lograr una mejor aplicación de esta tecnología también. Asimismo, los resultados indican que es 

casi tan frecuente encontrar en estas empresas la tecnología CNC como la tecnología tradicional 



y una tendencia cada vez mayor para incrementar las inversiones en tecnología de robots y 

prototipado rápido. Además, el genero masculino es predominante en el personal operativo y 

administrativo relacionado con TMA y el personal operativo promedia una antigüedad en un rango 

de 4-7 años. 

Palabras clave: Ergonomia de Compativilidad de Atributos, Tecnología de Manufactura 

Avanzada, Toma de Decisiones, Encuesta de compatibilidad ergonómico para TMA 

Abstract: This paper presents a descriptive study about the integration of Ergonomic 

Compatibility Attributes (ECA) on the selection of Advanced Manufacturing Technology (AMT) 

among 30 Decision Makers (DM) from enterprises of the metal-mechanical sector located in the 

borderland of Juarez City, Mexico. It is meant to increase knowledge about the consideration and 

importance of ergonomic attributes on the acquisition of Advanced Manufacturing Technology 

(AMT). Also, some characteristics of the personnel involved in its operation, management and the 

decision making processes were investigated. Additionally, common procedures for evaluation 

and selection of AMT were identified; a classification of the equipment used in these companies is 

provided according to the manufacturing purpose. 

The methodology exposes the ECA in a multi-attribute model and describes the Ergonomic 

Compatibility Survey (ECS) applied for gather information about the characteristics of the AMT 

selection processes used in these companies. The results show that most of the companies do 

perform some kind of diagnosis for AMT selection, but ergonomic attributes are often omitted or 

neglected among them. However, DM recognize that ergonomic attributes consideration in AMT 

selection may provide a strategic advantage in the way it would facilitate and promote safer 

operative conditions in these workplaces, and a more successful implementation of this 

technology as well. Also, results explain that CNC technology is almost as frequent to find in these 

companies as traditional technology and a growing trend to increment the investments in rapid 

prototyping technology and robots can be observed. Additionally, male gender is predominant in 

the operative and management personnel related with AMT and operative personnel average 

seniority is in a range of 4-7years. 



Keywords: Ergonomic Compatibility Attributes, Advanced Manufacturing Technology, Decision 

Making Processes, Ergonomic Compatibility Survey for AMT. 


This section presents the problem description, the objectives of this investigation and finally the 

justification and the scope. 

1.1 Problem Description 

According to the Metal-Mechanic Industry Directory 2008 (Directorio de la Industria Metal- 

Mecánica, DIMM, by its initials in Spanish) in Juarez City, there are approximately 200 companies 

in the field of Metal-Mechanic Industry, which represents an important source of jobs for the city. 

Thus, it is believed that there is substantial amount of workers engaged in the use of AMT. 

However, studies about the characteristics of the personnel and employees related with the 

operation and management of AMT and the integration of safety and ergonomic attributes in the 

decision making processes are scarce locally. 

It is well known that managers and DM face the problem of selection of many AMT 

alternatives; and there are multiple attributes involved in making a good decision, so it is difficult to 

consider all in their totality. In this way, this research pretends to explore the integration of ECA on 

the selection of AMT among 30 DM in local industries and to promote the consciousness about 

the benefits of ergonomics’ implementation. 

1.1.1 Objectives 

The objectives that arise in this work are divided into three specific and one general goal, which 

are explained below: 

1.1.1.1 General Objective 

Increase knowledge about the consideration of ergonomic attributes on the acquisition of 

Advanced Manufacturing Technology (AMT) by means of a descriptive study and the application 

of the ECS to 30 DM in local companies. 



1.1.1.2 Specific Objectives 

Describe some important characteristics of the personnel involved in its operation, management 

and in the decision making processes for AMT acquisition. 

Identify common procedures for evaluation and selection of AMT. 

Provide a classification of the equipment used in these companies according to the manufacturing 

purpose. 

Increase knowledge about the reasons they may or may not include ergonomic and safety 

attributes on their decision making processes. 

1.1.2 Justification and Scope 

This research will provide information to managers and investors of the Metal Mechanic Industry 

about the integration of ergonomic attributes on the selection of AMT, which may have been 

previously obviated. According to Helander (2006), companies that take into account the 

ergonomic attributes on the selection process of AMT will result in safety, productivity and 

satisfaction of their workers. 

This work was made in the Metal Mechanic Industry in Ciudad Juarez, Mexico, where an ECS 

was applied to DM to know some characteristics of their planning and selection processes of AMT 

and the personnel involved in such processes. 

2. LITERATURE REVIEW 

Ergonomic and safety aspects are significant for the design and operation of complex 

manufacturing systems like the ones related with AMT. These are being under estimated for the 

control of injuries and safety problems in the Manufacturing Industry (Karwowski, 1990, 2005). 

According to the Bureau of Labor Statistics of the United States, the Mexican Social Security 

Institute (IMSS), the European Agency for Safety and Health at Work, and the Report of Labor 

and Social Trends in Asia 2006 nowadays the Manufacturing Industry occupies one of the top five 

industries with the highest number of injuries, illnesses, days away from work, along with other 

important statistics worldwide. Additionally, in Mexico the operation of tools and machines is one 

of the top five occupations that report the highest numbers of these events also. However, there 

are difficulties to relate these events with the operation of AMT, due to insufficient information and 



lack of attention to this topic (Maldonado, 2009). Important authors recognize that even when AMT 

was introduced among others reasons to reduce safety risks and hazards for humans, new and 

more critical ergonomic and safety risks have been detected since its introduction in 

manufacturing processes (Nicolaisen, 1995; Karwowski et. al., 1988; Karwowski and Salvendy, 

2006; Sugimoto et. al., 1985). 

In this way, managers and DM may have underestimated Human Factors and Ergonomics 

attributes in their decision in the way priority is given to other factors. Also they are unaware of 

these attributes and their benefits. Such ignorance has serious consequences for companies and 

their workers, since the operators work under physical and mental stress, eventually develop 

musculoskeletal trauma disorders and injuries for life, which represents large losses for jobs and 

businesses (Prado, 2001). 


The methodology presents the description of ECA and the ECS. 

3.1 Ergonomic Compatibility Attributes 

Ergonomic Evaluation of AMT is not an easy topic since ergonomic requirements (attributes) are 

not clearly determined in the literature and disperse, also it implies quantitative and qualitative 

aspects and its complexity and vagueness make an even harder problem to resolve. For 

Karwowski (2005), advanced technologies with which human interaction constitute complex 

systems that require a high level of integration, he considers that Ergonomic Compatibility 

Attributes of AMT have to focus in the design integration of the interactions between hardware 

(computer-based technology), organization (organizational structure), information system, and 

people (human skills and training). This was the foundation of the literature search, but also 

Corlett and Clark (1996) ergonomic guide for machine design was used. In this way, ergonomic 

compatibility evaluation main attributes (ECMA) for AMT, were divided into five parts: human skills 

and training compatibility (A11), physical work space compatibility (A12), usability (A13), 

equipment emissions (A14) and organizational requirements (A15). The main attribute A11 

includes two sub-attributes: skill level compatibility (A111) and training compatibility (A121). The 

main attribute A12 includes five sub-attributes: access to machine and clearances (A121), 



horizontal and vertical reaches (A122), adjustability of design (A123), postural comfort of design 

(A124), physical work and endurance of design (A125). The main attribute A13 includes seven 

sub-attributes: controls design compatibility (A131), controls’ physical distribution (A132), visual 

work space design (A133), information load (A134), error tolerance (A135), man machine 

functional allocation (A136), design for maintainability (A137). The main attribute (A14) includes 

four sub-attributes: temperature (A141), vibration (A142), noise (A143), residual materials (A144). 

The main attribute (A15) includes two sub-attributes: rate of work machine compatibility (A151) 

and job content machine compatibility (A152). 

3.2 Ergonomic Compatibility Survey 

An Ergonomic Compatibility Survey (ECS) was designed for collect the information of the 

evaluation of AMT alternatives. The ECS has two versions; one of these versions was designed to 

be answered by experts and the other one to be answered by DM. For this work it will be analyzed 

the second version (DM). DM’ subjective opinions were needed. The ECS consists on 72 

questions but for the effects of this work only the first 22 questions were analyzed covering the 

sufficient information to make a descriptive study. 

3.2.1 Companies’ General Data 

The general data of the companies is requested in the first section of the ECS. Information 

includes average occupation and the respective gender. Also the workers’ average age for each 

gender is requested and workers’ average seniority to each gender. Finally, the kind of AMT used 

in the company is inquired. 

3.2.2 Characteristics of the Planning and Selection Process of Advanced Manufacturing 

Technology (AMT) 

This part includes 17 questions. This section aims to know some characteristics of the planning 

process for the acquisition of ATM in the company and who participate in the decision making. 

The first 3 questions refer to who makes the final purchasing decision of AMT. The next 3 

questions refer to how the AMT is identified and how the selection process is carried out. Finally, 

through the last 13 questions the integration of ergonomic and safety attributes on the selection 

process of AMT can be observed. 



4. RESULTS 

This section presents the results obtained of the ECS described above. 

4.1 Results of Companies’ General Data 

This section shows the results of general data company. 

4.1.1 Gender and average occupation 

Companies of the survey occupy mainly male workers in all positions. According to the survey, 

male gender is preferable due to the nature of the work and the applied force that is required in 

some activities. The majority of female personnel found in these companies usually have 

administrative positions. Figure 1 shows these results. Additionally, average occupation is of 46 

workers among the participating companies. 

Number of Employees 

female 

14 % 

Figure 1. Gender of employees in the Metal Mechanical Sector 

4.1.2 Average age of employees 

Figure 2 shows that male workers employed have on average 29.76 years of age and female 

workers have on average of 30.80 years of age. 

female 

30.80 

Figure 2. Employees’ average age in the Metal Mechanic Sector 


male 

86 % 

Average Age 

male 

29.76


4.1.3 Average Seniority of employees 

Figure 3 shows that the average seniority of male workers is 6.79 years while female workers 

have average seniority of 4.03 years. This results show also that male gender is still being 

preferable above female gender in these companies. 

Figure 3. Average seniority in the Metal Mechanical Sector 

4.1.4 Equipment Used in the Metal Mechanical Sector Companies 

Participating companies present a variety of equipment. Equipment was classified into seven 

categories according to the manufacturing purpose: CNC Technology, Cutting Technology, 

Traditional Technology, Molding of Plastic Technology, Cleaning and Treatment of Metals 

Technology, Welding Technology, and Others. 

As it is shown in Figure 4, actually CNC Technology is almost as frequent to find as 

traditional Technology. Finally, a growing trend can be observed on equipment such as electrical 

discharge machines, flexible manufacturing cells, robots, robo-drills, and progressive die press 

found in the Others classification. 

180 

160 

140 

120 

100 

80 

60 

40 

20 

0 

160 

female 

4.03 

12 

Average Seniority 

161 


21 

male 

6.79 

CNC Cutting Traditional Molding of Cleaning Welding 

Technology Technology Technology Plastics and Technology 

Technology Treatment 

of Metals 

Technology 

Figure 4. Classification of the Equipment Used in the companies 

27 

25 

64 

Others


4.2 Important Characteristics of the Selection Processes for AMT acquisition. 

This section shows the results of some characteristics of the planning and selection processes 

found in these companies. 

4.2.1 Planning Processes for the acquisition of AMT in the Industry 

Figure 5 shows that 77 % of the companies surveyed do perform some kind of planning processes 

for the acquisition of AMT; this indicates the relevance of a good decision making about AMT. 

Companies that do perform Planning 

Processes for AMT 


77 % 

YES 

Figure 5. Percentage of Companies that do perform Planning Processes for AMT acquisition 

In these companies, the planning processes performed for AMT acquisition are mainly part of 

engineering projects; this means that projects play an important role due to the specifications 

accomplishment on the selection of AMT. Also, in most of these companies the planning 

processes are executed only by the high management. Figure 6 shows the kind of personnel 

involved in the planning process for the acquisition of AMT. 

12 

10 

8 

6 

4 

2 

0 

4 

Management 

Group 

Sessions 

10 

E ngineering 

Project 

P lanning 

4 

23 % 

NO 

Upgrade of 

E quipment 

R equirements 

2 

Process 

E xecuted by 

Corporative 

Personnel 

7 

Process 

E xecuted by 

High 

Managemet 

Figure 6. Planning Process Execution for AMT acquisition 

Figure 7 shows that Executive and Administrative Personnel are mainly involved in the planning 

and selection processes; also in 35 % of the companies a group composed by executive, 

administrative and operative personnel conduct the decision for AMT acquisition.


35 % 

7 % 

17 % 

41 % 

E xecutive personnel 

Adminis trative pers onnel 

Operative pers onnel 

A group of the three 

Figure 7. Personnel who participate on the Planning Process for AMT acquisition 

Companies have different search methods for acquiring AMT. Some companies use two or three 

of this methods at the same time. Figure 8 shows that the use of internet web service and vendors 

casting are the most extended ways for search and acquire AMT, followed by benchmarking and 

equipment’s exhibit. Also the use empirical knowledge is included in the Others category. 

20 

18 

16 

14 

12 

10 

8 

6 

4 

2 

0 

13 

Vendors 

Casting 

7 

Equipment's 

E xhibit 


18 

Internet W eb 

Service 

8 

B enchmarking Others 

Figure 8. Searching Methods for AMT acquisition 

4.2.2 Application of Evaluation Processes for the selection of AMT 

Once the AMT has been identified, it is recommended to perform some kind of diagnosis 

processes to ensure that company’s expectations are met and avoid high costs. Figure 9 shows 

most of the companies do perform some kind of evaluation or diagnosis processes for AMT 

selection. 

Companies that perform some kind 

of evaluation 

20 % 

NO 

Figure 9. Companies that perform some kind of evaluation 

Among these companies, the processes are supported by experts in the first place; then by the 

use of checklists and standardized corporative formats, only a few use some specialized software; 

and one company uses only the experience (Figure 10). Companies that omit evaluation 

processes assume that the requirements are included by default in the equipment. 

80 % 

YES 

9


20 

18 

16 

14 

12 

10 

8 

6 

4 

2 

0 

13 

Vendors 

Casting 

7 

Equipment's 

E xhibit 


18 

Internet W eb 

Service 

8 

B enchmarking Others 

Figure 10. Diagnosis Methods for the selection of AMT in the Metal Mechanic Sector 

These results show that most companies recur to experts to enhance their decisions. 

4.2.3 Ergonomic Attributes on the Planning Process 

Figure 11 shows that slightly more than a half of the surveyed companies that do apply some kind 

of evaluation process also consider ergonomic attributes on the selection of AMT. It is inferred by 

the attitude shown by managers and DM during interviews that 45% of them are unaware of the 

ergonomic attributes that may be involved in the evaluation, even some of them had not even 

heard about the topic. 

Ergonomic Attributes on the Planning 

Process 

45% 

NO 

55% 

YES 

Figure 11. Ergonomic Attributes on the Planning Process 

Ergonomic attributes included in the diagnoses of the equipment were diverse, but it was 

emphasized that all managers are looking for comfort for their operative personnel through proper 

postures and less effort. It was also important for managers the adjustability of the equipment. 

Additionally, usability of the equipment is required since they look for easiness of use in 

equipment and tools, also, Compatibility with Human Skills and Training seems to be the most 

important ergonomic attributes for DM on the selection of AMT according to Maldonado (2009). 

About DM who do not consider ergonomic attributes in the diagnoses, they argue that the priority 

on AMT must be on the technical aspects, costs and lead times. Also the main reason to do so is 

the lack of knowledge about Ergonomics and the need of a pragmatic model or method that 

facilitates their integration in decision making. 

9


On the other hand, safety attributes are included in the evaluation processes in almost all 

companies. Among the 30 companies surveyed, only one refused to include safety attributes in 

the diagnosis. Figure 12 shows this fact. It is deduced that safety attributes are much better known 

than Ergonomic Attributes among DM. 

Safety Attributes on the Planning Process 


3% 

NO 

97% 

YES 

Figure 12. Safety Attributes on the Planning Process 

In this research, most of the companies recognized that the integration of ergonomic attributes 

can become a strategic advantage for competitiveness; and for DM the combination of 

ergonomics and safety attributes would enhance the implementation of AMT, therefore it is easier 

to derive the benefits that both aspects generate. Figure 13 shows this fact. 

Companies that consider Ergonomics 

and Safety attributes help to a best 

implementation of AMT 

17 % 

NO 

Figure 13. Companies that find a strategic advantage of Ergonomics 

5. CONCLUSIONS AND RECOMMENDATIONS 

It can be concluded that most companies surveyed do perform some kind of planning and 

selection processes for AMT acquisition. However, the integration of ergonomic and safety 

attributes are usually neglected in the diagnosis and selection processes for acquiring AMT. The 

final decision about AMT acquisition is lead by the high management personnel and is strongly 

supported by experts. It was found appropriate by DM to increase their knowledge about the 

ergonomics aspects that can be taken into account to support their decision due to they consider 

Ergonomic and Safety attribute as a strategic advantage. The AMT which predominate in the 

83 % 

YES


Metal Mechanic Sector in Juarez, Mexico has gradually been replacing traditional technology. 

Different practices for decision making about AMT among companies were studied, making clear 

that engineering projects are one of the most important reasons to replace or acquire equipment. 

Finally, it was analyzed the methods used by companies to identify and search AMT, where the 

internet web service was the method preferred by DM due to its convenience. 

It is recommended to extend this study among macro enterprises which have higher occupation 

and may have records of accidents, injuries, days away from work and other events related with 

the operation of AMT. This may help to obtain more accurate results of the importance of the 

integration of ergonomic attributes on the selection of AMT. 

6. REFERENCES 

Corlett E. N. y Clark T.S. (1995). The Ergonomics of Workspaces and Machines, 2a. Edición, 

Taylor and Francis. 

European Agency for Safety and Health. 2007. “Work ILO Facts European Agency for Safety and 

Health at Work”, 

http://www.ilo.org/public/english/standards/relm/ilc/ilc90/pdf/rep-v-1.pdf. 

Helander, M. (2006). A guide to human factors and ergonomics, 2 nd Edition, Taylor & Francis 

Group, pp. 8. 

IMSS. 2007. “Estadísticas laborales del Instituto Mexicano del Seguro Social”, 

http://www.siicyt.gob.mx/siicyt/Principal.do?urlc=4,14. 

Karwowski W. 1990. “Injury control and worker safety in integrated manufacturing systems”, 

Unpublished Technical Report, Center for Industrial Ergonomics, University of Louisville, 

Louisville, Kentucky, United Sates of America. 

Karwowski W. 2005. “Ergonomics and human factors: the paradigms for science, engineering, 

design, technology and management of human-compatible systems 1 ”, Ergonomics, Vol.48, No. 

5, Pgs. 436-463. 

Karwowski, W., Parsaei, H.R., Nash, D.L., and Rahimi, M. (1988). Human perception of the work 

envelope of an industrial robot, in Ergonomics of Hybrid Automated Systems, W. Karwowski, H. 

R. Parsaei, and M. R. Wilhem, Eds., Elsevier, Amsterdam, pp. 421-428. 

Karwowski, W. and Salvendy, G. (2006). Handbook of human factors and ergonomics, John Wiley 

& Sons Inc., United States of America. 

Labour and Social trends in Asean. 2007. “Labour and Social trends in Asean 

countries”,http://www.ilo.org/public/english/region/asro/bangkok/library/download/pub07-04.pdf. 

Maldonado Macías Aide Aracely, (2009). Tesis Doctoral, Instituto Tecnológico de Cd. Juárez. 

Diciembre 2009. 

Maldonado Aide, Noriega Salvador, Díaz Juan J., (2009). Ergonomic Compatibility Survey for the 

Evaluation of Advanced Manufacturing Technology, Proceedings of the International Safety and 

Occupational Ergonomics Conference. 



Nicolaisen. P. (1985). Occupational safety and industrial robots-present stage of discussion within 

the tripartite Group on robotic safety, in Robot Technology and Applications,-Proceedings of the 

1 st Robotics Europe Conference, Brussels June 27-28, 1984, K. Rathmill, P. MacConaill, S. 

O’Leary, and J. Brown, Eds., Springer-Verlag, Berlin, pp. 74-89. 

Prado León, L. (2001). Ergonomía y Lumbalgias ocupacionales. 

Sugimoto, N., and Kawaguchi, K. (1985). Fault-tree analysis of hazards created by robots, in 

Robot Safety, M. C. Bonney and Y.F. Yong, Eds, Spreinger-Verlag, KFS, Berlin, pgs.83-98. 

U. S. Bureau of Labor Statistics. 2005. “Survey Occupational Injuries and Illnesse Summary 

Estimates Package (Appendix B)”. 



Remote Ergonomics Evaluations in the Office 

Jeffrey E. Fernandez 1 , Gabriel Ibarra-Mejia 2 , and Brandy F. Ware 1 

1 JFAssociates, Inc 

Vienna, VA 22181 

Corresponding author’s email: jf@jfa-inc.com 

2 University of Texas at El Paso 

Department of Public Health Sciences 

College of Health Sciences 

El Paso, TX 

Resumen: Existe una prevalencia de trastornos musculo-esqueléticos, tales como el Síndrome 

del Túnel de Carpo en el medio ambiente de oficinas, debido a la presencia de factores de riesgo 

de lesión. Muy a menudo, los factores causales de incomodidad pueden ser detectados a través 

de una evaluación del lugar de trabajo realizada por un individuo calificado, como lo es un 

ergonomista. Gran cantidad de compañía y empresas no cuentan el personal con la experiencia 

para realizar estas evaluaciones en forma interna, de tal manera que recurren a contratar 

ergonomistas calificados. El creciente uso de la tecnología disponible en los lugares de trabajo y 

la disminución de tiempos de entrega al realizar evaluaciones de lugares de trabajo, ha producido 

que el ergonomista adopte nuevos abordajes para la solución de problemas relacionados con la 

ergonomía. Este documento plantea la aplicación de evaluaciones ergonómicas de oficina 

realizada a distancia (remotas) a través de un ergonomista virtual. 

Abstract: In the office environment, musculoskeletal disorders such as carpal tunnel syndrome 

are prevalent due the presence of injury risk factors. More often than not, the factors causing 

discomfort can be accessed through a workplace evaluation performed by a qualified individual, 

such as an ergonomist. Many companies do not have the expertise to conduct evaluations inhouse 

and hire a qualified ergonomist. The increasing use of enabling technology in the workplace 

and shrinking delivery times for workplace evaluations has necessitated that ergonomists adopt 

new approach to solving ergonomics related problems. This paper discusses the application of 

remote ergonomic evaluations of office workstations through a virtual ergonomist. 

Keywords: ergonomic evaluation, remote, office ergonomics 



1. BACKGROUND 

The repetitive nature of office work (long term keyboard and mouse use) or inappropriately 

adjusted office equipment (i.e. chair and desk) could cause discomfort or injuries. Injuries often 

begin as discomfort and are caused by exposure over a period of time to the repetitive nature of 

work (long term keyboard and mouse use) or inappropriately adjusted equipment (i.e. chair and 

desk). More often than not, the factors causing discomfort can be accessed through a workplace 

evaluation performed by a qualified individual, such as an ergonomist. 

When the ergonomist visits the workplace, he/she interviews the client, collects 

measurements of the client and workplace, and makes recommendations. During the on-site 

evaluation, the client must host the ergonomist by meeting them, escorting them to their work 

area, and spending undivided attention while the ergonomist is there. This time away from their 

work decreases productivity. From the ergonomist’s perspective, there is time spent commuting, 

and collecting measurements at the workplace. In both of these cases, the cost is transferred to 

the client. The speed of business today leads clients to expect a shorter delivery time for the 

evaluations. Due to these factors, there is a need for a cost effective approach to solving office 

ergonomics related problems. 

One approach is to provide ergonomic evaluations through a virtual ergonomist (i.e. not onsite). 

The evaluation is initiated by client contacting the service provider and concludes with the 

virtual ergonomist following up with the client after recommending the necessary modifications. 

This paper outlines the process employed by a virtual ergonomist for conducting an ergonomic 

evaluation of an office workstation. 

2. PROCESS AND DISCUSSION 

The evaluation of the workstation includes all of the same basic elements of an in-person 

evaluation along with the same deliverables. This process was initially implemented in paper / 

electronic form using email for data transfer. The evaluation process flow is shown in Figure 1. 



The first stage of the process is the initial contact with the client. The assessment sequence 

is generally triggered an employee or other individual (e.g. health services, management) 

requesting an evaluation of the workstation in response to a perceived issue such as discomfort or 

pain (reactive). 

The next stage includes obtaining background information, workstation and anthropometric 

measurements (as shown in a pictorial diagram that is provided), body part discomfort rating, and 

digital data from the client. The still photos and /or video clips of the work area and the activities 

being performed is the additional piece of data that is critical to the successful completion of a 

remote ergonomics evaluation. The still images should be of the client in their work environment 

simulating work tasks from different angles and locations to adequately demonstrate the postures 

obtained during work. When possible, video footage should also be obtained of the real-time 

performance of work (or simulated work) to demonstrate frequency information. A good rule of 

thumb is that video data should be 5-10 minutes in length and include all significant tasks 

performed by the client. 

During the time the ergonomist reviews the data provided by the client, there might be a need 

to contact the client to clarify or obtain more information about the discomfort, tasks, or 

workstation setup. During the evaluation, at least three opportunities for information exchange via 

phone call or video conference should be provided. The initial interaction should be to clarify the 

initial background information provided and educate the client on proper ergonomic setup. The 

second interaction should be to review the work related risk factors identified through the 

evaluation. At this time, the ergonomist will review the recommendations and discuss possible 

options for modification to a setup. The third interaction should occur after the workstation 

modifications have been made by the client. This interaction may be visual (e.g. include photos or 

video) in addition to verbal. This final stage of the evaluation is a very important element of the 

process. A follow-up is essential to ensure that the end-user neither experiences any discomforts 

similar to the ones before the workstation modification nor does he/she develop any additional 

discomforts. At this time, the virtual ergonomist reviews the worksite for completeness of the 

recommendations and to ensure that no other risk factors are present. Additional follows may be 

scheduled as per need. 



The output of a remote ergonomic evaluation will be very similar to those generated with a 

traditional, on-site evaluation. The output in a written report should include a review of the current 

status, a listing of the observed risk factors, and a list of recommended changes both short term 

and long term. 

Figure 1. Process Flow for an Ergonomic Office Evaluation through Virtual Ergonomist (Fernandez 

et. al, 2009) 



A remote system requires an understanding of the information needed, comprehensive 

mastery of the fundamental office ergonomics principles and their application, and an appropriate 

interpretation of the data provided by client. In most cases, only a certified and qualified 

ergonomist(s) is an appropriate choice for these evaluations. The affect of such remote 

evaluations could save clients money, decrease carbon footprint, and improve the transfer of 

ergonomic information to remote locations. 

The most advanced application of a virtual ergonomist involves the use of the internet as a 

platform for providing the aforementioned services. A website with interactive screens is required 

to solicit information. Additionally, the website should provide the user with the capability to upload 

pictures and videos for review. The interactive screens of the web site should parallel the flow of 

the remote evaluation. 

3. TESTING AND IMPLEMENTATION 

This process has been tested in the U.S. A. and Mexico. The testing involved the 

participation of clients in the same manner as the end product was intended. Throughout the 

testing, input was received on the nature of the questions that were asked and the 

appropriateness of the directions given. As a result of the testing, refinements were made to the 

processes and checklists to improve usability and ensure comprehensive collection of relevant 

data. 

4. REFERENCES 

Fernandez, J.E., Ware, B.F., Kumar, A., and Subramanian, A. (2009). Office Ergonomics 

Assessment Through Virtual Ergonomist. Proceedings of the 14 th International Conference 

on Industrial Engineering, Theory, Applications and Practice. Anaheim, CA. 



COMPARATIVE ANALYSIS BETWEEN AN ERGONOMIC EVALUATION AND THE USERS' 

SATISFACTION OF NEW EDUCATIONAL CENTERS 

B.Eng. Martín Daniel Del Sol Rangel 1 , M.Eng. Manuel Sandoval Delgado 2 

POSTGRADUATE DEPARTMENT AND INVESTIGATION 

INSTITUTO TECNOLÓGICO DE HERMOSILLO 

Tecnológico Ave. And Periférico Poniente Blvd, Sahuaro 

HERMOSILLO, SONORA, 83170 

Daniel-delsol@hotmail.com, msandoval@ith.mx 

1 INTRODUCTION 

Globalization is transforming all the products in comfort, while clients, current or potential, are 

constantly increasing demands and expectations, products seemed fine yesterday, today may not 

be satisfactory, it is then that to win and retain customers, organizations need to find something to 

turn into a competitive advantage, that element is the quality. All organization looking to be more 

competent and always at the forefront, offering the best to its customers and users, resulting in a 

successful project. 

The managing a project involves the application of knowledge, skills, tools, and techniques to 

project activities so that they meet or exceed the needs and expectations of the stakeholders of a 

project. The factors for the success of the project are the set of circumstances, facts, or influences 

which contribute to the project results. The success of the projects we perceive from two 

approaches, one micro which is represented by the cost, delivery time and meet customer 

specifications, the other is the macro that represents the total satisfaction of the user who uses it. 



The present work of investigation is a comparative analysis between studies of "Verification of the 

environmental conditions in the facilities design of new buildings at the preschool level creation in 

the education sector in Hermosillo, Sonora" and "Anthropometry and verification of facilities design 

buildings at the preschool level ups in the education sector in Hermosillo, Sonora”, against the 

results of the study “Factors influencing the satisfaction of user of schools newly created basic 

level in Hermosillo, Sonora ", There are no studies that serve as background or base for departure 

because it is a recent project of the Sonora Institute for Educational Infrastructure, which reports 

to the State Government and which has never measured the satisfaction of users of such works 

public. 

2 OBJECTIVES 

Making a comparison between the perceptions of the user against the measurements obtained in 

the two studies mentioned above, concurrent, and find out if its result compared with the official 

standards and anthropometric measures for installations in schools, have a value of significance 

in user satisfaction. Be conducted only in the municipality of Hermosillo, Sonora, in the four 

schools of this type found in the city. 

3 METHODS 

Was determined primarily based sample, in this case 32 which is the total of people working in 

these institutions, being interviewed teachers, administrative and support, were interviewed by 

school staff, as direct users , to hear his perspective from the macro environment, as well as 



some people working in the Sonora Institute of Educational Infrastructure to meet their 

expectations of the quality they deliver these works, that is, from the micro environment, with 

this design A pilot survey to discover the needs or problems that arose within those premises 

was a validation of the survey was applied in only one school, and was designed to be 

analyzed a survey based on certain items required for research using the method Servqual, 

which defines service quality as the difference between actual perceptions by users and is a 

multi-scale instrument that has a high level of reliability and validity, that any organization can 

use to better understand the expectations and perceptions about service users. The model 

includes two dimensions of expectations: expectations desired (which I'd like in ideal terms) 

and appropriate expectations (the acceptable level of service expected). Besides this is divided 

into headings such as, visual perception and environmental design, ambient conditions, safety, 

and responsiveness in terms of failures and complaints in the facility. 

Thus, a survey was designed to apply well-defined in the entire field of study, ie, universal primary 

education schools and kindergartens in the newly created municipality of Hermosillo. 

Respondents were only administrative and teaching staff, these being the ability to direct users to 

answer the survey because students are also users but do not have the maturity to respond 

coherently to the research questions. 

4 RESULTS 

In implementing the surveys, we will realize the factors that influence the level of satisfaction of 

users of each of these schools, we can compare each of them, finding differences and similarities 

between themselves and in turn, and by type of primary or preschool, and thus may provide 



feedback to those implementing this project, and be able to carry not only the success of the micro 

environment but also from the macro. As well as we can compare these plots obtained in the 

surveys carried out against the measurements obtained in the other two parallel research this and 

see whether they comply with official standards, and then be detected if it affects the user 

satisfaction. 

Figure 1. Results obtained in the survey research, “Factors are 

influencing the satisfaction of users of schools newly created basic 

level in Hermosillo, Sonora”, in the Kindergarten “Los Arroyos”. 

Figure 2. Results obtained in the survey research, “Factors are 

influencing the satisfaction of users of schools newly created basic 

level in Hermosillo, Sonora”, in the Elementary School “Los Arroyos”. 

The question 6, is related to the lighting of the classroom, if considered appropriate for the proper 

performance of students and teachers, including the cataloged in the case of kindergarten as 

excellent and as good in the Elementary School, giving it a rating 10 and 8 respectively. Here we 



see the data in the study of "Verification of environmental conditions in the facility design of the 

buildings at the preschool level ups in the education sector in Hermosillo, Sonora." 

Table 1. Results obtained in the ergonomic study research “Verification of 

environmental conditions in the facility design of the buildings at the preschool 

level ups in the education sector in Hermosillo, Sonora” in Kindergarten “Los 

Arroyos”. 

The minimum level of lighting according to the NOM 025 analyzed, the minimum standard of this 

factor must be 300 (lux) for the elderly, it is important to note that the measurement gives us a 

number below this value. This result gives justification to change the lighting to classify it as only 

good with an 8 on a scale of 5-10. The questioning in July, is related to the temperature of the 

room, if it is deemed for the good performance of pupils and teachers, cataloged them both in 

Kindergarten and Primary School under 8, or Regular. Here we see the data in the study of 

“Verification of environmental conditions in the facility design of the buildings at the preschool level 

ups in the education sector in Hermosillo, Sonora”. 



Table 2. Results obtained in the ergonomic study research “Verification of environmental conditions 

in the facility design of the buildings at the preschool level ups in the education sector in Hermosillo, 

Sonora” in Kindergarten “Los Arroyos”. 

The INIFED says that the environmental conditions that are suitable for work in comfort in the 

case of classrooms are 18 to 25 degrees Celsius and can see that this condition is not met, most 

of the measurements exceeds 25 degrees Celsius. Therefore, find out why the temperature is 

listed as fair, although the results reflected rather as bad. As for the results of the investigation 

"Anthropometry and verification of plant design of the buildings at the preschool level ups in the 

education sector in Hermosillo, Sonora" was against a comparative study and survey of the results 

were similar furnishings and facilities and equipment not designed for the good performance of 

students mainly, not based on anthropometric tables according to your needs. 

Thus, these results will support this project to strengthen Sonora School, offer these areas of 

opportunity for improvement in those who develop, ie, the Sonora Institute of Educational 

Infrastructure and also propose a concurrent engineering work, where without participation of all 



stakeholders, including of course, users who guarantee from a macro perspective, the success of 

our project. 

REFERENCES 

1. Cavassa Cesar Ramirez, Ergonomics and Productivity (2006), Cesar Ramirez Cavassa. - 2nd. 

Ed - Mexico: Limusa, Chapter 8 Ergonomics and working environment. 

2. Evan Lindsay (2000), Management and Quality Control, Ed Thompson 2000. 

3. Evaluación.pdf 

http://www.inifed.gob.mx/NORMASTÉCNICAS/VOLUMENTomo20PlaneaciónProgramaci 

óny 

4. Francis Quintero (2010) "Verification of environmental conditions in the facility design of the 

buildings at the preschool level ups in the education sector in Hermosillo, Sonora." 

5. Hiram Higuera (2010) Anthropometry and verification of plant design of the buildings at the 

preschool level ups in the education sector in Hermosillo, Sonora. " 

6. Julius Panero (1993), The human dimensions indoors, Ed G. Gili, SA., Mexico, D.F., pp. 23. 

7. C. S. Lim and M. Mohamed Zain (1999) "Criteria of project success: an Exploratory re- 

examination", International Journal of Project Management Vol 17, No. 4, Great Britain, 

pp. 243-248. 

8. O terminal, David J. (1990), Ergonomics in action: adaptation in the working environment of 

man. - 2nd edition - Mexico: Trillas, (reprint 2007). 

9. Roberto Hernandez Sampieri (1998) Research Methodology, Ed McGraw-Hill. 

10. Standardization of the STPS, www.stps.gob.mx 

11. Ted Klastorin (2008) Project management. Alfaomega Group Editor. Mexico City, Mexico. 242 

pages. 



DESIGN AND IMPLEMENTATION OF MANUFACTURING CELL 

WITH ERGONOMIC SUPPORT ANALYSIS 

MC. Rigoberto Zamora Alarcón 1 , Ing. Manuel Enrique Alcaráz Ayala 2 , 

MC. Julio César Romero González 3 

1 Ingenieria Mecánica-Industrial 

Universidad Autónoma de Baja California-Instituto Tecnológico de Mexicali 

Blvd. Benito Juárez S/N 

Mexicali, Baja California 21100 

mczamora02@yahoo.com.mx 

2 Ingeniero de Manufactura ambiental 

Consultor Independiente 

Mexicali, Baja California 

enrique.alcaraz@hotmail.com 

3 Ingeniero de manufactura y proyectos 

Instituto Tecnológico de Mexicali 

Mexicali, Baja California 

mc.julio.romero@gmail.com 

Resumen: Este estudio muestra el desarrollo del proyecto desde la perspectiva general del 

análisis de riesgo ergonómico utilizando el método RULA (Rapid Upper Limb Assessment). El 

análisis arrojo información para mejorar el ambiente de trabajo. Se desarrollo el Proyecto de 

evaluación ergonómica en una compañía metalmecánica con más de 16 años en Mexicali, con el 

propósito de enfocar esfuerzos en la prevención de riesgos ergonómicos. 

El proyecto se apoyo en las características retrospectivas (5 años) de los registros médicos, 

evidenciando lesiones músculo tendinosas en muñecas en las áreas de trabajo de ensamble, 

específicamente en una estación en particular; los cuales fueron determinantes para definir el 

proyecto en las celdas de manufactura. 

Objetivo: Reconocer evaluar y controlar los riesgos laborales por actividades repetitivas, 

posturas, y agentes del medio que por sus características puedan causar daños a la salud, 

considerado el análisis ergonómico aplicado al concepto de celdas de manufactura 

Metodología empleada: Normas oficiales Mexicanas de STPS (Secretaria de Trabajo y 

Previsión Social) vigentes, Evaluación RULA/BRIEF, Mediciones antropométricas, Principios de 

celdas de manufactura 


Resultados 


Tabla 1 Resultados del proyecto 

Mejora en Índice de frecuencia 

Tendinitis 95% 

Dolor de cuello 100% 

Espalda 90% 

Beneficio 

Rotación de personal 0% 

Desperdicio -33% 

Optimización de espacio 40% 

Productividad 40% 

Condiciones ambientales 

Iluminación 100% 

Ruido 100% 

Conclusiones: Con base a los datos obtenidos: 

Disminuyo el índice de frecuencia de lesiones por tendinitis, dolor de cuello y espalda; 

impactando de manera favorable la rotación 

Se considerarán para el diseño de las estaciones de trabajo, la media poblacional del estudio 

antropométrico 

Se comprobó que el costo beneficio de la aplicación de la ergonomía generó mejoras 

significativas en las condiciones laborales beneficiando a casi 500 empleados 

Palabras Clave: Celdas de manufactura, RULA, Análisis Ergonómico 

Abstract: This study shows the project's general perspective for ergonomic hazards using the 

RULA’s (Rapid Upper Limb Assessment) method. Analysis shows information to improve the work 

environment. Project ergonomics was developed in a metalworking company with over 16 years in 

Mexicali, with the proposed of focusing efforts on preventing ergonomic risk. 

The project was supported in retrospective characteristics (5 year) medical records, which showed 

muscle lesions in wrist tendon (CTD: Cumulative Trauma Disorder) areas specifically assembly 

work at a particular station, were decisive in defining the project in manufacturing cell. 



Objectives: Recognize asses and control the labor risks for repetitive activities, postures, and 

environmental agents that have certain characteristics may cause damage to health, considered 

the ergonomic analysis applied to the concept of manufacturing cells. 

Used methodology: Mexican official standards of existing STPS (Secretaria de Trabajo y 

Previsión Social), RULA Assessment, Anthropometric measurements and Principles of 

manufacturing cells. 

Results: 

Table 1 Project results 

Improved Frequency index 

Tendinitis 95% 

Neck pain 100% 

Back and shoulders 90% 

Benefits 

Absenteeism 0% 

Waste -33% 

Space optimization 40% 

Productivity 40% 

Environmental conditions 

Ilumination 100% 

Noise 100% 

Conclusions: Based on the data: 

Reduce the frequency index of tendinitis injuries, neck and back pain, favorably impacting the 

absenteeism. 

Will be considered for the design of workstations, the population mean anthropometric study. 

It was found that the cost benefit of the application of ergonomics to yield significant 

improvements in working conditions, benefiting nearly 500 employees. 

keywords. Manufacturing cells, RULA and Ergonomic Analysis 

1.- INTRODUCTION 

This study shows some of the environmental factors of process redesign in a metalworking 

company with over 16 years in Mexicali, initiating the development of the project from the overall 



perspective of ergonomic risk analysis methods using RULA (Rapid Upper Limb Assessment) / 

BRIEF. The analysis yields information to improve the working environment, in order to focus 

efforts on preventing ergonomic hazards. 

The project will support the features retrospectives (five years) of medical records, showing 

muscle tendon in wrist injuries in the assembly work areas, specifically in a particular season, 

which were crucial in defining the project in the cells manufacturing. 

Later it was necessary to implement each of the principles of manufacturing cells, which had as 

one of its aims to cut down injuries sustained when production lines were used and the 

advantages that the implementation of this system of manufacturing production in its approach . 

It was remarkable to observe that first applied the standards and principles Japanese and 

Mexican Americans than the standards established by federal labor law. 

2.- Objective 

Recognize evaluate and control occupational hazards by repetitive activities, postures, and 

environmental agents which by its nature could cause damage to health, considered the 

ergonomic analysis applied to the concept of manufacturing cells 

3. Methodology 

3.1. Factors and Design Techniques 

To develop improvements as a project in newly created department was required to first 

determine the factors necessary in a process or product improvement, further weighting. Factors 

that were discussed and were weighted were: packaging, ergonomics, reliability, maintenance, 

manufacturing, environment, performance and safety. Of the above factors stood out in his group, 

ergonomics and manufacturing, which were diagnosed as other such systems and subsystems as 

corresponded in the following items on this article. 

3.1.1 Weight and diagnostic medical. To be able to support the weight of the plant physician, was 

necessary to make a diagnosis of injuries in the last 5 years behavior which is shown in Figure 1. 



Figure 1. Injury graphic in the last five years in the production line 

As can be seen from the graph in Figure 1, tendinitis injuries were the most frequently expressed, 

in analyzing the documents supporting the physician receives a particular station as the main 

carrier of the injury. It was decided to take a more precise analysis of the case which had 

previously been tested ergonomically down significantly, however, the cases have involved the 

previous year that operators avoid working in the station. The weighting is determined whether 

one could know if our proposals were significant in their environment, it was necessary for the 

same thermal analysis on a ship operated blade in a municipality that maintains extreme 

temperatures in the year. Realising the study as shown in Figure 2, the tendinitis was found 

increased in the months where the heat is great in Mexicali. 

Figure 2. Tendinitis injury in the last five years 



3.2. Mexican Official Standards of STPS (Secretary of Labor and Social Welfare) in force Federal 

Labor Law art. 132 Obligations of Employers Cap. X, Ergonomics art. 102. (Federal Regulation on 

Safety, Hygiene and Working Environment 1997) 

The official Mexican standards determined by the Secretary of Labor and Social Welfare in effect 

allowed us to measure each of the parameters set by physical and chemical conditions, however, 

to labor issues in the area we focus on the chemical physics but also evaluated 

3.2.1 Physical 

Vibrations (NOM-024-STPS-2001), 

Noise (NOM-011 - STPS-2001). Concentration equivalent dB (A): continuous, intermittent, 

fluctuating and Impact, 

Lighting (NOM-025-STPS-1999) 

a) Disposition: General, located, and auxiliary 

b) Artificial: Incandescent, fluorescent, vapor and H 

c) Natural 

d) Combined 

Radiation 

a) Ionizing (NOM-012-STPS-1999) x-rays, radioisotope and other 

b) Non-ionizing (NOM-013-STPS-1993), ultraviolet, infrared, radio frequency and other static 

Electricity (NOM-022-STPS-1999) 

Thermal conditions (NOM-015-STPS-2001) 

3.2.2 Chemicals 

Substance (NOM-010 - 1999 STPS-) 

3.3. Anthropometric measurements 

Some anthropometric measurements of operators are working in the plant are shown in Table 1 



Table 1 Some anthropometric measurements of line operators 

3.4. RULA Assessment / BRIEF 

Poor posture is considered one that moves away from a neutral position or physiological, where 

they play an important role while maintaining the posture and the handling of heavy objects. 

(Kroemer 2000). Since the results were assessed at the station representing more problems in 

production lines using the method as the main tool right RULA showed results that could be 

considered in the design of new stations. First results were deciphered on the right of operators to 

both women and men as shown in Figure 3 where we obtained the results of urgent change of 

season. 

3.5 Principles of manufacturing cells (Villaseñor 2009) 

1. Place machines and workstations as close as possible to minimize the distance to be walking 

2. Free from obstructions routes and install comfortable floor worker 

Increase the safety of workers 

Improved productivity 

Greater flexibility of work for each operator 

2. Keep the cell width of 4 feet to allow flexibility, relocation and redistribution of work among team 

members 

Minimize distances of each operator 

Operators have access to both sides of the cell 

Increases the flexibility of the work cycle, so there may be operating on both sides of the 

cell U 



Figure 3. RULA Evaluation for production line (belt) 

4. Heights consistently maintain places of work and materials at the point of use 

5. Locate the end of the line as close as possible to the next line. 

6. Avoid carrying a piece of top-down and front-back 

Always avoid placing the parts manufactured in shelves, racks, boxes or any container that is 

out of the process 

7. Where possible, use gravity to assist the operator in the placement and movement of materials 



8. Design a system of two containers refill 

9. Install flexible and movable equipment in the cell distribution to fit easily 

Facilitates continuous improvement efforts, reduce time and costs for the relocation of 

production in cells 

Improve response times to changes in products or processes 

8. Manufacturing cell design for flexibility of volume 

a. Flexibility: 

b. Design assembly line layout to cellular manufacturing in a "U" or "U" open. 

c. Eliminate communication barriers and increase teamwork 

9. Minimize the distance between operations transfer 

10. Cycle times operator must be at or below the target time / takt 

a. Ensure that the cell meets the customer demand time 

b. Ensures that meets the capacity requirements 

13. Design routes operating within the cell, making sure not cross 

a. Increases operator safety 

b. Facilitates flow of material 

c. Optimize productivity by removing obstacles from the path 

d. Ensures follow-up sequence of work 

14. Design the cells for operators to work within it. 

a. Promotes communication and teamwork 

b. Improved response time and operating in several machines or workstations 

c. Optimize production space 

d. Reduce travel distances 

15. Design the cells so that the rotation of the work is against clockwise 

a. Improved ergonomic design 

b. Facilitates milestone 

c. Standardize more material flow 

d. Eliminate wasted movement when moving the product of the hand that receives the 

working 

16. Design the cells so that the operations are more than one piece among stations 

a. Minimize WIP 



b. Pull Production System or milestone 

17. Design the cells to ensure that all parties go through all seasons 

18. Design the cells so that the operator can easily perform various operations. 

a. Helps to improve the ergonomic design by reducing repetitive movements 

b. Improves mobility and versatility of workers 

c. Allows greater flexibility 

d. Promotes "system thinking", continuous improvement 

e. Eliminate each operation specialists 

f. Improved response time 

g. Improved communication 

h. Improved teamwork 

i. Improving the skills of each to rotate the cell operations 

19. Design the cells so that the operator never trapped 

20. Better handling of material 

a. Improving the response time 

4. Results 

4.1 Medical conditions for improved stations applied in manufacturing cells 

Measurements after the improvements implemented in the stations of the manufacturing cells 

reduce injuries allowed as shown in Figure 4 

4.2. RULA assessment implemented in manufacturing cells. Improvements in manufacturing 

cell stations were significant as shown below. First results on the right of operators to both 

women and men shown in Figure 8 and Figure 9 where we obtained the results to changes in 

tasks 



Figure 4 raph of injuries sustained in the first year of cells 

5. Conclusions: 

6. 

1. We complied with the standards prescribed by the current Mexican 

2. Engineering controls were implemented through: 

a) were improved work areas with more light, 

b) decreased redesign of machinery noise 

c) the use of workstations in the corresponding cells that fulfilled the relevant principles 

d) Development of tools to reduce ergonomic hazards 

e) Improved handling containers and material moving 

3. Administrative Controls 

• Work was rescheduled through the seasons in the manufacturing cell 

• were established relaxation breaks that allow staff 

4. Work practice controls 

• is looking to keep the body in neutral positions 

5. Based on the data obtained from the RULA ergonomic evaluation and implementation of 

manufacturing cells 



Figure 5 RULA evaluation in cell 

a. Reduce the frequency rate of tendinitis injuries, neck and back pain, impacting favorably 

rotation 

b. be considered for the design of workstations, the population mean anthropometric study 

c. It was found that the cost benefit of the application of ergonomics led to significant 

improvements in working conditions, benefiting nearly 500 employees 



5. REFERENCES 

Kromer, Grand Jean E (2000) Fitting the task to the human. Taylor & Francis 

Villaseñor, Contreras Alberto (2009) Lean Manufacturing ed. Limusa Mexico, D.F. 

Ley Federeal del Trabajo y Leyes de Seguridad Social 2009 Tax Editores unidos, S.A de 

C.V. Mexico, D.F. 

Zandin, Manual del Ingeniero Industrial quinta edición, ed. McGraw-Hill 

Niebel/Frievalds (2006) Ingenieria Industrial, Métodos, Estándares y Diseño del Trabajo, 

11ª Edición. (ed. Alfaomega) 

Mondelo, Pedro R, Gregori, Enrique, Blasco, Joan, Barran, Pedro (2004) Ergonomía 3 

Diseño de puestos de Trabajo, Ed. Alfaomega 

Baudin, Michel (2001), Design of Manufacturing Cells.

ERGONOMÍA OCUPACIONAL - SOCIEDAD DE ERGONOMISTAS ...

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