Sit-to-Stand Movement Pattern A Kinematic Study - Physical Therapy

Sit-to-Stand Movement Pattern
A Kinematic Study
SHARON NUZIK,
ROBERT LAMB,
ANN VANSANT,
and SUSANNE HIRT
A visual model of the sit-to-stand movement pattern was developed from the film
data of 38 women and 17 men as they assumed standing from a seated position.
We used the data from these film records to identify a representative initial
starting position and displacements of body segments for each of 20 equal
intervals throughout the movement cycle. Trajectories of data points on the head,
acromion, midiliac crest, hip, and knee also were plotted. These diagrams
demonstrate the time-space relationships of various body parts during the task.
This normalized model may be used by physical therapists as a standard to
which they can compare the movement pattern of a patient.
Key Words: Biomechanics, Movement, Physical therapy.
Standing from a seated position is an activity most people
perform many times daily. Despite its frequency of occurrence
and importance to functional activities, reports in the literature
are few and do not permit clinicians to generalize their
findings easily to the observed movement characteristics of a
patient. Based on observation and clinical experience, the
physical therapist develops a concept of a normal movement
pattern, assesses the quality of the patient's movement, and
trains the patient according to the idealized model. Although
such conceptualized models approach reality, therapists disagree
about their various components (eg, initial position or
postural set, maximal joint excursion, and most efficient
pattern of movement). Quantitative data derived from a large
sample may provide a realistic model of the movement pattern,
a baseline from which further comparisons may be made.
The physical therapist then might be more certain about the
excursion of each joint, the sequence of action, and the
components of movement. A patient's movement pattern,
thus, may be compared to this norm, and treatment may be
aimed at normalizing movement with respect to this model.
Jones and associates 1-4 and Kelley et al 5 have studied selected
aspects of the sit-to-stand movement pattern in healthy
adults. Jones and associates described the trajectory of the
head in space and the effects of various postural sets on this
trajectory. Kelley et al described the kinetic characteristics of
the lower extremities of six subjects under a controlled speed
Ms. Nuzik is Supervisor, Neuroscience-Pediatrics Team, Physical Therapy
Department, Medical College of Virginia Hospitals, Virginia Commonwealth
University, Richmond, VA 23298 (USA). She was a graduate student at the
Medical College of Virginia, Virginia Commonwealth University, when this
project was undertaken.
Dr. Lamb is Associate Professor and Director of Graduate Studies, Department
of Physical Therapy, School of Allied Health Professions, Medical College
of Virginia, Virginia Commonwealth University.
Dr. VanSant is Associate Professor, Department of Physical Therapy, School
of Allied Health Professions, Medical College of Virginia, Virginia Commonwealth
University.
Ms. Hirt is Professor Emeritus, Department of Physical Therapy, School of
Allied Health Professions, Medical College of Virginia, Virginia Commonwealth
University.
This study was completed in partial fulfillment of Ms. Nuzik's master's
degree, Medical College of Virginia, Virginia Commonwealth University.
This article was submitted March 7, 1985; was with the authors for revision
30 weeks; and was accepted March 19, 1986. Potential Conflict of Interest: 4.
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condition. In a recent study, Wheeler et al used two groups
of female subjects to study the influences of age and chair
design in rising from a chair. 6 Electromyographic activity of
the vastus lateralis muscle and medial head of the triceps
surae muscle was recorded, as were goniometric measurements
of elbow and knee flexion and forward angle of inclination
of the trunk. In another recent report, Burdett et al
compared joint moments and range of motion of the hip,
knee, and ankle in 10 healthy male subjects and in 4 patients
with various diagnoses as they stood from two types of chairs. 7
Because information from these reports was inadequate to
develop a clinically relevant visual model of the body rising
from a seated position, we undertook a descriptive study of
this movement pattern. The model generated from this study
provides a foundation for the evaluation of patients performing
this task, determination of treatment effectiveness, and
implications for further research.
METHOD
Subjects
The protocol for this study was approved by the Committee
on Human Research, and informed consent was obtained
from the 55 healthy adults (38 women and 17 men) who
participated in the study. This group, representing a sample
of convenience, was composed of graduate and undergraduate
physical therapy students, faculty members, and clinicians at
the Medical College of Virginia, Virginia Commonwealth
University. The ages of the subjects ranged from 20 to 48
years ( = 26.4 ± 5.1 yr). We filmed these subjects in the
sagittal plane as they stood from an armless wooden chair
with a seat height of 46 cm (18.1 in).
Instrumentation
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A spring-wound 16-mm Bolex* camera equipped with a 26mm
Macro-Switar † lens was positioned 7.32 m (24.01 ft) from
* Model H-16, Rex 5, Bolex International SA, Sante-Croix, Switzerland.
† Kern and Co, Ltd, Aarau, Switzerland.
PHYSICAL THERAPY