ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

spinal loading [16]. Muscle forces have been estimated form some standard exercises
like standing, flexion and extension of the upper body, and lifting a load [17, 18].
Difference approaches have been used in these studies. The average back strength of the
subjects has been measured using back dynamometer from 3 trails with 5 min rest
between each trail. During trails, subjects asked to pull the dynamometer handle hard to
their maximum capacity without bending their knees with 30 degree upper body bend.
At the same time, EMG experiment also performed to measure the back muscle strength.
A wireless type EMG measurement system (The Noraxon Telemyo 2400T G2
Telemetry System, Noraxon, USA Inc., USA) was used to capture the EMG signals of
the erector spinae with a sampling rate of 1000 Hz. All surface EMGs were collected on
both right and left side. EMG data were captured from the two muscles for a 5-s period
in each loading condition. The disc shaped (10 mm diameter) 3M red dot electrode was
used. The skin was abraded and cleansed with alcohol before placing the electrodes.
The electrodes were applied using standard placement procedures.
4. RESULTS
4.1 Spinal Shape Analysis
The spinal column is an elaborate “tunnel” of small, interlocking bones slightly curved
in the shape of the letter “S”. The spinal shape analyses were grouped by age (Fig. 1).
From C7 to Posterior Waist distance decreases, when age increases: 20’s 16.27 mm,
30’s 13.21 mm, 40’s 10.89 mm and 50’s 8.87 mm. One of the possible and suggested
causes for these changes is natural aging. From the spinal shape analysis, the key
characteristics of the spine have been extracted by age group. And for the safer spinal
traction pathway, the spinal shape templates have been created by considering the
Korean lumbar spinal shape characteristics.
Fig. 1. Shape of the spine grouped by age
4.2 Traction Calculation based on personal characteristics
The changes in the subject’s physical characteristics have been investigated using peak
RMS values from EMG experiment based on weight, age and exercise level. The
changes in the physical characteristics have been used to calculate traction strength
characteristics.