Abstract:
Low back pain is grouped under the musculoskeletal disorders which lead to disability, reduced
engagement in work activities, and considerable annual cost. It is a common and regular reason
for medical consultations, a large number of individuals experience low back pain at least once in
their lifetime. The onset of low back pain is unclear, which makes the diagnosis and prevention
process difficult. Different causes are set as a risk factor for low-back pain, sitting is one of them.
This study concentrates on the analysis of five different sitting positions, which are common sitting
positions in our daily activity. These positions include sitting on a stool (60-degree), sitting on a
reading chair (75-degree), upright sitting (90-degree), upright sitting with support (90 degrees with
lumbar support), and a relaxed sitting position (120-degree).
Surface electromyogram was applied on Iliocostalis lumborum muscle which is under the erector
spinae muscle group then signal was acquired and analyzed. A total of eleven features from the
time and frequency domain were extracted and analyzed. The ANOVA test was applied to identify
the significant features to study the five sitting positions. Force calculation using EMG signal was
calculated then the five sitting postures compared, sitting positions as supported and unsupported,
and on male and female subject differences were studied.
The best features identified to predict muscular force and fatigue from an EMG signal were mean
absolute value, mean frequency, and median frequency. The comparison of sitting postures with
and without a support shows that supported postures have less muscle load and fatigue than
unsupported postures. In male individuals, there was also reduced muscle load and less muscle
fatigue. Distinct sitting positions have different effects on muscle activity, according to the study.
Sitting 90 degrees with lumbar support is the best sitting position with minimum muscle load
(10.2885N) and less muscle fatigue. The posture at 60 and 75 degrees exhibits the largest muscle
stress (66.3207N and 60.9370N respectively) and maximum muscle fatigue. As a result, the two
positions are the least healthy and should be avoided at work or at home. This study will have a
significant impact on preventing low back pain and determining the ideal seating positions for a
healthy lifestyle.
