Thesis (M.Sc.)--Chulalongkorn University, 2015

This study aimed to investigate seat pressure distribution characteristics, i.e. average pressure (AP), peak pressure ratio (PP ratio), frequency of postural shift, and body perceived discomfort (BPD) during 1-hour sitting in office workers with and without chronic low back pain (LBP). Forty-six participants (chronic LBP = 23 and control = 23) typed a standardized text passage at a computer work station for an hour. A seat pressure mat device was used to collect the seat pressure distribution data. The results showed that workers with chronic LBP sat significantly more asymmetrically than their healthy counterparts. During 1-hour sitting, all workers assumed slumped sitting postures after 20 minutes of sitting. Healthy workers had significantly more frequent postural shifts than chronic LBP workers during prolonged sitting. The findings suggest that a person should avoid an asymmetrical sitting posture, change postures frequently, and have a short break from sitting every 20 minutes.