Effect of office chair design on users' response to pain

Only a fraction of several Office Chair Designs (OCDs) attempt to address the numerous musculoskeletal (MS) (as opposed to aesthetics) concerns of users with prolonged sitting. This study seeks to find the OCDs whose prolonged usage offers longer-lasting comfort before body-part pain and muscle fatigue set in. Self- administered questionnaires were purposively distributed electronically to voluntary office workers to collect their demographic information, chair type and time to discomfort in selected eight body parts during chair usage. Fifteen OCDs in the survey were grouped into 5 (3 designs each) and statistical analyses gave the proportional distribution of the OCDs according to the participants’ job status as well as measures of comfortability of the chair usage. There were 426 participants, 56% male, with modal age range of 51-60 yrs; comprising 83% regular computer users, 46% with knowledge of Ergonomics. Generally, OCD group-3 had the highest usage, while groups 4 and 5 had negligible number of users. Longest comfortability was found in groups 1 and 3, but least in group 5. Design 7 ranked the highest, while 10 ranked the lowest in comfortability. Discomforts were indicated in all 8 body parts relative to all the OCDs, but design 10 gave the most discomfort. There was positive correlation between the use of heavy-duty chairs with swivel. It took longer time to experience swollen leg (0.120), thigh pain (0.082) and buttock pain (0.097) during the usage of OCDs group-1. Similarly, there is a positive correlation between the use of lighter chairs and delayed body response to neck pain (0.078), indicating that users of OCDs group-2 had more working time before they develop neck pain. Inverse correlations were found in regular wooden chairs usage and delayed body response to neck pain (-0.094), shoulder pain (-0.086) and lower back pain (-0.086). Similarly, plastic chairs usage gave negative correlation with the body delayed response to neck (-0.1) pain, shoulder pain (-.113) and lower back pain (-0.081). Generally, the design of heavy-duty chairs and lighter chairs with swivels have comfortability advantage over the non-padded wooden / plastic chairs and stools.