Analysis of Back Forces While Sitting Down, Seated, and Rising from a Stationary Chair in Subjects Weighing 136–186 kg

Limited research was found related to the study of back forces on chairs sat on by people who weighed over 136 kg. The Business Institutional Furniture Manufactures Association needs force data for development of performance test standards to test chairs for users who weigh up to 181 kg. 20 participants who weighed from 136 to 186 kg completed six tasks on an instrumented chair in the sequence of sitting down, remaining seated, and rising. Effects of sitting motion, armrest use, and seat cushion thickness on back forces and centre-of-force were investigated. Results indicated hard sitting down yielded the highest back force of 34.7 % in terms of participants’ body weights. Armrest use and cushion thickness affected back forces of normal sitting down, but not of rising, hard sitting down, and remaining seated.