Seat forces as function of wheelchair back angle and foot rest height

Normal and shear forces were measured using a force plate mounted in the seat as a wheelchair back was reclined and returned to the upright and the foot rest height was changed. Ischial tuberosity (ISCH) pressure was also measured during the foot rest height change. Measurements were taken for five subjects sitting directly on the force plate and on ROHO and Jay cushions placed on the force plate. After the back was reclined 58° and returned to the upright position, the normal force increased by 5.5, 9.4 and 10.1 kg and the shear force increased to 5.1, 11.6 and 12.3 kg for the HS, Jay and ROHO cushions, respectively. Leaning forward after reclining returned the forces to near the starting values. ISCH pressure measurements show that with firm thigh support, lowering the foot rests will reduce ischial tuberosity pressure