Effect of push handle height on net moments and forces on the musculoskeletal system during standardized wheelchair pushing tasks.

The aim of this investigation was to analyze the external forces and biomechanical loading on the musculoskeletal system during wheelchair pushing, in relation to different push handle heights. In addition, recommendations for wheelchair pushing in accordance with push handle height are made. Eight young, female subjects carried out three different wheelchair transport tasks at five different push handle heights in a standardized laboratory setting. Five pushing heights were selected as a percentage of the subjects shoulder height (61, 69.5, 78, 86.5 and 95%). All three wheelchair transport tasks investigated required higher pushing handles in order to minimise net shoulder moments and external vertical forces on the hands. When pushing a wheelchair on to a pavement, net moments around wrists, elbows, shoulders compression and shear forces at L5-S1 and external vertical forces were lower using higher pushing heights. When low pushing handles are used, elderly female attendants are at risk of L5-S1 low back pain when lifting and pushing the wheelchair on to a pavement. A recommendation is made to reconsider height and position of the pushing handles of attendant propelled wheelchairs. For the investigated tasks, a pushing height of 86.5% (1.191 +/- 0.034 m) was most favourable.