Evaluation of shoulder joint kinematics and muscle activity during geared and standard manual wheelchair mobility.

Manual wheelchairs often lead to reduced independent function and an increase in shoulder pain and injuries. Geared manual wheelchairs may be a promising alternative that reduces the biomechanical demands of the shoulder needed for tasks such as propulsion on ramps and carpeted floors, while maximizing function and participation. To investigate the effects of geared manual wheelchair mobility during demanding tasks such as ramp ascent, six able-bodied subjects were evaluated in this study. Subjects were asked to propel both standard and geared manual wheelchairs on a tiled level floor and on a wheelchair ADA ramp. Shoulder muscle activity and glenohumeral joint kinematics were investigated. The results indicated that using geared manual wheelchair wheels did not alter the shoulder joint kinematics, but notably affected peak and integrated shoulder muscle activity. Muscle activity results normalized by stroke distance, indicated that using geared manual wheelchairs could decrease anterior deltoid, pectoralis major and infraspinatus muscle activity during ramp ascending, but on level floor infraspinatus muscle activity may increase. These results could have clinical implications for determining the types of functional mobility tasks for which geared manual wheelchairs are beneficial.