A comparison of glenohumeral joint kinematics and muscle activation during standard and geared manual wheelchair mobility

The high prevalence of upper extremity joint injuries among manual wheelchair users is largely attributed to the high repetitive loading during propulsion. The purpose of this study was to evaluate the effects of using geared wheels for manual wheelchair mobility on shoulder joint biomechanics. Fourteen able-bodied participants performed overground propulsion and ramp ascension using standard and geared manual wheelchair wheels. Spatial temporal parameters, glenohumeral joint kinematics, and shoulder muscle activity were quantified. Findings indicated that regardless of the level of slope, the propulsion speed and stroke distance decreased significantly (p ≪ 0.001), and the stroke frequency increased significantly (p ≤ 0.025) during geared manual wheelchair propulsion. The glenohumeral joint ranges of motion in the coronal plane (p ≤ 0.005) and peak joint angles in the coronal (p ≤ 0.023) and transverse (p ≤ 0.012) planes were significantly different between standard and geared wheels usage. Shoulder muscle activity was substantially less using the geared wheels with significant findings in the pectoralis major (level floor, p ≤ 0.008) and infraspinatus (p ≤ 0.014) peak muscle activity, and the anterior deltoid (p ≤ 0.014) and pectoralis major (p ≤ 0.015) integrated muscle activity. However, the shoulder flexor normalized integrated muscle activity (muscle activity per stroke distance) was not different between the wheels.