EMG-based evaluation of a detachable two-way propulsion system for manual wheelchairs: rehabilitative effects in older adults with spinal cord injury.

Background

A manual wheelchair is an essential assistive device for individuals with spinal cord injury (SCI). However, long-term use typically requires repetitive forward pushing on the pushrims, which overuses anterior upper-body muscles and contributes to shoulder muscle imbalance and pain. To address these issues, a detachable two-way propulsion system was developed to allow both pushing and pulling movements, with the pulling method designed to enhance posterior muscle activation.

Methods

Electromyography (EMG) was performed on eight upper-body muscles in eight older adults with SCI (mean age: 68.7 years) to compare muscle activation patterns between the pushing and pulling propulsion methods.

Results

The pulling method elicited significantly greater activation in the latissimus dorsi (p = 0.008), middle deltoid (p = 0.008), triceps brachii (p = 0.008), and upper trapezius (p = 0.008). Conversely, the pushing method resulted in significantly greater activation of the anterior deltoid (p = 0.008) and pectoralis major (p = 0.039). Discussion: The findings show that the pulling method effectively engages key posterior muscles while reducing reliance on anterior muscles. This redistribution of muscular workload suggests that the pulling method may help alleviate shoulder muscle imbalance and pain commonly experienced by older adults with SCI who rely on manual wheelchairs for daily mobility.