Comparison of shoulder muscle electromyographic activity during standard manual wheelchair and push-rim activated power assisted wheelchair propulsion in persons with complete tetraplegia.

Objectives: To compare spatio-temporal propulsion characteristics and shoulder muscle electromyographic activity in persons with cervical spinal cord injury propelling a standard pushrim wheelchair (WC) and a commercially available pushrim-activated power assisted wheelchair (PAPAW) design on a stationary ergometer.

Design: Repeated measures.

Setting: Motion analysis laboratory within a rehabilitation hospital.

Participants: Men (N=14) with complete (American Spinal Injury Association grade A or B) tetraplegia (C6=5; C7=9).

Intervention: Participants propelled a standard pushrim WC and PAPAW during 3 propulsion conditions: self-selected free and fast and simulated 4% or 8% graded resistance propulsion.

Main Outcome Measures: Median speed, cycle length, cadence, median and peak electromyographic activity intensity, and duration of electromyographic activity in pectoralis major, anterior deltoid, supraspinatus, and infraspinatus muscles were compared between standard pushrim WC and PAPAW propulsion.

Results: A significant (P<.05) decrease in electromyographic activity intensity and duration of pectoralis major, anterior deltoid, and infraspinatus muscles and significantly reduced intensity and push phase duration of supraspinatus electromyographic activity at faster speeds and with increased resistance were seen during PAPAW propulsion.

Conclusions: For participants with complete tetraplegia, push phase shoulder muscle activity was decreased in the PAPAW compared with standard pushrim WC, indicating a reduction in demands when propelling a PAPAW.