Effect of Wheelchair Stroke Pattern on Upper Extremity Muscle Fatigue

Background: Shoulder dysfunction is common in persons with spinal cord injury (SCI) with an incidence of up to 63%. Dysfunction is a result of muscle imbalances, specifically denervated rotator cuff muscles that are repetitively used during manual wheelchair propulsion. Objective: To determine which arm stroke technique, pump (P) or semicircular (SC), is most energy efficient for long periods of propulsion. Design: A randomized study with repeated measures observations. Setting: The study was performed at an institutional gait analysis laboratory. Participants: 18 able-bodied (AB) male participants were studied and randomized into one of 2 conditions, SC or P. Methods: Shoulder muscle fatigue was measured by changes in Borg CR10 Rate of Perceived Exertion (Borg RPE) and upper extremity strength via a handheld dynamometer. Participants were studied and assigned into one of 2 conditions of wheelchair arm propulsion patterns, SC or P group, and propelled on a wheelchair treadmill for 10 minutes. Main Outcome Measures: The primary outcomes included recordings of Borg RPE scale during continuous wheelchair propulsion and pre- and post-test dynamometer testing means for bilateral elbow and shoulder extension. Analysis of covariance, t-tests, and Kruskal-Wallis tests were used in analyzing data. Results: Although not significant (P =.23), the Borg RPE scores for the SC condition were consistently higher than the scores for the P condition. In addition, the dynamometer pre- and post-test readings demonstrated a larger decrease for the SC condition participants than for the P condition participants, but were not statistically significant. Conclusions: These data demonstrate that the SC wheelchair propulsion pattern appears to be more fatiguing to shoulder muscles than the P propulsion pattern. However, more data would need to be collected to find a significant difference.