Study design: Cross-over study. Objective: To determine the effect of strenuous wheelchair exercise on oxygen uptake ( . VO 2 ), muscle activity and propulsion cycle timing (including the push time and recovery time during one full arm cycle). Setting: Laboratory of Sport Sciences at the University of France-Comte in France. Methods: Two exercise bouts of 6-min duration were performed at a constant workload:(1) non-fatigable exercise (moderate workload) and (2) fatigable exercise (heavy workload). Measurement of .VO 2 , surface electromyographic activity (EMG) from shoulder muscles, and temporal parameters of wheelchair ergometer propulsion were collected from eight able-bodied men (2674 years). Results: A progressive increase in .VO 2 associated with EMG alterations (Po0.05), and a decrease of the cycle and recovery time (Po0.05) during the heavy exercise. Whereas the push time remained constant, an increased muscle activation time (Po0.05) was found during heavy exercise. Conclusion: Observations during wheelchair ergometry indicate the development of fatigue and inefficient muscle coordination, which may contribute to deleterious stress distributions at the shoulder joint, increasing susceptibility to injury.

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