Effect of wheelchair stroke pattern on mechanical efficiency

Objective: To investigate the effect of different wheelchair stroke patterns on efficiency and propulsion technique (force application and timing). Design: Inexperienced, able-bodied subjects were randomly divided into two velocity groups (1.11 m/sec [n = 13] and 1.39 m/sec [n = 11]). An external (medium) load was set at 0.23 N/kg. Subjects performed four 4-min exercise blocks on a wheelchair ergometer. The first block was performed with a freely chosen movement pattern of the hand. Thereafter, the pumping, semicircular, or single-looping over propulsion pattern were performed in a counterbalanced order. Gross mechanical efficiency and propulsion technique variables were measured with Oxycon Alpha and an instrumented wheelchair ergometer. Results: A significant difference was found for mechanical efficiency, with pumping showing the highest efficiency and semicircular the lowest efficiency, regardless of velocity. Timing variables and negative power deflections before and after the push phase showed significant differences between the stroke patterns. Conclusions: Pumping is the energetically most efficient stroke pattern in contrast to the semicircular pattern in this subject group. Propulsion technique could not explain the difference in efficiency.