Efficiency of wheelchair propulsion and effects of strategy.

The purpose of this study was to determine the contributions of arm frequency and propulsion mode on the internal work during submaximal wheelchair propulsion. Twelve able-bodied participants performed a V.O (2) peak test on a wheelchair ergometer. On a separate occasion, six (4 min) submaximal exercise conditions employing two modes of propulsion (synchronous, SYN vs. asynchronous, ASY) at arm frequencies of 40 and 80 rev . min (-1) were performed at 1.2 m . s (-1) and 1.7 m . s (-1). These conditions resulted in three push strategy combinations (ASY [20 : 20], SYN [40 : 40] & ASY [40 : 40]) at two speeds. Gross, net, work and delta efficiency were determined. The cost of unloaded exercise was significantly lower for the ASY [20 : 20] than both ASY and SYN [40 : 40] (0.49 vs. 0.58 and 0.57 L . min (-1), respectively). All the efficiency indices decreased as velocity increased (p < 0.01). ASY [20 : 20] was the least efficient (gross and work) mode (4.2 +/- 0.4 % and 6.2 +/- 0.8 % respectively). Comparison of equal arm frequencies (ASY [40 : 40] vs. SYN [40 : 40]); found the efficiency to be lower for ASY propulsion (p < 0.05). Under the current testing conditions SYN propulsion mode offers greater efficiency during wheelchair propulsion.