Peak Power Production in Wheelchair Propulsion

Abstract

The effect of resistance on sprint power and the relationship between sprint and aerobic power production in wheelchair propulsion was evaluated. Six able-bodied subjects performed nine 20-s sprint tests on a stationary wheelchair ergometer (varying workload of 0–22.4 Nm for each side) and an aerobic maximum wheelchair exercise test to study both anaerobic and aerobic power production. Ergometer data were analyzed unilaterally. Of all power and torque parameters, only maximal power output was independent of resisting load (mean value 375 W, one-sided). Mean sprint power output over 20 s (P mean; one-sided) increased from 21 W to 87 W. The highest power output, P5, calculated over a period of 5 s (unilateral) increased from 24 W to 101 W. The P mean and P5 reached more or less constant values at the final two levels of resistance. The observed increase in power output with increasing load is the result of a greater increase in torque compared to the decrease in velocity. Mean maximal power in the maximal aerobic exercise test (n = 5) was 79 W, representing 42% of mean power (averaged over the nine sprint tests) and 37% of P5. In contrast to P mean and P5, P max showed a significant association with peak aerobic power production and peak oxygen uptake. This may indicate that P max is an indicator of overall performance capacity, whereas P mean and P5 are much more sprint related. The methodology of wheelchair exercise testing requires further detailed study with respect to the physiology and bio-mechanics of arm work, the functionality of the subject population, and reliability and validity of procedures and techniques. Eventually this should lead to standardized and reliable testing procedures. Both a standardized sprint test and a standardized aerobic wheelchair performance test can serve as additional tools in the evaluation of physical performance in wheelchair sports medicine. Perhaps more important, they may also serve as clinical tools in the evaluation of the process of rehabilitation.