MECHANICAL ADVANTAGE IN WHEELCHAIR LEVER PROPULSION - EFFECT ON PHYSICAL STRAIN AND EFFICIENCY

In this experimental study on a prototype lever-propelled wheelchair, the effect of a range of mechanical advantages (MA) on physical strain , oxygen uptake, energy cost, mechanical efficiency, stroke frequency and perceived exertion was examined. Nine out of 10 male nonwheelchair users successfully performed five submaximal tests on a motor-driven treadmill in a prototype bi-manual asynchronous lever-propelled tricyc le. Each test contained the same protocol, but made use of one of the five different MAs. In every test the inclination level increased by 1 % every third minute, starting on 0% up to 3%. The velocity was kept c onstant at 0.97 m.s(-1). Variables measured included oxygen uptake, mi nute ventilation, respiratory exchange ratio, heart rate, and stroke f requency. Analysis for repeated measures was conducted on the main fac tors slope and MA and their interaction. Additional analysis include a multiple regression analysis. All statistics were conducted with a p< 0.05 level of significance. MA had a significant effect (p<0.05) on ox ygen uptake, energy cost, mechanical efficiency, and stroke frequency. These results suggest that the implementation of a range of MAs on a lever-propelled wheelchair may accommodate different external conditio ns (slope, climatic, surface conditions. sports, and recreational cond itions) and different user groups more readily. This may improve the s ocial radius of action and freedom of mobility of individuals confined to wheelchairs.