A kinetic analysis of trained wheelchair racers during two speeds of propulsion

The purpose of the study was to investigate the propulsion kinetics of whee lchair racers at racing speeds and to assess how these change with an incre ase in speed. It was hypothesised that propulsive force would increase in p roportion to speed, to accommodate the additional work required. Six wheelc hair racers volunteered to participate in this study which required each at hlete to push a racing wheelchair at 4.70 and 5.64 m s(-1) on a wheelchair ergometer (WERG). Eight pairs (16 in total) of strain gauges, mounted on fo ur bars attached to the hand-rim of a racing wheelchair wheel, measured the medio-lateral and tangential forces applied to the hand-rim. Kinetic data were sampled at 200 Hz while a single on-line (ELITE) infrared camera opera ting at 100 Hz was positioned perpendicular to the WERG to record the locat ion of the hand with respect to the hand-rim. In general, peak tangential f orce occurred when the hand was positioned on the hand-rim between 140 and 1800. With the increase in speed, the peak handrim forces applied tangentia lly increased from 132 to 158 N and those applied medio-laterally increased from 90 to 104 N. The ratio of tangential to total measured force was simi lar at both speeds (80 and 82%, respectively). In conclusion, these data in dicate that wheelchair racers adopt a different propulsion strategy than th at employed in everyday chairs and that the forces increase in proportion t o propulsion speed. (C) 2001 IPEM. Published by Elsevier Science Ltd. All r ights reserved.