Effects of wheel and hand-rim size on submaximal propulsion in wheelchair athletes

Purpose: This study aimed to investigate the effects of fixed gear ratio wheel sizes on the physiological and biomechanical responses to submaximal wheelchair propulsion. Methods: Highly trained wheelchair basketball players (N = 13) propelled an adjustable sports wheelchair in three different wheel sizes (24, 25, and 26 inches) on a motor-driven treadmill. Each wheel was equipped with force-sensing hand-rims (SMARTWheel), which collected kinetic and temporal data. Oxygen uptake (V·O2) and HR responses were measured with high-speed video footage collected to determine three-dimensional upper body joint kinematics. Results: Mean power output and work per cycle decreased progressively with increasing wheel size (P < 0.0005). Increasing wheel size also reduced the physiological demand with reductions in V·O2 for 25-inch (0.90 ± 0.20 L·min-1, P = 0.01) and 26-inch wheels (0.87 ± 0.16 L·min-1, P = 0.001) compared with 24-inch wheels (0.98 ± 0.20 L·min-1). In addition, reductions in HR were observed for 26-inch wheels (99 ± 6 beats·min-1) compared with 25-inch (103 ± 8 beats·min-1, P = 0.018) and 24-inch wheels (105 ± 9 beats·min-1, P = 0.004). Mean resultant forces also decreased progressively with increasing wheel size (P < 0.0005). However, no changes in temporal or upper body joint kinematics existed between wheel sizes. Conclusions: A greater power requirement owing to a greater rolling resistance in 24-inch wheels increased the physiological demand and magnitude of force application during submaximal wheelchair propulsion.