Purpose: To examine the effects of rear-wheel camber on the physiological and biomechanical responses during manual wheelchair propulsion in highly trained wheelchair athletes.
Methods: Participants (N = 14) pushed on a motorized treadmill (2.2 m·s-1, 0.7% gradient) in four standardized camber conditions (15°, 18°, 20°, and 24°). Standardization was achieved by controlling seat height, the distance between top dead center of the main wheels and "toe-in toe-out" across all camber settings. Power output (PO) and cardiorespiratory measures were collected for each camber setting. Three-dimensional upper body joint kinematics were also analyzed via two high-speed video cameras (100 Hz). One-way ANOVA with repeated measures was applied to all data with statistical significance accepted when P < 0.05.
Results: A significantly higher PO was observed for 24° camber (24.3 W) in relation to 15° (20.3 W) and 18° (21.3 W), and also for 20° (23.3 W) in relation to 15°. This resulted in an improvement in mechanical efficiency (ME) for both 24° (6.8%) and 20° (6.7%) compared with 15° (5.9%). However, significantly higher oxygen uptake (reduced economy) and HR responses were observed for 24° (1.04 L·min-1; 105 bpm) compared with 15° (0.98 L·min-1; 102 bpm) and 18° (0.97 L·min-1; 102 bpm). Also, significantly greater ranges of motion were established for shoulder flexion and elbow extension during the push phase for 24° and were likely to have contributed toward the increased oxygen cost in this setting.
Conclusions: This study revealed that 20° and 24° camber improved the ME of wheelchair propulsion in highly trained wheelchair athletes, yet these increased external power requirements and reduced the economy.
History
School
Sport, Exercise and Health Sciences
Published in
MEDICINE AND SCIENCE IN SPORTS AND EXERCISE
Volume
43
Issue
2
Pages
319 - 326 (8)
Citation
MASON, B. ... et al, 2011. Effects of camber on the ergonomics of propulsion in wheelchair athletes. Medicine and Science in Sports and Exercise, 43 (2), pp. 319 - 326.