Physical work capacity after 7 wk of wheelchair training: effect of intensity in able-bodied subjects

Purpose: The purpose of this study was to study the effects of a 7-wk wheelchair training program on physical work capacity in able-bodied subjects. Effects of training intensities of 50 and 70% heart rate (HR) reserve (HRR) were studied for different subject groups. Methods: Twenty-seven able-bodied male subjects participated in this study. They were randomly divided into a control group (N = 8), a 50%-intensity group (N = 9), and a 70%-intensity group (N = 10). The 50%- and the 70%-intensity groups received a 7-wk wheelchair training program: three times a week, one-half hour wheelchair exercise on a motor driven treadmill at an average intensity of 50 and 70% of the HRR, respectively. Before and after the training period, parameters for physical work capacity (maximal isometric strength (F-iso), sprint power (P30), maximal power output (POmax) and peak oxygen uptake (VO2peak)), and submaximal performance (mechanical efficiency, HR) at 20 and 40% of the estimated POmax (ME20, ME40; HR20, HR40) were obtained during tests on a stationary wheelchair ergometer. Results: A two-factor ANOVA for repeated measures on the within-subjects factor "pre-post tests," the between-subject factor training (50% and 70% training vs control) and the interaction term showed that the 50%-intensity group significantly increased on P30 and POmax compared with the control group. The 70% intensity group significantly increased on P30, POmax, and VO2peak, compared with the control:roup (P < 0.05). The 70% group did not show significantly higher increases in P30 and POmax over training than the 50% intensity. No significant effects were found for the F-iso and the parameters at submaximal PO. Conclusions: The wheelchair training at both intensities can have favorable effects on maximal physical work capacity in able-bodied subjects, and possibly also on mechanical efficiency at submaximal power output. Effects are seen in parameters for both aerobic and anaerobic work capacities. Although training at 70% intensity was more effective than the 50% intensity, training at 50% HRR may initially be more appropriate in untrained individuals, such as novice wheelchair users at the start of their rehabilitation, to prevent fatigue and enhance motivation.