RESUMO
The purpose of this study was to investigate the physiological responses during pushing of a racing-wheelchair. Five subjects with spinal cord injury (T4-L1) participated in two experiments. In the first experiment, the subjects pushed a racing-wheelchair mounted on a roller. Pulmonary ventilation (VE), oxygen uptake (VO<SUB>2</SUB>), heart rate (HR), blood lactate concentration (LA), and rating of perceived exertion (RPE) were measured to examine the physiological responses during submaximal and maximal tests of wheelchair exercise. The mean value of %VO<SUB>2</SUB>max at ventilatory threshold (VT) was 60.7±5.3%. VO<SUB>2</SUB> increased curvilinearly with speed, and HR increased with speed, forming an S-shape. HR increased linearly with increasing VO<SUB>2</SUB> before the VT, then showed a steeper parabolic rise to almost maximum, followed by a flat phase. In the second experiment, during 1500-m and 5000-m wheelchair races and a half-marathon, VE, VO<SUB>2</SUB>, and HR were measured to reveal the physiological characteristics of wheelchair racing as a competitive sport. During the 1500-m and 5000-m races by four subjects, the mean values of %VO<SUB>2</SUB>max were 73.1±7.3% and 66.0±13.3%, respectively. During the half-marathon by one subject, %VO<SUB>2</SUB>max reached 72.1%. These data suggest that wheelchair endurance athletes compete at very high intensity (over VT level) in wheelchair races.