Studies of physiological responses of thermoregulation, skin blood flow, osmolality, and catecholamine during exercise in wheelchair athletes in a hot environment

摘要

This study was carried out to clarify characteristics of responses of thermoregulation and other physiological responses in wheelchair athletes with spinal cord injury during exercise in a hot environment. Evaluations were made in a climatic chamber at a moderate exercise intensity and during actual training (field). The subjects were 5 wheelchair marathon racers(MG), 5 wheelchair basketball players(BG), and 5 healthy male college students(SG). The measurements were performed between late July and mid-October. In the climatic chamber, the subjects exercised on an arm cranking ergometer at 60% VO2max for 60 minutes after a 60-minute rest at a room temperature of 35℃ and a relative humidity of 60%. In the field, the subjects of Group MG drove the wheelchair at a mean speed of 35 km/h for 90 minutes in a 2-km outdoor course, those of Group BG performed routine practice for 90 minutes in the gymnasium, and those of Group SG performed 90-minute running. The WBGT(wet bulb globe temperature) in the field was 29.40-34.91℃. The subjects was allowed free access to a sports beverrage during the exercise. The items measured were heart rate, mean skin temperature, sweat loss, skin blood flow, tympanic temperature, blood lactate, osmolality and catecholamine leve. A. In a hot climatic chamber, mean skin temperature during exercise was higher in MGand BGthan in SG. Sweat loss during exercise was smaller in MGand BGthan in SG. During exercise, skin blood flow increased rapidly in all 3 groups, but it was always greater in MGand BGthan in SG. The increase in tympanic temperature during exercise was greater in MGand BGthan in SG. Catecholamine increased with adrenaline, noradrenaline, and dopamine progressively at 30 minutes after the beginning of exercise and at the end of exercise, and its increase was slightly greater in MGand BG than in SG. B. In the field, the heart rate during exercise was 132beats/min (bpm) in MG, 138 bpm in BG, and 133 bpm in SG. Mean skin temperature during exercise was highest in BG, followed by MG, and lowest in SG. Sweat loss during exercise was smaller in MG and BGthan in SG, but there was no difference in the fluid intake. The increase in tympanic temperature during exercise was the largest in BGand smallest in SG. Adrenaline, noradrenaline, dopamine, blood lactate and osmolality increased after the beginning of exercise, and its increase was slightly greater in MGand BGthan in SG. The sensitivity of thermoregulation during exercise was lower in the wheelchair athletes than in normal college students in the climatic chamber and outdoor and indoor exercise situations, probably because spinal cord injury has a considerable effect on thermoregulation during exercise in a hot environment. When wheelchair athletes exercise in a hot environment, special precautions such as a sufficient fulid intake and avoiding hot hours are recommended to avoid heatstroke.