Thermoregulation, peripheral vessel vasomotor regulation, and hormonal responses during cold exposure in wheelchair athletes

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The purpose of this study is to clarify the characteristics of thermoregulation and physiological responses during exercise in a cold and hot environment in wheelchair athletes with spinal cord injury. The subjects were male wheelchair athletes with spinal cord injury and healthy male college students. The maximal oxygen intake as a parameter of endurance exercise ability was higher in the wheelchair athletes than in the college students. Measurements were performed at an environmental temperature of 12℃ and 35℃ with a mean relative humidity of 60% at a mean air stream of 0.5m/sec. After rest for 30 minutes, the subjects performed arm cranking exercise at 20 watts(50 rpm) for 60 minutes. The measurement items were tympanic temperature, mean skin temperature, heat production, catecholamine, and cold-induced vasodilation.During exercise under exposure to cold, the tympanic temperature, heat production, and catecholamine more markedly increased in the wheelchair athletes than in the college students. The resistance index as a value of cold-induced vasodilation were higher in the wheelchair athletes than college students during cold exposure. On the other hand, the decrease in the mean skin temperature was slighter in the wheelchair athletes than in the college students. The thermoregulation sensitivity and heat production responses to exercise in a cold environment were more markedly increased in the wheelchair athletes than in the college students.During exercise under exposure to heat, the tympanic temperature, mean skin temperature, heat production, and catecholamine more markedly increased in the wheelchair athletes than in the college students. The thermoregulation sensitivity and heat production responses to exercise in a hot environment were lower in the wheelchair athletes than in the college students. These results suggested that spinal cord injury considerably affects thermoregulation during exercise in a hot environment.