身体鍛練 (持久的) と水分摂取が高温環境下での身体運動に及ぼす効果

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A healthy man performed three 2-hr bicycle works at about 30% of his aerobic power in a hot environment (50℃) to assess the effects of water intake and physical conditioning on the temperature regulation and other selected physiological variables during the work. When water was ingested during the bicycle work, the body temperature and heart rate were lower than those when no water was ingested (dehydration). In addition, they also lowered after physical conditioning of a 3-month period. Dehydration before the physical conditioning program resulted in a 2.7% decrease in body weight, a 12.2% decrease in plasma volume, and a 7.5% decrease in blood volume, while the corresponding values were 2.4%, 7%, and 4.5% decreases, respectively after physical conditioning. No body fluid loss was observed with water replacement. It was concluded that the thermoregulatory and cardiovascular failures due to work in high ambient temperatures can be ameliorated by water intake during the work and also by physical conditioning. Athletes exercising in hot environments frequently lose excessive water and electrolytes during athletic competitions or workout sessions. In addition, they also meet with an excessive rise in body core temperature. Such dehydration hyperthermia usually results in an decrease in work performance and heat tolerance. Previous studies have reported that dehydration of more than 2% significantly decreases man's working ability (4, 21). According to Adolf (1), acute dehydration limits man's working ability due mainly to impaired cardiovascular function. Thus, excessive water loss in sweat is a major problem for men exercising in hot environments. Since a high sweat rate is required for adequate evaporative cooling during exercise in stressful environments, the prevention of the progressive dehydration by replacement of body fluids in sweat must be taken into consideration in order to reduce the physiological impairements. Circulating blood volume is particularly affected by the progressive dehydration and the decrease in blood volume, in turn, causes added circulatory strain with eventually an excessive rise in core temperature. The relationship between physical conditioning and heat tolerance is interesting. It has been reported that the physical conditioning produces an improvement in heat tolerance (8). It is, therefore, of interest to investigate that to what extent, daily mild jogging affects work performance in stressful heat in terms of both circulatory and thermoregulatory responses. The present stduty was designed with two aims; first, the effects of water ingestion during work in heat and second, physical conditioning of jogging. They were examined on man's thermal and circulatory responses to work in heat.
中京大学の論文
1979-08-31

著者

小林義雄
中京大学教養部

身体鍛練 (持久的) と水分摂取が高温環境下での身体運動に及ぼす効果

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