Effects of environmental factors on heat tolerance during exercise.

本研究旨在探讨环境因素对运动耐热性的影响，并进行了以下三个实验：1.研究了适度运动后短暂的腿部降温对随后高温运动的心肺反应的影响。7名男性受试者在35℃(实验1)下进行40min的功率自行车运动(峰值摄氧量的65%)后，将双腿浸泡在35℃(对照条件：CONT)或20℃(冷却条件：冷)水中5min，然后重复重复(与之前相同，但不是10min)(实验2)。结果提示，在恢复期进行短暂的腿部降温可以有效地降低随后在高温下运动时的热负荷和心肺压力。2.我们调查了环境因素是否影响运动时的耐热性。16名学生在高温下进行了锻炼，并分析了这些生理参数与家乡气候条件和空调使用之间的关系。他们的耐热性指标如出汗率、前臂皮肤血流量增加率与气候数据之间的关系趋于显著，表明家乡的气候可能会影响学生的耐热性。3.我们检验了在高温下长时间锻炼时，核心温度的升高，而不是皮肤温度的增加，中介了分钟通气量(VE)的增加。13名受试者穿着10℃(T10)、35℃(T35)或45℃(T45)的西服，以50%的峰值摄氧量在功率计上运动60min。结果表明，在高温下长时间的亚极量运动中，VE随着核心温度的升高而增加，而不受皮肤温度或核心温度上升速度的影响。

We aimed to investigate the effects of environmental factors on heat tolerance during exercise and conducted the following three experiments.1.We investigated the effects of brief leg cooling after moderate exercise on the cardiorespiratory responses to subsequent exercise in the heat. Following 40 min of ergometer cycling (65% of peak O_2 uptake) at 35℃ (Ex.1), seven male subjects immersed their legs in 35℃ (control condition:CONT) or 20℃ (cooling condition:COOL) water for 5 min and then repeated the cycling (as before, but for 10 min) (Ex.2). The results suggest that brief leg cooling during the recovery period may be effective at reducing thermal and cardiorespiratory strain during subsequent exercise in the heat.2.We investigated whether the environmental factors affect the heat tolerance during exercise. Sixteen students exercised in the heat and the relationships among those physiological parameters, the climate conditions of their home towns and the usage of air-conditioner. The relationships between their heat tolerance index such as the sweat rate and increase rate of skin blood flow in the forearm and the climate data tend to be significant, suggesting the climate of the home town could affect the heat tolerance in the students.3.We tested the hypothesis that during prolonged exercise in the heat, an increase in core temperature, not skin temperature, mediates an increase in minute ventilation (VE). Thirteen subjects exercised for 60 min on a cycle ergometer at 50% of peak oxygen uptake while wearing a suit per fused with water at 10℃ (T10), 35℃ (T35) or 45℃ (T45). The results suggest that during prolonged sub-maximal exercise in the heat, VE increases with core temperature and is unaffected by skin temperature or the rate at which core temperature increases.