Studies on changes in human heat adaptability in an era of global warming and widespread use of artificial environments

为了对热带原住民热适应的一致性理解，我们比较了热带和温带原住民在静息、被动和主动加热条件下的种族差异。实验方案包括：(1)静息条件（28℃，50% RH）；(2)被动加热条件（28℃，50% RH；腿浸在42℃的热水浴缸中）；(3)主动加热条件（32℃，70% RH；骑自行车运动）。在形态和身体上匹配的热带土著（10名马来西亚男性，MY）和温带土著（10名日本男性，JP）参加了所有三个试验。结果发现：热带土著居民的静息直肠温度较高，静息时手脚温度较低，直肠温度上升较小，四肢温度上升较大，在被动和主动加热时的口渴感较低。结果表明，热带土著动物的体内温度稳定性提高，四肢血管循环能力增强，口渴感较低，可以有效地控制加热过程中的内稳态。

For the coherent understanding of heat acclimatization in tropical natives, we compared ethnic differences between tropical and temperate natives during resting, passive and active heating conditions. Experimental protocols included: (1) a resting condition (an air temperature of 28℃ with 50% RH), (2) a passive heating condition (28℃ with 50% RH; leg immersion in a hot tub at a water temperature of 42℃), and (3) an active heating condition (32℃ with 70% RH; a bicycle exercise). Morphologically and physically matched tropical natives (ten Malaysian males, MY) and temperate natives (ten Japanese males, JP) participated in all three trials. The results saw that: tropical natives had a higher resting rectal temperature and lower hand and foot temperatures at rest, smaller rise of rectal temperature and greater temperature rise in bodily extremities, and a lower sensation of thirst during passive and active heating than the matched temperate natives.It is suggested that tropical natives’ homeostasis during heating is effectively controlled with the improved stability in internal body temperature and the increased capability of vascular circulation in extremities, with a lower thirst sensation.