Shapiro Y, Hubbard R W, Kimbrough C M, Pandolf K B
J Appl Physiol Respir Environ Exerc Physiol. 1981 Apr;50(4):792-8. doi: 10.1152/jappl.1981.50.4.792.
Differences between acclimation to heat at the end of winter (W) and at the end of summer (S) were studied on the same eight male volunteers. Subjects were exposed to 40 degrees C, 30% rh for 10 consecutive days on two separate occasions approximately 5 mo apart (S and W). Daily exposures lasted 120 min: 10 min rest, 50 min walking 1.34 m . s-1 on the level, 10 min rest, 50 min walking. During W acclimation, rectal temperature (Tre) and heart rate (HR) decreased, sweat rate (msw) remained unchanged, and plasma and red cell volume of the blood expanded. During S acclimation, HR decreased while Tre and msw remained unchanged, and plasma volume increased. The Tre of the acclimated subjects remained higher in W, and the msw lower, than in S. It was concluded that acclimation does not totally eliminate the seasonal differences in thermoregulatory set point and sweating sensitivity. Further, acclimation to a more severe heat did not lower the thermoregulatory set point that was achieved by natural acclimatization to a milder heat but affected the cardiovascular adjustment and caused greater plasma volume expansion. W acclimation caused both plasma and blood cell volume expansion, whereas S acclimation affected only plasma volume.
在相同的八名男性志愿者身上研究了冬季末（W）和夏季末（S）适应热环境的差异。在大约相隔5个月的两个不同时间段（S和W），让受试者连续10天暴露于40摄氏度、相对湿度30%的环境中。每天的暴露持续120分钟：10分钟休息，50分钟以1.34米/秒的速度在平地上行走，10分钟休息，50分钟行走。在W适应期间，直肠温度（Tre）和心率（HR）下降，出汗率（msw）保持不变，血液的血浆和红细胞体积增加。在S适应期间，HR下降，而Tre和msw保持不变，血浆体积增加。适应后的受试者的Tre在W时仍高于S，而msw低于S。得出的结论是，适应并不能完全消除体温调节设定点和出汗敏感性的季节性差异。此外，适应更严酷的热环境并没有降低通过自然适应较温和热环境所达到的体温调节设定点，但影响了心血管调节并导致更大的血浆体积扩张。W适应导致血浆和血细胞体积都增加，而S适应仅影响血浆体积。
