Budd G M, Brotherhood J R, Beasley F A, Hendrie A L, Jeffery S E, Lincoln G J, Solaga A T
National Institute of Occupational Health and Safety, Sydney NSW, Australia.
Eur J Appl Physiol Occup Physiol. 1993;67(5):438-49. doi: 10.1007/BF00376461.
The purpose of this study was to investigate the thermoregulatory mechanisms underlying artificial acclimatization to cold and to compare them with those of naturally acclimatized men. Six white men were cooled, nude, in air at 10 degrees C for 2 h before and after they had been acclimatized by ten daily cold (15 degrees C) baths of 30-60 min followed by rapid rewarming in hot (38-42 degrees C) water, and again 4 months later after acclimatization had decayed. Six control subjects also underwent the same tests, providing an opportunity to discriminate between changes caused by the immersions and those caused by extraneous influences. Acclimatization significantly reduced heat production and heat loss (P < 0.05) but did not change heat debt. The reduced heat production was accompanied by reductions in shivering (P < 0.10) and in cold-induced muscle tenseness; no evidence of nonshivering thermogenesis or active brown fat was found. These findings are attributed to increased tissue insulation, mediated by an enhanced vascular response to cold that did not involve the cutaneous circulation and was probably located in skeletal muscle. Thermal sensation and discomfort did not change, although perceived strain tended to increase (P = 0.08). Acclimatization was accompanied by, but was unrelated to, slower cooling of the finger and toe. The main conclusions, and many specific findings, agree with those of two previous studies made by the same techniques in naturally acclimatized men wintering in Antarctica. Other significant findings included changes--in particular reduced thermoneutral rectal temperature and a delayed onset of shivering--that are commonly regarded as evidence of acclimatization but were in fact unrelated to it as they also occurred in the control group. They are attributed to extraneous influences, in particular the relaxation of heightened arousal ('first-time effects') found in the baseline tests.
本研究的目的是探究人工冷适应的体温调节机制，并将其与自然冷适应男性的机制进行比较。六名白人男性在经过为期十天、每次30 - 60分钟的15摄氏度冷水浴，随后在38 - 42摄氏度热水中快速复温进行冷适应前后，以及冷适应消退4个月后，于10摄氏度空气中裸体冷却2小时。六名对照受试者也进行了相同测试，从而有机会区分浸泡引起的变化和外部影响引起的变化。冷适应显著降低了产热和散热（P < 0.05），但未改变热债。产热减少伴随着寒颤（P < 0.10）和冷诱导肌肉紧张度的降低；未发现非寒颤产热或活跃棕色脂肪的证据。这些发现归因于组织隔热增加，这是由对寒冷增强的血管反应介导的，该反应不涉及皮肤循环，可能位于骨骼肌中。热感觉和不适感没有变化，尽管感知到的压力有增加趋势（P = 0.08）。冷适应伴随着手指和脚趾冷却变慢，但两者并无关联。主要结论以及许多具体发现与之前两项对在南极洲越冬的自然冷适应男性采用相同技术进行的研究结果一致。其他显著发现包括一些变化——特别是体温调节的直肠温度降低和寒颤发作延迟——这些通常被视为冷适应的证据，但实际上与冷适应无关，因为它们在对照组中也出现了。它们归因于外部影响，特别是基线测试中发现的高度唤醒状态（“首次效应”）的缓解。
