Castellani John W, Stulz Dean A, Degroot David W, Blanchard Laurie A, Cadarette Bruce S, Nindl Bradley C, Montain Scott J
US Army Research Institute of Environmental Medicine. Natick, MA 01760-5007, USA.
Med Sci Sports Exerc. 2003 Jan;35(1):175-81. doi: 10.1097/00005768-200301000-00026.
PURPOSE; This study examined the effects of short-term (3.5 d) sustained military operations (SUSOPS) on thermoregulatory responses to cold stress.
Ten men (22.8 +/- 1.4 yr) were assessed during a cold-air test (CAT) after a control week (control) and again after an 84-h SUSOPS (sleep = 2 h.d (-1), energy intake = approximately 1650 kcal.d(-1), and energy expenditure = approximately 4500 kcal.d(-1). CAT consisted of a resting subject (seminude) being exposed to an ambient temperature ramp from 25 degrees C to 10 degrees C during the initial 30 min of CAT, with the ambient temperature then remaining at 10 degrees C for an additional 150 min.
SUSOPS decreased (P< 0.05) body weight, % body fat, and fat-free mass by 3.9 kg, 1.6%, and 1.8 kg, respectively. During CAT, rectal temperature decreased to a greater extent (P< 0.05) after SUSOPS (0.52 +/- 0.09 degrees C) versus control (0.45 +/- 0.12 degrees C). Metabolic heat production was lower (P< 0.05) after SUSOPS at min 30 (55.4 +/- 3.3 W.m (-2)) versus control (66.9 +/- 4.4 W.m(-2)). Examination of the mean body temperature-metabolic heat production relationship indicated that the threshold for shivering was lower (P< 0.05) after SUSOPS (34.8 +/- 0.2 degrees C) versus control (35.8 +/- 0.2 degrees C). Mean weighted skin temperatures ( degrees C) were lower during the initial 1.5 h of CAT in SUSOPS versus control. Heat debt was similar between trials.
These results indicate that sustained (84-h) military operations leads to greater declines in core temperature, due to either a lag in the initial shivering response or heat redistribution secondary to an insulative acclimation.
目的；本研究考察了短期（3.5天）持续军事行动（SUSOPS）对冷应激体温调节反应的影响。
10名男性（22.8±1.4岁）在经历一周对照期（对照）后的冷空气测试（CAT）期间接受评估，在84小时的SUSOPS（睡眠=2小时·天⁻¹，能量摄入=约1650千卡·天⁻¹，能量消耗=约4500千卡·天⁻¹）后再次接受评估。CAT包括让一名静息的受试者（半裸）在CAT的最初30分钟内暴露于从25℃降至10℃的环境温度斜坡中，随后环境温度在10℃保持额外150分钟。
SUSOPS使体重、体脂百分比和去脂体重分别下降了3.9千克、1.6%和1.8千克（P<0.05）。在CAT期间，与对照（0.45±0.12℃）相比，SUSOPS后直肠温度下降幅度更大（P<0.05）（0.52±0.09℃）。在第30分钟时，与对照（66.9±4.4瓦·米⁻²）相比，SUSOPS后代谢产热更低（P<0.05）（55.4±3.3瓦·米⁻²）。对平均体温-代谢产热关系的检查表明，与对照（35.8±0.2℃）相比，SUSOPS后颤抖阈值更低（P<0.05）（34.8±0.2℃）。在CAT最初的1.5小时内，SUSOPS组的平均加权皮肤温度（℃）低于对照组。两次试验的热债相似。
这些结果表明，持续（84小时）的军事行动会导致核心温度下降幅度更大，这是由于初始颤抖反应滞后或隔热适应导致的热量重新分布。
