Flouris A D, Cheung S S, Fowles J R, Kruisselbrink L D, Westwood D A, Carrillo A E, Murphy R J L
Environmental Ergonomics Laboratory, School of Health and Human Performance, Dalhousie University, Halifax, Nova Scotia, Canada B3H 3J5.
J Appl Physiol (1985). 2006 Sep;101(3):802-8. doi: 10.1152/japplphysiol.00197.2006. Epub 2006 May 18.
We examined the influence of 1) prior increase [preheating (PHT)], 2) increase throughout [heating (HT)], and 3) no increase [control (Con)] of body heat content (H(b)) on neuromuscular function and manual dexterity of the hands during a 130-min exposure to -20 degrees C (coldEx). Ten volunteers randomly underwent three passive coldEx, incorporating a 10-min moderate-exercise period at the 65th min while wearing a liquid conditioning garment (LCG) and military arctic clothing. In PHT, 50 degrees C water was circulated in the LCG before coldEx until core temperature was increased by 0.5 degrees C. In HT, participants regulated the inlet LCG water temperature throughout coldEx to subjective comfort, while the LCG was not operating in Con. Thermal comfort, rectal temperature, mean skin temperature, mean finger temperature (T(fing)), change in H(b) (DeltaH(b)), rate of body heat storage, Purdue pegboard test, finger tapping, handgrip, maximum voluntary contraction, and evoked twitch force of the first dorsal interosseus muscle were recorded. Results demonstrated that, unlike in HT and PHT, thermal comfort, rectal temperature, mean skin temperature, twitch force, maximum voluntary contraction, and finger tapping declined significantly in Con. In contrast, T(fing) and Purdue pegboard test remained constant only in HT. Generalized estimating equations demonstrated that DeltaH(b) and T(fing) were associated over time with hand function, whereas no significant association was detected for rate of body heat storage. It is concluded that increasing H(b) not only throughout but also before a coldEx is effective in maintaining hand function. In addition, we found that the best indicator of hand function is DeltaH(b) followed by T(fing).
我们研究了在130分钟暴露于-20摄氏度（冷暴露）期间，1）体温含量（H(b)）预先升高[预热（PHT）]、2）全程升高[加热（HT）]和3）不升高[对照（Con）]对神经肌肉功能和手部手动灵巧性的影响。十名志愿者随机接受三次被动冷暴露，在第65分钟时穿着液体调节服（LCG）和军用北极服装进行10分钟的适度运动。在PHT中，冷暴露前50摄氏度的水在LCG中循环，直到核心温度升高0.5摄氏度。在HT中，参与者在整个冷暴露过程中调节LCG进水温度至主观舒适状态，而在Con中LCG不运行。记录热舒适度、直肠温度、平均皮肤温度、平均手指温度（T(fing)）、H(b)的变化（DeltaH(b)）、身体储热率、普渡钉板测试、手指敲击、握力、最大自主收缩以及第一背侧骨间肌的诱发抽搐力。结果表明，与HT和PHT不同，Con组的热舒适度、直肠温度、平均皮肤温度、抽搐力、最大自主收缩和手指敲击显著下降。相比之下，只有在HT组中T(fing)和普渡钉板测试保持恒定。广义估计方程表明，DeltaH(b)和T(fing)随时间与手部功能相关，而未检测到身体储热率有显著关联。结论是，不仅在冷暴露全程增加H(b)，而且在冷暴露前增加H(b)对维持手部功能均有效。此外，我们发现手部功能的最佳指标是DeltaH(b)，其次是T(fing)。
