Jovanović Dalibor, Karkalić Radovan, Zeba Snjezana, Pavlović Miroslav, Radaković Sonja S
Vojnosanit Pregl. 2014 Mar;71(3):259-64. doi: 10.2298/vsp120731045j.
BACKGROUND/AIM: In military services, emergency situations when soldiers are exposed to a combination of nuclear, biological and chemical (NBC) contamination combined with heat stress, are frequent and complex. In these specific conditions, usage of personal body cooling systems may be effective in reducing heat stress. The present study was conducted in order to evaluate the efficiency of four various types of contemporary personal body cooling systems based on the "Phase Change Material" (PCM), and its effects on soldiers' subjective comfort and physiological performance during exertional heat stress in hot environments.
Ten male soldiers were voluntarily subjected to exertional heat stress tests (EHSTs) consisted of walking on a treadmill (5.5 km/h) in hot conditions (40 degreesC) in climatic chamber, wearing NBC isolating impermeable protective suits. One of the tests was performed without any additional cooling solution (NOCOOL), and four tests were performed while using different types of cooling systems: three in a form of vests and one as underwear. Physiological strain was determined by the mean skin temperature (Tsk), tympanic temperature (Tty), and heart rate values (HR), while sweat rates (SwR) indicated changes in hydration status.
In all the cases EHST induced physiological response manifested through increasing Tty, HR and SwR. Compared to NOCOOL tests, when using cooling vests, Tty and Tsk were significantly lower (on 35th min, for 0.44 +/- 0.03 and 0.49 +/- 0.05 degrees C, respectively; p < 0.05), as well as the average SwR (0.17 +/- 0.03 L/m2/h). When using underwear, the values of given parameters were not significantly different compared to NOCOOL tests.
Using a body cooling system based on PCM in the form of vest under NBC protective clothes during physical activity in hot conditions, reduces sweating and alleviates heat stress manifested by increased core and skin temperatures and heart rate values. These effects directly improve heat tolerance, hydration state, decrease in the risk of heat illness, and extends the duration of soldiers' exposure to extreme conditions.
背景/目的：在军事行动中，士兵暴露于核、生物和化学（NBC）污染与热应激相结合的紧急情况屡见不鲜且情况复杂。在这些特定条件下，使用个人身体冷却系统可能有效地减轻热应激。本研究旨在评估四种基于“相变材料”（PCM）的当代个人身体冷却系统的效率，以及其在炎热环境中运动性热应激期间对士兵主观舒适度和生理表现的影响。
十名男性士兵自愿接受运动性热应激测试（EHSTs），测试内容为在气候舱内炎热条件（40摄氏度）下穿着NBC隔离不透水防护服在跑步机上行走（5.5公里/小时）。其中一项测试未使用任何额外的冷却溶液（无冷却），另外四项测试在使用不同类型的冷却系统时进行：三项为背心形式，一项为内衣形式。通过平均皮肤温度（Tsk）、鼓膜温度（Tty）和心率值（HR）确定生理应激，而出汗率（SwR）表明水合状态的变化。
在所有情况下，EHST均引发了生理反应，表现为Tty、HR和SwR升高。与无冷却测试相比，使用冷却背心时，Tty和Tsk显著更低（在第35分钟时，分别低0.44±0.03和0.49±0.05摄氏度；p<0.05），平均SwR也更低（0.17±0.03升/平方米/小时）。使用内衣时，与无冷却测试相比，给定参数的值无显著差异。
在炎热条件下进行体力活动时，在NBC防护服下使用基于PCM的背心形式的身体冷却系统，可减少出汗并减轻由核心温度、皮肤温度和心率值升高所表现出的热应激。这些效果直接提高了耐热性、水合状态，降低了热疾病风险，并延长了士兵暴露于极端条件下的持续时间。
