Constable S H, Bishop P A, Nunneley S A, Chen T
Sustained Operations Branch, Armstrong Laboratory, Brooks AFB, TX 78235-5000.
Ergonomics. 1994 Feb;37(2):277-85. doi: 10.1080/00140139408963645.
Requirements for special protective equipment while working in hazardous environments can present a significantly increased thermal burden and early onset of physical fatigue. Ambulatory (backpack) or tethered personal cooling can accelerate metabolic heat removal, but is often not practical from an ergonomic standpoint. The efficacy of incorporating personal cooling during non-ambulatory rest periods was evaluated in subjects (n = 8) with varying levels of fitness. Treadmill work (approximately 475 W, 40% VO2 max) was alternately performed for 30 min followed by 30 min of rest. Subjects walked and rested under three separate experimental conditions: (1) control (C), in which light clothing was worn; (2) CPE, in which a chemical protective ensemble (CPE) was worn, and (3) CPE plus intermittent microclimate cooling (COOL). The WBGT condition for all trials was 31 degrees C. During the COOL trial the subjects additionally wore a personal cooling vest which allowed for the circulation of chilled liquid over the torso during rest. Under C conditions, relatively modest changes in rectal temperature (Tre) were observed, which stabilized over time. CPE wear resulted in a progressive rise in Tre and early fatigue. The addition of intermittent cooling during each rest cycle (COOL trial) significantly attenuated heat storage such that an oscillating, but equilibrated Tre was established and work capacity was at least doubled. Moreover, the perceived cooling effect was appreciable for all subjects. Therefore, intermittent personal cooling provided a useful means of enhancing work productivity and may have application for certain military and industrial personnel performing heavy work in hot environments. This approach should provide a practical alternative for reducing stress/fatigue when work/rest cycles are employed.
在危险环境中工作时，对特殊防护装备的要求可能会显著增加热负荷，并导致身体疲劳过早出现。背负式（背包式）或系绳式个人冷却装置可以加快代谢产热的排出，但从人体工程学角度来看往往不实用。本研究评估了在不同健康水平的受试者（n = 8）非运动休息期间采用个人冷却的效果。受试者在跑步机上交替进行30分钟的运动（约475瓦，最大摄氧量的40%），随后休息30分钟。受试者在三种不同的实验条件下行走和休息：（1）对照组（C），穿着轻便服装；（2）化学防护服组（CPE），穿着化学防护服；（3）化学防护服加间歇性微气候冷却组（COOL）。所有试验的湿球黑球温度条件均为31摄氏度。在COOL试验中，受试者额外穿着一件个人冷却背心，在休息期间可使冷却液体在躯干周围循环。在C条件下，观察到直肠温度（Tre）有相对适度的变化，且随时间稳定。穿着CPE导致Tre逐渐升高并过早出现疲劳。在每个休息周期增加间歇性冷却（COOL试验）可显著减弱热量蓄积，从而建立起振荡但平衡的Tre，且工作能力至少提高一倍。此外，所有受试者都明显感觉到了冷却效果。因此，间歇性个人冷却为提高工作效率提供了一种有用的方法，可能适用于某些在炎热环境中从事繁重工作的军事和工业人员。当采用工作/休息周期时，这种方法应为减轻压力/疲劳提供一种切实可行的替代方案。
