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Effect of Palm Cooling with Negative Pressure on Heat Balance During Exercise in a Hot, Dry Environment

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Final rept. 1 Nov 2005-30 Nov 2006

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Military personnel often must work in hot environments, increasing the risk of hyperthermia. Our purpose was to evaluate a new rapid thermal exchange device RTX in slowing the development of hyperthermia and associated symptoms to 3 other conditions hand immersed in water bath WB, water-perfused vest VEST, and a no- cooling condition NC in subjects exercising in a hot environment 42C, 30 rh wearing summer fatigues, a backpack and body armor. Ten subjects age 25-3 yrs weight 74-6 kg performed 4 heat stress tests in a counter-balanced order NCRTXWB VEST The protocol consisted of two bouts of treadmill walking at 50 VO2max, separated by a 41-min cooling and rehydration period. The time to reach a pre-determined rectal temperature Tr in the 1st and 2nd bouts were not different among RTX mean - SD 52-14 and 42-l2 min respectively, NC 49-13 and 4l-14 min respectively, and WB 54-14 and 55-20 min respectively, but was longer for the VEST 85-30 and 65-12 min respectively in both bouts p0.05. The Trslope Cmin was significantly lower for VEST in the 1st and 2nd bouts versus the other conditions p0.05. HR was not different at 10,20 and 30 minutes of exercise in the 1st bout among RTC, NC, and WB, but was lower for VEST in the 1st bout p0.05. HR was not different among conditions in the 2nd bout. Therefore, the RTX unit B was not effective in slowing the development of hyperthermia in the present protocol. Aspects related to hand vasoconstriction and the severe workheat stress conditions possibly prevented the expected heat extraction.

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  • Anatomy and Physiology
  • Stress Physiology

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