Aerospace medicine and human performance
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Aerosp Med Hum Perform · Jan 2019
Randomized Controlled TrialPrecooling, Exertional Heatstroke Risk Factors, and Postexercise Cooling Rates.
Precooling (PC) before exercise may help prevent severe hyperthermia and exertional heatstroke (EHS). Before clinicians can advocate PC as an EHS prevention strategy, it must effectively mitigate factors associated with EHS development while not lessening the effectiveness of EHS treatment. Therefore, this study determined if PC affected rectal temperature (Trec), body heat storage, heart rate (HR), ratings of perceived exertion (RPE), thermal sensation, sweat rate, and postexercise cold-water immersion (CWI) Trec cooling rates. ⋯ PC lowered body heat storage and Trec by 15.7 ± 15.0 W · m-2 and 0.42 ± 0.40°C, respectively, before exercise. Subjects exercised significantly longer (PC = 66.7 ± 16.3 min, CON = 45.7 ± 9.5 min) and at lower Trec (∼0.5 ± 0.5°C) and HR (∼10 ± 7 bpm) following PC. PC significantly lowered sweat rate (PC = 1.02 ± 0.31 L · h-1, CON = 1.22 ± 0.39 L · h-1), but did not affect RPE or CWI cooling rates (PC = 0.18 ± 0.14°C · min-1; CON = 0.19 ± 0.05°C · min-1). Thermal sensation significantly differed between conditions only at pre-exercise (PC = 3 ± 1, CON = 5 ± 0.5).DISCUSSION: PC delayed severe hyperthermia and mitigated dehydration without affecting thermal perception or cooling rates posthyperthermia. PC may help prevent dangerous hyperthermia in athletes.Wohlfert TM, Miller KC. Precooling, exertional heatstroke risk factors, and postexercise cooling rates. Aerosp Med Hum Perform. 2019; 90(1):12-17.