EFFECTS OF HEAT ACCLIMATION ON HEAT-EXERCISE TOLERANCE IN UNTRAINED AND ENDURANCE-TRAINED MEN WEARING NBC PROTECTIVE CLOTHING

Authors
  1. Aoyagi, Y.
  2. McLellan, T.M.
  3. Shephard, R.J.
Corporate Authors
Defence and Civil Inst of Environmental Medicine, Downsview ONT (CAN)
Abstract
Responses were compared between nine untrained (UT) men and six men who had participated in 8 weeks of endurance training (ET). Both groups underwent 6 days of heat acclimation in a climatic chamber that was maintained at 40 plus or minus 0.5C and 30 plus or minus 1% rh. Subjects were tested before and after acclimation wearing either standard military combat clothing or nuclear, biological and/or chemical (NBC) protective clothing. Test sessions involved treadmill wakling at 4.8 km.h super -1 and 2% grade for a maximum of 120 min. In UT subjects, heat acclimation increased plasma volume (+8 plus or minus 2%), but VO sub 2max and heat-exercise tolerance time were unchanged. When wearing standard combat clothing, acclimation decreased average values of heart rate, rectal temperature, mean skin temperature, thermal discomfort, and metabolic heat production. When wearing NBC protective clothing, the only significant change was in rectal temperature. Acclimation induced an increase of sweat scretion but no statistically significant increase of sweat evaporation in NBC protective clothing. In ET subjects, acclimation reduced thermal discomfort when wearing standard combat clothing, and rectal temperature, and mean skin temperature when wearing NBC protective clothing in hot environments, although it reduced thermoregulatory strain by lowering mean body temperature, irrespective of training status. TRUNCATED
Keywords
Sweat production;Sweat evaporation;Rectal temperature;Skin temperature;Heart rate;Blood volume;Discomfort;Metabolic rate;Prolonged work
Report Number
DCIEM-93-47 — Research Report
Date of publication
01 Aug 1993
Number of Pages
38
DSTKIM No
94-01687
CANDIS No
140244
Format(s):
Hardcopy;Originator's fiche received by DSIS

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