The thermophysiology of uncompensable heat stress: physiological manipulations and individual characteristics


  1. Cheung, S.S.
  2. McLellan, T.M.
  3. Tenaglia, S.
Corporate Authors
Defence and Civil Inst of Environmental Medicine, Downsview ONT (CAN)
In many athletic and occupational settings, the wearing of protective clothing in warm or hot environments creates conditions of uncompensable heat stress where the body is unable to maintain a thermal steady state. Therefore, special precautions must be taken to minimise the threat of thermal injury. Assuming that manipulations known to reduce theremoregulatory strain during compensable heat stress would be equally effective in an uncompensable heat stress environment is not valid. In this review, we discuss the impact of hydration status, aerobic fitness, endurance training, heat acclimation, gender, menstrual cycle, oral contraceptive use, body composition and circadian rhythm on heat tolerance while wearing protective clothing in hot environments. The most effective countermeasure is ensuring that the individual is adequately hydrated both before and throughout the exercise or work session. In contrast, neither short term aerobic training or heat acclimation significantly improve exercise-heat tolerance during uncompensable heat stress. While short term aerobic training is relatively ineffective, long term improvements in physical fitness appear to provide some degree of protection. Individuals with higher proportions of body fat have a lwer heat tolerance because of a reduced capacity to store heat. TRUNCATED
Work tolerance time;Acclimatisation;Adaption (physiology);Endurance training;NBC clothing;Oral contraceptiive use;Menstrual cycles;Circadian rhythm
Report Number
DCIEM-SL-1999-017 — Paper
Date of publication
07 Nov 2000
Number of Pages
Reprinted from
Sports Med, vol 5, 2000, p 329-359
Hardcopy;Document Image stored on Optical Disk

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