Assessment of heat tolerance for post exertional heat stroke individuals

Background: The aim of this study was to evaluate the heat tolerance test, which was performed by individuals with high risk for heat injuries, for exposure duration and climatic conditions. Material/Methods: Nineteen young (19±1 yr) post heat stroke males performed 2 separate tolerance tests consisting of identical treadmill walking (5km·h^-1, 2% grade) for 120 min during hot (40°C, 40% RH) and comfort (20°C, 50% RH) climate conditions. Physiological monitoring included rectal temperature (T _re), heart rate (HR), skin temperature and sweat rate (m _sw). Concomitantly, strain evaluation was assessed by the physiological strain index (PSI) and the cumulative heat strain index (CHSI). Results: 14 subjects were categorized as heat tolerant (HT) aud 5 subjects as heat intolerant (HI). The comfort tolerance test was found as irrelevant for heat intolerance assessment. PSI after 60 min (PSI₆₀) was unable to predict PSI after 120 min (PSI₁₂₀) whereas there was not a high enough correlation between CHSI₆₀ and CHSI₁₂₀. Conclusions: It was concluded that tolerance to heat must be tested during heat stress and the test duration cannot be shorter than 120 min.