Heat intolerance: predisposing factor or residual injury?

Great individual variability exists in the ability to sustain heat stress. Some individuals are more susceptible to heat than others. Those individuals, among the young active population (athletes, military recruits, laborers), are at risk to contract exertional heat stroke. Low tolerance to heat results from either functional factors, or from congenital or acquired disturbances. In most cases heat intolerance can be foreseen. Cases of dehydration, overweight, low physical fitness, lack of acclimatization, febrile or infectious diseases, and skin disorders should be regarded a priori as predisposing factors for heat intolerance. Special attention should be paid to subjects with previous heat stroke episodes since it might reflect an underlying cause for heat susceptibility. The heat tolerance of these subjects should be tested 8-12 wk postepisode to detect a possible residual injury in the ability to thermoregulate adequately in the heat.