Physiological correlates of heat intolerance.

Although wide interindividual variation exists with respect to heat tolerance, research has pointed out common physical and physiological characteristics which are associated with a decreased ability to adapt to an imposed (internal or external) heat load. While it is difficult to predict individual responses, it is often desirable, e.g. in an industrial environment, to screen out those suspected heat-intolerant persons. Included among the correlates of heat intolerance are a history of heat illness, previous difficulty in acclimating or reacclimating to the heat, low aerobic fitness level, age, hypertension, body size and composition (high adiposity, small size), and drug use (prescription and narcotic) and alcohol consumption.