ABSTRACT
Exercise involves the generation of large amounts of heat which are proportional to the level of exertion. The body has complex mechanisms to regulate heat exchange and maintain body temperature within a few degrees so as not to suffer from unhealthy and even fatal levels of high or low temperature. The mechanisms of heat transfer in humans (radiation, conduction, convection, and evaporation) will be described in this chapter to provide a basis for the normal response. But certain humans live in or travel to regions of excessive heat or cold and undergo some degree of adaptation over time to insure comfortable survival. These adaptations will be reviewed and extended into the context of maladies that are incurred in extremes of environmental temperatures, such as hypothermia, hyperthermia, and heat stroke. Exercise testing should be undertaken in individuals who have suffered heat or cold illness. A decreased aerobic capacity from a cardiac standpoint is particularly associated with predisposition to thermal illness. Thus, the results from CPET in victims after recovery may be helpful in characterizing an association between impaired aerobic capacity and thermal disease and thus advising patients accordingly.
