Neuropsychological determinants of exercise tolerance in the heat.

Traditionally, exercise in the heat has been assumed to be primarily limited by cardiovascular constraints. However, an evolutionary perspective suggests that psychological safeguards should also protect individuals prior to catastrophic hyperthermia, and exposure to hot environments or elevated body temperature may directly attenuate central drive for exercise even well before the attainment of a critical limiting central temperature. Voluntary exercise tolerance or pacing may be influenced by a complex integration of peripheral and central thermal afferents, with regional differences in thermosensitivity across the skin surface and individual variability due to age and fitness. Despite the risk of accidents from impairments in mental function, heat exposure guidelines are commonly driven by physiological parameters, and the incorporation of a psychological component should be an important focus in occupational health and safety. In directly counteracting the effects of heat stress, the face and head is a region of high sudomotor and thermal sensitivity, and may thereby serve as an effective site for reducing perceptual and/or physiological heat strain via improvements in ventilation, airflow, or active cooling.