Heat flux and storage in hot environments.

When humans are exposed to extreme ambient temperatures, or generate internal heat by exercise, the body strives to maintain internal body temperature. The core and skin temperatures attained, as well as the physiological adjustments necessary to minimize temperature excursions, are governed by (i) heat generated by working muscle, (ii) external work performed, and (iii) biophysical heat exchange with the thermal environment. This paper provides an overview of these avenues of heat production and exchange, the aspects of the thermal environment which dictate the direction and magnitude of that exchange, and the mean body temperature response from a simplified biophysical perspective.