Control of sweating rate while exercising in the heat.

All of the heat produced during exercise in a hot environment is either stored in the body or dissipated to the environment by evaporation of sweat. In order to minimize the storage of heat, thereby resisting circulatory strain, the body must be able to effectively increase sweating rate in these conditions. This paper characterizes the physiological control of sweating as a proportional control system, with increases in internal temperature having the greatest effect upon increasing the sweating rate. Factors which modify the threshold and gain of the sweating response, such as occur with dehydration or physical training, affect the storage of heat and therefore the steady state internal temperature during exercise in the heat.