Temperature regulation during exercise: directions--1983.

During exercise, internal body (core) temperature (Tc) rises to new plateau levels with increasing intensities of steady-state exercise independent of ambient temperature over a wide range (prescriptive zone). This rise in Tc is proportional to relative rather than absolute work load and provides the central stimulus to sweating and cutaneous vasodilation. The system seems to function in the same way during rest and exercise since the rise in Tc during exercise can be explained in fundamental terms of heat production and heat dissipation. Changes in sweating and skin blood flow (SBF) are largely explained by changes in core and skin temperatures; however, there is strong evidence for non-thermal input into the control of these responses. The control of SBF is more complex than the control of sweating because SBF is influenced by cardiovascular as well as temperature regulations. Moreover, hydration state can markedly alter these effectors, indicating that fluid volume and/or fluid composition also contribute to these control mechanisms. Major advances in the future will come from the further development of animal models that allow for studies designed to elucidate the interaction between regulatory systems and the neurochemistry underlying central effector mechanisms.