The Roles of Central and Peripheral Mechanisms in the Sweat Rate Change during Exercise

Abstract

This study was conducted to determine the roles of central and peripheral mechanisms of sweating during exercise. Six healthy males each performed 40-min bicycle exercise at 500, 700 and 900 kpm/min at ambient temperature of 25°C (45%RH) . Rectal temperature (Tre), mean body temperature (Tb), mean skin temperature, local sweat rate, frequency of sweat expulsions, etc. were measured. The following results were obtained: 1) Slopes of relationship between local sweat rate and body temperature changed with a breaking point at specific temperature (Tre and Tb were about 37.7°C and 36.8°C, respectively) during exercise. 2) The rate of increase in mean skin temperature peaked at the above breaking point. 3) With the increase in work rate, the local sweat rate for a given body temperature (Tre, Tb) became higher. 4) The sensitivity of central sudomotor and sweat gland decreased when mean body temperature exceeded 36.8°C. 5) With the increase in work rate, central sudomotor activity was enhanced, but no distinct change could be detected in sweat gland activity. It was concluded that a remarkable change occurs in the central and peripheral mechanisms for sweat regulation at a mean body temperature of about 36.8°C during exercise.