SummaryHeat dissipation, under conditions of thermal stress, is mediated primarily by evaporation of sweat. Physical training has been shown to enhance sweat production by eliciting changes in the sensitivity of eccrine glands, total sweat output and distribution of gland activity. These adaptations afford partial acclimation. Heat acclimation produces similar changes, and also results in reduced sweat thresholds. To account for these different responses it has been hypothesised that physical training induces peripheral adaptations, while acclimation produces both peripheral and central modifications. It is suggested that repeated cutaneous heat detection may be essential to the development of central sudo-motor changes.