Heat Balance Regulation during Exercise: Circadianity

Recent reviews of the literature on thermoregulation during exercise including the regulation of thermal sweating have been made by many scientists [see (1) for Jessen's review]. Human body temperature is determined by the balance between heat accumulation, whether generated by physical activity (metabolic heat production) or gained from the environment (environmental heat), and heat dissipation. Heat storage is, thus, the result of either excessive heat accumulation or reduced ability to dissipate body heat In human exercise-thermoregulation, there exist physiological variables affected by his internal and environmental factors (2-6). The purpose of the present study is to investigate heat balance during exercise under controlling seasonal and circadian variations.