Physical Exercise-Induced Changes in Brain Temperature

Abstract Evidence suggests that brain temperature (T BRAIN ) is a more sensitive index than the temperature of peripheral tissues for determining physical performance and thermoeffector activity. Because direct measurements of T BRAIN in exercising humans are not currently possible, several studies have been performed in rats to investigate the extent to which T BRAIN increases during exercise and whether selective brain cooling occurs in mammals that do not possess a carotid rete. These studies have reported that (1) T BRAIN increases during exercise and can reach values above 40°C when physical exertion is performed in a hot environment or during prolonged exertion (duration longer than 1 h) in a temperate environment; (2) a dorsoventral temperature gradient exists between brain regions, with the ventrally-located structures being warmer than the dorsally-located structures; (3) the observation of selective brain cooling in rats seems to depend on the brain site where temperature is measured; and (4) the exercise-induced increase in T BRAIN negatively affects physical performance at different exercise intensities and ambient temperatures.