Thermal behavior remains engaged following exercise despite autonomic thermoeffector withdrawal.

ABSTRACT

We tested the hypothesis that thermal behavior during the exercise recovery compensates for elevated core temperatures despite autonomic thermoeffector withdrawal. In a thermoneutral environment, 6 females and 6 males (22 ±â€¯1 y) cycled for 60 min (225 ±â€¯46 W metabolic heat production), followed by 60 min passive recovery. Mean skin and core temperatures, skin blood flow, and local sweat rate were measured continually. Subjects controlled the temperature of their dorsal neck to perceived thermal comfort using a custom-made neck device. Neck device temperature provided an index of thermal behavior. Mean body temperature, calculated as the average of mean skin and core temperatures, provided an index of the stimulus for thermal behavior. To isolate the independent effect of exercise on thermal behavior during recovery, data were analyzed post-exercise the exact minute mean body temperature recovered to pre-exercise levels within a subject. Mean body temperature returned to pre-exercise levels 28 ±â€¯20 min into recovery (Pre 33.5 ±â€¯0.2, Post 33.5 ±â€¯0.2 °C, P = 0.20), at which point, mean skin temperature had recovered (Pre 29.6 ±â€¯0.4, Post 29.5 ±â€¯0.5 °C, P = 0.20) and core temperature (Pre 37.3 ±â€¯0.2, Post 37.5 ±â€¯0.3 °C, P = 0.01) remained elevated. Post-exercise, skin blood flow (Pre 59 ±â€¯78, Post 26 ± 25 PU, P = 0.10) and local sweat rate (Pre 0.05 ±â€¯0.25, Post 0.13 ±â€¯0.14 mg/cm2 min-1, P = 0.09) returned to pre-exercise levels, while neck device temperature was depressed (Pre 27.4 ±â€¯1.1, Post 21.6 ±â€¯7.4 °C, P = 0.03). These findings suggest that thermal behavior compensates for autonomic thermoeffector withdrawal in the presence of elevated core temperatures post-exercise.