Characteristics of the control of human thermoregulatory behavior

The aim of this study was to characterize several of the thermal input(s) that influence thermo-behavior in humans. Eight male subjects completed two trials in which they were free to initiate an exit from a hot chamber (45 °C) to a cold chamber (10 °C; H → C) or from a cold chamber to a hot chamber (C → H). Upon initiating an exit from the chamber, mean skin temperature (T_Sk), rectal temperature (T_Rectal), subjective thermal comfort, and time in the climate chambers prior to exit were recorded. Thermo-behavior was defined as the initiation of exit. All variables were similar (P ≥ 0.05) between the two trials. T_Sk and thermal comfort at H → C were significantly (P ≤ 0.05) higher (34.0 ± 1.1 °C, and 7.3 ± 0.6, respectively) than at C → H (29.4 ± 0.9 °C, and 3.0 ± 0.6, respectively). No significant differences (P ≥ 0.05) were found between H → C and C → H for T_Rectal (H → C: 37.0 ± 0.2 °C vs. C → H: 37.0 ± 0.2 °C) or time prior to exit (H → C: 3.9 ± 2.3 min vs. C → H: 3.9 ± 1.7 min). The frequency distributions and the probability of the initiation of exit curves at H → C and C → H for both T_Sk and thermal comfort were significantly negatively skewed (P ≤ 0.05) and normally distributed, respectively (P ≥ 0.05). Skin temperature appears to be an important thermal input mediating thermo-behavioral responses. This behavioral response appears to be more precise when exposed to hot temperatures compared to cold temperatures.