PMC

Dry and evaporative heat loss (n = 12, mean ± SD). (A) Dry heat loss outside the suit top, (B) dry heat loss under the suit top, (C) total dry heat loss, (D) evaporative heat loss outside the suit top, (E) evaporative heat loss under the suit top, (F) total evaporative heat loss during 90 min of recovery from low intensity cycling exercise. ^# Different from 60 min (end-exercise) (p < 0.01); * Behavior different from control (p ≤ 0.05).

Total heat loss (Q_bill) is shown in (A) and the percent of total heat loss through the bill (percent Q_bill) is shown in (B). Black lines = model averaged predictions of linear mixed models ± unconditional standard errors. Gray lines = raw data.

Left panel: the initial increase in evaporative heat loss during exercise is dictated by the onset threshold for sweating, with the subsequent linear increase in evaporative heat loss a function of the change in mean body temperature (thermosensitivity). However, the level of evaporative heat loss attained during exercise is determined by the required evaporation for heat balance (E_req). Right panel: when the required evaporation for heat balance does not exceed the individual's maximal evaporative (sweating) capacity (E_sk,max ≥ E_req), the level of evaporative heat loss attained during exercise is determined by the required evaporation for heat balance (blue colour). However, when the required evaporation for heat balance exceeds the individual's maximum evaporative capacity (E_sk,max < E_req), the level of evaporative heat loss attained during exercise is determined by the individual's maximal evaporative (E_sk,max) capacity (orange colour).

A 3D image showing how activity (heat production) and thermal admittance (heat loss) affect the thermal gradient (T_B-T_W) held by juvenile leatherbacks. In cold water heat loss was minimized and activity was proportional to the thermal gradient held. In warm water activity was very low and thermal gradient was due to varying heat loss.