Abstract

Ten heat-acclimated females exercised seminude on a treadmill at 30 VO2max (M = 152 W.m-2) under eight air temperatures (Ta) ranging from 30 Grad C to 52 Grad C. Each experiment involved 1 h of fixed and a 2nd h of progressively increasing water vapor pressure (Pw) with either air movement of 1m.s-1 or still air. The equilibrium values of rectal temperature (Tre), mean skin temperature (Tsk), and heart rate (HR) reached in the 1st h were forced upwards in the 2nd h by the rising Pw. The critical Pw was defined by the Tre inflection point for each Ta. The loci of the critical Pw were used to delineate the thermal limits on the psychometric chart and were used to derive the effective evaporative coefficient (Ke) applicable to the ambient capacity for evaporative cooling (Emax). The derived Ke was 17.6 +/- 4.2 W.m-2 (mean +/- SD) for VO6m.s-1. Isotherms constructed on the basis of the obtained Ke, Tsk, and sweating capacity were higher than the physiologically based Pw limits. Verf.-Referat