The authors have proposed a simple model of predicting mean skin and core temperatures for protecting disorder due to hot indoor and outdoor conditions. The purpose of this paper is to analyze individual variability of human sweating rate and to evaluate a risk of disorder due to humid hot environment using the model based on the individual variability. Nine male subjects carried out a cycle ergometer exercise test in indoor and outdoor environments. Coefficient kadp which was defined as individual properties of thermal sweating in humans was calculated from weight loss by sweating and respiration. The subjects approximately had a normal property of sweating response (kadp = 0.85 +/- 0.19; mean +/- SD) against average sweating capacity (kadp = 1) in this model. kadp changed over the range from 0.4 to 1.2. The variation of kadp was caused by not only interindividual variability but intraindividual variability. Those who showed half kadp (= 0.5) of average humans existed in approximately 5 %. Equal mean skin temperature lines of 36 degrees C based on the variation of kadp were described using the model on psychrometric chart. As a result, on 50% relative humidity line, air temperature at which mean skin temperature became 36 degrees C was 32.5 and 27.5 degrees C for 1.0 and 0.4 of kadp, respectively. Therefore, it is significant for a risk evaluation of heat disorder to evaluate both respects of physiology such as body temperature and of the event probability.

DESCENTE SPORTS SCIENCE Vol.28/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE