VALIDATION AND ADJUSTMENT OF THE MATHEMATICAL PREDICTION MODEL FOR HUMAN RECTAL TEMPERATURE RESPONSES TO OUTDOOR ENVIRONMENTAL-CONDITIONS

Models to predict rectal temperature (T-re) have been based on indoor laboratory studies. The present study was conducted to validate and ad just a previously suggested model for outdoor environmental conditions . Four groups of young male volunteers were exposed to three different climatic conditions (30 degrees C, 65% rh; 31 degrees C, 41% rh; 40 d egrees C, 20% rh). They were tested both in shaded and open field area s (radiation: 80 and 900 W . m(-2), respectively) at different work lo ads (100, 300 and 450 watt). Exercise consisted of two bouts of 10 min utes rest and 50 minutes walking on a treadmill, at a constant speed ( 1.4 m . s(-1)) and different grades. The subjects were tested wearing cotton fatigues and protective garments. Their T-re and heart rate wer e monitored every 5 min and skin temperature every 15 min, oxygen upta ke was measured towards the end of each bout of exercise; concomitantl y, ambient temperature, relative humidity and solar load were monitore d. We concluded that: (a) the corrected model to predict rectal temper ature overestimates the actual measurements when applied outdoors; (b) radiative and convective heat exchanges should be considered separate ly when using the model outdoors; (c) radiative heat exchange should a lso be considered separately for short-wave radiation (solar radiation ) and long-wave emission from the body to the atmosphere. Finally, an adjusted model to be used outdoors was suggested.