Institutional Repository Prediction of core body temperature from multiple variables

9 This paper aims to improve the prediction of rectal temperature (Tre) from insulated 10 skin temperature (Tis) and micro-climate temperature (Tmc) previously reported (Richmond 11 et al. 2013) using additional physiological and/or environmental variables, under several 12 clothing and climatic conditions. Twelve male (25.8 ± 5.1 yr; 73.6 ± 11.5 kg; 178 ± 6 cm) 13 and nine female (24.2 ± 5.1 yr; 62.4 ± 11.5 kg; 169 ± 3 cm) volunteers completed six trials, 14 each consisting of two 40 minute periods of treadmill walking separated by a 20 minute 15 rest, wearing permeable or impermeable clothing, under neutral (25 °C, 50 %), moderate 16 (35 °C, 35 %) and hot (40 °C, 25 %) conditions, with and without solar radiation (600 17 W·m). Participants were measured for heart rate (HR) (Polar, Finland), skin temperature 18 (Ts) at 11-sites, Tis (Grant, Cambridge, UK) and breathing rate (f) (Hidalgo, Cambridge, 19 UK). Tmc and relative humidity were measured within the clothing. Tre was monitored as 20 the ‘gold standard’ measure of Tc for industrial or military applications using a 10 cm 21 flexible probe (Grant, Cambridge, UK). 22 A stepwise multiple regression analysis was run to determine which of 30 variables 23 (Tis, Ts at 11 sites, HR, f, Tmc, temperature and humidity inside the clothing front and back, 24 body mass, age, body fat, sex, clothing, 2 O V , Thermal comfort, sensation and perception, 25 and sweat rate) were the strongest on which to base the model. Using a bootstrap 26 methodology to develop the equation, the best model in terms of practicality and validity 27 included Tis, Tmc, HR and ‘work’ (0 = rest; 1 = exercise), predicting Tre with an SEE of 28 0.27 °C and adjusted R of 0.86. The sensitivity and specificity for predicting individuals 29 who reached 39 °C was 97 % and 85 %, respectively. 30 Insulated skin temperature was the most important individual parameter for the 31 prediction of Tre. This paper provides novel information about the viability of predicting 32 Tc under a wide range of conditions, using predictors which can practically be measured in 33 a field environment. 34