Abstract
With increasing global temperatures and interest in sports participation, more physically active men and women are exposed to hotter temperatures. To ensure the safety of these individuals, it is essential to identify the predictors of the rate of core temperature rise. PURPOSE: To determine the predictors of the rate of core temperature rise between males and females while exercising in warm and hot environments. METHODS: Physically active eleven males (age: 23±5 yrs, body mass: 72±8 kg, height: 175±8 cm, estimated maximal oxygen uptake [VO2max]: 51.6±5.9 ml⋅kg-1⋅min-1) and six females (age: 27±8 yrs, body mass: 56±6 kg, height: 164±3 cm, estimated VO2max: 46.9±3.7 ml⋅kg-1⋅min-1) completed dual-energy X-ray absorptiometry to assess their body composition followed by an estimated VO2max test. Then, participants completed 62 minutes of exercise in a warm (27℃, 40% relative humidity [RH]) and hot (35℃; 50% RH) condition; 20 minutes of treadmill running at 5.5 m×h-1, stopped for 2 minutes to don a 20 pound military vest, and walked for 40 minutes at 3.5 m×h-1 with a 6% grade with a work to rest ratio of 4 to 1 minute. Rectal temperature and heart rate were assessed every 5 minutes and sweat rate during exercise was calculated. The rate of core temperature rise was separated into two sections: 0-20 and 0-62 minutes. The potential predictors assessed were sex, environmental condition, age, lean body mass (LBM), body fat percentage, bone mineral density, VO2max, sweat rate, % heart rate, body surface area (BSA), and BSA to Mass ratio. A linear-mixed effects model was used to determine the predictors of rate of core body temperature rise. RESULTS: During 0-20 minutes, LBM (β = -0.003℃/min) was a significant predictor (p < 0.05). During 0-62 minutes, both environmental condition (β = -0.004℃/min) and VO2max (β = -0.001℃/min) were significant predictors (ps < 0.05). All other variables were not significant predictors (ps > 0.05). CONCLUSION: Overall, sex was not a predictor of rate of core temperature rise. During the initial exercise, while controlling for everything else, greater LBM predicted a slower rate of rise. During the entire protocol, while controlling for everything else, performing exercise in the warm predicted a slower rate of rise compared to in the hot. Additionally, greater aerobic fitness predicted a slower rate of rise.
Recommended Citation
Hernandez, Mario I.; Brojanac, Alexandra P.; McCollum, Tyler B.; Roberts, Rachel R.; Sassetti, Caitlin C.; and Sekiguchi, Yasuki
(2026)
"Determining the Predictors of Rate of Core Temperature Rise in Physically Active Men and Women,"
International Journal of Exercise Science: Conference Proceedings: Vol. 2:
Iss.
18, Article 24.
Available at:
https://digitalcommons.wku.edu/ijesab/vol2/iss18/24