Exercise Heat Stress Responses in Unacclimatized Endurance- and Resistance-Trained Women

INTRODUCTION: Sex-specific responses to heat stress are not well characterized in women with different training backgrounds. This study examined physiological and perceptual responses to moderate-intensity exercise in the heat among endurance-trained (ET) and resistance-trained (RT) women.

METHODS: In a counterbalanced crossover design, 17 (8 ET, 9 RT) healthy, well-trained, heat-unacclimatized women performed a 75-min walking exercise session at 60% $\dot{\mathrm{V}}$o_2peak (maximum volume of oxygen consumption) in both Hot (33°C, 50% relative humidity) and Neutral (21°C, 50% relative humidity) conditions. Rectal temperature (T_rec), heart rate (HR), minute ventilation ($\dot{\mathrm{V}}$_e), blood lactate, urine specific gravity, and body mass loss were assessed. Perceptual measures included overall, central, and local ratings of perceived exertion (RPE), thermal sensation, thermal comfort, thirst, and the Environmental Symptoms Questionnaire.

RESULTS: Across both groups, T_rec, HR, $\dot{\mathrm{V}}$_e, and perceptual responses were significantly elevated in Hot vs. Neutral. No group differences were observed in T_rec, HR, $\dot{\mathrm{V}}$_e, or perceptual ratings. RT women exhibited significantly higher post-exercise lactate levels in Hot, but this did not correspond to higher RPE or Environmental Symptoms Questionnaire scores. $\dot{\mathrm{V}}$o_2peak was a significant predictor of RPE responses in Neutral but not Hot. No moderation effect of training group was observed.

DISCUSSION: ET and RT women experienced comparable physiological and perceptual strain during prolonged exercise in the heat. Despite metabolic differences, perceptual responses were consistent across training backgrounds. These findings highlight the role of training stimulus over $\dot{\mathrm{V}}$o_2peak in thermoregulatory outcomes and support inclusive heat tolerance recommendations for active women across training disciplines.

Sanchez BN, Soufi S, Saenz C, Kraemer WJ, Lee EC, Volek JS, Maresh CM. Exercise heat stress responses in unacclimatized endurance- and resistance-trained women. Aerosp Med Hum Perform. 2025; 96(10):872–883.