Sex Differences In Perceptual Adaptations During Heat Acclimation In Endurance Runners

Exercising in the heat negatively impacts performance. To combat this, heat acclimation (HA) is used to mitigate performance decrements through various physiological and perceptual adaptations. However, perceptual adaptations may differ during HA due to physiological differences between females and males. PURPOSE: To investigate perceptual adaptations between sexes during 7-day HA in endurance runners. METHODS: Seven female and four male endurance runners (age: 22 ± 5 years, body mass: 64.30 ± 7.97 kg, height: 168.00 ± 6.43 cm, maximal oxygen uptake [VO2max]: 58.30 ± 4.28 mL/kg/min; age: 21 ± 4 years, body mass: 78.63 ± 9.01 kg, height: 182.55 ± 3.97 cm, VO2max: 73.93 ± 9.69 mL/kg/min, respectively) participated in this study. Participants completed a 7-day HA protocol consisting of running at 50% velocity at VO2max for 60 minutes in a hot condition (ambient temperature, 40 °C; relative humidity, 35%). Perceptual variables, including rating of perceived exertion (RPE), fatigue, thirst level, and thermal sensation, were assessed every 10 minutes to investigate perceptual adaptations with HA. Two-way repeated measures ANOVAs were conducted to investigate perceptual adaptations between sexes during 7-day HA. RESULTS: There were no significant differences in maximum RPE, fatigue, thirst level, and thermal sensation between females and males (p > 0.05). Independent of sex, RPE on day 5 (14 ± 4, p = 0.036), day 6 (13 ± 4, p = 0.012), and day 7 (14 ± 4, p = 0.034), were significantly lower than day 1 (16 ± 4). Fatigue on day 2 (6 ± 2, p = 0.036), day 4 (6 ± 2, p = 0.024), day 5 (5 ± 2, p = 0.011), day 6 (5 ± 2, p = 0.006), and day 7 (5 ± 3, p = 0.009) were significantly lower than day 1 (7 ± 2). Thirst levels on day 2 (5 ± 2, p = 0.001), day 4 (5 ± 2, p = 0.035), and day 6 (5 ± 2, p = 0.012) were significantly lower than day 1 (6 ± 2). Thermal sensation on day 4 (7 ± 1, p = 0.03) and day 6 (7 ± 1, p = 0.012) were significantly lower than day 1 (7 ± 1). CONCLUSION: Endurance male and female runners exhibited beneficial perceptual adaptations following 7-day HA. However, no significant sex differences were observed. Ultimately, HA shows to be beneficial in endurance male and female runners alike and should be an integral part of preparing for competing in hot environments. Supported by: This research was supported by a World Athletics Research Grant from the American College of Sports Medicine.