Sex differences in adaptation to intermittent post-exercise sauna bathing in trained middle-distance runners

Background The purpose of this study was to investigate the effect of sex on the efficacy of intermittent post-exercise sauna bathing to induce heat acclimation and improve markers of temperate exercise performance in trained athletes. Methods Twenty-six trained runners (16 female; mean ± SD, age 19 ± 1 years, V̇O 2max F: 52.6 ± 6.9 mL⋅kg −1 ⋅min −1 , M: 64.6 ± 2.4 mL⋅kg −1 ⋅min −1 ) performed a running heat tolerance test (30 min, 9 km⋅h −1 /2% gradient, 40 °C/40%RH; HTT) and temperate (18 °C) exercise tests (maximal aerobic capacity [V̇O 2max ] and lactate profile) pre and post 3 weeks of normal exercise training plus 29 ± 1 min post-exercise sauna bathing (101–108 °C) 3 ± 1 times per week. Results Females and males exhibited similar reductions (interactions p > 0.05) in peak rectal temperature (− 0.3 °C; p 0.05) improvements in V̇O 2max (+ 5%; p = 0.02) and running speed at 4 mmol·L −1 blood lactate concentration (+ 0.4 km·h −1 ; p = 0.001). Conclusions Three weeks of post-exercise sauna bathing effectively induces heat acclimation in females and males, though possibly amid different thermoeffector adaptations. Post-exercise sauna bathing is also an effective ergogenic aid for both sexes.