This study investigated whether post-exercise sauna bathing can effectively heat acclimate middle distance and endurance runners. 16 runners (age 20 ± 2 years, BMI 21.3kg/m² ± 1.2kg/m², 11 females: 5 males) performed a heat tolerance test (HTT, 30 minutes running at 9kph, 2% incline; 40°C, 40%RH) pre, 3 weeks and 7 weeks after heat acclimation (HA; 30-minutes post-exercise sauna bathing (105-108°C) 3±1 times per week) or control. Measures included rectal temperature, skin temperature, sweat loss, heart rate, and forearm blood flow. Perceptual responses (perceived exertion, thermal comfort and thermal sensation) were also recorded.
3 week cohort: (n = 16, 10 Sauna, 6 Control). Following HA, sauna participants showed significantly reduced core temperature (p = .023), skin temperature (p = .020), HR (p = .020), increased sweat sensitivity (p = .032) and improved perceptual responses (all p = <.01) during the HTT. Controls saw no significant changes in any measure.
7 week cohort: (n = 7, 5 Sauna, 2 Control). Core temperature (p = <.01), skin temperature (p = .03), exercising heart rate (p = .017) and perceptual measures (all p= <.01) during the HTT were further reduced in sauna participants. Additionally post-exercise forearm blood flow and forearm blood flow sensitivity decreased from pre-intervention to 7 weeks (p = .015 and p = .008 respectively). Controls saw no significant changes in any measure.
This study found 3 weeks of post-exercise sauna bathing to be an effective heat acclimation strategy. Data from the 7-week cohort shows some evidence that continuing HA from 3 weeks to 7 weeks results in further adaptation
