Intermittent post-exercise sauna bathing improves markers of exercise capacity in hot and temperate conditions in trained middle-distance runners.
Level 3 - non-randomized controlled study
Controlled trial without explicit mention of randomization in the abstract
PubMed 33211153 · doi:10.1007/s00421-020-04541-z
What was done
Twenty trained middle-distance runners (13 female, 7 male; age 20 ± 2 years; baseline VO2max 56.1 ± 8.7 ml/kg/min) completed 3 weeks of normal endurance training alone (CON, n=8) or normal training followed by 28 ± 2 minutes of sauna bathing (101–108 °C, 5–10% relative humidity) 3 ± 1 times per week (SAUNA, n=12). Heat tolerance tests (30-minute run at 9 km/h, 2% gradient, 40 °C, 40% relative humidity) and temperate (18 °C) tests of VO2max and running speed at 4 mmol/L blood lactate were conducted before and after the 3-week intervention. Six sauna participants continued the protocol for a total of 7 weeks and completed an additional heat tolerance test.
What was found
Compared to control after 3 weeks, post-exercise sauna bathing resulted in significantly greater reductions during the heat tolerance test in peak rectal temperature (-0.2 °C), skin temperature (-0.8 °C), and heart rate (-11 beats/min) (all p < 0.05). In temperate conditions, the sauna group showed greater gains than controls in VO2max (+0.27 L/min, p = 0.02) and running speed at 4 mmol/L blood lactate (+0.6 km/h, p = 0.01). Extending the protocol to 7 weeks in 6 runners yielded a modest additional decrease in peak rectal temperature (-0.1 °C, p = 0.03) but no further changes in other physiological variables (p > 0.05).
Why it matters
Post-exercise sauna bathing provides an accessible, practical protocol for heat acclimation and aerobic performance enhancement without requiring environmental chambers. The primary physiological benefits occurred within the first three weeks.
Limits
The total sample size was small (n=20) with unequal group sizes (n=8 vs n=12) and an even smaller 7-week follow-up subgroup (n=6). The abstract does not indicate whether participants were randomized to groups. Real-world competitive performance or time trials were not tested.
Cited by
- supports Post-exercise sauna use can improve VO2 max.
- supports Sauna use improves exercise performance in both hot and temperate (normal) weather conditions.