Exercising in high temperatures stresses the body and reduces performance. Acclimation in a heat chamber improves performance but is costly and time-consuming. A recent study found that supplementing normal endurance training with intermittent post-exercise sauna bathing improves heat tolerance.

The study involved 20 male and female trained middle-distance runners between the ages of 18 and 22 years. Participants completed 30-minute sauna sessions (101° to 108°C; 214° to 226°F) three times a week for three weeks within roughly five minutes of engaging in low-intensity, continuous outdoor exercise. They underwent heat tolerance tests before and after the intervention.

The heat tolerance tests revealed that the sauna users' peak rectal temperature decreased 0.2°C (0.36°F); skin temperature decreased 0.8°C (1.4°F); and heart rate decreased 11 beats per minute, compared to those who did not use the sauna. Those who used the sauna also saw improvements in VO2max and speed. The improvements appeared to plateau, however, with four weeks of additional sauna exposure eliciting improvements in rectal temperature only (decrease of 0.1°C, 1.8°F).

These findings suggest that sauna bathing after engaging in endurance training improves heat tolerance and boosts performance.

• Link to full study.

• Learn more about sauna in our overview article.