Does a sauna after training improve endurance?

A 2025 meta-analysis of 10 trials (199 participants) found that a sauna or hot bath after training changed endurance performance in the heat by a trivial and imprecise amount (ratio of means 1.04, 95% CI 0.94 to 1.15). The authors graded the certainty of the evidence as low to very low across all outcomes, so the question is open rather than answered.

What did the meta-analysis of post-exercise heat exposure find?

Solomon and Laye, BMC Sports Science, Medicine and Rehabilitation 2025 pooled trials in healthy adults (156 men and 43 women, aged 20 to 32). Each trial compared training followed by sauna or hot water immersion against the same training without heat exposure.

The main outcome was performance in hot conditions (33 to 40 °C). The ratio of means was 1.04, with a 95% CI of 0.94 to 1.15 (P = 0.46) and a 95% prediction interval of 0.81 to 1.33. That interval includes no effect at all as well as a difference of up to 15%, which is why the authors call the estimate imprecise.

Performance in thermoneutral conditions (18 to 24 °C) and speed at lactate threshold showed trivial effects. Effects on VO2 max, heart rate, core temperature and sweat rate were small, and thermal sensations showed a moderate effect. Certainty was low to very low because of small samples, high risk of bias and imprecision.

Is the wider evidence any clearer?

Not much. A systematic review by Ahokas et al., Sports Medicine Open 2025 covered 14 trials (194 participants) whose protocols differed too much to pool.

Among nine studies of acute recovery, four found no effect, four found a benefit and one found an adverse effect on performance. The five training-intervention studies suggested post-exercise heating may improve running performance, at least in hot conditions. Repeated heat exposure had no effect on cycling performance or VO2 max. The authors rated the evidence low to moderate and said definitive conclusions are not possible.

This is separate from the Finnish sauna and mortality data, which come from cohorts of habitual sauna users, not endurance trials.

The bottom line

• A meta-analysis of 10 trials (199 participants) found a trivial, imprecise effect of post-exercise sauna or hot bath on performance in the heat (ratio of means 1.04, 95% CI 0.94 to 1.15).
• A systematic review of 14 trials found mixed results for recovery and no effect on cycling performance or VO2 max, with low to moderate evidence quality.
• Both reviews call for larger, higher-quality trials before firm conclusions can be drawn.