The effect of post-exercise heat exposure (passive heat acclimation) on endurance exercise performance: a systematic review and meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of controlled trials evaluated with Cochrane RoB 2
PubMed 39762944 · doi:10.1186/s13102-024-01038-6
What was done
A systematic review and random-effects meta-analysis evaluated five databases for trials in healthy adults comparing exercise training combined with post-exercise heat exposure (sauna or hot water immersion) against exercise training alone. The primary outcome was exercise performance in hot conditions (33–40 °C), alongside secondary outcomes including performance in thermoneutral conditions (18–24 °C), V̇O2 max, lactate threshold, economy, heart rate, RPE, core temperature, sweat rate, and thermal sensations. Risk of bias was assessed using Cochrane RoB 2, and evidence certainty was graded using GRADE.
What was found
Across 10 studies (199 participants: 156 male, 43 female, aged 20–32 years), post-exercise heat exposure produced a trivial effect on endurance performance in hot conditions (ratio of means = 1.04, 95% CI 0.94–1.15, P = 0.46; 95% prediction interval 0.81–1.33). Effects on thermoneutral performance and speed at lactate threshold were also trivial. Small effects were observed for V̇O2 max, heart rate, core temperature, and sweat rate, with a moderate effect on thermal sensations.
Why it matters
While active heat acclimation improves performance, passive post-exercise heat exposure currently lacks robust evidence supporting its efficacy for enhancing endurance exercise performance.
Limits
The certainty of evidence was graded as low to very low across all outcomes due to small sample sizes (199 total participants across 10 studies), low statistical power, high risk of bias, potential publication bias, and substantial male predominance (78% male, ages 20–32).
Cited by
- context Post-exercise sauna use can improve VO2 max.