Effect of post-exercise sauna bathing on the endurance performance of competitive male runners.
Level 2 - randomized trial
Crossover intervention trial in humans
PubMed 16877041 · doi:10.1016/j.jsams.2006.06.009
What was done
Six competitive male distance runners completed a crossover study consisting of 3 weeks of post-exercise sauna bathing and 3 weeks of normal control training, separated by a 3-week washout period. During the sauna block, subjects sat in a humid sauna at 89.9 ± 2.0 °C for 31 ± 5 minutes immediately post-training on 12.7 ± 2.1 sessions. Performance was evaluated via a treadmill run to exhaustion at 5-km race pace (approximately 15 minutes) on the first and second days after each period, with the two times averaged. Plasma, red-cell, and total blood volume were measured using Evans blue dye dilution.
What was found
Compared with the control period, post-exercise sauna bathing increased run time to exhaustion by 32% (90% confidence limits: 21% to 43%), calculated by the authors as equivalent to a 1.9% (1.3% to 2.4%) improvement in an endurance time trial. Plasma volume increased by 7.1% (5.6% to 8.7%) and red-cell volume increased by 3.5% (-0.8% to 8.1%) after sauna relative to control. Performance improvements correlated strongly with changes in plasma volume (r = 0.96, 90% CL: 0.76 to 0.99) and total blood volume (r = 0.94, 90% CL: 0.66 to 0.99), whereas the correlation with red-cell volume change was unclear (r = 0.48, -0.40 to 0.90).
Why it matters
This study provides early experimental evidence that post-workout heat exposure can induce plasma volume expansion and improve endurance performance in trained runners.
Limits
The sample size was extremely small (n = 6), and all participants were male competitive runners, limiting generalizability to females and non-athletes. The abstract does not state whether the crossover order was randomized or counterbalanced, and participants could not be blinded to the sauna intervention.
Cited by
- supports Sauna use improves exercise performance in both hot and temperate (normal) weather conditions.