A study conducted by researchers aimed to determine whether sauna bathing could enhance endurance performance in distance runners. In this crossover study, six male distance runners underwent two phases: a 3-week sauna bathing regimen and a 3-week control period, with a 3-week washout in between. During the sauna phase, participants used a humid sauna set at 89.9°C for about 31 minutes immediately after each training session. The primary performance test involved a treadmill run to exhaustion, where the runners were asked to run at their best 5 km pace. The study found that sauna bathing significantly improved running endurance, with the runners able to sustain their treadmill run for 32% longer after sauna sessions compared to control periods, translating to about a 1.9% improvement in endurance.
The researchers also measured changes in plasma volume, red-cell volume, and total blood volume to understand the physiological mechanisms behind this improvement. Sauna bathing resulted in a 7.1% increase in plasma volume and a 3.5% increase in red-cell volume, both of which were linked to improved performance. Strong correlations were found between changes in blood plasma volume and total blood volume with increased endurance, suggesting that the enhanced performance may be due to increased blood volume, which helps improve oxygen delivery to muscles during exercise. The study concluded that post-exercise sauna bathing could be a beneficial practice for improving endurance performance in athletes, likely due to its positive effects on blood volume.
