We conclude that 3wk of post-exercise sauna bathing produced a worthwhile enhancement of endurance running performance, probably by increasing blood volume.- results of a study that involved runners spending an average of 31 min in a sauna following a run on 12 occasions over 3 weeks. The test was a 15 min run to exhausion at 5K pace. Effect of post-exercise sauna bathing on the endurance performance of competitive male runners
Spending time in a sauna is not the ideal way to acclimatize for hot weather running, but according to this small study it may benefit peformance. I'm headed to Phuket on Thanksgiving day and running a 6K on Sunday, so between now and then I will hit the sauna a few times. Looks like it as long as I stay hydrated, it can't hurt.
