Some experts think that saunas could help to reduce the symptoms associated with seasonal affective disorder (SAD). Other research highlights their potential benefit for our brains, hearts, and overall mental well-being. And now, new research published in the Journal of Science and Medicine in Sport suggests that “sauna bathing” could help to shave minutes off your marathon time, too. After incorporating three half-hour sauna sessions after their workouts a week for three weeks, long-distance male runners saw about a 2% improvement in their speed. That might not sound much, but when you realise it’s about 5 minutes and 21 seconds shaved off a 4-hour 37-minute marathon time, it starts to look pretty exciting. Why might saunas help with running performance? The researchers got runners to perform a 15-minute treadmill performance test “to exhaustion at the runner’s current best speed over 5km” both before and after the sauna sessions. After three weeks of triweekly, half-hour-long “saunabathing” sessions, scientists compared their pace and noticed a 32% increase in endurance, from which they calculated the projected 1.9% speed increase. They also measured participants’ plasma, red-cell, and total blood volume before each of the performance runs on the treadmill. Changes in the runners’ performance had “high correlations with change in plasma volume and total blood volume,” which seemed to have happened because of the “saunabathing” sessions. “We conclude that [three weeks] of post-exercise sauna bathing produced a worthwhile enhancement of endurance running performance, probably by increasing blood volume,” the study authors wrote. How long should I spend in a sauna? Though this study included half-hour-long “saunabathing” sessions, Harvard Health said that 15-20 minutes ought to be long enough to reap rewards without becoming dehydrated. They added that those with uncontrolled high blood pressure and/or heart disease should speak to their GP before stepping into a sauna. UCLA Health also recommended limiting sessions to 20 minutes, “with new sauna bathers starting with shorter sessions (five to 10 minutes) and building up to 20 minutes”. If you begin to feel poorly while saunabathing, leave at once , and don’t go to begin with if you feel ill beforehand. Related... The 20-Minute Activity That May Reduce SAD, Dementia Risk, And Blood Pressure The Science Behind How Saunas May Ease Seasonal Affective Disorder Sauna Or Steam Room? Experts Reveal The Different Benefits Of Each