Sauna visits affect BP, heart rate like moderate exercise

A 25-minute steam in the sauna could be just as beneficial for heart health as a moderate physical workout, researchers at Martin Luther University Halle-Wittenberg and the Medical Center Berlin have found.

Lead investigator and sports scientist Sascha Ketelhut, PhD, and colleagues found that, contrary to popular belief, a person’s blood pressure doesn’t drop during a sauna visit—it rises. Their study of 19 healthy volunteers suggested both sauna sessions and exercise raise BP levels and heart rate in a comparable way, dropping below participants’ baseline levels after either activity.

Ketelhut said in a release that scientists previously assumed sauna steams raised BP because, logically, heat would dilate a person’s blood vessels, causing their blood pressure to plummet. Patients with low BP have historically been advised against using saunas, since a further drop in BP could cause them to faint.

“However, it is important to distinguish between the acute effects of a sauna session and the effects that were noted during the rest period after the sauna session,” Ketelhut said. “Many previous assumptions have been made about the acute effects of sauna use, but so far little research has been done.”

Ketelhut et al.’s study participants were exposed to two scenarios: one in which they underwent a 25-minute sauna session and the other during which they completed a short workout on an exercise bike. In both situations, subjects’ blood pressure and heart rate were continuously measured.

The team found patients’ BP and heart rate both rose immediately during each activity. After a sauna visit, participants’ BP and heart rate began to drop below their baseline levels.

“Comparing the two conditions, the participants’ blood pressure and heart rate reached the same levels during the sauna session as they did with a load of about 100 watts during the exercise test,” Ketelhut said. “Saunas can actually be used by anyone who can tolerate moderate physical stress without discomfort. However, people with low blood pressure should be cautious afterwards, as their blood pressure may then fall below the levels registered before the sauna visit.”

Ketelhut said saunas do promote healthy sweating, but they’re not a path to weight loss. We technically lose weight in the sauna, he said, but that’s because we’re sweating out fluids that will later be restored. Since there’s no muscle activity involved in a sauna session, it doesn’t have significant weight-loss potential.

Ketelhut and colleagues’ results were published this June in Complementary Therapies in Medicine.