Taking a sauna session causes the same effects on our body as a short, moderate workout, a study has found.
Contrary to previous assumption, researchers at Martin Luther University Halle-Wittenberg (MLU) and the Medical Center Berlin (MCB) in Germany found that the blood pressure does not drop during a sauna session.
Instead, they found that the blood pressure rises along with the heart rate—an increase comparable to the effect of a short, moderate workout.
For the study published in the journal Complementary Therapies in Medicine, the researchers placed participants both in a sauna and on a bicycle ergometer on separate days.
"It was thought that the heat dilates the blood vessels and that this lowers the blood pressure," said Sascha Ketelhut, a sports scientist at MLU.
People with low blood pressure or cardiovascular disorders have traditionally been advised not to use saunas, as a further fall in blood pressure can lead to fainting.
"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," said Ketelhut.
"Many previous assumptions have been made about the acute effects of sauna use, but so far little research has been done," he said.
The scientists conducted their study by recruiting 19 volunteers to measure the immediate effects of sauna use on the cardiovascular system.
The participants were exposed to a 25-minute sauna session, while having their blood pressure and heart rate measured. Both rose immediately during the sauna visit.
After the sauna session, both blood pressure and heart rate began to drop below participant's baseline levels that were measured before the sauna session.
In the second part of the study the participants completed a short exercise program on an exercise bike while also having their blood pressure and heart rate assessed.
"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," said Ketelhut.
This shows that a sauna session is kind of a burden on the body.
"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.
The observations made by the researchers are supported by previous studies that focused primarily on the long-term effects of sauna use, demonstrating positive effects on the cardiovascular system, for example.
"A sauna session is a physical strain. Its long-term positive effects are similar to sports activities," said Ketelhut.
Nevertheless, the healthy sweating does not contribute to weight loss.
"The effect is too low as there is no muscle activity. Although we lose weight in the sauna, but these are just the fluids that we sweat out. One should rehydrate after a sauna session, though," said Ketelhut.