The title of the post is a copy and paste from the title and fourth paragraph of the linked academic press release here:
Sweating for science: A sauna session is just as exhausting as moderate exercise
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”, says Ketelhut.
S. Ketelhut, R.G. Ketelhut.
The blood pressure and heart rate during sauna bath correspond to cardiac responses during submaximal dynamic exercise.
Complementary Therapies in Medicine, 2019; 44: 218
• Contrary to previous reports that BP drops during a sauna stay, the data shows a continuous increase in BP and HR during the sauna session.
• The acute heat exposure in the sauna is a burden comparable to moderate physical exercise.
• The sustained decrease in BP after heat exposure suggests that the sauna bath will have a beneficial effect on the cardiovascular system.
In the present study, the reaction of blood pressure and heart rate are examined during and after a single acute sauna application.
In 19 healthy adult volunteers (7 women, aged 46.4±10.2 years, BMI 24.4±2 kg /m2), blood pressure (BP) and heart rate (HR) were measured during a 25-minute sauna session (93°C, 13 % humidity) and during a subsequent 30-minute rest period. The parameters obtained were compared with the BP and HR responses during submaximal dynamic exercise testing.
The heat exposure resulted in a significant (p<0.01) and progressive increase in systolic and diastolic BP. After the sauna bath, BP decreased and showed significantly (p<0.001) lower values compared to baseline. HR also increased continuously during heat application (p<0.001), resulting in a significant increase (p<0.001) in systolic BP x HR as a measure of myocardial oxygen consumption. After the end of the sauna session, both the BP and the HR decreased steadily (p<0.001).When comparing BP and HR during the sauna session with the reaction during a dynamic exercise test, sauna bathing was equivalent to an exercise load of about 60-100 watts.
Contrary to popular belief, acute sauna use does not lead to a reduction, but to an increase in BP and HR with a consequent increase in myocardial oxygen consumption. The cardiac load during the sauna use corresponds to a moderate physical load of 60-100 watts.