henry copeland:

Sauna Use as an Exercise Mimetic for Heart and Healthspan

Some of the positive benefits of the sauna on heart health may have to do with similar physiological changes that also occur during physical exercise. For example, there is a 50-70% redistribution of blood flow away from the core to the skin to facilitate sweating. You start to sweat. Heart rate increases up to 150 beats per minute which correspond to moderate-intensity physical exercise. Cardiac output (which is a measure of the amount of work the heart performs in response to the body’s need for oxygen) increases by 60-70%. Immediately after sauna use, blood pressure and resting heart rate are lower than baseline similar to physical activity.
- www.foundmyfitness.com