And here's why:
Growth hormone is crucial for repair and recovery of muscles, and research has shown that two 20-minute sauna sessions separated by a 30-minute cooling period elevated growth hormone levels two-fold over baseline. Two 15-minute sauna sessions at an even warmer temperature separated by a 30-minute cooling period resulted in a five-fold increase in growth hormone.
Perhaps even more nifty is that repeated exposure to whole-body, intermittent hyperthermia through sauna use boosts growth hormone immediately afterward, and two one-hour sauna sessions for 7 days has been shown to increase growth hormone by 16-fold. Yeah, that’s right: you don’t need to go buy fancy supplements or creams to increase growth hormone. You can just make your body hot instead and get a growth hormone increase
It is also important to note that when hyperthermia and exercise are combined, they induce a synergistic increase in growth hormone, which is why I do yoga, push-ups and squats in my infrared sauna. For an additional recovery benefit, sauna also increases blood flow to the skeletal muscles, which helps to keep them fueled with glucose, amino acids, fatty acids, and oxygen, while removing by-products of metabolic processes such as lactic acid and calcium ions.
Arthritic & Muscular Pain Relief
In a report in The Annals of Clinical Research Volume 20, Dr. H. Isomäki discusses research results that show benefits of sauna for relief of pain and increased mobility. In the study, the pain relief induced by a sauna was attributed to an increase in the release of anti-inflammatory compounds such as noradrenaline, adrenaline, cortisol and growth hormones, as well as an increase in positive stress on the body, causing it to releases natural pain-killing endorphins. More than 50% of participants reported temporary relief of pain and an increase in mobility, most likely due to the fact that tissues comprised of collagen, such as tendons, fascia, and joint articular capsules, become more flexible when exposed to increased temperatures."
Read more http://www.bengreenfieldfitness.com/2015/10/science-of-sauna/