The term “sauna” can refer to any type of small or large room or device designed to help the user experience dry heat or wet heat (steam). There are now also infrared (far and near) saunas that emit infrared light and claim to heat the body more effectively.

    Saunas or “sweat lodges” have been used for centuries by different cultures, and while there is a large amount of anecdotal evidence about their benefit, the scientific research is limited and focuses mainly on Far Infrared Saunas (FIR).

    According to a review of all of the published scientific literature about these types of saunas, the biggest researched benefit seems to be the coronary benefits, most notably in their ability to help normalize blood pressure and reduce the chance of congestive heart failure. Other research shows the benefits of FIR saunas for chronic pain and to a lesser degree, obesity.

    An interesting and unusual benefit: Far-infrared sauna use is safe and effective for increasing lactation in breastfeeding mothers ,  the heat itself seems to be the most beneficial part of sauna use and Infrared saunas are simply able to heat the body more efficiently without the person feeling as hot. There is some concern about EMF exposure from FIR Saunas, and a few sources recommend Near Infrared Saunas instead, though I’m yet to find any scientific evidence backing this claim.

 

The Benefits of Heat

    Though there is debate on the ability of saunas to detoxify or remove cellulite, but there is well documented research on the ability of heat (or “hyperthermic conditioning”) to improve performance.

    Tim Ferriss recently interviewed Dr. Rhonda Patrick about the benefits of heat conditioning. Some key points:

·  Increased Endurance: “[Hyperthermic conditioning] increases plasma volume and blood flow to the heart (stroke volume). This results in reduced cardiovascular strain and lowers the heart rate for the same given workload. These cardiovascular improvements have been shown to enhance endurance in both highly trained and untrained athletes.”

·  Natural Growth Hormone Production: “For example, two 20-minute sauna sessions at 80°C (176°F) separated by a 30-minute cooling period elevated growth hormone levels two-fold over baseline.1,15 Whereas, two 15-minute sauna sessions at 100°C (212°F) dry heat separated by a 30-minute cooling period resulted in a five-fold increase in growth hormone.1,15 However, what’s perhaps more amazing is that repeated exposure to whole-body, intermittent hyperthermia (hyperthermic conditioning) through sauna use has an even more profound effect on boosting growth hormone immediately afterward: two one-hour sauna sessions a day at 80°C (176°F) dry heat (okay, this is a bit extreme) for 7 days was shown to increase growth hormone by 16-fold on the third day.14 The growth hormone effects generally persist for a couple of hours post-sauna.1 It is also important to note that when hyperthermia and exercise are combined, they induce a synergistic increase in growth hormone.20”

·  Faster Recovery: “It increases blood flow to the skeletal muscles, keeping them fueled with glucose, esterified fatty acids, and oxygen while removing by-products of the metabolic process such as lactic acid. The increased delivery of nutrients to muscles reduces their dependence on glycogen stores.”

·  “One study demonstrated that a 30-minute sauna session two times a week for three weeks POST-workout increased the time that it took for study participants to run until exhaustion by 32% compared to baseline.”

·   Increased Muscle: It has been shown that a 30-minute intermittent hyperthermic treatment at 41°C (105.8°F) in rats induced a robust expression of heat shock proteins (including HSP32, HSP25, and HSP72) in muscle and, importantly, this correlated with 30% more muscle regrowth than a control group during the seven days subsequent to a week of immobilization.

·   Increased Insulin Sensitivity:For this reason, hyperthermic conditioning may also lend itself to promoting muscle growth by improving insulin sensitivity and decreasing muscle protein catabolism. Intermittent hyperthermia has been demonstrated to reduce insulin resistance in an obese diabetic mouse model. Insulin resistant diabetic mice were subjected to 30 minutes of hyperthermic treatment, three times a week for twelve weeks. This resulted in a 31% decrease in insulin levels and a significant reduction in blood glucose levels, suggesting re-sensitization to insulin