A recent report by Dr. Rhonda Patrick Ph.D. suggests that extended use of sauna may increase longevity. The report lists additional benefits of sauna use including increased endurance, easier acquisition of muscle mass, and a general increased capacity for stress tolerance. Using a sauna may also have “nootropic” like effects that promote the growth of new brain cells, improve focus, learning and memory, and may also help with depression and anxiety. Dr. Patrick uses the term “hyperthermic conditioning” to refer to the acclimatization to heat.
Hyperthermic conditioning increases the plasma volume in blood which in turn optimizes the blood flow to the heart, skeletal muscles, skin. Those who are hyperthermically conditioned will see improved cardiovascular mechanisms and lower heart rate as well as a lower core body temperature. These physiological adaptations will result in an enhanced endurance. One study shows that a 30 minute sauna session two time per week for three weeks post-workout increases the time for a runner to run to exhaustion by 32%!
Muscle Growth and Heat Shock Proteins
Hyperthermic conditioning may also lead to an increase in lean muscle mass. This is due to spike in protein synthesis cause by a process known as hormesis. Hormesis is the body’s stress response when it encounters certain stressors such as toxins. The body rapidly reacts to the stressor to prevent harm. When the body is in a hyperthermic state it induces a hormetic response which promotes the expression of a gene called heat shock factor 1 which in turn leads to production Heat Shock Proteins(HSPs). HSPs help to prevent protein damage cause by oxidative stress (which happens just by breathing!), and also helps to repair previously damaged proteins. The result is an increase in net protein synthesis and in turn, muscle growth.
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Studies show that a 30 minute intermittent hyperthermic treatment at 41 C in rats induced a robust expression of HSPs which correlated with 30% more muscle growth. The hormetic effect was measure to persist for up to 48 hours after the treatment.
Release of Growth Hormone
Hypethermic conditioning may also result in a massive induction of growth hormone. Growth hormone has been known to decrease protein oxidation and degradation by as much as 50%. Studies show that two 20-minute sauna sessions at 80 C separated by a to minute cooling period elevated growth hormone by 100%. This induced growth hormone production persists for a couple of hours after sauna use.
Studies in flies and worms show that heat stress treatment increases their lifespan by up to 15% due to production of HSPs. One study looked at the relationship between sauna use and longevity. 2,315 Finnish men between the ages of 42 and 60 were studied and they found that those who used the sauna 4-7 times per week saw a 50% in deaths due to cardiovascular disease and a 24% reduction in all causes mortality (deaths not including accidental death). Take a look at Dr. Patrick’s video below for more information.
Heat Stress and the Brain
It appears the heat stress cause by sauna use induces the activation of the sympathetic nervous system in the brain. Studies show that men who stayed in 80 C sauna until exhaustion received a 310% increase in norepinephrine, a 1000% increase in prolactin and a decrease in cortisol. Norepinepherine helps with focus and attention while prolactin promotes myelin growth (which makes your brain function faster).
While there certainly seems to be significant benefits to using the sauna caution should be observed. Heat Stress can have adverse effects on the body. Dr. Patrick advises that you should not use a Sauna while drinking alcohol, while pregnant or if you have a medical condition in which heat may have adverse effects.