Saunas - Hot Fad or Beneficial?

Today we are going to take a dive into Saunas and its effects on strength, hypertrophy, general recovery and overall health.


Welcome to a new week! A few issues ago, we covered Ice baths and CWI (Cold Water Immersion) and its effects on strength and hypertrophy which you can read with the link below.

Today we are going to take a dive into Saunas and its effects on strength, hypertrophy, general recovery and overall health.

🗞 In Today’s Issue

🤓 What The Science Has To Say On Saunas

Unfortunately for those of us chasing strength and hypertrophy gains, most of the studies done with regards to saunas and training have been largely focused on endurance athletes, one of which by (Scoon et al., 2007) studied 6 male distance runners over 9 weeks, where 3 weeks of the 9, included a post exercise sauna bathing segment for 30 minutes at ~90℃. The sauna bathing increased “run time to exhaustion” by 32%. The studies authors state this was likely due to increased blood volume.

One study we did find regarding muscle mass was a 6 week study by (Toro et al., 2021). They took 23 men and split them into a control group and a sauna group. Both groups underwent the same training programme, the sauna group however had heat exposure 3 times per week for 4 weeks of the study. The sauna protocol was 5 sets of 10 minutes in 100℃ followed by 5 minutes at room temperature. The authors results state “It seems that exposure to heat at high temperatures could produce improvements in bone and muscle mass”.

Saunas have also been proven to be beneficial for reduced risk of cardiovascular disease and lower “all cause mortality rates” ← which basically means “death from any cause 💀”. (Laukkanen et al., 2018)

We can still dig deeper into this topic to find some answers. Specifically extreme heat exposure on the body’s human growth hormone, cortisol levels and “heat shock proteins”.

💪 Human Growth Hormone, Cortisol & HSP’s

Human growth hormone (HGH) is important for several reasons. Stimulating muscle growth, strengthening bones, repairing tissue, and increasing metabolism to name a few. HGH is usually released at night when we sleep however as we age the amount released decreases.

In one study by (Leppäluoto et al., 1986) had seven men and ten women exposed to one-hour sauna sessions twice per day at 80°C dry heat (standard Finnish-style sauna) for seven days the results showed a 16-fold increase in growth hormone levels by the third day.

Cortisol is the bodies “Stress Hormone” is has various important roles including → regulating your body's stress response (it’s what gives us our fight or flight response as humans) and helping control your body's use of fats, proteins, carbohydrates and overall metabolism.

Although this hormone is essential, higher concentrations of cortisol for a prolonged period of time can block recovery and muscle growth through inhibiting the release of testosterone, which is the body’s most important growth hormone for muscle development.

A study published in the American Journal of Men’s Health by (Podstawski et al., 2021) took 30 men aged 19-26 years old and had them perform 4 sauna sessions lasting 12 minutes each (Note: these sessions were finished with a cool down period in cold water) Cortisol levels were measured before and after the treatment showing a significant decrease from 13.61 to 9.67 ug/ml. They also found an increase in Testosterone levels. Results can be seen below 👇.

Heat Shock Proteins (HSPs), are released under heat stress. One of the main functions of HSPs is to protect other proteins from degradation, leading to improved protein synthesis, meaning a better balance between breakdown and the building processes in the muscles.

This study by (Iguchi et al., 2012) found an increase of ~48.7% in HSP72 after 30 minutes of heat stress in a sauna.

A review by (Patrick & Johnson, 2021) found that whole body “hyperthermia” (not Hypothermia) may preserve and even help increase muscle mass.

Dr. Rhonda Patrick, (from the study linked above) states “This may have special relevance for slowing age-related sarcopenia, a progressive condition characterized by loss of skeletal muscle mass and strength”

✍️ Key Takeaways & Practical Applications

  • Saunas have been shown to increase HGH and lower cortisol levels. These increases may be beneficial for building muscle mass, strength, recovery and optimizing your overall health.

  • Reviews have largely agreed on the benefits of saunas towards your overall health through reducing risk of cardiovascular disease and all cause of mortality.

  • Saunas have a positive effect on endurance likely due to increased blood volume which allows muscles to be better supplied with oxygen and other nutrients.

  • In terms of Strength and Hypertrophy the evidence is limited with only a few to pull from, however none show a negative trend. Plus we can draw educated conclusions from increasing HGH , increasing HSP’s and lowering cortisol levels that it may be beneficial.

  • The positive effect of increased blood volume, better supplying our muscles with oxygen and nutrients may help strength & hypertrophy training in moderate to high rep ranges with better recovery between sets.

👉 Note: All of the above studies carried out ensured adequate hydration of test subjects throughout the sauna protocols. This is something to bear in mind if adding this into your health programme. Non optimal hydration could lead to several health side effects. Ensure proper electrolyte consumption especially Sodium, Potassium and Magnesium.

In general, pregnant women and children younger than 16 should not use the sauna.

Don’t take the above cardiovascular benefits to mean you can replace your normal activity and training programme with sitting in a sauna. I would still say regular exercise and lifting to be more beneficial to your overall health, but the results suggest that sauna bathing could complement your current training programme.

Which type of sauna? Most of the scientific literature has been done with regards to a typical “Finnish” style sauna. These usually involve high temps of 85-110℃ and low humidity of 10%. The temperature you use should align with your own heat tolerance though, perhaps start with cooler temperatures if your not used to it.

  • For general health and improvement of cardiovascular benefits use a Finnish style sauna 2-3 times per week for 5-15 minutes each.

  • To lower cortisol levels and increase testosterone try a contrast Heat + Cold exposure protocol outlined in the study by (Podstawski et al., 2021) above.

  • To raise HGH levels try the longer protocol of 1 hour exposure but be mindful of your hydration levels due to impaired recovery if dehydrated + other health concerns.

Personally, time cost vs benefits taken into consideration. I’d run with the shorter higher temp protocols which have been shown to improve general health, decrease risk of cardiovascular disease, lower cortisol levels and increase testosterone. Most of us simply don’t have to time to spend one hour in a sauna.

Everyone is different so find which works best for you. Sometimes using the sauna straight after a workout or training session could prove to be just a bit too much stress on the body, see how you get on or try keeping it for recovery / rest days perhaps?

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