Beyond the Sweat in the Sauna

We've all seen them. The creepy old guys that frequent the sauna fully nude flaunting something they shouldn't be proud of. You may have heard them quote why the sauna is 'good for you'. "It's good for the skin." "It flushes out toxins." "It's good to sweat." — All the dumbed down sauna benefits you see on grocery store checkout lane magazines.

The sauna craze is real. But it's more than (sweaty) skin deep. The benefits are quite astounding and backed up by growing amounts of research. 

A sauna is a small room to experience dry heat sessions. Heat is generated by a small stove, radiator, infrared or traditionally hot stones. Generally it is low in humidity, but some enjoy ladling water on hot stones to generate a small amount of steam. A steam room can be sometimes mistaken for a sauna, but steam rooms operate at a lower temperature and very-high humidity (a lot of steam) [1].

Why

If you want to talk about an easy fitness tool that provides so many benefits, it's hard not to have sauna at the top of the list. Walking into a heated room and sitting for a period of time sounds way more appealing than leg-day or running 5 miles.

Listen to a podcast, chat with others, read a book, meditate, or just stare at the wall for 20+ minutes all while knowing the sauna heat is working magic to improve your muscles, cognitive function, and overall health.

Muscle growth, recovery, & endurance

  • Saunas can increase athletic endurance by 32%. This was achieved by measuring participants' run time to exhaustion after 12 post-workout sauna sessions over 3 weeks. Plasma volume and red blood cell count increased by 7.1% and 3.5% respectively increasing oxygen delivery to muscles and optimizing blood flow to the heart, muscles, skin, and other tissue [5].
  • Heat therapy induces muscle hypertrophy (growth and strength) via up-regulation of heat shock proteins (HSP), growth hormone, and improved insulin sensitivity [2]. Muscles grow due to more protein synthesis occurring than protein degradation (2 min protein synthesis video summary). Key takeaway: protein synthesis > protein degradation = muscle growth. 
    • Heat shock proteins (HSP) are a protective stress response once exposed to heat. Just as exercise grows muscle over time by inducing small stress with each workout, heat therapy does the same. HSPs prevent and repair protein damage.  As proteins in our bodies get misfolded or damaged (our bodies aren't perfect), HSPs clean house at a cellular level by correcting protein folds and/or sweep up loose protein bits to be input into the protein synthesis cycle once again. This ensures proteins have their proper structure and function.
    • Growth hormone through insulin-like growth factor (IGF-1) activates the mTOR pathway, which is responsible for protein synthesis. IGF-1 also inhibits FOXO activation and inhibits protein degradation. Research shows growth hormone levels elevate by 142% after sauna use and return to baseline an hour after [6].
    • Insulin sensitivity increases protein synthesis by stimulating the uptake of amino acids in muscle, and decreases protein degradation by inhibition of the proteasome, a protein complex inside cells responsible for protein degradation.
  • Muscle recovery and repair are improved with sauna use thanks to elevating HSPs, blood oxygen transport, blood pressure, red blood cell count, and core temperature. Increasing blood flow and repairing protein damage in the muscles are key ingredients to shortening your muscle pain, soreness, and injury cycles. This is key knowledge. If you are recovering from an injury and been instructed to maintain strict rest, sitting in a sauna frequently will retain muscle mass and speed up recovery [7]. 
  • You may have heard that our boys need a Goldilocks zone of temperature to keep our testosterone up. Hence, the reason why they hang externally. Note that testosterone is unaffected up to 1 hour at normal sauna temperatures, and if hydrated properly can slightly increase testosterone [4].

Cognitive performance, mood, memory, & attention

  • Decrease anxiety, depression, and stress levels [2]. A run, exercise, AND sauna heat all produce that runner's high or euphoric feeling from the interplay of endorphins (feel-good), beta-endorphins (pain-blockers), and dynorphins (discomfort) on your brain. The sauna heat creates hormetic stress ramping up pain-blockers suppressing the discomfort allowing more experienced feel-good from endophins. Better put, the greater the your workout or sauna discomfort, the better the high will be afterward. Even better news, this is semi-permanent, and actually make you happier in everyday life.
  • Increase focus and memory retention through upping a few neural expressions [2]. Brain-derived neurotrophic factor (BDNF) increases the growth and survival of brain neurons which enhances learning, long term memory. BDNF has also been shown to play a role in improving anxiety and depression as well as repairing and growing new muscle cells. Saunas also increase norepinephrine (focus and attention) by 3X, prolactin (faster brain function) by 10X, and a decrease in cortisol (stress) levels. Heat stress also can increase our capacity to store norepinephrine for later release.

Health & longevity

  • Increase insulin sensitivity from frequent sauna use. Heat therapy increases glucose transporters (GLUT-4) which decrease insulin and blood sugar levels [2]. Improving insulin sensitivity will increase muscle mass by better storing glycogen as well as reduce risks of diabetes, Alzheimer's, and Metabolic Syndrome #comingsoon. 

  • Warning. The following longevity statistics may be the craziest you've read. Using the sauna 4 to 7 times a week was associated with a 50% lower cardiovascular disease risk, a 40% lower all-cause mortality (all non-accidental deaths), a 66% lower risk of dementia, and a 65% lower risk of Alzheimer’s disease [3] ... wow! The longevity benefits from sauna treatment are accomplished through multiple different channels all mentioned above (HSP's, neural receptors, cardiovascular mechanisms, oxygen transport, blood pressure, red blood cell count, core temperature, etc). 

The list of controlled research proven sauna benefits is growing with each day. Beyond this amazing list above, us here at Bachelor.Fitness stay engaged with the latest news on any additional sauna learnings. If you want to dive even deeper, Dr. Rhonda Patrick has written and interviewed extensively on sauna. A good place to start is her interview with Dr. Jari Laukkanen, a prominent figure in therapeutic sauna research.

Outside of the controlled research, I can personally attest to the sauna even after a single 30 minute session. My sample size of n=1 isn't significant, but my mental attitude, stress, and muscle recovery improved immediately after and carried into the next day. Time permitting, I now look forward to a dose of sauna after every workout (~6 times a week). - Jacob

How

Access to a sauna is step one. Typically any decent gym will have a sauna in the locker room. Whether or not it works is another thing. The steam room at my YMCA hasn't worked for a month straight since I've been a member. Along that topic, you may be wondering if a steam room, hot tub, or even a hot bath can bring the same benefits as dry sauna heat therapy. The answer is ... probably not, but maybe. 

Not much research has been done on comparing sauna versus other types of heat therapy such as steam rooms or hot tubs. At the core, sauna research is all about raising the internal body temperature inducing heat stress to gain the beneficial neurological and muscle effects. If you look at the temperature of steam rooms and hot baths, it ranges between 100 to 120°F. From my experience, the most enjoyable and effective has been the dry sauna. The steam room may feel hotter due to the water droplets on your skin and breathing becomes tough, but the dry sauna is actually warmer - don't be fooled. Steam rooms benefit your allergies or sinuses and hot tubs are fun on vacation, but the proven bang for your buck comes from the dry sauna.

Ready for some sauna action?! Below are criteria gathered from studies in order to get all the therapeutic effects of a sauna session [3]. Strip down, grab a towel, hydrate up, bring a book (binding glue may melt), watch your phone (probably will over temp), wear a heart rate monitor or fitness band, and have access to a clock as you step inside for your meditative sauna session. Enjoy.

  • Type: Hot-dry sauna
  • Temperature: ~174°F
  • Length of time: ~20 min or more depending on temperature and heart rate
  • Heart rate: get up to 130-150 bpm for a few minutes (your normal aerobic workout bpm)
  • Frequency: 2-4 times a week
  • Timing: post-workout for optimal muscle recovery growth hormone boost

My local Cincinnati YMCA is where I sauna almost every day. The temperature is normally 170°F or less — under the 174°F published in the research. In order to get my heart rate up to 130+ BPM, it takes around 30 to 40 minutes sometimes. While I've had many interesting (and odd) sauna encounters, it can be a bit time consuming. If your sauna can't get up to 170°F, I recommend running a mile or cycling prior to entry. That way your body is already primed for heat rise.

My sauna session this week is detailed below along with a visual of my heart rate increasing over time. Notice how I seek to hit >130BPM for a few minutes before I call it a day. Also, if you're wondering, yes, I was caught taking this photo of myself and looked like a huge idiot. - Jacob



PS Look out for even more benefits of hyperthermic conditioning through cold showers #comingsoon.

BE CAREFUL AND SMART

As young professional bachelor, a 20 minute session can feel easy and even relaxing. Like any exercise, apply caution to pushing the limits. Go into the sauna properly hydrated, bring a water bottle, consume enough electrolytes (salt), bring a buddy, or let someone know you're in there. If you feel you're heart racing, it's tough to breathe, feel like it's torture, or have a medical condition, get out when you feel it's necessary and consult your physician for guidance.