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The Science of Cryotherapy

Intermediate

Article at a Glance

  • Cryotherapy is a medical treatment that involves short exposures of extreme cold air, often below -166°F.
  • Cryotherapy’s ability to trick our brain and body into regenerating itself are incredible and backed by science.
  • In addition to the physical benefits, cold exposure has been shown to improve depression, anxiety, and other mood disorders.

Cryotherapy – anyone interested in their health has likely heard of it by now. Maybe you’ve even tried a session or two and are now curious to understand the science of cryotherapy and exactly what is happening to your body and cells.

There’s actually a whole debate as to whether the treatment is as beneficial as the hype says or if it’s just another unsubstantiated marketing scheme.

Well, we’ve done some digging, we’ve consulted the (real) science out there. We have some information that should clear some doubts you may have because, in all honesty, we had some too.

Here, we’ll unravel cryotherapy and present some empirical evidence regarding its effects on the brain and body. More specifically, we’ll explore what happens to our bodies when undergoing the treatment, the after-effects of the treatment, as well as the optimal time exposure, temperature, and number of sessions.

What is Cryotherapy?

In short, cryotherapy is a medical treatment that involves short exposures of extreme, cold air, often below -166°F (-110°C).

The first low-temperature cold rooms were introduced towards the end of the 1970s in Japan by Professor Toshiro Yamauchi who successfully treated rheumatism with a cryogenic chamber. He found that rapid short-term freezing of the skin’s surface to a temperature of 32°F (-1°C) has a more beneficial effect than the gradual cooling offered by cold water immersion, where the lowest skin temperature possible is 41°F (5°C).

This led to the introduction of whole-body cryotherapy (WBC) in the clinical setting, but its ability to repair and rehabilitate cells made it popular in the entire health sector.

It helps decrease fatigue and pain associated with exercise, alleviates psychiatric disorder symptoms, relieves chronic pain disorders, and generally improves well-being, offering an anti-aging effect.

What is the Science of Cryotherapy?

extreme cold environment therapy

When our skin is exposed to the low temperatures in a cryo chamber, the surface of the skin quickly reaches below freezing levels (30.2°F/-1°C), and cold sensors are activated and send a very strong signal to the brain.

Instantaneously, to protect the body and prevent hypothermia, the brain then sends signals to maintain heat by constricting blood vessels that supply muscles and other tissues, which leaves more blood available for the core, where vital our organs are. The body’s core temperature must remain at a constant 37°C (98.6°F). Even slight changes lead to damage and possibly even death. So, the body will do what it takes to maintain this for survival.

This peripheral vasoconstriction leads to an immediate increase in blood pressure by about 10 points.

As blood surrounds the core, it’s simultaneously being enriched with oxygen as well as other necessary enzymes and nutrients, including an increase in hemoglobin, all to ensure the body does what it can to survive under the perceived danger.

So essentially, cryotherapy is tricking the body into making new, regenerative blood. After the treatment, when you warm up, that high blood pressure obtained in the chamber pumps that super blood to the periphery again, so those organs can also benefit from its regenerative properties.

Now, that’s quite a generalized response to cold exposure, so how does cryotherapy actually lead to all of this and what else is going on at the physiological level?

Effects on the Brain

Cold exposure has been shown to improve depression, anxiety, and other mood disorders [R]. The most noteworthy physiological effects cryotherapy has on the brain is the increase in neurotransmitter and hormone norepinephrine (NE), involved in mood, attention, focus, and even pain alleviation.

Upon extreme cold exposure, cold receptors on the skin signal the brain to release this hormone, inducing an overall anti-depressive and energetic effect, through activation of the sympathetic nervous system [R].

A long-term study on humans found that NE levels increased on average 200%-300% after 12 weeks of cryotherapy, 3 times a week at -166°F- (110°C) for 2 minutes [R]. That’s quite impressive.

NE is a very powerful compound. Amongst a myriad of other roles, NE:

  • induces peripheral vasoconstriction
  • increases blood pressure
  • influences metabolic rate
  • has an anti-inflammatory effect

Effects on Metabolism

When our bodies are exposed to extreme cold, for the first few times, we shiver. Shivering is a homeostatic mechanism, aimed to maintain core temperatures optimal for the proper functioning of our cells. When we shiver, the mechanistic process creates heat. However, it’s not a thermodynamically efficient process. Upon multiple exposures to cold, our cells adapt and move to more favorable thermogenesis, namely mitochondrial biogenesis [R].

In an attempt to create more energy, and therefore heat, the body, through the hormone NE, upregulates its mitochondria production, most notably in fat tissue. This increase in mitochondria turns white fat tissue (with low mitochondria levels) into brown fat tissue, also called brown adipose tissue (BAT).

BAT is thought to be crucial for the regulation of body weight in healthy men and is positively associated with metabolic rate [R]. Interestingly, BAT declines with age, explaining the age-related weight gain.

While white fat tissue (WAT) stores energy from food, BAT cells burn energy to produce heat.

Does that mean you can freeze yourself to a slimmer you? Yes! A recent study published in 2018 found a significant decrease in waist circumference (3.3%) following 3 sessions of localized cryotherapy [R].

Effects on Inflammation

The pain-reducing and anti-inflammatory effects of cryotherapy are probably the most desired results by athletes and patients alike. Inflammation is thought to be the key process involved in delayed-onset muscle soreness (DOMS), joint pain, diabetes, rheumatism, injury pain, cancer, and other aging-related diseases. A reduction of inflammation is thus associated with longevity and well-being.

Inflammation is a protective response to injury or infection leading to a localized gathering of cells and chemicals that prompt swelling, heat, redness, and pain in an attempt to either regenerate the injured tissue or eliminate the foreign pathogen.

In excess, inflammation can quickly cause disease and premature aging of cells.

inflammation cryotherapy

The effectiveness of cryotherapy on inflammation and pain reduction has been demonstrated by various studies. In the case of athletes or those exercising in general, a single session can enhance muscular recovery through the restriction of inflammatory processes [R].

More specifically, levels of cytokine tumor necrosis factor alpha (TNFα), a powerful pro-inflammatory compound, were shown to decrease nearly 2-fold when cryotherapy was combined with training, in comparison to training without treatment [R]. This is due to the high expression of NE after a cryotherapy session, which has a direct inhibitory effect on TNFα. In addition, WBC leads to an increase in interleukin (IL-10) levels, which is a powerful anti-inflammatory compound, and a decrease in proinflammatory compounds IL-2 and IL-8

As well as treating DOMS, WBC has a preventative effect on exercise-induced inflammation.

That is, when the treatment is done prior to exercise, the usual inflammation induced by exercise is decreased [R]. This preventative effect was seen after a single session of -202°F (-130°C) at 3 minutes prior to exercise [R].

How Many Cryotherapy Session Do I Need?

All these effects of cryotherapy are great, but they’re only interesting if they are long-term. Like with most things that make a difference, repetition and consistency are key.

In fact, this is probably why there still isn’t as much data out there as the treatment deserves. Many (not all) studies or just average people trying it judge its effects after a single session. While one session can have positive effects, it’s not enough for neither significant nor long-term changes.

According to one study, 10 sessions of WBC are needed to significantly reduce the inflammatory response that is induced by exhaustive exercise [R]. Yet another study suggests a minimum of 20 consecutive sessions for effectiveness and 30 sessions for optimal results [R].

A lot of these studies found that there are significant differences in the effect of cryotherapy with every individual. Factors like body composition and activity level influence how cryotherapy can have an effect.

When Should I Get Cryotherapy?

When to get a cryotherapy treatment depends on your aim. To reduce pain associated with exercise, studies suggest not to undergo cryotherapy immediately after exercise. Instead, waiting is recommended so that the body has time to repair itself on its own, and then cryotherapy can be used to lessen the damage of prolonged inflammation. You may have heard that cryotherapy reduces the effects of hypertrophy, which is the process of making new muscle, so it has been accused of causing less muscle gain.

However, this is due to the use of cryotherapy too close to an exercise session, interrupting the benefits of inflammation that allow repair and muscle gain. Most studies suggest a waiting time of around 1 hour before practicing any post-exercise cold therapy.

To alleviate acute pain after an injury or acute inflammation of any sort, it is recommended to undergo cold exposure within the first 72 hours of the first symptoms in order to get optimal results.

How Cold is Cryotherapy?

When it comes to cold on the body, the right temperature and exposure time are also crucial. We want enough time for physiological changes to take effect, but not long enough for cold to inflict harm. One study concluded that a 2-minute session at -211°F (-135°C) was optimal, though this is aimed at elite athletes [R]. Others observe effectiveness with 2 minutes at -166°F (-110°C). Yet others tend to go for 3 minutes.

So there is no exact temperature or duration that you could really call optimal for every person and body composition, but, in general, between 2-3 minutes at -166°F (-110°C) and -211°F (-135°C) is the norm. You can consult a cryotherapy center for advice on your specific needs.

Conclusion

Cryotherapy’s ability to trick our brain and body into regenerating itself is incredible and quite well-backed by science. We still do not know the exact mechanisms for everything, but, so far, it seems rather promising.

That said, it’s important to be cautious and bear in mind that cryotherapy is not a treatment that can nor should be done without supervision. Extreme temperatures can inflict harm when not used properly. You can refer to our directory of aging and longevity clinics to find the right cryotherapy center for you.

Happy Freezing!

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