The Science behind Cryotherapy

Updated: Feb 14

What is it?


Broadly-defined, cryotherapy refers to using cold exposure, in some form, for treatment. This can range from the whole-body cryotherapy that we offer at The Fit Partnership, to the small area cryotherapy used by doctors and dermatologists. More specifically, cryotherapy tends to refer to technological forms of cold-exposure, rather than the more natural alternatives (e.g. sitting in an ice bath or winter swimming).


Benefits


Cold exposure has been used by many cultures for centuries. Apparently, Hippocrates in 400 BCE was already recommending cold water to relieve fatigue[1].


Icing an injury is widely-used as a first step to reduce inflammation and pain. However, whole-body treatments can yield other interesting results.


Beauty


Cryofacials are becoming more popular. They often involve the targeted application of nitrogen to your face to stimulate the constriction and then dilation of blood vessels to reduce any puffiness.


The initial effect of the cold is to decrease circulation to the skin: your blood vessels constrict to reduce blood flow to the surface and retain heat. Once the cold stimulus subsides, you then get blood vessel dilation and increased circulation to the surface of the skin.


The theory is that this increased blood flow brings with it more nutrients to the cells at the surface of the skin, encouraging better skin health and collagen production.


The same principles that are applied for cryofacials are at play across your whole body when you expose it all to a drop in temperature. Not only are the skin health benefits available across a greater area than just your face, but the exposure of a greater area to a drop in temperature is likely to lead to greater blood vessel constriction, and so greater dilation.

[1] https://www.mdpi.com/1660-4601/17/23/8984/htm




Weight Loss


Cold exposure has been shown to increase metabolic activity by as much as 350% in healthy individuals[1].


When you shiver in the cold, the muscle contractions increase energy metabolism and heat is produced as a byproduct. The extra heat production warms you up. However, non-shivering thermogenesis is responsible for the “fat burning” effects that cold exposure can have. This is due to the action of brown fat[2]. We’re not used to hearing about body fat in a positive context, but brown fat is very “metabolically active”: i.e. it contains more mitochondria (the powerhouses of your cells that burn calories and generate energy) and actually burns calories.


In the presence of cold exposure, brown fat increased its glucose uptake by a factor of 15[3] (the implication being that it was taking up more glucose as fuel to produce heat). Following from this, it has been suggested not only that brown fat calorie combustion may be significant for our metabolisms, but that an absence of brown fat may increase a tendency to obesity[4].


In fact, it has even been shown that there is an inverse correlation between the amount of brown fat and the percentage body fat of an individual[5]: i.e. the greater the amount of brown fat, the lower the percentage body fat. The good news is that it has also been shown that cold adaptation, as a result of repeated cold exposures can increase the amount of brown fat in humans, and increase our capacity for non-shivering thermogenesis[6].


Taken together, this suggests that cold exposure can increase your metabolism not just as a short term response to the cold, but over the long term by encouraging your body to carry more brown fat, which will then trigger more calorie burning every time your are exposed to the cold.


It has also been shown that cold exposure increases insulin sensitivity[7]. With Type 2 diabetes becoming ever more prevalent, maintaining insulin sensitivity, and doing things to improve it, is broadly beneficial.


Mental Health


A study comparing regular winter swimmers to healthy controls found that those who regularly engaged in winter swimming had significant decreases in tension, fatigue, and negative memory and mood states; while also feeling more energetic and having higher activity scores than the controls. The authors concluded that regular winter swimming induced general well-being[8].


It has been hypothesised that cold showers can treat depression[9]. Cold exposure has been shown to activate the sympathetic nervous system, increase blood levels of endorphins, and trigger the release of norepinephrine in the blood and the brain. Decreases in norepinephrine have been shown to cause depression[10]. There is further theory that the cold stimulus on the skin could send an overwhelming amount of electrical impulses to the brain that could have an anti-depressive effect[11].


Cold exposure, particularly of the face, can stimulate the vagus nerve. Vagus nerve stimulation has, in turn, been shown by Cambridge University to be an effective treatment for some individuals with chronic treatment-resistant depression[12].


From our experience at the studio, the rush of endorphins and mental clarity that come after a cryotherapy session never fail to leave clients smiling.


Pain Reduction


A study on patients with a variety of conditions (fibromyalgia, rheumatoid arthritis, chronic low back pain, ankylosing spondylitis, osteoarthritis and other autoimmune diseases) found that pain levels after the application of whole-body cryotherapy decreased significantly. It was further noted that the reduction in pain allowed for other treatments (e.g. physiotherapy) to be better tolerated[13].


For women in particular, a randomised clinical trial showed that cryotherapy was effective in reducing period pain[14].


Immunity


A study looked at the immune-modulating chemicals released in a group of habitual winter swimmers compared to a control group of inexperienced winter swimmers. The habitual swimmers were not only found to have lower levels of pro-inflammatory chemicals, but were also found to release fewer inflammatory chemicals in response to an inflammatory stimulus. The conclusion was that the winter swimming had led to beneficial adaptations in the swimmers’ immune systems[15].


It has even been hypothesised that the hormetic (i.e. “what doesn’t kill you makes you stronger”) effect of repeated cold exposures could enhance anti-tumour immunity, as it has been shown that brief cold stress can increase the numbers and activity of immune cells that target tumours[16].


Healthy winter swimmers have been found to have higher baseline levels of glutathione than controls[17]. This was seen as a positive adaption to regular oxidative stress. Glutathione is regularly referred to as the body’s “master antioxidant” and has roles both in the immune system and in detoxification.


A study on national rugby players found that sessions of whole-body cryotherapy on alternate days led to a decrease in pro-inflammatory cytokines (chemical messengers) and an increase in anti-inflammatory cytokines. They also found an improvement in recovery from, “exercise-induced muscle injury and/or damage associated with intense physical training”[18].


Another study looked at the effects of cold exposure on the immune system and found that: “acute cold exposure has immunostimulating effects”[19].


Overall, there is broad evidence that regular cold exposure leads to less inflammation and so a healthier immune response.


Cardiovascular Health


A comparison of well-adapted cold swimmers with non-adapted cold swimmers found that those who were accustomed to cold swimming had improved cardiovascular risk factors, which indicated the positive effects of cold-adaptation on cardio-protective mechanisms[20].


Joint Health


Collagenase is the enzyme that breaks down collagen. Collagen is a protein found both in skin and in the cartilage within joints. It was found that a decrease in temperature caused a decrease in the activity of collagenase[21]. This suggests that one of the benefits of cryotherapy is that it decreases the breakdown of collagen.


Neurological Health


In mice, it was shown that mice exposed to cold shock before having a neurodegenerative disease induced had more protection and maintained more synapses (connections between brain cells) than mice that had not undergone cold exposure[22]. The real cause for excitement here is that the mechanism by which the brain was protected, the activation of the cold shock protein RBM3, is conserved in humans: we have this mechanism too[23].


Although it has not yet been demonstrated in humans that cold shock could ward of neurodegenerative diseases, there is plenty of evidence for the use of cold to reduce neuroinflammation. Cooling caps are often used to reduce neuroinflammation in newborn babies.


Longevity


The effects of the cold on reducing inflammation are well-known, well-established, and it is the mechanism behind many of the the benefits listed above. Inflammation has been established as the key driver of the ageing process[24], and so reducing it, via whole body cryotherapy among other interventions, will hopefully have positive implications for the ageing process to which we are all subject.


We have seen above that cold exposure leads to increased levels of norepinephrine. This in turn has been shown to lower levels of inflammation[25].


Although the free radical theory of ageing is less popular these days, there is no doubt that maintaining a good supply of antioxidants is beneficial in reducing inflammation, and so the ageing process, as well as reducing cancer risk. The hormetic stress of whole-body cryotherapy was found to enhance the antioxidant system, doubling the activity of glutathione, “the body’s master antioxidant”, and increasing the amount of another potent antioxidant enzyme, superoxide disumutase, by around 43%[26].


Although there are not yet human studies confirming it, mouse studies indicate that cold exposure could mitigate the effects of muscle atrophy via mechanisms that would be conserved in humans.


It has been noted that brown fat levels generally decrease with age[27]. Cold exposure promotes the creation of brown fat so could be another way to mitigate the effects of ageing.



Exercise Performance


Cryotherapy’s established effects reducing inflammation mean that it has often been looked at for improving recovery after exercise. But the effects go further to actually improving performance too.


It is well-known that exercise itself initially promotes an increase in inflammation, before leading inflammation levels to decrease below baseline levels. This initial inflammatory response tends to occur about an hour after exercise. This explains some of the evidence that cold exposure, or even taking a large dose of an antioxidant, such as vitamin C, can blunt the hormetic adaptive response to exercise if done within an hour of the exercise session.


A study using whole-body cryotherapy at least one hour after exercise found both improvements in performance and reductions in pain at rest and in the next work out[28]. Another study, again using whole-body cryotherapy for 3 minutes at -110 degrees C, as we have at The Fit Partnership, found that there was enhanced muscle recovery due to a decrease in the inflammatory process and an increase in the anti-inflammatory process[29].


Beyond enhancing recovery, it has been shown that cold exposure can enhance mitochondrial biogenesis[30]: the process by which new mitochondria are created. More mitochondria per cell means greater aerobic capacity, and more energy. Failing mitochondria can be another facet of ageing, and so the potential for mitochondrial biogenesis could be another reason for those interested in longevity to explore cryotherapy.


Sleep


It has been shown in a number of studies that cold exposure increases the production of norepinephrine in the body. Among the many roles the norepinephrine plays, it has a crucial role in sleep regulation[31]. This can explain the widely reported beneficial effects of cryotherapy on sleep. In particular, one randomised controlled trial found that whole-body cryotherapy for 3 minutes improved: “subjective and objective sleep quality… and improved parasympathetic [(rest & digest)] nervous activity”[32].


Differences


We are often asked about the differences between the benefits seen from our whole-body cryotherapy unit and a traditional ice bath or cold water immersion.


A study looking at the mechanisms behind the pain-reduction from both cryotherapy and cold water swimming found that there was a: “sustained cold-induced stimulation of norepinephrine”; and that cortisol levels following the cold exposure were significantly lower after the participants had done it for a few weeks, probably due to habituation[33]. Norepinephrine is involved in reducing inflammation, regulating sleep, increasing alertness and attention, and enhancing the formation of memories. Cortisol is a hormone released in response to stress: its decrease can be indicative of reduced stress levels. Crucially, this study found no difference in the effects between those who did the cold water swimming and those who did the cryotherapy.



One randomised study compared the effects of different cryotherapies, and found that the most effective for pain reduction was whole body cryotherapy at -110 degrees C for 2-3 minutes[34], which is exactly what we have at The Fit Partnership.


On the practical level, cryotherapy is a dry cold and so is more easily tolerated by those who would not tolerate an ice bath. In addition to that, the treatment time is only three and a half minutes at most, whereas one would have to spend more time in an ice bath to see the benefits.


While it has generally been noted that regular exposure to cold water has positive effects on the cardiovascular, endocrine, and immune systems and on the psyche; it has also been noted that cold water swimming poses, “a significant health risk”, to those new to it[35]. Having to adapt to the cold water, while being in it, carries risks of drowning as well as of cardiac events.


Whereas in a cryotherapy chamber, you don’t have to worry about keeping your head above the water while you’re dealing with the cold. You’re monitored the whole time and the environment is much safer.


Finally, most people would not be able to hold their breath long enough to get the same benefits that are possible because our cryotherapy unit is whole body and does include your head. The vagus nerve in your face is connected to nerves through your body. So being able to include your face and head in the cold exposure can lead to greater systemic benefits.





For whom?


As you will have gathered, whole-body cryotherapy is a very exciting treatment with a multitude of positive effects. It can bring all the benefits of other forms of cold exposure, with far fewer health risks.


Whether you’re looking to boost your recovery from your work outs, lose weight, improve skin health, thinking more clearly, brighten your mood or you’re simply interested in promoting your longevity, cryotherapy can be a brilliant addition to your life.



To find out more about the benefits of Cryotherapy, or to book a session in our Wimbledon Cryotherapy Chamber at The FIT Partnership, contact us:



[1] https://link.springer.com/article/10.1007/s004210050065 [2] https://www.jci.org/articles/view/60433?key=5e3684aee3d55b74adc8 [3] https://www.nejm.org/doi/full/10.1056/NEJMoa0808949#t=article [4] https://www.jci.org/articles/view/60941 [5] https://pubmed.ncbi.nlm.nih.gov/19357405/ [6] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3726172/pdf/JCI68993.pdf [7] https://pubmed.ncbi.nlm.nih.gov/26147760/ [8] https://www.tandfonline.com/doi/abs/10.3402/ijch.v63i2.17700 [9] https://pubmed.ncbi.nlm.nih.gov/17993252/ [10] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3131098/ [11] https://pubmed.ncbi.nlm.nih.gov/17993252/ [12] https://www.cambridge.org/core/journals/the-british-journal-of-psychiatry/article/vagus-nerve-stimulation-in-chronic-treatmentresistant-depression/C4C5073ED6D265283D40F273F1944E25 [13] https://pubmed.ncbi.nlm.nih.gov/10832164/ [14] https://www.liebertpub.com/doi/pdf/10.1089/ther.2021.0002 [15] https://pubmed.ncbi.nlm.nih.gov/10735978/ [16] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2211456/ [17] https://doi.org/10.1016/0891-5849(94)90030-2 [18] https://www.sciencedirect.com/science/article/abs/pii/S030645650800106X [19] https://journals.physiology.org/doi/full/10.1152/jappl.1999.87.2.699 [20] https://www.sciencedirect.com/science/article/abs/pii/S0306456515300668 [21] https://www.nejm.org/doi/pdf/10.1056/NEJM197401032900101 [22] https://pubmed.ncbi.nlm.nih.gov/25607368/ [23] https://www.athletespotential.com/uploads/2/4/7/3/24730224/cold-stress.pdf [24] https://www.sciencedirect.com/science/article/pii/S2352396415300815 [25] https://pubmed.ncbi.nlm.nih.gov/1845768/ [26] https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0046352 [27] https://www.athletespotential.com/uploads/2/4/7/3/24730224/cold-stress.pdf [28] https://onlinelibrary.wiley.com/doi/full/10.1111/sms.12074 [29] https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0022748#s2 [30] https://journals.physiology.org/doi/pdf/10.1152/ajpregu.00031.2015 [31] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2812689/pdf/nihms151918.pdf [32] https://pubmed.ncbi.nlm.nih.gov/30551730/ [33] https://pubmed.ncbi.nlm.nih.gov/18382932/ [34] https://pubmed.ncbi.nlm.nih.gov/16870097/ [35] https://www.mdpi.com/1660-4601/17/23/8984/htm


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