Temperature doesn’t really seem to be a major problem for us in our modern day lives. The buildings we work in and the homes we live in are nicely temperature controlled in some form or fashion. Whether it be air conditioning in the summer or a roaring fire in the winter, we have found a way to protect ourselves from harsh weather. However, for the large majority of human existence, there was no such thing as temperature control. When winter came, people simply had to bear the harsh conditions with much less protection than we have today. Naturally, we evolved to deal with those conditions through physiological mechanisms that helped us survive. Nowadays, these mechanisms mostly lie dormant as we rarely expose ourselves to the elements. But what happens to us if we begin to tap into those mechanisms through deliberate cold exposure? We can all remember our mothers telling us to wear a jacket to avoid getting sick. Just how accurate was that motherly advice? There is an emerging body of evidence that suggests we might want to rethink the way we avoid extreme temperatures. Cold water immersion and whole body cryotherapy are beginning to gain a foothold as robust health and performance boosting activities. In fact, some of the potential benefits may just shock our well intentioned moms completely.
Health Benefits of Cryotherapy
As it turns out, there seem to be a plethora of benefits that accompany cryotherapy. From mental health benefits to improved mitochondrial health, there is a lot to get into here. So let me break it down into subsections to help you keep things organized:
One of the main physiological responses that occurs after cold exposure is a robust increase in norepinephrine. In fact, some studies show that a proper dose of cryotherapy can increase norepinephrine by 200-500% . Norepinephrine is known as a hormone that is released during the “fight or flight” response. However, this hormone has several effects in the body besides motivating us to run from danger. For starters, norepinephrine acts to increase attention and mood when it binds to receptors in the brain. For this reason, cold exposure therapy has been suggested as a potential treatment for those who suffer from depression or attention disorders . However, even if you do not suffer from one of these conditions, the increase in norepinephrine will still help you feel motivated and focused for long periods of time if cryotherapy is used often.
Other potential benefits to the brain have been discovered through mouse studies involving cryotherapy. Researchers have found that extreme cold exposure activates cold shock proteins in the body. These proteins are found in several major organs and are thought to serve a protective role. In the brain specifically, certain cold shock proteins have been found to have a neuroprotective effect by way of recovering lost synapses. Researchers found that exposing mice with neurodegenerative diseases to cold therapy early in life was effective in preventing the onset of neurodegenerative symptoms associated with the disease. Mice who were exposed to cold therapy kept over two times as many synapses and did not display behavioral or cognitive declines compared to the mice who were not exposed to cold therapy . If this same phenomenon holds true in humans (we do have the same cold shock proteins), we could see cryotherapy become preventative treatment for conditions like Alzheimer’s or traumatic brain injury.
The topic of inflammation has become a hot one in recent times given its association with health and longevity. Those who live longer and healthier lives tend to have lower levels of systemic inflammation. Additionally, many chronic diseases go hand in hand with inflammation, although it is not clear which one causes the other just yet. We have all heard the advice of putting ice on an injury in order to keep the swelling and inflammation down. So what happens when we effectively ice our whole body through cryotherapy?
Once again, norepinephrine comes to the rescue with respect to inflammation. The robust increases in this hormone act to decrease the levels of certain inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) and macrophage inflammatory protein 1 alpha (MIP-1α) . These cytokines drive inflammatory pathways related to arthritis, diabetes, and other chronic diseases. Adding to this evidence, one study found that just a few minutes of whole body cryotherapy three times a week reduced pain in patients with arthritis . Whether this relief stems from the pathways listed above we can’t be sure, but this is good evidence that cryotherapy helps to improve inflammation.
Simply put, in order for us to remain healthy, we must have a robust and effective immune system. Without our immune system, we would succumb to any number of simple illnesses such as the cold or flu. Ideally, we would like to have a large and diverse number of immune cells that mostly lie inactive unless a legitimate threat enters our body. Cryotherapy may help to quiet some of the immune cells that tend to be overactive as we saw earlier with TNF-α and MIP-1α. However, cryotherapy also seems to play a role in increasing our army of immune cells as well.
Studies have found that several forms of cryotherapy are effective at increasing certain immune cells. Chronic cold water immersion for six weeks was found to increase the number of lymphocytes in circulation . Exposure to the cold via a cold chamber also had the effect of increasing T lymphocytes and natural killer T cells . All of these immune cells play a role in fighting off diseases or eliminating cancer cells in the body. In other words, cold exposure seems to make us healthier and more resistant to illness. So although our mothers used to tell us that going out in the cold without a jacket would make us sick, the opposite might actually be true.
Performance and Cryotherapy
Interestingly, the topic of cryotherapy and performance seems to be a controversial one. You may have noticed that many professional, collegiate, and even high school teams use ice baths as a recovery strategy from hard workouts. Some people will swear by the use of cryotherapy as a helpful tool while others regard it as a waste of time. Making things even more confusing are the contradictory results that have been found in the research related to the use of cryotherapy for recovery and performance. It seems that the application of cryotherapy to sport is not a simple one. The timing of the therapy as well as the type of exercise being done may determine the nature of the effect that is seen.
When it comes to resistance training, we have rather limited evidence so far. Some studies have shown that training followed by cryotherapy is more effective for improving power development and reducing perceived measures of soreness compared to training that was not followed by cryotherapy . Additionally, one study found that the use of ice packs on active muscles between sets of resistance training lead to increased work, power, and decreased fatigue compared to the control group . However, one major study showed that 12 weeks of resistance training followed immediately by cold water immersion resulted in significantly less skeletal muscle hypertrophy, strength, and satellite cell activity compared to active recovery control .
What seems to be important here is the timing of the cold exposure therapy. The use of cryotherapy immediately after resistance training may blunt the inflammatory response that is necessary to elicit the beneficial effects of resistance training. If that is true, then perhaps waiting at least an hour between training and cryotherapy is a better strategy for preserving the effect of training while also gaining the benefits of cryotherapy.
The Aerobic System
This is the area of exercise where cryotherapy and cold water immersion seem to shine brightest. As you may know, endurance exercise is highly dependent on the amount and efficiency of skeletal muscle mitochondria. One of the major adaptations that occurs from cold exposure therapy is an increase in the protein PGC-1α . This protein is the master regulator of mitochondrial biogenesis. So, by increasing the expression of PGC-1α, cryotherapy causes an increase in mitochondria in the muscle. This should theoretically lead to an increase in aerobic capacity during exercise. Looking at the evidence for cryotherapy as it pertains to performance enhancements, it has been shown in several populations that post exercise cryotherapy induces greater adaptations in power, work capacity, and recovery from endurance type exercise .
If you’re a strength fanatic, you may be tempted to swear off cryotherapy for its endurance promoting effects. Indeed, increasing mitochondria in the muscle tissue tends to signal a shift from type IIx fibers (powerful) toward type I fibers (slow, oxidative). However, it is also useful to think of this from a recovery aspect. An increase in aerobic capacity will lead to greater recovery ability as well. Not only will you recover more quickly between sets, but you will also recover more quickly between training sessions. In fact, it has been shown that HRV is improved by cryotherapy by way of increasing parasympathetic tone in the nervous system . HRV is a measure of nervous system recovery that many use to determine how well a person is recovering from a given exercise stimulus. So while it is possible that you could lose some fast twitch fibers, the trade-off still seems to favor those who train for strength.
The evidence for the use of some form of cryotherapy for health and longevity seems to be mounting. Certainly, it would make sense that these effects are hard wired inside our DNA given our ancestors inevitable exposure to cold many years ago, but it is rather surprising that such robust health benefits could be had from cryotherapy. Furthermore, the evidence for performance benefits seems to be positive as well. It is possible that some of the performance adaptations come about through the same mechanisms which produce the health benefits we see. At the end of the day though, benefits are benefits. It certainly seems that the aerobic system stands to gain the most from cryotherapy given the direct impact on mitochondria. However, those studies that separated the cryotherapy and resistance training by an adequate amount of time did see some benefit. At the very least, careful application of cryotherapy will bring a major boost to health and aerobic capacity while preserving or slightly enhancing strength training adaptations as well.
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