Introduction
Cryotherapy was conceptualised in physical medicine for athlete recovery, sports performance improvement and in the healing of inflammatory and muscular pathologies. As the science around metabolic health, exercise and wellness continues to progress, it has found many other applications. Cryotherapy literally means cold therapy. Let’s examine some of the types, applications, benefits and risks of cryotherapy.
What is cryotherapy?
According to Pharmaceutical Journal, cold analgesia or cryotherapy is defined as the ‘local or general use of low temperatures (close to or below freezing) in medical therapy, or the removal of heat from a body part to relieve pain’. Essentially, the reduction of temperature in one part of the body or throughout the body can have many uses.
In the process of cryotherapy, a medical professional or healthcare provider applies extremely cold air with the aid of liquid nitrogen or argon gas to abnormal tissue. The cells are unable to survive the harsh temperatures and perish. This extreme cooling technique has now also begun to be used on the entire body as a form of treatment. Proponents of cryotherapy suggest that it stimulates the body’s natural healing abilities and provides many benefits apart from just pain relief.
The impact of cryotherapy is reliant on the duration, method, cold temperature and the depth of the subcutaneous fat.
Types of cryotherapy
There are two major types of cryotherapy—topical or local cryotherapy, which is applied to a particular part of the body; and whole-body cryotherapy (WBC), which is the therapeutic application of extremely cold dry air, usually below -100°C.
There are many forms of local cryotherapy—the most common ones include ice packs, topical cooling gels and freeze sprays. Other forms of local cryotherapy are cryotherapy facials, which apply cold to the face only, or cryotherapy ‘wands’, which target specific areas, such as a painful joint.
WBC, on the other hand, cools the entire body and is most commonly used in physical therapy, athletic training or holistic medicine. Ice massages, ice baths or cold whirlpools are methods that can provide cryotherapy to the entire body. However, the most popular form of WBC involves sitting in a cryotherapy booth or cryo-chamber for 3–5 minutes, where extremely cold, dry air between -100°C and -140°C drastically reduces the body temperature. This extreme cold induces responses in the circulatory system, muscular tissue and the nervous system. WBC began in Japan but has developed in Europe and the United States after a number of clinical studies have shed light on its various benefits.
Benefits of cryotherapy
Ice has been used as a form of pain relief for many generations, and is a commonly used clinical intervention, particularly for injuries and reducing inflammation and pain. Though plenty of research supports the claim that cryotherapy offers similar benefits, there are also a number of other health advantages, particularly related to WBC, that are still being researched or show promising results.
Cryotherapy and pain relief
The most popular application of cryotherapy has been in treating various kinds of pain, such as muscle pain, athletic injuries, fibromyalgia, multiple sclerosis, and so on. There are a number of ways in which cryotherapy reduces pain—it effectively acts as local anaesthesia, by reducing swelling, nerve conduction and blood flow.
Cold causes vasoconstriction, or the narrowing of blood vessels, which results in decreased tissue blood flow, and reduces tissue metabolism, oxygen utilization, inflammation and muscle spasms. It helps to avert swelling and bleeding.
The constriction of blood vessels increases blood pressure as the blood vessels try to trap heat due to the sudden reduction in temperature. This is followed by vasodilation (the dilatation of blood vessels, which decreases blood pressure) a few minutes after cold application. The alternating processes are referred to as the Lewis reaction, which is accompanied by a release of neurotransmitters from the sympathetic nerves that can facilitate improved healing.
In addition to pain relief for injuries, cryotherapy has also proven to be effective in treating chronic conditions like migraine and rheumatoid arthritis. A study found that a wrap containing ice packs applied to carotid arteries in the neck significantly reduced the pain from a migraine, by numbing the nerves in the neck and cooling the blood passing through the intracranial vessels. Various other studies have also found that WBC was effective in significantly relieving pain symptoms for people suffering from rheumatoid arthritis, osteoarthritis and chronic lower-back pain, as well as helping with faster rehabilitation for people with those conditions or acute injuries.
Many athletes are known to use cryotherapy to lessen delayed onset muscle soreness (DOMS) and to enhance faster muscle recovery.
Cryotherapy and cancer
Because it helps with reducing inflammation, cryotherapy has also been reported to lower the incidence of chronic inflammatory diseases, including cancer. Research in rats has suggested that because cryotherapy reduces inflammation throughout the body and can also reduce oxidative stress, it may be an effective tool in the prevention of cancer. More research is being done on the ways in which WBC can prevent cancer, and how it can also be used as a tool to fight precancerous cells or certain types of tumours.
Targeted, localized cryotherapy, which is also referred to as cryosurgery in medical contexts, has been used as a form of treatment for cancer. It works by freezing cancerous cells and surrounding them with ice crystals, to destroy the damaged tissue. It’s currently used as a way to treat tumours for certain types of cancer, including cancer of the prostate, liver, skin and cervix. In most of these instances, particularly in the cases of prostate and cervical cancer, results of studies using cryotherapy have suggested it is an extremely effective way to combat or remove tumours.
Cryotherapy and mental health
The extremely cold temperatures in WBC have been shown to create physiological and hormonal responses. Amongst these, the release of adrenaline, noradrenaline and endorphins can have effects beyond mere pain relief, and help alleviate certain negative moods. One study showed that WBC was actually effective in short-term treatment for both anxiety and depression, with over 46 per cent of patients reporting great improvements in their symptoms or moods.
Apart from these disorders, it has also been posited that WBC may address illnesses such as Alzheimer’s or other forms of dementia since cryotherapy has demonstrated anti-oxidative and anti-inflammatory effects, which could combat the high levels of oxidative stress and inflammatory response that occurs in Alzheimer’s patients. While more research is required to evaluate the effectiveness of this strategy, the results of studies have been promising in terms of increasing total antioxidant levels and reducing the levels of markers that are known to lead to Alzheimer’s and dementia.
Cryotherapy and blood pressure
Since cryotherapy, particularly WBC, leads to marked improvements in circulation, and the alternating of vasoconstriction and vasodilation that occurs after cryotherapy has been shown to improve blood flow, there also exists a link between cryotherapy and blood pressure. Because the cold reaction forces blood vessels to dilate and expand, the work required by the heart is reduced and high blood pressure could reduce over time.
In a 2004 study, the blood pressure responses to an acute and long-term (three-month-long) WBC were measured in men and women. Acute cold exposure increased both systolic and diastolic blood pressures temporarily. However, the amount of C-reactive protein in the blood was reduced in both acute and long-term cryotherapy. C-reactive protein is a marker of inflammation, and lower levels are correlated with lower cholesterol plaque and blood pressure. Cryotherapy has also been linked to reduced inflammation and weight loss, both of which can reduce blood pressure.
Cryotherapy and glucose
Cryotherapy can also play a role in the regulation of blood glucose. A 2014 study in Diabetes journal exposed participants to increasingly cold temperatures and then increasingly warmer temperatures every night for 4 months. It was found that this exposure can make your brown adipose tissue (BAT, a type of tissue that can burn white fat and increase the metabolic rate without glucose) more responsive to these temperature changes and help your body become better at processing glucose.
Another study found that WBC over repeated sessions ‘had a positive effect on glucose homeostasis’, reporting lower blood glucose concentrations and lower levels of insulin. Cryotherapy has also been found to release adiponectin (a hormone that breaks down fat and conveys glucose to the muscles), which can lead to lower blood sugar. Similarly, cold exposure has been found to increase BAT in individuals.
Cryotherapy has been reported to reduce oxidative stress and improve sleep quality, both of which impact the regulation of blood sugar.
Cryotherapy and weight loss
Though it has been found that exposure to extreme cold leads to a spike in metabolism, some studies have found no significant lasting change in body composition. Others suggest that the benefits of cryotherapy, such as recovery from injury or improved glucose regulation ( by helping the body digest sugars which would otherwise be stored as body fat) can eventually lead to weight loss.
A 2013 study in the Journal of Clinical Investigation found that daily exposure to cold temperatures (below 17°C) for 2 hours a day over 6 weeks reduced total body fat by about 2 per cent. A 2018 study in the Journal of Obesity found that long-term cryotherapy activates a process in the body called cold-induced thermogenesis. This led to an overall loss of body mass particularly around the waist by an average of 3 per cent.
One factor which is agreed upon is the impact of cold on BAT, which, as discussed above, burns fat to help make energy when the body is exposed to extreme cold.
Other research supports the idea that cryotherapy works best when it’s combined with other strategies for weight loss, such as exercise, particularly since it helps with recovery of the muscles or improved healing after injury.
Cryotherapy has also been found to be effective in the treatment of certain skin conditions such as eczema, atopic dermatitis and the removal of warts.
Side effects and risks of cryotherapy
Like any treatment, cryotherapy has its risks and should be used with caution. Since it deals with extremely low temperatures, WBC, specifically, must be utilized very carefully.
The most frequent side effects of any type of cryotherapy are numbness, tingling, inhibited muscle function and irritation of the skin. These side effects are usually temporary. But if you’re not careful, cold therapy applied for a long period can result in skin, tissue or nerve damage.
Although there are claims that cryotherapy can lead to people catching a cold, there is limited evidence of this. The immediate impact consequently leads to a raising of the internal body temperature for a short period, and cryotherapy has also been shown to improve overall immune functioning.
One should be careful to never apply cryotherapy for longer than the recommended period or fall asleep while applying cold. WBC should rarely be done for more than 3–4 minutes. Ignoring this precaution can result in frostbite, tachycardia or other severe conditions.
If one has certain conditions, such as cardiovascular or heart disease, diabetes, circulation or nervous system disorders, it is important to consult your doctor before using cold therapy. Usually, cryotherapy is not recommended for people with these conditions because it may exacerbate nerve damage or have effects that can compromise patient safety.
Conclusion
Cryotherapy, particularly WBC, is a relatively modern treatment that is still being researched. Using cold therapy for pain relief has been found to be effective in many situations. Research suggests that cryotherapy has positive effects on glucose regulation, blood pressure control and inflammation reduction. It has also found some applications in the field of cancer and mental health. Although the link between cryotherapy and weight loss is still being researched, the signs are promising, especially when used in conjunction with exercise. However, it is important to be aware of the risks and potential side effects of cryotherapy, especially if you suffer from cardiovascular or nervous system conditions.
Disclaimer: The contents of this article are for general information and educational purposes only. It neither provides any medical advice nor intends to substitute professional medical opinion on the treatment, diagnosis, prevention or alleviation of any disease, disorder or disability. Always consult with your doctor or qualified healthcare professional about your health condition and/or concerns and before undertaking a new healthcare regimen including making any dietary or lifestyle changes.
References
- https://www.medicalnewstoday.com/articles/319740
- https://www.healthline.com/health/cryotherapy-benefits#benefits
- https://my.clevelandclinic.org/health/treatments/21099-cryotherapy
- https://pharmaceutical-journal.com/article/ld/thermotherapy-and-cryotherapy
- https://www.nature.com/articles/s41598-021-86430-9
