Cryo comes from the Greek word cryo, or (κρύο), and means cold. Cryotherapy refers to any form of medical treatment that relies on the application of cold temperatures. Whole Body Cryotherapy (WBC) is most commonly utilized in the field of sports medicine as a mode of muscle recovery and pain relief.
However, it has recently gained notoriety for its use in the treatment of eczema, depression, and anxiety, and even in the prevention of symptoms of multiple sclerosis. The focus of this article will be on the benefits and limitations of entering the extremely cold environment of the cryo chamber.
What Is Whole Body Cryotherapy?
Whole Body Cryotherapy (WBC) involves immersing the body in a cold chamber, which emits vapors that reach extremely low temperatures ranging from -110℃ to -160 ℃ (around -160℉ to -220℉). This is usually done for an interval of 2 to 4 minutes [1, 2].
When in the cryogenic chamber, individuals are undressed with the exception of underwear, socks, and gloves to protect the extremities .
What Is a Cryo-chamber?
The cryo-chamber is an individual, tube-shaped enclosure that covers a person’s body with an open top to keep the head at room temperature. The frigid environment is generated by the emission of cool air, but some cryogenic chambers generate these temperatures by forced convection, which involves pumping the cool air from an external circuit [4, 4].
Mechanism of Action
The fundamental change in the body caused by whole body cryotherapy is the reduction of tissue temperature .
The change in tissue temperature also causes a reduction in core body temperature. This sensory shock leads to an activation of the autonomic, or unconscious, nervous system. This is characterized by rising norepinephrine levels, increased blood pressure, and heart rate variability [6, 7].
When the body is exposed to extreme cooling, the blood vessels are constricted and reduce blood flow to the areas of inflammation. Once outside of the cryogenic chamber, the vessels expand, and an increased presence of anti-inflammatory proteins (IL-10) are found in the blood [8, 9].
In a randomized crossover study, 11 athletes performed better on a protocol test before and after a run. The improvement was supported by lower heart rates, oxygen consumption, and rates of perceived exertion. This recovery is presumed to be a result of more oxygen for the working muscles and less strain on the heart and veins .
A within-subject control study showed that ankle-localized cryotherapy in 23 participants leads to slower conduction of nerve signals in the treatment site. It can also lead to improvements in pain threshold and tolerance .
Health Benefits of Cryotherapy & Side Effects
1) Exercise Recovery
Studies have shown varying results on the effectiveness of whole-body cryotherapy in muscle recovery and healing.
In a randomized crossover trial of 11 athletes, those athletes who engaged in cryotherapy performed better on an exercise test, indicating quicker muscle regeneration. In addition, WBC increased blood-oxygen levels in the thigh and decreased heart rate and perceived exertion .
In a randomized trial, 9 trained runners regained maximal muscle strength and sensation post-high-endurance exercise after the first cryo chamber session. In comparison to far infrared and passive methods, the cold chamber provided the most effective recovery .
However, a randomized crossover study of 14 soccer athletes found no indicators of improvement after a single session in the cryo chamber .
A randomized crossover study monitored for signs of overtraining in 10 elite swimmers that performed WBC daily during 2 weeks of intensified training. Those in the cryogenic chamber group presented better sleep patterns, less fatigue, and increased exercise capacity .
In another randomized trial, 64 young adults (60 of whom were male) tried various recovery methods, including whole body cryotherapy, passive recovery, and cold-water immersion. After the uniform exercise routine, the study found very low-quality evidence for a reduction in muscle soreness and pain sensation within the WBC group .
In another randomized study, 36 subjects were analyzed for muscular force, extension, and soreness in their left knee after performing an exercise routine the day before and engaging in 2 cold chamber sessions. However, there was no measured improvement in knee function or in muscle soreness .
2) Reduces Inflammation
In 3 randomized control studies, ranging from 10 to 45 subjects, cryogenic chamber treatment increased the presence of anti-inflammatory proteins (cytokines IL-6, IL-10, and IL-1ra). It also decreased pro-inflammatory cytokine (protein) levels(IL-1α). These changes lasted longer for those who completed more cold chamber sessions [8, 19, 20].
In a controlled laboratory study, 12 athletes were treated with whole-body cryostimulation. A reduction in inflammatory proteins (tumor necrosis factor α) and improvements in tennis strokes were recorded amongst the cryotherapy group .
WBC treatment increased the number of anti-inflammatory cytokines (IL-1Ra and IL-10), while pro-inflammatory cytokines (IL-1β and CRP) decreased in randomized crossover studies following 11 and 18 young athletes. This protein profile in combination with restricted blood flow helped reduce exercise-induced inflammation [22, 23].
Another controlled study examined the effects of WBC prior to exercise. These 18 athletes also showed a decreased presence of pro-inflammatory proteins (IL-1β in the blood after exercise .
Reduced inflammation allows for a faster return to the high-intensity physical activity that would otherwise require more recovery time. Prolonged inflammation can lead to impaired blood flow, increased pain, and less mobility .
3) Rheumatic Diseases
Rheumatic diseases refer to conditions that cause chronic pain in joints and muscles, the most well-known of which is rheumatoid arthritis.
In a controlled study of 64 women with rheumatoid arthritis, cryo chamber treatment reduced pain, and improved mobility, well-being, and functional impairment. These results lasted for 3 months after rehabilitation .
In a randomized control trial, 60 patients with rheumatoid arthritis were assigned to groups of WBC at -110℃, WBC at -60℃, localized cold air application at -30℃, and cold pack application. Pain decreased in all subjects but decreased most in those who underwent cryo chamber therapy .
Another controlled study of 44 participants found equally positive recovery markers for 25 patients who did WBC. Regardless of the recovery track (WBC versus traditional rehab), both groups showed similar improvement in pain relief, fatigue, disease activity, and degree of inflammation .
In a pilot study of 50 participants with different forms of arthritis, cryo chamber treatment reduced pain and the need for medication. Additionally, well-being and mobility of the patients improved .
WBC significantly reduced pain and disease activity in a prospective and pilot study of patients of 60 and 10 participants, respectively, with varying rheumatic disorders. Patients also had higher functionality in their joints, and pain reduction lasting up to 2 months (especially in women) [30, 31].
Ankylosing Spondylitis (AS) is arthritis in the spine .
Two controlled studies assessed the effectiveness of the cryo chamber in comparison to normal physical therapy techniques in AS patients. The results show significant improvements in mobility assessments and disease activity [33, 34, 35].
A review of all WBC treatments of rheumatic diseases indicates that cryo chambers should be used as a supplement to prescribed treatment measures, such as corticosteroid and nonsteroidal anti-inflammatory medication .
4) Reduces Pain
Participants were monitored for performance recovery and pain sensation with and without cryo chamber treatment after a hamstring-focused exercise in a controlled crossover study. There was an improvement in pain relief after cryosauna treatment during the 5-day period. However, the results are not wholly supportive of its use as recovery enhancement .
In a study of 42 participants (21 males and 21 females) with lower back pain, participants engaged in cryogenic chamber treatment in conjunction with physical therapy exercises. Pain sensation and spinal mobility improved, but only in the male group .
In a randomized trial, 80 elderly men with chronic back pain were split into 2 groups: WBC twice a week and WBC treatment every day throughout the week. The study showed that those receiving consistent cryogenic chamber treatment led to a more significant reduction in pain sensation over a 3-month period .
A controlled study following 96 elderly men with chronic back pain issues split participants between a pre-exercise WBC group and only exercise control group. After the 3-month period, the cryo chamber group experienced a significant increase in spine mobility and range of motion .
5) Frozen Shoulder
Frozen shoulder (adhesive capsulitis) is a painful syndrome that restricts shoulder mobility, characterized by stiffness .
In a randomized study, 30 individuals with adhesive capsulitis engaged in either physical therapy treatment or standard therapy in conjunction with cryogenic chamber treatment. There was a significant improvement in shoulder mobility, rotation, and functionality in the whole body cryotherapy group .
6) Reduces Oxidative Stress
In a randomized control study of 32 healthy males multiple studies, cryo chamber treatment decreased most of the criteria indicating oxidative stress and increased the presence of antioxidants in the blood .
In a longitudinal study, 30 healthy males engaged in daily WBC treatment while concentrations of important antioxidant components in blood cells were measured. After 20 treatments, there was an increase in superoxide dismutase. However, there was also a decrease in glutathione and GPx activity, which assists in breaking down harmful free radicals .
One crossover study involving 9 kayaker women found that antioxidant activity is higher when cryogenic treatment occurs after training, compared to exercise alone .
7) Multiple Sclerosis
- Weak muscles, fatigue, and painful spasms
- Numbness and dizziness
- Mood changes and depression
Two within-subject studies following between 20 to 28 patients diagnosed with MS were treated with 10 exposures in the cold chamber. Cryosauna treatment significantly reduced oxidative stress [46, 47].
In a within-subject study of 48 MS patients with fatigue, 10 cryogenic chamber sessions improved functional status and fatigue levels. Those with higher fatigue levels experienced a more significant change .
Two controlled studies with 24 to 44 participants showed that the cryogenic chamber improved MS patients’ exercise ability and duration of activity. In addition, it improved the functional status for over 1 to 3 months in those with secondary-progressive MS, which is characterized by worsening disability with little possibility of recovery [49, 50].
8) Boosts the Immune System
In a longitudinal study of 15 active young men, 10 sessions of whole-body cryotherapy increased white blood cell count (especially lymphocytes and monocytes) and Interleukin-6, a protein that has both pro and anti-inflammatory effects .
9) Increases Energy Capacity for Exercise
In a longitudinal study, the effects of 10 sessions of whole-body cryotherapy on the aerobic and anaerobic capacity of 30 subjects were examined. Although the study did not find any change in aerobic capacity after treatment, there was a marked increase in anaerobic capacity amongst male participants .
10) Reduces Anxiety and Depression
Studies have also been carried out to assess the ability of whole body cryotherapy to heal psychological strain.
In a preliminary study, 23 individuals (ages 37 to 70) suffering from depression were monitored for depressive symptoms after 10 sessions of cryo-chamber treatment while continuing their prescribed medication plan. WBC treatment led to lower overall scores and scores in each symptom of the Hamilton Depression Rating Scale, except for day-night mood fluctuations .
According to a longitudinal study of 55 patients (43 women, 12 men) with spinal pain disorder or joint pain issues, 10 sessions in the cryosauna increased well-being and quality of life. Interestingly, the worse the mental state of the patient prior to the study, the more effective the treatment .
Fibromyalgia is a disorder that can lead to amplified pain sensations in both the muscles and bones, leading to fatigue and difficulty sleeping.
In a controlled study, 100 patients with fibromyalgia continued routine medication plans, while half were treated with a cold chamber session. The whole body cryotherapy group reported significant improvements in quality of life scale assessments measured by World Health Organization Quality of Life questionnaire and the Psychological General Well-Being Index .
Another controlled study examining 11 patients with fibromyalgia reported similar improvements in quality of life, lasting for at least 1 month after treatment .
12) Heart Health
A randomized study of 30 healthy male subjects showed that WBC decreases resting heart rate and cardiac output while increasing the stroke volume (more blood pumped per beat). Additionally, receptors controlling blood pressure (baroreceptors) immediately increased activity and later dropped, indicating a balanced blood pressure after the initial increase .
Two controlled studies following 20 and 45 participants showed that cryo chamber treatment increases norepinephrine (a stress response hormone and neurotransmitter) levels. This indicates the activation of the autonomic nervous system (controlling heart function) in response to extreme temperatures [7, 60].
13) Improves Eczema (Atopic Dermatitis)
In a within-subject study of 18 patients with eczema, WBC led to reduced dermatitis and water loss from the skin. Women showed more improvement than men. It must be noted that 1 patient stopped due to a worsening condition .
14) Restless Leg Syndrome
A randomized pilot study followed 35 patients with restless leg syndrome and examined the effect of a cold chamber and local cryotherapy treatment on symptoms and quality of life. Whole body cryotherapy, in comparison to localized cryotherapy, at -60℃ led to the most significant improvements in symptoms and quality of life .
There is no clinical evidence of the cryogenic chamber as a treatment method of dementia; however, there is a proposed strategy to use WBC to prevent the cognitive impairment that can lead to dementia and Alzheimer’s disease. Due to its anti-inflammatory and antioxidative properties, WBC could possibly halt the development of symptoms years before incidence [63, 43, 19].
In a randomized control trial, 55 participants with severe migraines were either treated with ice wraps around the neck or none at all. A major cause of migraines is the expansion of blood vessels in the neck, and cooling helps constrict blood vessels. The wraps significantly decreased pain. This example of localized cryotherapy shows the potential of WBC to treat such headaches .
Tinnitus is known as ‘ringing in the ears’ and is a symptom of other conditions, such as ear injury and loss of hearing.
In one study, 80 patients with tinnitus were exposed to the cryo chamber. In 4 patients, cryotherapy completely eliminated their tinnitus, whereas 47 reported a decrease in intensity, 13 reported no change, and 16 reported an intensified ringing. There was a measured decrease in average hearing loss and hearing damage in the group .
Cryotherapy and Weight Loss or Cryotherapy and Body Fat
A within-subject study explored the changes in the body composition in 18 participants after a single exposure in the cryosauna. After the cold exposure, the decrease in skin and core temperature was correlated with an increase in body fat percentage in all participants, and body mass index in male participants only .
Blood Pressure and Heart Function
In a within-subject study following 25 young male participants, cryo chamber treatment increased blood pressure immediately after each session and decreased heart rate .
A controlled study followed 23 subjects from the ages of 35 to 69 with varying levels of blood pressure. After 21 cryo chamber sessions, a significant rise in blood pressure was recorded. Although there were no long-term effects in either study, it is suggested that patients who have a heart condition or issues with blood pressure should be cautious with cold chamber exposure .
A within-subject study followed 39 WBC participants, 13 of whom had untreated hypertension. WBC caused strong cardiovascular changes in both groups, but adaptations after were inconsistent. The disparity suggests to caution against WBC for those with cardiovascular conditions .
There is a case of a 56-year-old patient who experienced a stomach aortic dissection( tear to the inner wall of the main artery pumping blood to the lower body) after 15 cold chamber sessions. Given no previous history of heart complications and the understood effects of extreme cold on the heart and blood flow, this case could be considered a complication of cryotherapy .
Twenty-five non-smoking young men engaged in 3 months of WBC while measuring their lung function (via peak speed of exhalation, known as peak expiratory flow rate). There was a visible decrease in the rate immediately after treatment that became more significant over the next 3 months. WBC may cause minor constrictions in these pathways and should be used with caution .
Transient Global Amnesia
Transient global amnesia is characterized by a brief loss of memory of the recent past (although it can also affect long-term memory) that lasts no more than 24 hours .
A 63-year-old male experienced a case of transient global amnesia after engaging in whole-body cryotherapy. Although the man fully recovered, this case illustrates there are insufficient studies and presents the possible risk of cryotherapy on cognitive function .
Different Types of Cryotherapy
Cryotherapy generally refers to the application of cold temperatures on the body for therapeutic treatment. Cryotherapy can be used in dermatology treatment, surgery, and even refers to ice bath immersion and ice pack application to combat muscle soreness [73, 27].
Localized cryotherapy also produces a significant decrease in inflammation in other parts of the body, such as the mouth and lips .
Limitations of Whole-Body Cryotherapy
Although whole-body cryotherapy presents the largest temperature gradient, its ability to cool the body is compromised by air’s poor conduction ability .
For instance, one randomized crossover study following 10 patients found that cold-water immersion led to greater reductions in the skin, deep tissue, and core temperature in comparison to whole-body cryotherapy .
Another randomized controlled crossover study following 10 patients found that whole-body cryotherapy immediately led to lower recorded skin and tissue temperatures in comparison to cold water immersion (CWI). However, the average skin and tissue temperatures were lower more consistently and for a longer period after treatment .
However, another study states that the cold chamber and cold-water immersion lead to remarkably similar reductions in both muscle and core temperature readings. Additionally, whole body cryotherapy lowered skin temperature more significantly than cold water immersion .
Studies also found that cryo chamber treatment leads to a lower recorded body and skin temperature in female participants in comparison to males. However, men recorded greater increases in blood pressure after exposure in comparison to women .
Cryotherapy and Exercise Recovery
In a randomized crossover study comparing whole body cryotherapy and cold water immersion (CWI), 10 active men performed an exercise routine and their recovery was monitored. The CWI group showed moderately greater leg strength and performance recovery, in addition to improvements in soreness and perceived recovery .
When considering the use of cryotherapy, it is important to understand the distinction between subjective recovery and functional recovery. In a 2014 review, it was found that cryotherapy led to a reduction in pain and soreness (subjective sensations), but produced little evidence in actually repairing the tissue (functional) .
A 2015 Cochrane review considered the experimental guidelines, study groups, and collected evidence from major whole body cryotherapy studies. The review found that there is insufficient evidence in its effects on decreasing muscle pain and soreness. It also criticizes the lack of focus on female subjects or elite athletes in these studies .
However, studies support the anti-inflammatory and pain-relieving qualities of whole body cryotherapy. The degree of cooling depends on the percentage of fat mass and starting fitness level of subjects, indicating that the use and effectiveness of whole-body cryotherapy will differ from person to person [12, 84].
Drug Interactions – How, Where, and How Often & User Experiences
No studies explored the interaction of WBC and specific medication.
How, Where, and How Often
Whole-body cryotherapy must always be performed under careful supervision. Be sure to wear underwear, socks, and a headband. Never enter the chamber with any wet clothing – even sweat can lead to frostbite .
A randomized crossover study involving 14 athletes found that the optimum time for each session to be around 2 minutes. Anything less will not be enough to induce the biological changes associated with body cooling .
When left alone in the tank for too long, one can lose the ability to breathe and become debilitated. In one case, a woman entered the cryosauna alone and died from the overexposure.
It is important to take precautions before entering the cryo chamber. A randomized crossover study following 14 athletes advised prior screening because of the incidence of skin damage in one of the participants. Also, a review states that the WBC-induced increase in blood pressure is a reason for prior screening, especially for those suffering from cardiovascular disorders [86, 12, 68].
Some users have shared that whole body cryotherapy is effective in managing chronic pain issues, such as rheumatoid arthritis. The ability to overcome the pain in the long term was described to increase with each session. Users have also described the treatment as revitalizing, aiding in sleep and providing energy throughout the day.
Other users have provided cautionary tales of the cold chamber. Some patients reported exaggerated pain sensations after exposure to extreme temperatures.
Others state that the shock of sub-Arctic temperatures is almost unbearable. Another point of criticism was the difference in price and accessibility in comparison to an ice bath or ice packs, which can provide similar results.
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