Cryotherapy: What Works and What Doesn’t
A recent email from a fan asks, “What is your take on the benefits or consequences of cryotherapy?” That’s a very broad question since the word cryotherapy is a non-descript term, like “oxygen therapy.” Cryotherapy is a type of proven medical treatment, but it’s limited to a very narrow set of applications and there are uses of that term that have a much shakier foundation. The term describes a myriad of questionable practices; some are built upon plausible mechanisms that lack a clear scientific foundation, and some are out-and-out chicanery. As such, the word derives its practical meaning from the methods and the purpose of the treatment. So let’s take a look at some of the common uses of the term and try to tease out the science vs the sham.
In science-based medicine, the word cryotherapy usually refers to a surgical procedure called cryoablation. Cryoablation is the use of extreme cold in surgery to destroy abnormal or diseased tissue. It is typically used to treat benign and cancerous lesions through cellular destruction. Usually this is done using a variety of gases, sometimes cold laser.
Although the biology underlying tissue injury by freezing is complex and incompletely understood, we know the rapid development of intracellular ice crystals produces shearing and rupture of cell membranes, organelles, and the cytoskeleton. Tissue damage also occurs because ice crystallization extracts free water from the intracellular solutes, resulting in protein denaturation. These complex mechanisms of cell death are further enhanced by damage to the microvascular circulation, which results in secondary anoxia and hemorrhagic necrosis. The two parameters that correlate best with the magnitude of cell destruction are the lowest temperature achieved and the rate of cooling during freezing. Cell death requires temperatures lower than -20ºC, but temperatures as low as -40ºC may be necessary to ensure complete freezing of the intracellular compartment. Many cryoablation techniques use proprietary and formulary gas mixes. Most include liquid nitrogen, but not all. You can buy cryoablation kits over the counter in the US for wart removal (those formulations do not include liquid nitrogen).
Another cryotherapy is used to treat heatstroke, especially in children, by a method called evaporative cooling. In that process, ice packs are applied to the neck, axilla, and groin and room-temperature intravenous normal saline may be administered to patients as a complementary treatment. Cold water immersion is another adjunctive cooling modality when evaporative cooling with or without selective ice application is not possible. Treatments of this type that are effective for children may be less successful for adults. In adults, cooling methods such as cooling blankets, covering patients in ice, covering patients with a wet sheet while fanning, or selective application of ice packs to the neck, axillae, and groin have very low to negligible cooling effect. This is due to the relative surface area verses body mass problem. Younger children have a higher surface area to mass ratio, resulting in a greater rate of heat/cooling absorption.
The most common medical use for cryotherapy is very low tech and is very common. Icing is an effective symptom reliever for a variety of pain-related issues—everything from muscle pain and sprains to postoperative swelling. Superficial icing can cool the dermal tissue and induce a restriction of blood flow. Additionally it provides a pain-numbing-and-distraction effect in your pain receptors. Essentially in all cases of cold applications you are helping the affected area by reducing swelling and distracting you from the pain while you heal. It does not directly stimulate any healing process and is not a curative treatment. It’s a symptomatic treatment, like taking acetaminophen.
Although any medical treatment involving cold is in-fact “cryotherapy,” this does not mean all forms of cryotherapy are a medical treatment. The term cryotherapy sounds science-y and futuristic but it is a very featureless description. The combination of science sounding terms plus imprecise meaning makes it a pseudoscience bonanza. Similar to the oft-abused physics term “quantum,” using the word cryotherapy gives the aura of scientific treatment. The sham uses of cryotherapy go far beyond any medical science or any plausible medical benefit. Internet searches for the term produce a multitude of expensive and useless treatments bearing the name cryotherapy. The most egregious one, in my opinion, is “Whole Body Cryotherapy” AKA cryosauna.
The Cryosauna (also called a cryochamber) is a device used in therapeutic treatment with cold, commonly called whole-body cryotherapy (WBC). The cryosauna is exactly what it sounds like: a cold sauna. It’s expensive, with an average cost of $70.00 per treatment. Each different type has its own marketing, but all of them use essentially the same method. Wikipedia gives this description of the device:
The cryosauna reduces outer skin temperature from 32.5 °C to +5 – +12 °C in 60 seconds or less maintaining it at this level for up to 3 minutes. … Its main purpose lies in strengthening the immune system of the human body. Cryotherapy stimulates the immune system and induces processes for recovery in the body.
Wikipedia shares other common claims about the cryosauna:
Cryotherapy is popular in sports medicine and physiotherapy. Sportsmen undertake cryotherapy procedures in order to increase their chances for faster recovery from injuries. The beauty and cosmetics industries are using cryotherapy to improve blood-circulation, to make skin look and feel healthier, to fight age-related deficiencies and for the removal of toxins from the body. In medicine, cryogenic chamber procedures are expected to help to recover after illness or surgery, help to treat skin diseases, help to increase general improvement of health during various diseases.
As Skeptoid fans well know the term “strengthening the immune system” is almost always a red flag for pseudoscience. Here are some other examples of other marginally factual claims from a spa advertisement:
This modality was first utilized in Japan in 1978 to treat rheumatoid arthritis. Studies conducted over the last two decades have established WBC as a powerful treatment for inflammatory disorders and injuries. … WBC boosts the body’s metabolic rate, accelerating weight loss outcomes. Professional athletes have discovered WBC as a powerful treatment to decrease recovery time and increase athletic performance.
Or, from another promotional site:
Whole Body Cryotherapy stimulates the body’s natural healing abilities. WBC uses Extreme Cold to induce responses on Three Levels: the Circulatory System, the Energy Meridians and the Nervous System. There is no other therapy known to elicit such a powerful, positive and holistic response. [sic]
Anything that talks about energy meridians is pseudoscientific nonsense. When that statement is included in marketing claims it is a very bad sign. When marketers have to reach for magic to make their arguments it is synonymous with useless. I have reviewed the extensive “research” on multiple sites related to this “treatment.” All of the research has a similar theme and/or flaw. I will take the claims in order of plausibility.
Could WBC decrease recovery time and improve performance? Sure, it’s possible, even reasonable, to assume that it can improve performance. There is plenty of solid research surrounding athlete recovery time and icing. Research related to WBC found the treatment to be just as effective as an ice bath or swimming in cold water. What was demonstrably lacking from the research was anything showing a superior effect over conventional recovery methods—e.g. massage, ice bath, localized icing—that would justify big claims and high prices.
Is it a “powerful treatment” for inflammatory disorders? No, not really. There is a ton of bad research related to this claim. The research shows either a fundamental failure to comprehend how the human immune system works or how to design an experiment. This research uses the same kinds of modalities employed to support other nonsense treatments like homeopathy, cold remedies, organic food benefits, and vitamin supplementation. Such research includes, but is not limited to, uncontrolled heme comparative blood count tests, small sample sizes, unblinded testing, anecdotes, and vague performance measures. These types of studies permeate all sorts of bad, sales-pitch medical advice and appear to often be used solely to inject an air of legitimacy and scientific foundation into brochures. The only sham research missing from this hodpodge of crap is a rodent study. WBC may help alleviate a person’s rheumatoid arthritis, but so does an ice pack.
Does cryosauna treatment boost the metabolic rate? No: the studies used to support this claim is as minimal and poorly structured as the immune research. The only research showing a benefit uses WBC in conjunction with an exercise program without controls. An exercise program boosts your metabolism, but there’s good evidence that the combination of cold and exercise produces a net-total reduction in metabolism. It seems counter-intuitive, but the human body seems to be more efficient using waste heat from exercise than radiating that net heat in warm environments. So it’s unlikely that WBC would increase metabolism; there is no research to counter the growing body of evidence indicating the opposite.
Does cryosauna have cosmetic, psychological, or neurological benefits? Despite many claims of improved skin and cellulite etc., there is no evidence for its cosmetic usefulness—not even bad evidence. There is no evidence of any kind that it has a lasting effect on circulation, nervous function, depression or any other health issue. Promoters claim a myriad of health benefits, but provide no actual evidence, not even minimal anecdotal evidence. Overall, despite marketing statements that might sound like scientific evidence, WBC is physiologic nonsense that, as is sadly too common, oversimplifies how the human body works.
Is cryotherapy dangerous? No. Although I looked through several databases, I could not find any incidents of harm related to cryosauna, except for minor frostbite issues. Essentially it has no greater risk of injury than an ice bath. Hypothermia is theoretically possible, as well as suffocation if the system malfunctions and introduces too much nitrogen. These things have never happened.
The real danger is in surrendering your health to charlatans. Ice baths don’t market themselves as cure-alls. Neither do they make spurious claims about general health benefits. Whole-body cryotherapy is a basic pain-relieving method that charges a high premium price for its show: an expensive piece of equipment with sub-zero temperatures and liquid nitrogen. It sounds like it should do something spectacular, but it doesn’t. PT Barnum would be proud of cryosauna and cryotherapy. Save your money: stay away from whole body cryotherapy. I would recommend that you stay away from any place that markets it. It is a pretty good indication you have good reason to be skeptical about any spa, therapy, or website that promotes it.