Last week a Hawaiian woman living in Las Vegas, Chelsea Ake, was found dead in a cryotherapy chamber where she works. Apparently she was using the chamber unsupervised and accidentally locked herself in or passed out, and was found 10 hours later. Her death, of course, is tragic and we have nothing but sympathy for her and her family.
The event, however, was the first time many people heard of whole body cryotherapy (WBC) and prompted many questions. Three months ago Zachary Hoffman published a guest post on SBM about cryotherapy, showing that the science is just not there. He focused mainly on using ice packs to treat sprains and sports injuries (which is surprisingly not evidence-based, but also perhaps not unreasonable), I am going to focus on using WBC for general health.
What is whole body cryotherapy?
As is often the case, perfectly legitimate or perhaps preliminary medical procedures are hijacked by entrepreneurs and hyped into a bogus “spa” therapy, snake oil, or medical device. Preliminary evidence or legitimate uses are then used to justify the pseudoscientific extrapolations. Stem cells are a legitimate area of medical research, but I would not go to a stem cell clinic in China to treat your ALS.
In this case, any medical use of cold or any basic science showing that cold temperatures have some physiological effect on the body are wildly extrapolated into claims that cooling the entire body with extreme temperatures has some overall health benefit.
One cryotherapy sauna provider claims on their website:
Clients report that the experience is invigorating and improves a variety of conditions such as psychological stress, insomnia, rheumatism, muscle and joint pain, and various skin conditions.*
*These statements have not been evaluated by the FDA. These products are not intended to diagnose, treat, cure, or prevent any disease.
We see many of the signs of medical pseudoscience right here – using anecdotal claims, vague complaints, and now the common FDA “quack Miranda warning.”
At the extreme end, alternative medicine gurus are claiming that WBC treats cancer, and pretty much whatever ails you. They offer the usual hand-waving nonsense to justify such extreme claims:
Your body effectively goes into survival mode when it rushes all the blood to your core. In the process, your blood picks up extra enzymes and nutrients normally held in storage-mode by your body.
And of course they claim this can “detoxify,” boost the immune system, and improve circulation – the usual trifecta of alternative medicine bogus claims.
The procedure involves spending 1.5-3 minutes in a chamber of dry air cooled to -200 to -240°F. Treatments cost between $40 and $100 for a single three minute session. Frostbite is a very legitimate concern, so your skin cannot touch any surface. Entering with damp socks is enough to produce frostbite.
The evidence
Perhaps the most plausible claims made for WBC is its use following exercise to speed recovery or sore muscles. There is a September 2015 Cochrane systematic review of this specific claim which concludes:
There is insufficient evidence to determine whether whole-body cryotherapy (WBC) reduces self-reported muscle soreness, or improves subjective recovery, after exercise compared with passive rest or no WBC in physically active young adult males. There is no evidence on the use of this intervention in females or elite athletes. The lack of evidence on adverse events is important given that the exposure to extreme temperature presents a potential hazard.
Other reviews have come to the same conclusion – there is simply a lack of high quality clinical studies to draw a firm conclusion. What evidence we do have is not impressive. Effects seem to be very small, and only when compared to no intervention. Doing a usual exercise warm down is just as effective as cryotherapy – meaning that any beneficial effect disappears when basic controls are put into place.
Much is made by proponents of WBC of the research into its effects on depression and anxiety. However, the entire literature seems to consist of three studies performed by the same researchers, led by J. Rymaszewska. The three studies are small and poorly controlled, either without a control group or with no apparent blinding. These studies are all preliminary at best and cannot be used to draw conclusions, and I could not find any independent replication.
WBC has also been studied for rheumatoid arthritis (RA), which is a chronic inflammatory disease. A 2014 systematic review found:
Cryotherapy should be included in RA therapeutic strategies as an adjunct therapy, with potential corticosteroid and nonsteroidal anti-inflammatory drug dose-sparing effects. However, techniques and protocols should be more precisely defined in randomized controlled trials with stronger methodology.
In other words, well-designed clinical trials are still lacking.
Conclusion: Cryotherapy is plausible but unproven
Cryotherapy in general, the use of cold to affect physiology, is a reasonably plausible treatment for various conditions, but requires further study before the net health effects can be sorted out for specific indications.
Whole body cryotherapy, cooling down the entire body (which may or may not include the head) to extreme temperatures for a brief time, seems less plausible in terms of having long term physiological benefits. Something real is happening to the body, however, and so there may be sufficient plausibility to warrant clinical research.
Currently, however, the clinical research for the most plausible applications, muscle recover from exercise or injury and chronic joint inflammation, is lacking. In both cases there is insufficient evidence to warrant making clinical claims, and less extreme interventions are likely to be just as effective. There is room, however, for further high quality clinical research.
Mental health applications are less plausible, and only have the most preliminary of studies from a single group. High quality studies are necessary to take such claims seriously.
Other applications of WBC are progressively less plausible and completely lack evidence. There is absolutely no reason to recommend the treatment for a serious illness, like cancer, or for overall health. This, of course, makes it the perfect spa treatment.
As always, with any treatment we need to consider risks vs benefit. The benefits are unproven, and in some cases implausible. There is insufficient rationale for treatment to justify any significant risk. The research is just as lacking on risks as it is on benefits, and it does not seem reasonable to assume such an extreme treatment is risk free.
WBC has now caused at least one death (even if accidental). That stands against the relative lack of evidence for any benefit.