Physical therapy is a field vulnerable to trends, fads, and pseudoscientific ideas. We treat patients in severe and significant pain. We deal with suffering directly, and up close. We work with patients who have conditions that we know won’t really improve. It is only natural to want to research new ideas, practice new skills, and learn new treatments to best help our patients. The problem comes, however, when we we are too hopeful and put stock into these new things before critically evaluating the scientific evidence, or lack thereof, behind them.
As new graduates in the physical therapy field, we need to be on the front lines. It is our responsibility as healthcare professionals to be able to provide accurate and unbiased translations of the scientific literature on the latest health trends. One such trend that is illustrative of our responsibility is the rise of whole body cryotherapy. WBC is the latest panacea that can help you do anything and everything: recover from workouts, reduce inflammation, treat and prevent cancer, lift your mood, ease your pain, boost your immune system, increase your energy levels, speed your healing . . . the list goes on. Does it really do any of these things? How do we know? Is it all just marketing hype? Physical therapists are the ideal professionals to evaluate these new or recycled ideas in musculoskeletal health. Here, I will evaluate the scientific evidence on whole body cryotherapy, dissect why trends like this arise, and show why we are in the best position to educate the public.
The basics of whole body cryotherapy
A WBC treatment involves standing in a specially designed device where patients are exposed to water vapor that is -200 to -300 degrees F for up to 2-4 minutes.12 This can be done as frequently as someone can pay, as many WBC locations offer deals for the more sessions you book or unlimited monthly use for a recurring fee. The severe cold is said to have many effects on the body, and through specious reasoning not constrained by science, is connected to any given therapeutic goal you may have. It is most typically used to treat pain and improve recovery, but it is challenging to catalogue the proposed benefits because there really is no limit to what purveyors claim. Here is just a sample:
- Burn 400-800 calories in one treatment6
- Increase energy5
- Clear toxins3
- Improve your mood and relieve stress7
- Create a whole body healing response4
- Prevent cancer13
And of course, often buried at the bottom of the webpage is the disclaimer that WBC has not been evaluated by the FDA and the treatments are not designed to diagnose, treat or cure any disease.
The evidence on whole body cryotherapy
There are already a few red flags here that should give you a clue as to what is going on, but we will discuss these a bit later. What does the actual science say? Is there any reason to believe the claims put forth? Should people be taking these claims seriously? The evidence really does tell a different story, and if you read a few papers with a skeptical eye, what’s going on becomes clear.
Systematic And Narrative Reviews
The most common claim is that WBC can help speed up recovery after exercise or performance. A Cochrane review from 2015 looked at four studies that compared WBC to rest or infrared sauna therapy for the treatment of delayed-onset muscle soreness. They found that there was some evidence showing those that had WBC had reports of decreased soreness, but more importantly, there were significant methodological issues in each study that limited the believability of the conclusions. The studies were small and only featured 64 patients total between all four, there was absolutely no blinding of patients or outcome assessors, the study designs were weak, and the majority of studies did not compare WBC to a similar treatment. The authors conclude “the currently available evidence is insufficient to support the use of WBC for preventing and treating muscle soreness after exercise in adults.”2
A narrative review from 2014 looked at a few different aspects of WBC treatments. They found that WBC reduces tissue temperature in a way that is “comparable to or less significant than traditional forms of cryotherapy.”1 Most of the studies they looked at showed that ice packs reduce skin temperature the best, and there were only small reductions in core temperature that were similar across all methods that were assessed. In addition, they reported that WBC may affect inflammatory mediators, antioxidant capacity and autonomic function during recovery, but there findings are only preliminary, and need to be further explored in more robust studies. They also reported that there is evidence that WBC treatment can help improve subjective pain scores during recovery, but there is no evidence of improvement on more objective measures. They conclude that until we have stronger research, “athletes should remain cognizant that less expensive modes of cryotherapy, such as local ice-pack application or CWI [cold water immersion], offer comparable physiological and clinical effects to WBC.”1 Another review of 16 studies from 2017 found that WBC consistently reduced pain levels as compared to controls, may diminish the inflammatory response associated with exercise-induced muscle damage, and may have a role in recovery. However, the reviewers point out that the research thus far has not effectively ruled out placebo effects, study designs were extremely variable, and there has not been a standardized treatment protocol.14
The majority of smaller trials that have been performed do not strongly support the claims made either; regardless of the outcomes of these studies, methodological issues cloud the conclusions that can be drawn. Either the methodological issues raise sufficient doubt on the results, or the results were equivocal or negative. Many studies had very small sample sizes or designs that do not appropriately compare treatments. Many studies made no attempt to blind patients, researchers, or assessors. We have not thus far seen an appropriately designed and adequately powered study showing that WBC has true benefits over sham treatments or other types of cold therapy, but here are a few studies that attempted that feat.
One study from 2015 found that in a group of 44 patients with rheumatoid arthritis, the addition of WBC to traditional physical therapy and exercise made no difference in outcomes.8 A small study from 2016 on 35 people with restless leg syndrome found that those who underwent true WBC had slightly improved symptoms as compared to a sham WBC group and a local cryotherapy group.9 One study from 2015 found that in a group of about 60 patients with chronic, non-specific back pain, it made no difference if a patient received true WBC with a temperature of -67 deg C or sham WBC -5 deg C. Both groups had similar reductions in pain after ten daily treatments.11
Another small study from 2013, found that the addition of WBC to multi-modal physical therapy resulted in better improvements in ROM and pain for patients with frozen shoulder.10 However, there was no blinding of the patients, and the study design (A versus A + B), is not appropriate to truly assess the effectiveness of a treatment. Patients in the A + B group know they are getting the experimental treatment and this may result in placebo effects.
A new smaller scale trial from 2018 compared WBC, cold water immersion, and a placebo group of a fruit-flavored drink that was supposed to have phytonutrients in it, but really did not, for recovery after a marathon. There were ten runners in each group, and the results showed that WBC had an unclear or negative impact on many of the indicators of muscle performance and blood markers. With the exception of perception of soreness, “the implementation of a cryotherapy intervention resulted in unclear, trivial or harmful effects for every outcome measure when compared to the placebo intervention.”16 One study from 2008 found that WBC treatments had a positive effect on measures of depression and anxiety in 26 people as compared to controls, but the control group only received standard treatment and the sample size was small.15
Do not expect to find any studies on WBC and cancer, weight loss, detoxification, or any other hyperbolic claim, because these are merely marketing points not based on evidence.
The anatomy of a trend
This is not a full review on the evidence regarding WBC, but a selection of well controlled studies that suggests, depending on the claim, the support is either mixed, inconclusive or negative. This picture is in stark contrast to the view pushed by WBC companies, marketers, and less-than-skeptical bloggers. As new physical therapists, we have a duty to dissect these trends and provide accurate, honest, and unbiased information. WBC has many of the features of a health trend that rises in popularity in spite of negative or inconclusive evidence, and it will be useful to go through some of the signs.
It starts with a plausible mechanism that makes sense to patients and therapists, but is then expanded upon. It might seem reasonable to think that since ice is utilized for injuries, exposing the whole body to extremely cold temperatures may be even more effective.
From a plausible mechanism, leaps of logic are made, and claims are extrapolated without supporting evidence along the way. For example, ice is commonly known to help with inflammation, and inflammation can be associated with cancer, so therefore, maybe WBC can help prevent or treat cancer.
The claims are bold, vague, and not constrained by robust and rigorous evidence. The claims mentioned above are a good example; an uncritical person or someone without training or experience in healthcare research may come away believing that WBC can help with anything and everything.
Weak research is cited and there is never a “smoking gun” study. Often, the research cited in support of these trends has many methodological flaws that limit the applicability and believability of the findings. These include the lack of blinding, poor research design choices, inappropriate or absent control groups, surrogate outcomes, small samples sizes, and incomplete reporting of the interventions and protocols used.
Purveyors of the treatment in question cite anecdotal evidence. It is never hard to get to the patient testimonial and athlete or celebrity endorsement page on any WBC website. This creates the impression that the elites are using it and getting results, and you will too.
The marketing materials and company websites seem sophisticated, modern, sexy. A well done website can lend an air of credibility and make it seem like the treatment in question is legitimate.
Companies attempt to make these treatments financially attractive. Many WBC treatment centers offer deals that get better if you buy more sessions or sign up for a monthly pass.
A new role for PTs
There is a significant amount of misinformation, pseudoscientific ideas, and “alternative” treatments in all domains of healthcare, and physical therapy is no different. WBC demonstrates this; the claims about it are extraordinary, but the evidence certainly isn’t. While there is still room for more research, WBC is an unproven therapy that our patients are spending money on. As physical therapists highly trained in evidence-based practice, we need to be the scientific gatekeepers for our patients. We must be able to sift through the nonsense, decode the science behind popular trends, and educate our patients to the best of our ability.