The health and wellness industry is worth an estimated $4 trillion. This extraordinary valuation encompasses the sale of health club memberships, exercise classes, fad diets, supplements, alternative therapies, and thousands of other products and practices, all vying for our attention.

In this, the inaugural article in “The Skeptic’s Guide to Sports Science” column, I chose to scrutinize whole-body cryotherapy. Not only does it illustrate the industry’s preference for hype and hearsay over hard data, but it’s also marketed on the exploitation of several ingrained cognitive biases. This makes it an ideal case study for the critical thinker.

What Is Whole-Body Cryotherapy?

While cryotherapy is the generic term for cold therapies (e.g., ice baths, cold packs, etc.), whole-body cryotherapy is the practice of “cold air exposure,” which emerged in the 1970s and now boasts commercial cryotherapy centers around the world. Sufficiently expensive and theatrical to attract the rich and famous (thereby adding to its appeal), cryotherapy has also become a mainstay in professional sport, embraced by teams in the NFL, NBA, and pro-soccer. It was even used by athletes at the Tokyo Olympic Games (whole-body cryotherapy was invented in Tokyo), despite being prohibited by the International Olympic Committee.

 

During a typical two- to four-minute exposure, the client enters an upright tank that resembles a steam room from the future. Inside, the air has been cooled to between −150°C (−238°F) and −200°C (−328°F) using argon and liquid nitrogen. The major premise is that whole-body cryotherapy facilitates recovery by constricting the body’s blood vessels and reducing blood flow to inflamed muscles and joints. In this way, the practice exploits the notion that injuries benefit from the cold; the same conventional wisdom that for decades saw ice packs being used, somewhat erroneously, to treat swollen ankles and sprained wrists.

Before we get to the evidence, it’s worth briefly exploring the marketing claims surrounding whole-body cryotherapy. There’s the mechanism stated above, but other claims are altogether more extravagant. For instance, it’s been suggested that the cold temperatures cause blood to be retained in the body’s core, where it’s enriched with oxygen, enzymes, and nutrients, all of which get released in a cascade when the individual vacates the tank. Some websites even tout whole-body cryotherapy as a treatment for illness, despite a clear FDA statement to the contrary (These statements have not been evaluated by the FDA. These products are not intended to diagnose, treat, cure, or prevent any disease). I also take issue with the way “recovery” is employed in the advertising rhetoric: It’s vague and undefined, allowing the endpoint to be amended as necessary, like a moving goalpost.

The Science

I’ll spare the reader a lengthy review of the data, but here are the cliff notes. The keywords whole-body cryotherapy, exercise, sport, performance, and recovery will return over 2,500 papers in PubMed. Among them are seven meta-analyses (comprehensive reviews) focusing on the efficacy of whole-body cryotherapy to enhance recovery from exercise.

The findings can be split into two main outcomes. In terms of subjective ratings, a few small studies found that whole-body cryotherapy reduced muscle soreness but with effects that were too small to be reliable (Torres et al. 2012). As a result, there was little benefit on functional recovery (Bleakley et al. 2014). The problem with subjective ratings as an outcome is that they’re predisposed to bias if the study doesn’t account for the subject’s expectations and beliefs (i.e., placebo effects), and most cryotherapy studies don’t. A meta-analysis from the famous Cochrane Database concluded that the evidence is insufficient to determine whether whole-body cryotherapy reduces perceptions of muscle soreness or recovery (Costello et al. 2015). So much for the subjective data.

Also studied are objective measures of inflammation (biochemical markers in the blood), which aren’t influenced by placebo effects. While most research suggests no benefit, there are several studies reporting reduced inflammation with whole-body cryotherapy compared to passive rest (Banfi et al. 2010; Pournot et al. 2011). These findings must be contextualized. First, the magnitude of the observed effect is generally very small: statistically “significant” but unlikely to be clinically significant. Second, any effect generally occurred following several days of multiple daily exposures and, given the expense of a typical session ($50–100), it’s unlikely a viable option for most people. Finally, and perhaps most importantly, studies showing positive effects generally compare whole-body cryotherapy to passive rest, which isn’t a like-for-like comparison. When whole-body cryotherapy was compared to cold water immersion (Poppendieck et al. 2013) or even heat therapy (Wang et al. 2021), there were generally no differences. Even the FDA has weighed-in on the research, concluding, “We found very little evidence about its safety or effectiveness in treating the conditions for which it is being promoted.” The FDA also warned of potential side effects, including frostbite, burns, and asphyxiation when liquid nitrogen is used for cooling; risks it says are “readily apparent.” There are published case reports to this effect (O’Connor et al. 2018).

A generous interpretation of the data would be that small studies show a benefit on muscle soreness and possibly inflammation, but these effects are very small and appear no better than other thermal recovery strategies. A less generous interpretation would be that whole-body cryotherapy is an expensive, largely unproven, and potentially dangerous intervention that detracts from more effective and economical forms of recovery. With either interpretation, it’s clear that most commercial claims are considerably overreaching.

The Marketing

Here’s the reality check. Despite the immensely unimpressive data, whole-body cryotherapy is still wildly popular. This is because, like many other unproven practices, it thrives in a commercial space where science is subordinate to marketing. It’s easy to forget that the commercial world doesn’t play by the same set of rules that underpin scientific inquiry. Lax regulations on the products we’re sold allow marketing campaigns to operate relatively unburdened by facts and data, instead making unproven claims that exploit our cognitive biases. It’s also clear that, for many consumers, the scientific literature just doesn’t register. These folks are more interested in the powerful images of a celebrity endorsement (the argument from authority), or the fallacious “it worked for me” argument (the appeal to anecdote), which multiplies product sales without consideration of the objective evidence. There are even those who confuse the popularity of the product with its effectiveness (the appeal to popularity/exposure effect). These are all symptoms of a broader problem in contemporary health and fitness (i.e., blunted critical faculties), one I’ll be returning to frequently in this column.

Conclusions

The world of sport and exercise is a breeding ground for pseudoscience and misinformation, and whole-body cryotherapy is just the tip of the iceberg. The falsehoods often start here but quickly bleed into other facets of modern culture. Afterall, while people are spending their limited time and money on unproven fads, they’re ignoring scientifically proven modalities that may have genuine benefits. What’s more, it’s sadly common to see minor medical ailments turn into serious ones because they were “treated” with placebo medicine. Consequently, bad science in health and fitness can have profound downstream implications for population health and clinical practice. It’s for these reasons that tackling pseudoscience in the industry is so crucial.

We have much work to do.

References

Banfi, G., G. Lombardi, A. Colombini, et al. 2010. Whole-body cryotherapy in athletes. Sports Medicine 40(6): 509–517. doi:10.2165/11531940-000000000-00000.

Bleakley, C.M., F. Bieuzen, G.W. Davison et al. 2014. Whole-body cryotherapy: Empirical evidence and theoretical perspectives. Open Access Journal of Sports Medicine 5: 25–36. doi:10.2147/OAJSM.S41655.

Costello, J.T., P.R.A. Baker, G.M. Minett, et al. 2015. Whole-body cryotherapy (extreme cold air exposure) for preventing and treating muscle soreness after exercise in adults. Cochrane Database of Systematic Reviews 5(9): CD010789. doi:10.1002/14651858.CD010789.pub2.

O’Connor, M., J.V. Wang, and A.A. Gaspari. 2018. Cold burn injury after treatment at whole-body cryotherapy facility. JAAD Case Reports 5(1): 29–30. doi:10.1016/j.jdcr.2018.10.006.

Poppendieck, W., O. Faude, M. Wegmann, et al. 2013. Cooling and performance recovery of trained athletes: A meta-analytical review. International Journal of Sports Physiology and Performance. 8(3): 227–242. doi:10.1123/ijspp.8.3.227.

Pournot, H., F. Bieuzen, J. Louis, et al. 2011. Time-course of changes in inflammatory response after whole-body cryotherapy multi exposures following severe exercise. PloS One 6(7): e22748. doi:10.1371/journal.pone.0022748.

Torres, R., F. Ribeiro, J. Alberto Duarte, et al. 2012. Evidence of the physiotherapeutic interventions used currently after exercise-induced muscle damage: Systematic review and meta-analysis. Physical Therapy in Sport 13(2): 101–114. doi:10.1016/j.ptsp.2011.07.005.

Wang, Y., S. Li, Y. Zhang, et al. 2021. Heat and cold therapy reduce pain in patients with delayed onset muscle soreness: A systematic review and meta-analysis of 32 randomized controlled trials. Physical Therapy in Sport 48: 177–187. doi:10.1016/j.ptsp.2021.01.004.