Whole Body Cryotherapy for Pain

This is a science-based and mostly skeptical guide to whole body cryotherapy. The internet is awash in articles singing the praises of ice baths and cryo chambers — a lot of them from the makers of ice tubs and chambers. What I do here is more like screeching the faults. You know in your heart that a lot of this ice bath stuff is faddish crap. I am a professional wet blanket and science journalist, my bias is “I highly doubt it,” and I’m here to confirm what you already suspected.

But I do not entirely doubt cryotherapy. There are some reasons to remain mildly curious about trying to cure with cold. A certain amount of screwing around with it is justified for a some people. For instance, not much works very well for most kinds of puzzling persistent pain, and so relatively harmless experiments make sense for the desperate. But I urge you not to "swear by" it just because it’s an impressive sensory experience.

There have always been people who swear by a cold morning swim or dunk, and there probably always will be — no matter what the science says. Freezing your ass off is purportedly good for you, despite the fact that it’s also obviously quite stressful1 — please ignore the contradiction!2 Cold immersion has been used as a health tonic throughout history, and baths in general are a kind of shrine to wellness (consider Epsom salts). Since the advent of the health spas of the 19th Century, the idea has never entirely gone out of style. It has enjoyed many faddish revivals, and the idea of therapeutic cold immersion is currently quite hot. As of 2023, there are three major examples:

1. Ice baths are currently hot amongst athletes, who believe — far out of proportion to any credible evidence — that a Siberian soak will help them recover from training and competition faster.
2. The Wim Hof Method, named for Wim “The Iceman” Hof, created an empire based on his almost literally unbelievable cold tolerance (which is probably genetic, not trained, see below). He inspired millions of people to try some combination of meditation exercise, hyperventilation, and freezing themselves in whatever way they can manage. Some of them have hurt themselves doing it; some have even died. (There’s a big lawsuit about that starting early 2024.) And it doesn't appear to work very well, if at all.3
3. Dr. Huberman’s extremely successful podcast (since 2021) is probably the best new example of pseudoscientific wellness grifting, and it’s almost impossible to mention cryotherapy without someone saying, “Have you heard Huberman’s ice bath episode?” Yes, I have. No, I’m not impressed. But I’m clearly in the minority! Huberman’s mainstream credibility and credentials may actually be powering even crazier cryotherapy hype than Hof. Huberman attracted extensive sharp criticism from many experts in 2023 for his blatant supplement-selling profit motive4 and platforming blatant pseudoscience and false balance on topics like the flu.5

The evidence on all forms of cold immersion seems underwhelming to me, regardless of the goal or the details of implementation. That doesn’t mean there’s nothing there at all, but it seems suspiciously hard to confirm anything specific. If there are benefits, they are playing hard to get.

Why do people take ice baths?

Here are all the major reasons why people use whole body cryotherapy:

• invigoration, performance enhancement
• training for cold tolerance
• “shock” therapy for mental health
• entertainment, social and cultural (polar bear swims)
• reduction of post-exercise muscle soreness
• immunomodulation
• extending exercise time in the heat
• treating heat stroke

Ice bath safety

Is it dangerous to dip yourself in very cold water for therapeutic purposes? Probably not as dangerous as many other popular activities! Including a bunch of other water-related ones (drowning is the 3rd most common type of injury death).

But there is a medical consensus that the ice bath danger is real. Although younger and fitter people are much less likely to have trouble, the popularity of the practice has led to large numbers of more vulnerable people giving it a try — especially people who are actually struggling with their health. These are literally motivated by their vulnerability! (Not the only place we see this pattern.)

The risks include hypothermia, shock, heart attack, and stroke.6 However, documentation of injuries and deaths by these causes during full body cryotherapy is minimal — either because it’s quite rare, or under-reported (always likely), or a bit of both.

There have been quite a few documented deaths related to “hypoxic blackout,” AKA “shallow water blackout.” This sinister phenomenon, well known to free divers, occurs when hyperventilation is combined with water and breath holding. Significant hyperventilation temporarily suppresses the reflex to breathe, creating the illusion that you can hold your breath for longer than you actually can. You feel like you can keep going when you cannot, which leads to (unpredictable) blackouts while in the water.

But who’s hyperventilating and swimming or breath holding in the water? Who would do such a thing?! Other than free divers?

🙋🏻‍♂️ Uh, I have. Quite a bit of it, actually. (See next section.)

It’s more common than you might think, primarily because of the popularity of the Wim Hof Method, which includes both hyperventilatory breathing exercises and immersion. While taking this risk is officially discouraged by the WHM, abuses and careless malpractice may be common (that’s a substantive video on this topic, worthwhile if you’re interested).

To minimize your cryotherapy risks:

1. Do not take up cold bathing — or do it more conservatively — if you have significant health issues, especially cardiovascular pathology.
2. Go feet first, and keep breathing steadily.
3. Allow time for re-warming, and don’t do dangerous things like driving until you have fully recovered.
4. Important! Never hyperventilate before swimming or breath holding in water. Just don’t do it.

Ice baths for exercise recovery

Intense exercise causes delayed-onset muscle soreness — the deep muscle soreness that surges 24-48 hours after an unfamiliar workout intensity. It’s a plague on athletic training, and there isn't a serious athlete on Earth that doesn't want to do away with it. A true cure for DOMS would be worth billions.

Much more down to earth, many people with chronic pain and other chronic illnesses are extra vulnerable to this soreness — it’s part of the phenomenon of exercise intolerance — and would be grateful for any help they can get with it.

Unfortunately, physiologists still can’t properly explain DOMS, let alone treat it. Popular cures are mostly ineffective, such as massage … and ice baths. (I review a bunch of others in my DOMS article.)

The science of ice baths for recovery is not complete, but it’s further along than many other topics in this field. There are some positive studies. Pournot et al. is one of the best examples.7

Ice baths for chronic pain

Whole body crypotherapy might be a good treatment for some kinds of chronic pain … because it might be anti-inflammatory in a general way. Probably not. But maybe. Hope springs eternal and all that.

Elevated systemic inflammation is probably a major mechanism for many kinds of chronic pain, and we intuitively suspect that being chilled is a way to quench the “heat” of inflammation — just like we think ice will suppress the fire of a fresh injury or a flaring case of Achilles tendinitis. But systemic inflammation is not "hot" in any sense except poetically.10

Unfortunately, there’s no good evidence that you can quench any kind of inflammation with cold, and in fact there’s good evidence that it is probably not the case. For instance, we know that local icing appears to have no effect on injury recovery at all, good or bad. What few studies we have of this just show no difference.11

Inflammation is a function of mind-bendingly complex immunology, and probably cannot be reduced with temperature — and it’s not even clear that it would be a good idea. A common opinion of dubious value is that's unwise to interfere with inflammation. That's debatable, but probably a moot point given that icing doesn't seem to have what it takes anyway.

Ice baths for performance? No!

Not many people do ice baths before exercise, but it’s not unheard of — the invigorating sensation fools many people into thinking that it’s an ergogenic aid. Unfortunately, testing has taught us that it’s the opposite. You might feel “invigorated,” but you are actually de-vigorated! Even a quick bath, just cooling the skin, impairs perfomance quite a bit. And if core body temperature drops by even just a degree, it hits your endurance quite a lot harder … and it’s surprisingly persistent.

I bet I haven’t let my core temperature drop more than fraction of a degree in twenty years. That is, cold enough to really get shivering — mild hypothermia. I hate that state, and I’m pretty good at avoiding it!

And apparently it’s amazingly hard to recover from. I absolutely would have assumed that hard exercise would nuke mild hypothermia, within a matter of minutes. But, as Alex Hutchinson explains in this piece, evidence from a 2024 trial shows that even slightly reduced core body temp is incredibly stubborn: “even cycling to exhaustion isn’t enough to warm you up if you’ve lingered for long enough in temperatures around the freezing mark.”12

I am very impressed by how little effect hard exercise had on those low core body temperatures. Definitely a surprising result.

The other noteworthy result here is much less counter-intuitive, but still interesting: endurance performance was strongly impaired by being chilled, even if it’s just superficial (rather than a drop in core body temperature). While athletes were able to warm up from superficial chilling much quicker, their performance was greatly reduced. A bit more from Alex, summing up:

The revelation that being really cold is bad for endurance may not seem that surprising. The most interesting distinction here, I think, is between exercising in the cold and being cold before you start exercising. One of my pathological neuroses as a runner is the fear of hearing the starting gun fire while I’m still wrestling to get my sweatpants off over my racing shoes. As a result, I often strip off my warm-ups well before the start even in sub-freezing temperatures. If there’s one idea I’ll take away from Wallace’s research, it’s that I need to invest in some tearaway pants.

Invigoration versus therapy

It’s easy to confuse feeling better with being better. (And to some extent they do overlap, especially with pain, which is almost certainly reduced by feeling better about it. But it’s also not going pull a thorn out of your paw.13)

As with so many other popular rehab and wellness practices, ice bathing is probably popular not because it actually does what it says on the tin — or not very strongly — but because of how it makes people feel. Ice baths are definitely invigorating! They get the adrenaline pumping, literally (and a cocktail of other hormones). It’s like excitement in a tub.

Paradoxical pleasure is also a major factor here. No one actually thinks that cold immersion creates pleasant sensations up front (that’s for the hot immersion). But for many people, especially athletes, there is no gain without pain — and the fact that cold immersion is so uncomfortable must mean it’s doing something. “What doesn’t kill you makes you stronger.” This effect can be so strong that history is full of examples of people believing that they were being helped by medicines and treatment protocols that were literally harming them, or at least flirting with significant harm.14 The strong pattern fits full body cryotherapy like a glove.

The Wim Hof Method vs. The Null Hypothesis

I took more cold showers in 2023 than I did for my entire life before that — and probably the rest of it, too.

Why would I do such a thing? To reduce inflammation, naturally. Hopefully. I was mostly inspired by a study, although ironically not one that particularly supported cryotherapy.15 The nippy showers were actually a sideshow: I was really in it for the breathing, because the evidence showed some anti-inflammatory potential for that (hyperventilating specifically), while cold didn’t actually move the needle (and neither did expert coaching). But I wanted to do both, partly because I knew the combo is similar to the famous Wim Hof Method (WHM), the popular cocktail of breathin’, meditatin’, and chillin’.

And I just get a kick out of (safely) treating myself like a lab rat. I don’t mind a little sensory drama “for science.” It’s almost part of my job!

I thought the showers were a species of fun. That’s probably all they were: transient physiological invigoration, an amusing way to just feel quite different … but who couldn’t use a bit of that now and then? I felt alive after those showers! For a good twenty minutes! Maybe even thirty!

And then, every time, I slipped back into the usual, remembering how easy it is to confuse “invigoration” with “real health benefits.”

The first real test of Wim Hof Method

The first direct test of the Wim Hof Method by Ketelhut et al. was published in late 2023.16 Several studies have been WHM adjacent, and its ingredients have been studied independently quite a bit (especially meditation), but no one has yet studied Hof’s recipe, the Iceman’s own protocol (the Ice-meister, the Ice-inator, makin’ copies…).

And many are saying that they still haven’t! But that was certainly the idea of the study.

The official WHM has many touted health benefits, and has catapulted to fame based on Hof’s genuinely remarkable cold tolerance (which, importantly, may well be genetic, not trained). If the WHM does what it says on the tin, then it shouldn’t be hard to prove it. And if it is hard to prove it, how good can it be? So just get some people to make a good faith effort for a couple of weeks, and they should show some signs of boosted health.

People aren’t going to turn into superhumans that fast, not even if WHM is genuinely effective. But they should show some signs.

They didn’t in this test. It wasn’t just a case of “technically positive but not impressive” (which I routinely round down to “negative”). No statistically significant benefits were detected at all.

Unsurprisingly, skeptics are smugly sharing the bad news, while the WHM faithful are screaming, “Objection!” The reactions are as perfect an example as we’ve ever seen of how enthusiastically people nitpick studies they don’t like, or avoiding nitpicking the ones they do. Here’s a reminder about how this works (I really get a lot of use out of this flowchart these days):

This study is not a huge win for Wim Hof skeptics

Perhaps a battle, but maybe not even that, and certainly not the war. As negative as this trial of the Wim Hof Method was, it’s just not quite the satisfying game-ender of a slam dunk that some skeptics seem to think it is. There are many good reasons to be skeptical of the Iceman’s claims… but not yet conclusive evidence of absence.

This trial is just not enough. For many reasons (cultural and scientific), you cannot put a topic like this to rest without extremely robust evidence. Which this is clearly not.

I’ve seen several commentators mistakenly identifying it as a study in the journal Nature, which would certainly boost its credibility. But nope! Although it’s on Nature.com, this paper is not published by “the” journal Nature — it’s their huge open-access mega-journal subsidiary, Scientific Reports, which has some quality control and credibility issues — although many papers are just fine. So…no prestige boost.

The most legitimate gripe about the study is that we don’t know just how frigid those showers actually were… because none of this went down in a Level 3 Shower Lab. The authors acknowledge this problem, and there are some reasonable reasons why it’s only a “limitation” and not a deal-breaker… but clearly someone should do this again with more exactingly shivery showers.

So the study just can’t be nail-in-coffin material. Even if it was seemingly perfect, it would still only be one negative study: discouraging, but not definitive.

Meanwhile, the evidence is already a bit tricky, because the components of WHM have been tested in so many other ways, sometimes even in very Hof-ian combinations. Zwaag et al. was really quite close, and genuinely encouraging … about breathing. But specifically not about cryotherapy — which is obviously the heart of the Iceman's method. (For my full report on that study, see “Anti-inflammatory hyperventilation: I’ll huff and I’ll puff and I’ll blow my pain away”.)

But the study is credibly discouraging (despite much scoffing from the WHM camp)

Ketelhut et al. may not have “proved” that WHM is bogus, but it also was not the doomed-to-fail dumpster fire of a trial that every WHM apologist is hollering about.

There’s a strong theme in the objections: it wasn’t true WHM’ing. Not good enough meditating, not good enough breathing, and definitely not good enough cryotherapy (the showers of uncertain coldness).

But this study was never intended to be a study of perfect WHM’ing. It was clearly conceived as a more realistic study of the kind of WHM that the average person can realistically be expected to achieve short of showering with Wim Hof himself. Mr. Hof has been clear that ordinary people can get these benefits quickly and easily — that is part of the legend and the marketing. (Importantly, we also already know from Zwaag et al. that more advanced training with teachers was not superior.)

Despite the fact that it wasn’t a test of the best possible WHM, it was roughly as good as you could ever expect from the average person.

And if a modest, achievable dose of WHM gets you zero benefit, then it’s just too hard to be useful for most people, and it’s directly at odds with how it is being advertised.

In other words, if you have to be hardcore to get a benefit, most people cannot get it.

This is far from “proof” that WHM doesn’t work. Being hardcore might actually work, for instance! But it is a legitimately discouraging result.

Never bet against the null

Wim Hof does not have a monopoly on breathing exercises, meditation, and cryotherapy: they are each popular in their own right, and there are good reasons for skepticism about each of them.

Hof is promoting the idea of a just-right cocktail of these practices. It’s plausible that his blend is effective, but it’s not particularly likely given the generally poor scientific track record of the independently tested ingredients.

Never bet against the null hypothesis (“there is no effect”). In every trial, The Null is like a champion boxer in the other corner of the ring, menacing and extremely hard to take down, waiting to thump the hypothesis. Sure, sometimes the hypothesis wins… but rarely. And that’s the point.

I am not planning on taking many more cold showers in my life either. But I’ll probably do it more often than I bet against the null.

About Paul Ingraham

I am a science writer in Vancouver, Canada. I was a Registered Massage Therapist for a decade and the assistant editor of ScienceBasedMedicine.org for several years. I’ve had many injuries as a runner and ultimate player, and I’ve been a chronic pain patient myself since 2015. Full bio. See you on Facebook or Twitter., or subscribe:

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Notes

1. The human body takes serious cold very seriously, and has very strong physiological responses to it. It is absolutely a physiological "stress," and it is hard on the cardiovascular system.
2. Stress is demonized! There is an army of people out there ideologically committed exaggerating the evils of stress of all kinds, and evangelizing (and often selling) the alleged solutions to it (meditation etc). But many of those people are weirdly okay with whole body cryotherapy … even though it’s blatantly a very significant stress! So much so that it’s actually dangerous, and there are many people who absolutely will not attempt it, and even many who do attempt it are wary of being too hardcore about it.
3. Ketelhut S, Querciagrossa D, Bisang X, et al. The effectiveness of the Wim Hof method on cardiac autonomic function, blood pressure, arterial compliance, and different psychological parameters. Scientific Reports. 2023 10;13. PainSci Bibliography 51590 ❐ This is a decent quality direct test of the Wim Hof Method that found exactly zero measurable benefits after two weeks in a couple dozen people making a good-enough effort to produce an effect if it works. This will probably be the best single citation on this topic for quite a while. I'll explore it in much more detail below.
4. www.mcgill.ca [Internet]. Jarry J. Andrew Huberman Has Supplements on the Brain: Office for Science and Society - McGill University; 2023 Apr 7 [cited 24 Mar 1]. PainSci Bibliography 51662 ❐
5. Immunologic.substack.com [Internet]. Love A. Andrew Huberman spreads misinformation about influenza and flu vaccines; 2024 February 28 [cited 24 Mar 1]. PainSci Bibliography 51663 ❐

   This is one of several pieces by science advocate Dr. Andrea Love about Dr. Andrew Huberman's podcast, offering extremely strong criticism of his solo episode about cold and flu prevention:

   He made patently false statements about basic immunology, downplayed evidence-based measures to mitigate and prevent respiratory illnesses, and overhyped measures that aren’t supported by the body of evidence (many of which he profits from directly). While this episode was a particularly egregious example, it is not the only one.

6. Tipton MJ, Collier N, Massey H, Corbett J, Harper M. Cold water immersion: kill or cure? Experimental Physiology. 2017;102(11):1335–1355. PainSci Bibliography 51608 ❐
7. Pournot H, Bieuzen F, Duffield R, et al. Short term effects of various water immersions on recovery from exhaustive intermittent exercise. Eur J Appl Physiol. 2011 Jul;111(7):1287–95. PubMed 21132438 ❐
8. Higgins TR, Greene DA, Baker MK. Effects of Cold Water Immersion and Contrast Water Therapy for Recovery From Team Sport: A Systematic Review and Meta-analysis. J Strength Cond Res. 2017 May;31(5):1443–1460. PubMed 27398915 ❐
9. Moore E, Fuller JT, Bellenger CR, et al. Effects of Cold-Water Immersion Compared with Other Recovery Modalities on Athletic Performance Following Acute Strenuous Exercise in Physically Active Participants: A Systematic Review, Meta-Analysis, and Meta-Regression. Sports Med. 2023 Mar;53(3):687–705. PubMed 36527593 ❐
10. We think of inflammation as "hot" because the inflammation caused by acute trauma brings a lot of circulation to the injury site, making it literally hot to the touch. Fevers also literally increase our body temperature. But these are very specialized forms of inflammation, and there are *many* others that have no effect on tissue temperature at all.
11. See Collins and Malanga. These are both explored in detail in Icing for Injuries, Tendinitis, and Inflammation.
12. Wallace PJ, Hartley GL, Nowlan JG, et al. Endurance capacity impairment in cold air ranging from skin cooling to mild hypothermia. J Appl Physiol (1985). 2024 Jan;136(1):58–69. PubMed 37942528 ❐ PainSci Bibliography 51499 ❐

    I bet I haven’t let my core temperature drop more than fraction of a degree in twenty years. That is, cold enough to really get shivering — mild hypothermia. I hate that state, and I’m pretty good at avoiding it!

    And apparently it’s amazingly hard to recover from. I absolutely would have assumed that hard exercise would nuke mild hypothermia, within a matter of minutes. As Alex Hutchinson explains, this new evidence from Wallace et al. says nope: even slightly reduced core body temp is incredibly persistent: “even cycling to exhaustion isn’t enough to warm you up if you’ve lingered for long enough in temperatures around the freezing mark.”

    And I am very impressed by how little effect hard exercise had on those low core body temperatures. Definitely a surprising result.

    The other noteworthy result here: endurance performance was strongly impaired by being chilled, even if it’s just superficial (rather than a drop in core body temperature). While athletes were able to warm up from superficial chilling much quicker, their performance was greatly reduced.

13. For a comprehensive review of the power of the mind over pain, see Mind Over Pain: Pain can be profoundly warped by the brain, but does that mean we can think the pain away?.
14. Ingraham. Popular but Weird & Dangerous Cures: The most dangerous, strange, and yet popular snake oils and “treatments” in history (and why anecdotes and testimonials cannot be trusted). PainScience.com. 2219 words.
15. Zwaag J, Naaktgeboren R, van Herwaarden AE, Pickkers P, Kox M. The Effects of Cold Exposure Training and a Breathing Exercise on the Inflammatory Response in Humans: A Pilot Study. Psychosom Med. 2022 May;84(4):457–467. PubMed 35213875 ❐ PainSci Bibliography 52067 ❐

    This fascinating experiment put dozens of healthy young male subjects through days of intense hyperventilation exercises and cold exposure, and then “poisoned” them with injections that caused substantial systemic inflammation. The effect of the poisoning was clearly attenuated by hyperventilation alone, and somewhat more so when combined with cold exposure. This was essentially a test showing that the Wim Hof Method is indeed anti-inflammatory … but also that the whole cocktail probably isn’t necessary, and in particular the cryotherapy isn’t necessary — just the relatively simple and easy hyperventilation exercises are probably the only “active ingredient” you need.

    (See more detailed commentary on this paper.)

16. Ketelhut 2023, op. cit.