The ecliptic of an internet health craze: is the sun now setting on the cold water plunge?

It’s hard to pinpoint exactly when this (anti? Will you give me anti?) sun rose. Cold water exposure was, after all, practiced in Ancient Greece (it’s not new). More recently, in his book labelled as “the worlds fittest”, Ross Edgley discussed cold water exposure as a way to build a “bullet-proof immune system”; that was 2018. In 2019 the world began to get a bit sick; by 2020 all the pools were closed. Then, at some point during this prolonged sick day, whilst churning, at the coalface of engagement, the internet suddenly hit upon ice, and a charismatic Ice Man.

It’s hard to pinpoint exactly why this happened, too. But it did. And recently we hit a mood swing - there’s been some pushing back. So what is happening, out there, on the ever-reliable plains of competing attention - is the sun about to set on the cold water plunge?

Rise and shine

Wim Hof, the Ice Man, has endured some cold yards for that nickname - a barefoot marathon on ice; a world record for being in ice; a world record for swimming under ice. The latter of those was achieved after a failed attempt in which Mr Hof swam without goggles, went blind due to frozen corneas, and had to be rescued, unconscious, by a diver (the next day Wim achieved 57.5 metres - the current record stands at 81). It’s no wonder this caught on.

Wim is a 65-year-old, ultra-fit, and authentically weird bloke. In both tone and topic, he is comitted to avoiding normalcy. On his podcasts and his YouTube, he speaks with shouts, whispers or changes of pace that seem entirely random in his sentences. This eccentricity is seductive - it suggests a different mind, a different world view. One that, if only out of interest, is worth engaging with. And if there’s one thing the cold has garnered over the past few years, it’s engagement. So what actually happened?

Here - there’s the science, then there’s the internet.

Dawn

Though the internet isn’t famed for it’s sound bases to health advice, nothing completely made up tends to garner significant attention. So, let’s quickly survey the academic terrain from which this whole gig took off.

Is it dangerous?

The potential negatives of being in the cold are actually where most of the research has steered itself, and for good reason. Cold can kill. And when you and your tropical heritage undertake that initial plunge - your body is shocked into the cold shock response. You gasp (which can cause drowning) and then breathe heavily; your heart rate and blood pressure increases. This first minute is the most dangerous. Then you calm slightly, your breathing slows. And the water continues to sap heat from your body more than 25 times more quickly than air. Blood is drawn from extremities to protect vital organs. And your nerves could experience damage. And your muscles could cramp. And your heart might also be harmed. Then you climb or jump or run out, and enter another danger zone - the “after-drop”, this is where cold blood from your skin begins to seep through the rest of you, potentially causing a further drop in core temp. The advice here is to keep moving, to stay vigilant with raising your core temperature slowly again.

Is it healthy?

We've established, then, that cold as a natural stressor is potent. And it’s exactly this potency, this extremity, that provides the basis for the proposed benefits that are outlined here. There's loads of suggestions (and everything cures cancer on the fringes), but lets stick to the mainstream: improvements in insulin sensitivity, improvements to the immue system, alleviation of chronic inflammation, improved recovery, and benefits to mental health, such as helping with anxiety, depression, and stress.

The difficulty in interpretating this research lies in a kind of sporadic eclecticism. Some of it, for example with the immune system, has shown mixed results anyway. And, whilst some other studies might begin to suggest things, overall you're observing data taken from different populations, using different temperatures of water, with participants submerged for differing periods of time. Universal conclusions are therefore difficult to come by.

Across these data though, the latter of those proposals - the potential benefits for your mental health - is where, starting with anecdotes, there could be the least rocky ground. There’s just one important pre-consideration. If you go for a cold dip in the sea, say - you get up early (well done), you see your pals (hello, Suzie. Good morning, Amanda), you’re in nature (there’s a Wagtail, there look), you get in the sea (the waves, the open skies), then you withstand the cold (well done again), debrief with your pals (goodbye, Suzie. Have a good day, Amanda), and head home. You feel class now. Which is class. It’s just that scientifically, this scenario means elucidating the actual affect the cold is having on your improved mood is challenging.

But the lab coats are trying. In a study by John Kelly and Ellis Bird, one submersion in cold water caused a self-reported improvement in mood for a group of undergraduate students (noting the specifically young population); in another study by Burlingham et al., 61 participants were recruited to eight sessions of sea swimming, self-reporting positive changes to their mental health. This is all preliminary evidence, however - more research is definitely needed.

Why did it go viral?

Broadly speaking, then, the research did not have a strong footing for any of the claims made. And the cold still caught on, big style. But why, exactly? Ice baths were never on the fringes. And, whilst the colds popularity might now be equilibrating, everyone seems to have at least tried it over the past few years. So what happened?

The moment definitely helped - there was a pandemic on, and here was something, it was claimed, that could boost immunity (see this video from Mr Hof on how we can tackle COVID). The pools were also closed, which meant people who wanted to swim had to do so outside. Then there's the manosphere - you can’t endure ice without discipline, without resilience. All prime narrative material for the bros. And, not entirely unrelated to this - there's also mental health, everyone is justly keen for a boost to their mental health. Foundational to any health advice lifting a finger (see Methylene blue for the latest instalment in this series), influencers were also out and about post-plunge, saying it makes them feel “energised”.

What tap are you going to turn on here then? Be honest

Noon

For whatever reason or reasons the cold caught on. And anecdote became influencer videos became full-throttle viral movement. Wim Hof launched a podcast which ran for 10 episodes throughout 2021, with eminent figures in the guru-sphere like Jordan Peterson and Russel Brand amongst its guests. He released a book in 2020, an app in 2020, and was the figurehead for a BBC reality TV series in 2022, in which celebrities did their own plunging. And, whilst his appearances are becoming more sporadic, Wim has sustained a podcast presence elsewhere to this day, most recently appearing on the Diary of a CEO (famed for its reliable health advice, is the Diary of a CEO) with Steven Bartlett. Huberman lab released an extensive review episode on the topic in 2022, outlining optimal, to use a Hubermanian term, “protocols”, for cold exposure, which included recommendations on temperature, duration, as well as mental tips and tricks to help you through. Huberman lab also appeared on other podcasts during this period, summarising these same protocols and promoting the same data from his original show (more on this later).

The cold plunge also cut through to popular culture. Celebrities everywhere espoused about the incorporation of a dip into their routines, Joe Rogan regularly posted videos enduring his own tub, Mark Whalberg does it, Josh Brolin does it, Lizzo and Thor do it. And, as for the public, the trends in outdoor swimming report from 2021 showed a marked increase in participation; speaking on the Healthy-ish podcast in April, Professor Mike Tipton from The University of Portsmouth mentioned how his local outdoor swimming club went from just 25 members to over 1000.

Golden hour

The cash grab

The UK in particular is not short of cold water - check out your nearest tap, or your nearest lake or even the whole coast - sewage-laden, overly-dredged and above all freezing seas are one of the few things we actually have an abundance of. Despite this, the plunge market has successfully engineered some “artificial scarcity” and pivoted itself for income. Google “ice baths for sale” and you’ll see a range of shapes not so different from the version not including the word “ice”; these tubs cost anywhere between 30 quid and 15 grand (the USD market for Ice Baths was 318.63 million in 2023 - it is expected to grow 4.3% from 2024 to 2030). Wim Hof now has a subscription service for his app, which allows you to unlock “its full potential”, and there’s now cold-water therapy coaches online, as well as coaches who coach the cold water coaches.

The attention grab

Aesthetically, and on grounds of demonstrating prestige, the ice bath is also dynamite content for the influencer. Give your algorithm a whiff of health interest and sooner or later you’ll be treated with something resembling this: a god or goddess pre-dressed for their bathe, and taking a hammer to a top-layer of ice. Around them it’s preferably snowing, and above it’s preferably dark. Then, after their stoic, emotionless submersion, the video speeds up, the slow breathing becomes a pant, and a timer on the screen counts up to something like a week.

The attraction of virtuous resilience that is on display here is undeniable - and is the reason this, along with early morning runs or meditations are all good boosters for engagement.

Dusk?

The developing science

In February 2022 Jozo Grgic published a meta-analysis, concluding cold water immersion could actually attenuate muscle strength gains. In February 2024 Alec Piñero et al. published another meta-analysis, finding that a bout of cold immersion straight from exercise could also attenuate muscle growth. Then, in October 2024, a study by Batista et al., looking at adolescent swimmers, found no effect on recovery or performance when comparing the cold water plunge to different recovery strategies (they did note a subjective preference for the cold, potentially because of the placebo effect). And, to close out the year, Benîot Sautillet et al. published a study in December 2024, suggesting that hot water immersion actually improves recovery from exercise relative to cold.

When looking more specifically at the “Wim Hof method”, which includes regular breathing exercises and meditation. In March 2024, Omar Almahayni and Lucy Hammond published a systematic review, surveying 8 trials on the method. In the review, they concluded that improvements in recovery and exercise performance had mixed findings - there could, however, exist some benefit for reducing inflammation, with a catch. The various protocols in the Wim Hoff intervention make it difficult to prescribe any benefit directly to the cold. They also stressed that “the qualities of the studies is very low” and that “all the trials had a very high risk of bias”; it is difficult to do a proper blind crossover trial here - you can’t just placebo an ice bath, you’d know if you had one.

Regarding mental health, on the 29 January, Cain et al. published a meta-analysis of the effects of cold water immersion on health and wellbeing, concluding that there could be some time-dependant benefits for mental perimeters such as stress, sleep quality and quality of life, however, they also stressed the lack of high-quality data across the studies they looked at.

The developing perceptions

But that is academia - more prescient for the prospects of this trend is the airtime counterarguments are now being given in the pop science sphere. Joe Rogan mentioned the potential negatives to hypertrophy of the cold plunge in 2023. Chris Williamson, on his primetime bro podcast Modern Wisdom (which has over a billion downloads on Spotify), had Dr Mike Israetel on in September 2024 - Dr Mike Israetel spoke, with good use of analogy, on the misconceptions surrounding the cold plunge. A different Doctor Mike, this one boasting 13.4 million subscribers, can be seen here in a video from October 2024 outlining a position we might define as hard against. As well as this, videos began appearing online, such as this one from TheGrowthEquation in November 2024, that attacked the original, flimsy evidence base used by Andrew Huberman to justify the health benefits of cold plunging. Then, in February, the BBC also posted an article stressing the nuances of this topic.

What are we seeing here then - the story of a public awareness shifting in harmony with the developing science? Well, as you’ll remember, there wasn’t a massively sound basis to begin with. And what could be important is not the push back in of itself, or even the people doing the pushing - its the fact that push back has recently become desirable, or at least acceptable to the attention consumer. Is this the media phenomenon of building someone up to knock them down, only applied to health? Or just a natural waining of interest, being capitalised on for content? More important for us is where this all leaves the scientific reality of the plunge. As to that - you might like it. And the prevailing consensus seems to be uncertainty, not detriment. So if you do like it, why not? Ya mays well crack on with ya dipping anyhow :)