THESE DAYS YOU can’t scroll far on your insta feed without seeing an eager, usually ripped dude jumping in a tub of frigid water. The ice bath is up there with fasting as the 2020s’ most popular health and wellness hack, a practice long popular with elite athletes that’s gone mainstream in the last five years thanks to the remarkable frigid feats and evangelising efforts of Dutchman, Wim Hof.
If you’re one of the many cold-water masochists who’s eagerly jumped on board this trend and now regularly hop in a tub of icy water post-workout as a matter of course, you may want to hit pause. While an ice bath can offer respite from aching limbs, its status as a wider mental health tonic and all-compassing salve for the trials of modern life (as some influencers and Tiktokkers claim) is far more tenuous, according to renowned Aussie scientist Dr Karl Kruszelnicki, who recently expressed scepticism about the breadth of claims made by cold water immersion advocates.
While conceding ice baths could be useful as a recovery tool in treating cuts, delayed onset muscle soreness (DOMS) and osteoarthritis, the popular broadcaster says using them to treat wider ailments isn’t backed by scientific evidence.
“There is some degree of usefulness in hot or cold therapy for certain types of injury for 20 minutes at a time, but specifically only those,” says Kruszelnicki. “I am kind of lukewarm on it as a cure for everything including sunstroke, syphilis, varicose veins and bad handwriting.”
Many fitness influencers, along with the Andrew Huberman tribe of self-optimisers known as “Huberman Husbands”, like to bookend their days with an icy shower and a a post-gym sauna and cold plunge. Kruszelnicki says they could be wasting their time.
“[Cold] reduces inflammation, yes, but sometimes you want a bit of inflammation because it can act as a local anaesthetic and it’s good for recent injuries, sprains, and tendonitis.”
Kruszelnicki said heat therapy, meanwhile, had some usefulness, since it could open up blood vessels and remove metabolites such as lactic acid. This can be beneficial for muscle sprains, strains, tendonitis, and warming up stiff muscles, he says.
Interestingly Kruszelnicki says Wim Hof’s identical twin showed high tolerance to cold, which suggests the Dutchman’s astonishing cold tolerance was genetic rather than something acolytes can develop with dedicated practice.
Kruszelnicki urged caution with both hot and cold therapies, saying extremes of temperature could adversely affect blood pressure, leading to fainting. A dip in the ocean is fine, he says, “But making it a religion to go to zero? Nah.”
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Is there evidence for physical benefits of ice baths?
Yes, but much of it is mixed and conflicting. A study by researchers in Australia, Norway and Japan, compared ice baths with a gentle warm down.
In the study, nine active men took part in a 45-minute session of lunges, squats and other exercises. One week they were instructed to take an ice bath afterwards, spending 10 minutes sitting up to their waists in cold water. Another week they spent 10 minutes cycling slowly on an exercise bike. Researchers took blood samples from the men at two, 24 and 48 hours after the cold bath or cycling and biopsies from each man’s thigh muscle. Markers of inflammation and stress response were found to increase after exercise, however, the ice bath made no difference to these levels.
On the plus side, though, a recent systematic review published in the journal Sports Medicine found cold water immersion was an effective recovery tool after HIIT exercise, with participants reporting feeling better, increased muscular power and experiencing relief from muscle soreness.
Can ice baths boost mental health?
Proponents of cold water immersion say it leaves them feeling invigorated, clearheaded and better able to handle stress. Some say that it has helped them cope with grief, anxiety, depression and other mental health challenges. While preliminary evidence has shown promise, more robust clinical trials are required, with the science behind how or why cold water affects mental health still unclear.
A 2020 study conducted in Britain found that 61 people who took a 10-week course to learn to swim in cold seawater experienced greater improvements in mood and wellbeing than 22 of their friends and family members who watched them from shore. Of course, their moods may have been buoyed by a number of factors, including the fact they were exercising, doing something positive for themselves and the sense of community the activity engendered. It’s difficult to isolate the root cause of their spiking mood.
The positive expectations many advocates associate with cold water immersion could also lead to a placebo effect, something even Hof himself acknowledges is a prerequisite for success: “To get the most out of the method, you have to mentally invest in it,” he writes in The Wim Hof Method.
But there is some evidence of a biological mechanism for the reported benefits of cold water immersion. A study published in the journal Biology last year aimed to examine how mood changes after cold-water immersion are associated with changes in brain connectivity.
Thirty-three healthy adults with no previous experience in cold-water swimming undertook a 20 °C 5-min whole-body bath. The researchers measured brain connectivity and self-reported emotional state before and after cold-water immersion, finding that participants felt more active, alert, attentive, proud, and inspired and less distressed and nervous after having a cold-water bath. The changes in positive emotions were associated with connections in brain areas involved in attention control, emotion, and self-regulation.
A reduction in negative emotions, however, did not show strong associations with changes in brain connectivity. The researchers say the results indicate that short-term whole-body cold-water immersion may have integrative effects on brain functioning, contributing to the reported improvement in mood.
Again, this is a small study but it at least shows evidence of an underlying cognitive pathway for the claim that cold water immersion leads to improved mood. As always with emerging trends, more research is required. But if you’re a cold water immersion advocate, your best bet is to continue the practice and disregard any of the uncertainty outlined in this story, for even if the cold water itself doesn’t boost your mood, the wonders of the placebo effect will likely ensure you emerge from the tub with a smile on your face.
Related:
Everything you need to know about ice baths
I attended a breath and ice workshop and here’s what happened
