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Shivering for health: The myths and truths of ice baths explained

Researchers are disputing unscientific benefits of cold plunges (Pexels/Andrea Schettino) Researchers are disputing unscientific benefits of cold plunges (Pexels/Andrea Schettino)
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In recent years, ice baths have been championed as an optimal remedy for physical recovery.

In a climate of social media-endorsed wellness rituals, plunging into cold water has promised to aid muscle recovery, enhance mental health and support immune system function. But the evidence of such benefits sits on thin ice, according to researchers.

The Mayo Clinic, a U.S.-based academic medical centre focused on integrated health care, education and research, says many ice bath claims are not rooted in qualitative science.

In an article published on its website, the clinic said the physiological benefits of cold plunges "do not live up to the hype."

In a 2023 study published in Nature Scientific Reports, for instance, researchers aimed to measure positive changes in blood pressure, heart rate, heart function or mood among participants after 15 days of cold water exposure.

The study found no notable changes among participants.

"In addition, while other scientific evidence seems to point to some benefits of (cold water exposure), much of the research is too weak to support many of the claims with confidence," the Mayo Clinic wrote.

"Moreover, consideration must also be given to the lengths you'd need to go to achieve, at best, a modest beneficial effect."

Athletic recovery

Andrew Jagim, a sports medicine specialist with Mayo Clinic, says the science and practical applications of cold exposure have changed in recent decades.

In the article, Jagim recommended applying ice to the location of an acute injury to reduce swelling and pain, adding that ongoing cold therapy beyond the first few days could slow healing and delay recovery.

"If an athlete has an intense two-week period of practice or a three-day tournament and they are struggling with pain or soreness, I may recommend adding ice baths post-workout or throughout the day," he said.

"But I would advise against using them every day throughout an entire season or training cycle as research shows that they may hinder long-term adaptations in athletes, particularly for strength and muscle growth."

 

'Metabolic response'

The Mayo Clinic also pointed out a gap in research regarding changes in fat tissue as a response to cold-water immersion.

One study, involving laboratory rodents, was able to draw a correlation between cold exposure and metabolic responses, but the literature on human metabolic systems is far more ambiguous.

"Just because rodents become a little leaner doesn't mean that the same thing will happen in humans, were it to be studied," the Mayo Clinic explained.

The Mayo Clinic also mentioned that conclusions drawn about the mental health response of cold water immersion are built on weak scientific foundation.

One small study, with a sample size of 33 participants, found that a five-minute dip in cold water enhanced alertness and decreased anxiety, suggesting that cold plunges can trigger the release of endorphins and noradrenaline in the brain.

Another small study, which had participants immerse their hand in cold water for three minutes after being awoken in the middle of the night, suggested that the cold water can improve cognition despite sleepiness.

"These studies are not only small but offer scenarios for achieving benefits that are far from practical — unless you really need to solve math problems at two in the morning," the Mayo Clinic said.

"Larger-scale, randomized controlled trials in humans are needed to know whether this effect might extend to more realistic and routine situations."

Open water dangers

According to the Mayo Clinic, "Scientists know much more about the dangers of cold temperatures than they know about the benefits."

Researchers know that cold water immersion can trigger a "cold shock response" that can lead to hyperventilation, as well as increased heart rate and spikes in blood pressure, "all of which could pose health risks for people who are susceptible to cardiac events," the Mayo Clinic points out.

Aside from the threats of hypothermia or frostbite, which are more tied to open-water swims in a frozen lake, for example, Jagim says cold plunges in controlled tubs are not a "big level of concern."

"However, if someone walks across a frozen lake in sub-zero temperatures, cuts a hole in the ice, jumps into 30-degree to 40-degree waters, and then exits the lake into a cold and sub-zero environment while being wet, the risks would be significantly higher."

'A garnish'

To help people understand the potential benefits of cold plunges, Jagim uses an analogy.

"Exercise, a nutritious diet, sleep and stress management are the veggies, whole grains and meat are the main course. Cold plunges serve as a potential garnish," he said.

"Focus on the entree before worrying about the garnish." 

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