The benefits of cold water immersion are not supported by good science, the report says

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A systematic review of scientific studies on the Wim Hof ​​​​​​cold water therapy method found that the quality of the research was inadequate to support most claims of effectiveness without additional research.

Wim Hof, a Dutch extreme athlete and motivational speaker, is known for his ability to withstand the cold.

“It must be noted that the quality of the studies is very low, which means that all results must be interpreted with caution,” said the analysis published Wednesday in the journal PLOS One.

Hof attributes his success to his training method, which focuses on a commitment to practicing cold water therapy with a special form of breathing. Exercise reduces stress, improves sleep, strengthens the immune system and increases energy, focus and willpower, according to Hof.

Although some research has suggested “promising” anti-inflammatory effects of a combination of cold water immersion and the Wim Hof ​​breathing method, “more high-quality research” would be needed to confirm that finding, the researchers noted.

“As the review revealed, the science is too weak/biased to conclude what Wim Hof's method achieves,” cold water survival expert Mike Tipton, professor of human and applied physiology at the University of Portsmouth in the United Kingdom, said in an email. . He was not involved in the study.

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Wim Hof ​​broke his own record by sitting in ice water for hours.

Known as the “Iceman,” Hof swam 66 meters (72 yards) under the ice, ran a half-marathon barefoot in the snow and climbed Mount Everest shirtless. According to the Guinness World Records Hall of Fame, Hof has earned 18 Guinness World Records titles, often surpassing his own records.

Other health benefits listed on Hof's website, which have not been scientifically validated in large, clinical trials, include increasing athletic performance, reducing post-workout recovery time, improving blood pressure, relieving pain, boosting the body's metabolism, overcoming multiple sclerosis and providing relief from arthritis. , asthma, autoimmune diseases, fibromyalgia and Lyme disease syndrome after treatment.

The review examined eight randomized clinical trials — considered the gold standard of research — but found that small sample sizes ranging from 13 to 40 mostly male participants in each study prevented the results from being generalizable to other populations.

In addition, Tipton said, the studies in the review did not compare the effects of ice water with any other physical activity such as indoor swimming, yoga or walking.

“We have no idea what the 'active ingredient' is in Wim Hof's method, if any. We have no idea if the benefits derived from the Wim Hof ​​method can be more safely achieved by other means,” Tifton said. “I don't agree that anyone can do things like cold water immersion.”

Immersion in cold water is not advised for a number of medical conditions, Tipton said. These include asthma, high blood pressure, heart rhythm disorders or any heart disease, unstable diabetes, seizure disorders such as epilepsy, and a family history of sudden or unexplained cardiac death.

“We recognize the need for more high-quality research to substantiate the promising effects of Wim Hof's method,” a Hof spokesperson told CNN via email. “It is our ongoing commitment to work with the scientific community to conduct larger, more inclusive studies that address these issues.”

Cold water draws heat from the body up to four times faster than cold air, according to the National Weather Service. “When your body hits cold water, 'cold shock' can cause dramatic changes in breathing, heart rate and blood pressure,” the service's website says. “Sudden gasps and rapid breathing alone (create) a greater risk of drowning even for confident swimmers in calm waters.”

Still, the popularity of cold water therapy has exploded, with many people taking home ice baths and cold showers, as well as swimming and bathing in the water, Tipton said.

“Wim Hof ​​is encouraging people to be more physically active, which, in a time of increasing sedentary lifestyle disease, is a good thing, as long as it's done safely,” Tipton said.

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Anyone who wants to try cold water therapy at home should do so carefully and only after a thorough medical examination.

For anyone who wants to try the method, Tipton published a list of tips in September 2022 on how to do it safely.

First, do a thorough medical examination.

“A recent study shows that up to 43% of drownings are related to pre-existing medical conditions,” Tipton said. “Pharmaceutical therapies, both acute and chronic, can alter an individual's response to CWI (cold water immersion) and their perception of cold.”

Swim at the beach only with lifeguards and others, he noted, and be sure to check the forecast to avoid hazards like rip currents. Wear a high-visibility cap, take a tow float and consider a thermal wetsuit for buoyancy.

Get used to the water by starting the procedure in warmer weather. As the water gets colder, enter slowly, allowing the shock to wear off before submerging your body. Avoid holding your breath; do not stay in colder water for more than 10 minutes; and don't rely on how you feel because that can be “dangerously unreliable,” Tipton said. If you get into trouble, float on your back.

Once out of the water, dry off quickly and change into warm clothing with a windproof outer layer and avoid driving for at least 30 minutes after swimming.

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