"The Iceman" Wim Hof claims a combination of breathing exercises and cold exposure can bring people many benefits, including increased willpower; fat loss; a "fortified" immune response; "balanced" hormones; and reduced inflammation.
The jury is still out on whether the Wim Hof Method (WHM) has any of these benefits, but are the teachings also dangerous?
Experts told Live Science that some of Hof's practices, as shown in some videos online, pose a risk of drowning, as well as potentially dangerous heart-rhythm irregularities. However, a spokesperson for the WHM said these videos are not reflective of the official method, but simply examples of Hof doing "extreme feats," and that they provide safety videos and instructions on their website explaining how to safely practice the WHM.
Whatever the official guidance on the WHM website states, some Wim Hof-branded social media videos give a very different, and dangerous, impression of how to practice the method, experts say. What's more, there is evidence that people have died doing WHM breathing exercises while in water.
Related: How to swim in the ocean
What is the "Wim Hof Method"?
The basic WHM breathing exercise described on the company's website involves taking deep, consecutive breaths, a form of deliberate hyperventilation. After hyperventilating, you hold your breath "until you feel the urge to breathe again."
Separately, the WHM also involves "cold therapy," or exposure to cold. The WHM website says cold therapy can involve cold showers and ice baths. However, in social media videos, Hof and other practitioners often submerge themselves in bodies of water outside.
There are also paid WHM online courses, which Live Science didn't access while reporting this story. (Nor did Live Science watch the WHM-focused episode of "The Goop Lab", featuring Gwyneth Paltrow.)
WHM safety videos and written safety instructions warn against combining any deep breathing exercises and water — but Hof's social media videos often show him seemingly doing just that. For instance, a 2021 YouTube video shows Hof taking repetitive deep breaths and then plunging his head underwater to hold his breath.
"I did that every day since 44 years ago up till now," Hof says in the video. After coming out of the water, he adds, "Back then, I was alone. Right now, millions are doing it!" The video, which had more than half a million views as of April 3, then cuts to a montage of people going into cold water to follow Hof's lead.
Related: Why do we shiver when we're cold?
Dangers of breath-holding in water
Experts told Live Science that, if people do as Hof does in that 2021 video, they can face life-threatening consequences.
Hyperventilation can cause people to black out underwater. Before the WHM gained popularity, decades' worth of reports described people drowning after hyperventilating and then holding their breath underwater, something free divers sometimes do because they don't use breathing apparatuses.
Hyperventilation and breath holding decrease the carbon dioxide in the blood and the pressure the gas would usually exert in blood vessels. This delays the brain's signal to resurface and breathe, according to a 2015 Centers for Disease Control and Prevention report. That's because, normally, the signal to breathe is triggered when carbon dioxide levels go up in the blood.
"If you remove it, it's like you are gambling with your life," Dr. Frank Pernett, a pulmonary medicine doctor and doctoral candidate at Mid Sweden University, told Live Science.
Hyperventilation alone can make people pass out, as can following hyperventilation with a deep breath, Pernett said. You can also black out from just doing a breath hold. In all these scenarios, the loss of blood-borne carbon dioxide causes blood vessels to narrow and prevents enough blood from reaching the brain, inducing unconsciousness.
That's why combining any form of deep breathing exercise or extended breath hold with water is a bad idea. Pernett, a free diver himself, said three of his friends, all trained diving instructors, have died while training alone in pools. "If you are underwater and you faint, and nobody is there to help, you will die," he said.
Related: How does a person freeze to death?
This is true in water of any temperature, but cold water brings unique risks because it can trigger the cold shock response, a reflex that causes you to gasp, the National Oceanic and Atmospheric Administration (NOAA) warns.
That response makes jumping into cold water — as Hof and his followers do in some videos — particularly dangerous because a single gasp underwater can be enough to cause someone to drown, said Mike Tipton, a professor of human and applied physiology at the University of Portsmouth in the U.K. (Tipton has written a guide on minimizing the risks of cold-water therapies and advises cold-water swimming groups.)
Tipton also explained that, when your face goes underwater, your body tries to slow your heart rate, but the cold shock response accelerates it. Activating both responses simultaneously mixes the signals sent to the heart in what's called autonomic conflict, potentially leading to arrhythmias, or irregular heartbeats. NOAA notes these arrhythmias, as well as spikes in heart rate and blood pressure tied to the cold shock response, can pose a risk of heart failure and stroke in people vulnerable to the conditions.
"What Wim Hof did is about the most dangerous thing you can do when you go into cold water," Tipton told Live Science, in reference to the 2021 video.
Do as I say, not as I do
Multiple people who have reportedly done the WHM breathing exercise in water have died.
In 2016, Amsterdam-based newspaper Het Parool reported that at least three people had died after practicing the WHM — specifically while combining the breathing techniques with water immersion. Journalist Scott Carney told Live Science that he's linked 31 deaths to the method, drawing from public news reports and people who privately told him about deaths related to the WHM. Most were drownings, but none have yet been confirmed to have involved the WHM in a court of law, Carney noted.
However, WHM representatives say they make clear their two practices shouldn't be combined.
"Since we heard about people potentially drowning because of malpractice of the WHM breathing in water in 2015, we warn people on how to practice the WHM breathing exercises correctly and how not to practice the WHM breathing exercises," Isabelle Hof, a spokesperson for the WHM and Wim Hof's daughter, told Live Science.
Related: Free divers' heart rates can drop as low as 11 beats per minute
Of the 2021 video, she told Live Science that the video isn't part of the "standard WHM curriculum" and not an instructional guide. WHM safety videos and its website tell people to sit or lie down in a safe place during the breathing exercise and to never practice it or any form of deep breathing ahead of or during immersion in or over water.
Isabelle Hof sent Live Science the protocols for "level 1" certified WHM instructors, and these include many of the safety tips raised by Tipton and also warn of autonomic conflict. However, this more-detailed information is given to aspiring WHM instructors who pay for a course and is not freely available on the company's website.
The WHM website's frequently asked questions page advises people to consult a medical professional before attempting the method — something Tipton also recommended for people planning to enter cold water. But under the question "How do you prepare yourself before going into the cold?" the website simply links to a video of Hof telling viewers to trust their gut, spirit and intuition.
Ultimately, the degree of danger posed by the WHM depends on whether the method encompasses what Hof and his followers do in popular Wim Hof-branded videos or just what is written on the WHM website.
"If you think that the Wim Hof Method is just the written instructions on his website, then there may not be a major problem because it includes warnings," Carney told Live Science. But if everything Wim Hof does is taken as an example of his method, "then there's a huge problem with the Wim Hof Method because he's constantly demonstrating practices which are dangerous."
This article is for informational purposes only and is not meant to offer medical advice.
