Study Finds No Strong Evidence for Benefits of Wim Hof Method

New research this week seems to throw cold water on the Wim Hof method, an endurance training technique that intentionally exposes people to frigid temperatures. The study, a review of the scientific literature, did find some evidence that the method could have anti-inflammatory properties, but did not find strong data supporting any other supposed benefits, such as better exercise performance.

The method is named after Wim Hof, a Dutch athlete and motivational speaker who has accomplished some remarkable feats in extreme conditions. Hof, nicknamed the Iceman, has reportedly run a half marathon (13.1 miles) above the Arctic Circle barefoot, climbed Mount Kilimanjaro in just shorts, and withstood being immersed in ice water for nearly two hours. Critics have scrutinized some of his purported accomplishments, but he is still officially recognized as having earned 18 Guinness World Records.

Hof has long credited his endurance and general well-being to the namesake method, which combines being submerged in cold water with specific breathing and meditation techniques. And there have been some empirical attempts to validate his claims. The authors of this new research, published Wednesday in the journal PLOS-One, reviewed data from nine such studies, including eight trials. Overall, the verdict was decidedly indecisive.

The review found that the method might reduce inflammation in both healthy and unhealthy individuals, for instance, possibly by increasing the body’s levels of adrenaline. But the research looking at whether the method actually improved someone’s exercise performance “showed mixed findings.” And even the positive results should be taken with a grain of salt, the authors noted, since most of the studies were judged to have a high risk of bias and were generally considered poor quality for various reasons, such as a small sample size and an inability to blind participants to whether they were using the method or not (without good blinding, it can be easy for things like the placebo effect to affect results).

Despite these important caveats, the authors tried to paint their results in the best light possible, stating that the Wim Hof method “may produce promising immunomodulatory effects but more research of higher quality is needed to substantiate this finding.” But outside experts have been more openly critical about the implications of this study.

“As revealed by the review, the science is too weak/biased to conclude what the Wim Hof method achieves,” Mike Tipton, a professor of human and applied physiology at the University of Portsmouth in the United Kingdom and cold water survival expert, told CNN.

The method might not come without its risks either. There have been numerous deaths possibly tied to the practice. In December 2022, the family of California teenager Madelyn Rose Metzger sued Wim Hof, alleging that his breathing techniques contributed to 17-year-old Madelyn’s accidental drowning death earlier that summer (the case appears to be ongoing). And people with certain health conditions such as asthma, high blood pressure and a history of seizures are not advised to submerge themselves in cold water, according to Tipton.

A spokesperson for Wim Hof and his organization told CNN that it recognizes the need for better quality research to validate the claimed benefits of the method, and that it is committed to collaborating ”with the scientific community to conduct larger, more inclusive studies that address these concerns.”