Finland’s Arctic circle might not seem like a great place to run a marathon barefoot and in shorts—unless you’re Wim Hof. Hof, better known as “The Iceman,” has attained roughly two dozen world records by completing marvellous feats of physical endurance in conditions that would kill others. Yet even he was understandably nervous the night before his 26-mile jaunt at -4 degrees Fahrenheit.
“What did I get myself into?” he recalls thinking. But from the moment his bare toes hit the snow, he began to feel “surprisingly good.”
The 59-old Dutchman has climbed Mount Everest in Nepal and Mount Kilimanjaro in Tanzania—Africa’s tallest peak—wearing shorts. “I’ve done about anything I can fantasize about in the cold,” Hof said in an interview. He holds the Guinness World Record for longest swim under ice, and has also endured the extremes of dry heat, running a half marathon through the Namib Desert without drinking any water.
Athletes aren’t the only ones interested in these feats. Now doctors have put the Iceman’s brain—and body— on ice in an effort to better understand the mental and physical mechanisms that allow Hof to seemingly defy the laws of nature. Otto Musik, a pediatrician in Wayne State University’s School of Medicine and his coauthors recently put Hof into a magnetic resonance imaging (MRI) machine while exposing him to cold water and analyzed what happened inside his body.
The results, published recently in a study in the journal NeuroImage, might at first sound more like mumbo jumbo than fact: Researchers found that Hof is able to use his mind to artificially induce a stress response in his body that helps him resist the effects of cold. Musik frames it as a case of “brain over body,” in which Hof activates an internal painkiller function by conducting breathing exercises, then exposing himself to a threat like extreme, sudden cold.
“By accident or by luck he found a hack into the physiological system,” Musik says. He adds that this “hack” allows Hof to feel euphoric while in a freezing cold environment that would be unpleasant in normal circumstances. The researchers tested Hof’s responses alongside around 30 control subjects.
The pediatrician had conducted other research on the way the human body reacts to extreme temperatures. When he heard about a man who sits in buckets of ice cubes for hours at a time and walks up the Himalayas like it was a summer stroll through a wine vineyard, he was intrigued.