In a recent Runner’s World article, Dr. Kenzie Johnston, a primary care sports medicine physician and assistant professor at Duke University School of Medicine, provides a detailed examination of the physiological effects of the Wim Hof breathing method and its potential implications for runners.
“When that balance is off, it can change the pH of your blood to be more basic, also called acute respiratory alkalosis,” Dr. Johnston explains. The method involves rapid breathing that lowers carbon dioxide levels (hypocapnia), followed by breath holds that induce low oxygen (hypoxia). While these shifts may sound extreme, Johnston notes that they can activate the parasympathetic nervous system, potentially aiding in stress regulation and mental focus.
Although some athletes, such as ultrarunner Tom Evans, swear by the technique for achieving pre-race calm and clarity, Johnston emphasizes that scientific support is still emerging. “There are several theoretical benefits,” she says, including improved lung priming and oxygen transport, “but so far, there isn’t much research to support them.”
A few small studies have yielded mixed results—some suggesting reduced inflammation when combined with cold exposure, while others have shown no measurable improvement in exercise performance. Still, Johnston acknowledges that breathwork in general has been consistently linked to reduced stress markers, improved focus, and even enhanced pain tolerance.