Chill Factor

Before every tennis match, superstar Rafael Nadal takes a teeth-chattering shower to help him find what sports psychologists refer to as flow state – a state of alert concentration where his body moves by instinct. According to an ever-growing body of science, this is just one of many ways a douse of cold water can enhance performance. Studies have shown that cold exposure revs our metabolism, reduces inflammation and can help with muscle recovery after a strenuous workout.

Hydropathy, also known as the cold-water cure, dates to the 1820s, when an Austrian farmer started touting the healing powers of cold-water compresses, baths and showers. Fast forward to the early aughts and Dutchman Wim Hof, nicknamed the Iceman for his frozen exploits, started touting cold exposure as a mood booster.

The Wim Hof Method, a combination of cold exposure and breathing techniques, has since been taught to NAVY Seals and mere mortals looking for everything from pain and stress relief. Researchers from major universities have studied Hof and found evidence that his method allows him to control his nervous system, body temperature and immune response as well as release, at will, mood-boosting chemicals, like opiates, that provide natural pain relief and a...