New York Times - The Athletic on Cold Exposure
Rafael Nadal had a famous pre-match ritual: an ice-cold shower roughly 45 minutes before stepping onto the court, including before the 2008 Wimbledon final against Roger Federer. He described the experience as transformative — emerging "activated," "in flow," and ready for battle. While Nadal treated this as personal superstition, this article recently published in The Athletic, explores whether there's real science behind it.
The author consulted Sylvain Laborde, a sports scientist at German Sport University Cologne who has spent two decades researching self-regulation techniques in athletes, with a focus on heart rate variability — a marker of how well the body adapts to stress, linked to vagus nerve activity. Laborde explained that activating the vagus nerve helps people better regulate their physical and emotional responses.
The author tested three methods:
Cold showers – Produced an immediate adrenaline rush and increased alertness (sympathetic activation), but the effect was short-lived. A Dutch study of 3,000+ adults found cold showers reduced sick days from work, but didn't reduce illness itself, and longer cold exposure (30 vs. 90 seconds) made little difference.
Ice baths – Full-body immersion adds hydrostatic pressure, which can stimulate the vagus nerve more strongly than a shower, producing calm after the initial shock. Laborde cautions this carries real risks for people with heart conditions and recommends never doing it alone.
The mammalian dive reflex – Submerging your face in cold water (something Laborde does daily) triggers a unique "autonomic conflict": heart rate slows (parasympathetic activation) while the trigeminal nerve simultaneously triggers fight-or-flight alertness. This combination, Laborde says, creates an ideal athletic state — vigilant but calm, with faster reaction times and reduced impulsivity.
The takeaway: cold exposure offers a real but temporary physiological boost, useful for the start of competition rather than sustained performance. Just as importantly, rituals like Nadal's may work partly through psychological belief and routine, helping athletes mentally prepare to perform at their peak.