Cold plunge timer

What the research shows, and doesn’t

Søberg and colleagues compared 7 young men who swam in cold water through the winter with 8 who did not. The winter swimmers averaged about 11 minutes a week in cold water and 57 minutes in sauna heat, and showed differences in how their bodies produced heat in the cold (Søberg et al., 2021). The authors could not say whether winter swimming caused those differences, because people with a certain physiology may simply be more likely to take it up. Treat 11 minutes a week as a description of that group, not a target.

A 2022 review of 104 studies concluded that some studies point to benefits, but most were small, often of one sex, and used different water temperatures, so the health effects remain a subject of debate (Espeland et al., 2022).

Why cold water is risky

Sudden immersion triggers the cold shock response: a racing heart, gasping, uncontrollable hyperventilation, narrowed blood vessels and a rise in blood pressure, which is connected to an increased risk of drowning (Espeland et al., 2022). Cold water submersion can also cause a high incidence of heart rhythm disturbances in healthy volunteers, and the clash between the cold shock and diving responses may be behind some deaths that were blamed on drowning or hypothermia (Shattock & Tipton, 2012).

The timer is a ceiling, not a goal: get out whenever you need to. To read your recovery against your own normal, use the HRV baseline calculator; for cold sessions outdoors, check the wind chill calculator.