- Cold-water swimming can be beneficial to the immune system and the endocrine system.
- Cold-water swimming can also lead to hypothermia, cardiac arrhythmia, and unconsciousness.
- The psychological benefits may also be achieved through running, hiking, or climbing in the cold.
Watching the Baltimore
Watching the Baltimore Ravens play the Tennessee Titans in an NFL game in London recently in temperatures close to freezing, fans in the stadium must have felt cold, but the players must have felt even colder at the start of the game when they arrived on the pitch in t-shirts. NFL players, footballers, rugby players, and people in other team sports regularly brave the snow and freezing weather. It made me wonder about the impact of exercising in cold temperatures. Although professional sportspeople don’t have a choice about whether to skip a game until the weather is warmer, the idea of exercising in cold weather is becoming more popular among the general population.
Why is cold-water swimming becoming popular?
One popular trend is for cold-water swimming. As someone who once lived on a cold beach along the North Sea, where the wind used to howl for most of the winter and blow people across the street to the point where it was common to see people holding onto railings, I used to marvel at people who went sea kayaking or swimming in the middle of winter. I wondered why they tortured themselves by going into the icy sea, but recent research shows that many people enjoy and benefit from exercising in the cold. The reasons are twofold: psychological and physiological.
The physiological and psychological benefits and risks
Researchers define cold-water swimming as that which involves temperatures below 15 degrees Celsius or 59 degrees Fahrenheit, but some people go further and engage in ice-water swimming, which involves temperatures below 5°C/41°F, such as in “ice mile” competitions.1 Cold-water swimming can be dangerous because such temperatures can lead to hypothermia, cardiac arrhythmia, and unconsciousness; therefore, it should not be attempted without adequate knowledge, training, and safety precautions. People need to be aware that long-term exposure to low temperatures is particularly dangerous; therefore, ice water swimming should not be attempted for more than a very short time. The narrative review reported incidences of death after cold-water swimming and the finding that it can be dangerous for people with certain cardiovascular conditions.1
The review, however, also found evidence that cold-water swimming is beneficial to the immune system because it increases leucocytes, monocytes, and the body’s resistance to respiratory-tract infections. Studies suggest that cold-water swimming benefits the endocrine system by decreasing triglycerides and norepinephrine as well as increasing insulin sensitivity. It can also lower blood pressure and have an antidepressant effect.1 The reasons why it improves mood are unclear. They might be physiological, but it might also be because of social aspects of cold-water swimming or the sense of achievement that people feel when they overcome the cold and swim a distance.2 It might also be because of rewards that people associate with the activity such as wrapping up warmly afterward, enjoying a hot cup of tea, or feeling gratitude about indoor comforts after being in severely cold water. A study asked people what they experienced when open-water swimming, and many mentioned cold-water immersion and the temperature aspect as giving them feelings of achievement, closeness to nature, and exhilaration.2
Benefits of other cold-weather exercising
The psychological benefits of cold-water swimming are unlikely to be unique to this type of exercise; you might also get them through running, hiking, climbing, or other types of exercise. I recall once going on a 10-mile hike with some friends in the English countryside on a cold wintry day soon after it had been snowing. It then started raining with wind that blew horizontally, making holding an umbrella pointless, so we braved the rain as it came. Our hike then turned to a hilly field that had been recently dredged up by a tractor because the farmer was preparing to sow some seeds. The field was comprised entirely of soil, which, in that weather, felt like navigating quicksand. As we walked uphill in the cold, wind, and rain, our shoes started getting stuck in the mud, and it took lots of effort to make it through. At the time, I was new to hiking, so I was wearing ordinary trainers rather than proper waterproof hiking boots typically worn by seasoned hikers. The field went on for what felt like miles but when we finally reached the end, we burst out laughing and said it was a fantastic workout. I imagine that was similar to the enjoyment that people get going trail running in the winter and could also explain why cold water swimming is so popular.
Thinking back to the NFL athletes braving the cold in London, it seems clear that more research is needed about the effects of non-swimming exercise in cold weather. If you don’t like the idea of swimming in a cold lake, sea, or ocean, consider runs or long walks in the winter to get a similar psychological boost.
References
Knechtle B, Waśkiewicz Z, Sousa CV, Hill L, Nikolaidis PT. Cold Water Swimming-Benefits and Risks: A Narrative Review. Int J Environ Res Public Health. 2020 Dec 2;17(23):8984.
Christie, M., & Elliott, D. (2023). ‘I get headspace here… you forget everything when in open water’: motives for participation and perceived benefits derived from open water swimming: a rapid ethnographic study. Sport in Society, 1–24.