Here’s why you should keep sea swimming throughout the winter

For those people who have consigned their swimming togs to the back of the drawer until next summer, it might be time to think again. While sea swimming has grown hugely in popularity in recent years, and especially during lockdown, a new book provides even more reasons to keep it going even as temperatures drop.

In Winter Swimming: The Nordic Way to a Healthier and Happier Life, Dr Susanna Søberg explores the science behind the claims that taking a dip in cold water is one of the best things you can do for your health. The book delves into the ‘cold shock’ effect and says that those who take the plunge will feel a range of benefits, from the surge in feelgood hormones to the relief of pain.

Søberg’s scientific area of ​​expertise is metabolism; her most recent research focused on fat reduction through winter swimming at the Tryg Foundation’s Center for Physical Activity in Denmark. winter swimming also features her PhD research on brown fat, which is activated by cold and generates heat, leading to increased burning of calories. Søberg examines how it could help fight obesity and type 2 diabetes.

While all of this may, in theory, tempt people to dip a toe into freezing water, in practice, many will be put off by the element of discomfort involved.

Søberg urges perseverance, writing about her own experience: “There was a time when I found very cold water difficult to endure, but now I’ve become a winter swimmer and the cold bothers me much less. If a popsicle like me can learn to winter swim, anyone can. It’s a question of mindset.”

For Søberg, the gain easily outweighs the pain, and the immediate effect on the body will also benefit the mind.

You build up courage and confidence and that is a very powerful part of it because it really empowers people.

“People say, ‘yes I did it, I survived it’ and that is exactly what the body is telling you — wow, you just did this and you have all these hormones and neurotransmitters and a stress response going on.”

As Søberg points out, winter swimming is not a new invention and the benefits of taking to cold water were discussed by the ancient philosophers Socrates and Hippocrates.

The recent surge in popularity is no coincidence, she says.

“This movement, this renaissance, it is because we need it right now. Even before lockdown, there was an increased need because of increasing depression, stress and anxiety worldwide.

“Society is so stressful and we don’t know how to feel our body and mind connect. This is how the cold, the heat, and our breathing comes into the picture. These three things, together with nature … if you can get out and try the cold water, you will immediately feel how you can connect your body and mind.

“You cannot think yourself out of stress, for example. I love that we try to do that — we tell people ‘go and talk to someone’ and it does help to some degree. But the cold water takes you out of your mind, into your body and back to your mind.”

Brown fat benefits

Søberg’s findings on ‘brown fat’ and the role it plays in our metabolism when we are exposed to cold water is particularly fascinating.

“Brown fat is the healthy kind of fat we have; it is located very close to our central nervous system. The main thing that the brown fat does is to increase our heat and warm us up when we get cold.

“And when we get cold, the brown fat is activated and is used as sugar and fat from the bloodstream as fuel. The white fat stores energy and the brown fat uses energy.”

In her own study of a group of experienced winter swimmers, Søberg found more activation of brown fat.

The benefits of taking to cold water were discussed by the ancient philosophers Socrates and Hippocrates.

“They burned more calories when they were cold. They could also get rid of sugar very easily in the body, better than the control group could do. So it means that if you go into the water, you can build up more brown fat, so you can burn more energy and it can make you feel warmer.

“That is why it is even better to start winter swimming when you are a young adult, because then you can keep your brown fat – we know that it disappears with age.”

Søberg also refers to one study of middle-aged women who swam in cold water for an entire season — it found an increased sensitivity to insulin, suggesting that cold water has long-term effects on balancing blood sugar.

While anecdotally there have been many claims for sea swimming in terms of its impact on depression, Söberg says she would love to see some more research on this particular aspect.

However, she says the feedback she gets from people is testimony to the positive effects of winter swimming in general.

“Every day I get people writing to me saying how much it has changed their lives. I have people who were addicted to drugs who tell me they are not doing drugs any more. They use the cold and exercise as a way to keep the dopamine and serotonin levels more stable.”

Immune boosters

For those who don’t have easy access to the sea, Söberg says cold showers or baths aren’t the optimum replacement but they will have some benefits, increasing energy, boosting the immune system and promoting initial habituation to the cold.

“It is not quite the same because you miss out on the nature part. I will always say it is better with a dip but if you just need an energy boost, then cold showers are great,” she says.

You also don’t need to be an avid swimmer — according to Söberg, a few minutes in cold water is enough to see benefits. She also recommends heating up with a sauna in between dips, which is now a possibility in Ireland with mobile saunas popping up around the coast.

A few minutes in cold water is enough to see benefits.A few minutes in cold water is enough to see benefits.

Soberg’s book offers plenty of inspiration for those thinking about taking some ‘vitamin sea’, and the pictures of winter swimmers around the world, including at the famous Forty Foot in Dublin, are a glowing testimonial to the positive effects. She suggests that people start in the summer if possible and that they also do not do it alone.

“Find yourself a swim buddy, someone who can motivate you to get out there. Also, tell people about it because that will keep you on the mission. Put it in your calendar — going once a week is a good way to start.”

And don’t talk yourself out of it before you have even begun.

“The most important part is to concentrate on not discussing with yourself whether it is a good idea — eventually it will be a bad idea because there is always something else to do. In the beginning, it is a bit of a struggle, but eventually, when you are used to it, then you will want to go. The more times you go, the benefits better too.”

The cold facts

  • Cold-water swimming has many beneficial effects on the body including:
  • Temporarily impaired cognitive function — meditative state.
  • Increases endorphins, an important hormone and neurotransmitter for pain relief and mood.
  • Activates the sympathetic nervous system, which increases noradrenaline, an essential hormone for activating your cold response and healthy brown fat.
  • Activates the parasympathetic nervous system and stabilizes serotonin and cortisol.
  • Increases noradrenaline and cortisol by activating your cold-shock response and all your muscles.
  • Increases immune response (leukocytes and monocytes), leading to fewer infections.
  • Cold-water habituation decreases blood pressure, circulating levels of lipids, blood sugar, noradrenaline and cortisol – anti-inflammatory effect and potential reduction of atherosclerosis.
  • Cold-water habituation increases insulin sensitivity — prevention of type 2 diabetes.
  • Anti-inflammatory effect — reduction in swelling and joint pain.

Winter Swimming: The Nordic Way to a Healthier and Happier Life, by Dr Susanna Søberg, published by Maclehose Press and available now

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