This activity can do wonders for health

By Alistair Gardiner
Published April 26, 2021

Key Takeaways

Cold-water swimming—the kind that involves swimming outdoors in lakes, rivers, the sea, or unheated swimming pools—is gaining popularity. And, according to research, there are numerous healthful reasons for taking a polar plunge.

Of course, along with the benefits, there’s the inherent physical discomfort of freezing water—and taking regular dips in cold water does pose some risks, with hypothermia being the most obvious. Here are the health benefits and risks of cold-water swimming, and how to practice it safely, based on the most recent research.

Health benefits 

According to the aforementioned review, several studies have found that cold-water swimming can result in improvements to cardiovascular risk factors, like lipid profile and blood pressure. The authors cited one study, which followed a group of 34 cold-water swimmers aged 48-68. Data suggested that the cohort exhibited a drop in triglycerides and lower levels of the amino acid homocysteine, of which high levels are linked to heart disease.

Evidence from the review suggests that the practice has a positive impact on insulin metabolism, although possibly only for female swimmers. The authors cited one study in which the insulin sensitivity of 30 cold-water swimmers was monitored for six months. Results suggested that, for female swimmers with lower body fat percentages, insulin sensitivity increased and there was a reduction in insulin secretion and resistance.

The practice can also improve tolerance to stress factors. Regular cold-water immersion has an effect on several hormones, including catecholamines, thyroid-stimulating hormone, adrenocorticotropic hormone, and cortisol. According to the review, these “stress” hormones will become less reactive to exposure to cold water the more regularly you practice cold-water endurance swimming. Additionally, cold-water swimming can result in an increase in norepinephrine, which may lead to reduced perceptions of pain.

Through this increase in catecholamines, cold-water swimming activates the sympathetic nervous system and increases levels of norepinephrine and beta-endorphin. Via these means, the practice has been shown to have potential as a treatment for depression, much in the same way that other exercise does.

This hypothesis was illustrated in one case study, published in the BMJ, which described a 24-year-old woman with symptoms of major depressive disorder and anxiety, who had been receiving treatment with medication since the age of 17. After undergoing a program of swimming weekly of cold water, the patient showed immediate improvement in mood and gradually a reduction in symptoms. One year after beginning the program, the patient was medication-free.

Various other studies have demonstrated the positive mental health impacts of cold-water swimming. The authors of the review note that it’s been shown to improve the general well-being of patients with rheumatism, fibromyalgia, or asthma.

According to the review, there is also a growing body of evidence that suggests cold-water swimmers are more resistant to certain illnesses and infections. The authors cite one study that found the rate of upper respiratory tract infections was 40% lower among a group of cold-water swimmers, compared to a control group. The review states that improvements to the immune system are likely a result of the release of stress hormones in response to the cold. 

Health risks

While evidence of the health benefits of cold-water swimming abounds, the practice does come with some risks. For example, one study cited in the aforementioned IJERPH article found that incidents of upper respiratory tract infections actually increased with a group of cold-water swimmers, which the authors note may have been a result of insufficient recovery between exposure. 

Similarly, prolonged exposure to cold water can result in hypothermia, and cardiac risks like dysrhythmias and arrhythmias or even cardiac arrest—primarily in those with pre-existing conditions. 

Among the greatest risks when cold-water swimming (especially for those who are new to the sport) is drowning. This is mostly due to the cold shock response when the swimmer initially enters the water. For up to 2 minutes, the swimmer may experience uncontrollable hyperventilating and loss of breathing control, along with increased heart rate and blood pressure. Swimmers may also experience peripheral paralysis, as the low temperatures provoke a nerve block in both motor and sensory neurons, and induce temporary cognitive decline.

In light of all of this, it’s important to know how to start cold-water swimming in a safe way.

How to practice safely

As the authors of the IJERPH review noted, a “step-by-step strategy is recommended both to start and to build and expand this activity,” in order to build acclimatization and protect against the potential risks of cold-water swimming. 

In a blog, avid open-water swimmer Michelle Rogalski of Michigan advises beginning cold-water swimmers to have a plan before diving in. That includes surveying the environment, including water depth, temperature, possible turnaround landmarks, and watercraft and marine life you might encounter. Always ensure you have a safe exit strategy out of the water. Beginners should wear the proper protective-wear, and swim with a buddy or group.

According to a guide from The Outdoor Swimming Society, the best ways to build up your tolerance safely include:

  • Swim regularly, a least once a week.

  • Don’t set time goals for how long you should stay in the water. Listen to your body.

  • Neoprene socks and gloves are recommended to protect extremities.

  • Get out of the water if you feel uncomfortable, or start to shiver.

This means, at first, you probably won’t be in the water for more than a few minutes. But as your body starts to adapt, you’ll find you can spend more and more time in cold water. If you begin to experience any signs of hypothermia (like slurred speech, mental confusion, and poor movement coordination) you should leave the water immediately and begin the rewarming process.

Once you leave the water, your body will continue to cool for up to 30 minutes. As such, warming up immediately is vital. So bring lots of warm, dry clothes (including hats, gloves, and thick socks), dry yourself off as quickly as possible, let yourself shiver, and have a warm drink.

Bottom line

If you’ve read this far, we’re guessing you have more than a passing interest in this chilly pastime, so why not give it a try? With enough patience and gumption, you may start to feel the benefits after your first swim.

And don’t forget, regular swimming, without the icy temperatures, is also good for your health. To learn more about the benefits of swimming, click here

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