Benefits of cold water swimming explained by health experts - an icy dip really is so good for you

Although it may be a shock to the system initially, the benefits of cold water swimming are praised by health experts across the world. Not only does it offer the chance to get outdoors, enjoy some fresh air, and take in some exercise, regular dips can have an overwhelmingly positive impact on our mental health.

Cold water swimming, open water swimming, or wild swimming - as it's often called - has become one of the longest-standing health trends over the last couple of years with over 4.1 million of us taking to ponds, lakes, lochs, rivers, and seas every year. While it's always been popular, with literature going back to ancient times reviewing the positive effects of cold water on the body, more of us are taking on the challenge than ever before as we learn about the incredible health benefits of cold water swimming. 

To discover all the amazing reasons to try wild swimming, we spoke to health experts and cold water swimmers themselves to find out exactly why this fitness trend isn't going anywhere. 

Combine an intense dopamine hit with all the benefits of ecotherapy, and it's easy to see why so many of us are becoming addicted to open water. Including our former editor, Miranda McMinn, who became a cold water convert after braving the icy waters at Hampstead Ladies' Ponds. "Like increasing numbers in lidos, lakes, and seaside locations around the country, I’ve become obsessed," said McMinn, whose perception changed after a lifeguard revealed the key dos and don’ts of the activity. “She recommended neoprene socks and gloves, never staying in too long, super-warm clothes to get changed into, and, most usefully, having a cold blast in the shower every day at home to stay in the zone." 

Kristy Field, the co-founder of Wiltshire Wild Swim, finds that wild swimming is such a popular activity due to the community it creates - another one of the many benefits of swimming generally too. "I am constantly buoyed up by the sense of camaraderie. It’s like a club for women who put vanity aside for this portion of the day for the sheer joy of the experience. I feel inspired by the 70 and 80-somethings who come regularly. It gives me a sense of hope for active enjoyment of old age."

How does cold water therapy work? 

Mark Harper, a consultant anesthetist and cold-water swimmer himself, is part of the team at the University of Portsmouth driving research into the benefits of cold-water immersion. He explains that when the face is submerged in cold water, "messages are sent out through the parasympathetic nervous system that put your organs into 'rest and digest' mode, lowering heart rate and reducing inflammation. This is the opposite of 'fight or flight', so we become completely relaxed. As a result, chemicals such as serotonin and noradrenaline are released into the bloodstream, which is believed to create pain-inhibiting pathways in the brain," he explains. 

Cold-water therapy is nothing new with its origins tracing back to Ancient Greece and the principles of thermal medicine, according to historic research by the University G. Marconi of Rome. Here the water was used at different temperatures to soothe muscle fatigue and other health ailments. In fact, Hippocrates himself was the earliest recorded champion of an ice-cold dunk. In documented his experiences with the 'magic waters' for reducing pain, a technique that undoubtedly led to explorations into modern-day hydrotherapy.

Nowadays, the benefits of cold-water therapy - also known as cold hydrotherapy - are accessed through cold showers, plunge pools, and of course, cold water swimming. 

Benefits of cold-water swimming for body and mind

1. Cold water swimming is an instant mood booster

“Apart from the reputed physical benefits of cold-water swimming, the emotional benefits are hard to overstate," Field, of Wiltshire Swim, told us. "The (enjoyable) pain of plunging into cold water is rewarded with a tsunami of endorphins, and afterward, you feel happy as a clam. Plus, once you’ve swum in a 4°C pond, you feel like you can take on anything the day throws at you." 

When endorphins - which are hormones created in response to stressors that help us relieve pain and improve our general wellbeing - attach to the brain's reward centers, they trigger the release of another hormone called dopamine. Also called the 'happy hormone', a study by Charles University found that cold-water immersion can boost dopamine levels by 530%, making it one of the biggest benefits of cold water swimming. 

This is something that keen cold water swimmer, Sally Sellwood, can relate to. "I love cold water swimming because it never fails to make me feel invincible, even for a short period. It helps me deal with work, teenagers, and everything that life throws my way. I've never once regretted going for a swim and I often make time to go for a swim when I might not otherwise have planned it. It's almost impossible to describe the sense of calm I get when entering the water, pushing through the initial excruciating cold to the point of full immersion." 

And while the mood boost that comes with cold-water swimming may be instant, research shows that its positive effects stand the test of time. A study by University College London found that it can be used effectively to treat some cases of depression, for instance. In this study, the researchers reviewed the case of a 24-year-old woman who had been dealing with depression and anxiety since she was 17, after finding out that various antidepressant medications were ineffective. They gave her a program of weekly cold water swimming and found that there was a mood improvement immediately following each swim and a sustained positive reduction in symptoms of depression over time. One year later, the participant was still medication-free. 

2. Shocking the system jump starts your metabolism

The same study by Charles University discovered that cold-water therapy can also increase your metabolism, the process that transforms what you eat into energy, by as much as 350%. As another study by NUTRIM in the Netherlands explains, this is because cold water produces a state called cold-induced thermogenesis, where your body is actively using more energy to try and bring up your internal temperature in response to the temperature change.

While there are plenty of health benefits associated with a higher metabolic rate, it's particularly of interest to those who want to lose weight without dieting as a higher metabolic rate means you can burn more calories via non-exercise-related daily activities like sitting, eating and sleeping.

The study also found that more brown fat - also known as brown adipose tissue - is produced by humans in cold temperatures. Brown fat contains more mitochondria (a type of cell), which act as 'engines' to burn calories and produce heat. Brown fat has been a topic of interest in the medical sphere as it appears to use other fat stores as fuel to aid healthy weight loss, though more research needs to be done until we know exactly what this means for the human body. 

3. Wild swimming a full-body workout

"Swimming is one of the most beneficial exercises for people of all ages because it provides a workout for your whole body," says Sonia Khan, a senior pharmacist specializing in women's health at Medicine Direct. "When doing swimming as a workout for beginners, your arms, legs, feet, and hands are all needed to stay afloat and move around. For this reason, it makes it a great form of exercise."

However, if you decide that a chilly dip isn't for you, it's also worth noting that any kind of swimming is an effective cardio and strength training workout. It's just that adding the complication of cold water makes the movement more strenuous since your body is also working harder to keep you warm at the same time.

Plus, the added weight of swimming boots, gloves, and (potentially) a wetsuit adds to the challenge of open-water swimming and so also burns more calories. As well as aiding weight loss, this kind of intensive workout is also one of the best sleep aids. 

4. Improved cardiovascular health

According to David Sautter, NASM-certified personal trainer, one of the top physical benefits of cold water exercise is, "improved cardiovascular health through giving our heart and lungs a workout". 

However, if you're not prepared for the challenge, you may run into issues. “Breathing in open water is going to require some getting used to," he warns. "You’ll need to try to experiment with breathing on both sides of the body instead of the one side you're accustomed to, and learn how to breathe better generally. Your body might require some getting used to water temperature so I’d recommend starting with a wetsuit, which will dramatically cut down on the cold.”

5. Cold water swimming helps maintain your immune system

While the link between cold water swimming and maintaining the immune system isn't entirely conclusive, there's mounting research to suggest that those who go wild swimming regularly are more resistant to certain illnesses and infections. 

Several studies, including two carried out by Jerzy Kukuczka Academy of Physical Education and Istituto Ortopedico Galeazzi, have found that cold water immersion reinvigorates the immune system by forcing it to produce more white blood cells and antioxidants to come with the new stressor. Though more studies are needed to validate these findings on a wider scale.

6. Reduced pain and inflammation

It's no secret that cold temperatures can be used as natural pain relief. An ice pack is the first port of call to reduce swelling and ice baths have been used by athletes to help prevent muscular injuries for hundreds of years, so this isn't without a solid foundation. A group of researchers from Hong Kong Polytechnic University has also found that cold-water immersion after exercise can lead to decreased inflammation and pain for up to 24 hours a workout. 

However, when it comes to tackling chronic pain, much of the evidence citing the healing effects of cold-water swimming is anecdotal, as Anna Deacon and Vicky Allan found when researching Taking The Plunge. They write, "Back in the 18th century, sea swimming, especially during winter, was recommended for the treatment of a range of diseases. Whole seaside resorts were founded on these perceived health benefits. We still, centuries later, await firm scientific evidence, but anecdotes abound of cold water's pain-relieving benefits. Dawn [a regular wild swimmer who previously struggled with constant pain due to a genetic back condition] for instance, experienced a phenomenal turnaround, from struggling to walk to hiking up to the shelter hut halfway up Ben Nevis and summiting the iconic Suilven." 

"In medical and scientific circles there is a growing interest in whether cold-water immersion may help the pain and inflammation associated with certain chronic conditions," they continue. "It's this kind of chronic pain that is at the heart of the Taking The Plunge project. From the moment we started, the personal stories of such cold-water relief gripped us. Even if the pain wasn't the reason why people were choosing to swim, they were certainly reporting the benefits. People like Lil, who found relief from the ache of her fibromyalgia, said that following a swim she will 'just dance'." 

7. Wild swimming is effective ecotherapy

We're fully acquainted with the benefits of nature, with walking meditation now a very popular version of the classic mindfulness method. Whether you want to reap the benefits of swimming in the sea or take in the serenity of a still lake, wild swimming offers up some idyllic landscapes and can lead to a similar relaxed mindset.

"A large part of the effect is the beauty of being outside in nature, especially for those of us who live in a city," says enthusiast McMinn. "I’ve swum alongside a brilliant blue kingfisher darting from branch to branch. The resident heron at the lake has swooped to land above my head. There are flocks of electric green parakeets and the unfolding annual soap opera of whether the mallard ducklings and moorhen chicks will get eaten by the carp. And that’s all on top of the startling beauty of the changing seasons in the trees."

Between lengths, or while warming up after a quicker plunge, taking a moment to observe the wild and natural habitat around you can truly help you to slow down and connect with nature in an effective way to reduce stress. It's also been cited by some studies, including those by the University of Oulu, as a way to alleviate early symptoms of depression and even stop panic attacks. 

8. It builds a sense of community

Perhaps one of the most appealing benefits of cold-water swimming is the sense of community it brings, with fellow swimmers eager to share their experiences. “The group offers mutual support that goes well beyond swimming,” Field explains. “The other side to swimming is that we’re a communal support group. Lots of us joined at difficult times, struggling with different areas of our lives. We’re like family, a swim family."

For Field, open-water swimming also encourages self-acceptance and body confidence. “There’s nothing like seeing a lot of other midlife women in the buff to make you feel normal. Unlike at the gym, there’s seldom a G-string in sight, just a lot of sensible pants and necessary fleeces.” 

Some safety consideration for cold water swimming 

Of course, you have to be sensible. Cold-water swimming can be dangerous and can cause cold shock (particularly if you're not acclimatized to the temperature) as well as hypothermia in some extreme conditions. Common sense dictates you shouldn’t just jump headfirst into a freezing pond in the middle of January without any preparation. Talk to a lifeguard at your local lido, ponds, or on a beach near you before attempting a swim and (where possible) complete a cold-water induction session before getting started. 

Most community groups operate by the legal framework set out in the Outdoor Swimming Society Swim Responsibility Statement. This essentially means that swimmers are individually responsible for their own safety when swimming with groups and cannot rely on information or advice given by members. 

“With an informal group, an individual’s safety is nobody’s responsibility but their own," Field tells us. "There are probably no lifeguards in the group and the other swimmers are fairly occupied looking after themselves, so it’s vital that individuals understand that they are solely responsible for their own well-being and safety."

When you are ready to take the plunge, it's important to remember:

• Wear adequate protection: If swimming in winter, invest in a good-quality wetsuit, neoprene gloves, and boots, as well as a woolly hat. 
• Acclimatize: It's easier to start your new hobby in the summer months, when waters are warmer, and build up a tolerance over time. Entering waters below 10°C can create a shock response and cause rapid breathing, as well as numbness and pain in the hands and feet. You could also introduce cold showers or baths into your daily routine to get your body used to the idea. Take a look at the Outdoor Swim Society's acclimatization guide for more information. 
• Warm-up immediately: It's important to warm up straight away and stay warm for 20-30 minutes after leaving the water. Remove all cold and wet clothing, wrap up in insulated layers and sip on a hot drink after your swim. A dryrobe, for instance, can be a great addition to your swim kit if you're swimming outdoors as you can peel off your layers underneath and get warm with the 100% synthetic lambswool lining. 
• Focus on breathing: In colder temperatures, your breathing may become quicker and shallow, so it's important to have some calming breathing techniques in mind to help you relax. The Wim Hof breathing technique - which involves controlled breathwork to relax your mind and body - may come in useful. 
• Don't stay in too long: Particularly if you're new to cold-water swimming. A couple of minutes is enough to reap the benefits. 
• Get some rest: Open-water swimming is a vigorous activity that should be followed by some downtime. Make sure you take the time to recover, ensuring you get all the types of rest you need.
• Be wary of the risks: The Outdoor Swimming Society advises getting expert medical advice before winter swimming if you have a heart condition, high blood pressure, asthma, or are pregnant.