Into the blue: The health benefits of ocean swimming

High angle view of black woman relaxing in the water with closed eyes. Portrait of happy cheerful woman in bikini floating in a swimming pool. Top view of relaxed african girl in swimming pool with copy space smiling.
A refreshing ocean swim may bring a host of health benefits. (Posed by a model, Getty Images)

For many, summer is signified by ice creams on the beach, walks along golden sand and swimming in the sea – even if it makes you shiver.

Sizzling in the sun forces many into the ocean to cool off, perhaps without realising that dip could have some serious health benefits.

Any form of exercise is good for us, with swimming in particular being linked to a reduced risk of heart disease, obesity and type 2 diabetes.

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Couple that with the immune boosting, mood lifting and even fat-burning properties of invigorating sea water – and a trip to the beach may be just what the doctor ordered.

Female feet step on the sea wave. Summer vacations concept
Enter the sea feet first to acclimatise to the cold water. (Stock, Getty Images)

"Swimming is one of the best all round exercises and works almost all body muscles," Dr Sarah Brewer, medical director of Healthspan, tells Yahoo UK. "It is also non-weight bearing, so good if you have aching joints."

While the cardiovascular benefits can also be obtained in a swimming pool, an ocean dip is hard to beat for its health-boosting properties.

Even during the height of summer, British seas are rarely balmy. While not everyone enjoys that cold sharp shock, its health benefits could be vast.

According to Dr Brewer, being immersed in a chilly ocean temporarily lowers our cholesterol, improves water retention and even burns fat.

When swimming in cold water, ensure you have the right kit. (Posed by a model, Getty Images)
When swimming in cold water, ensure you have the right kit. (Posed by a model, Getty Images)

"Your metabolic rate increases by at least 80% and up to five times its resting level during a cold swim to help maintain your core body temperature at 37°C (98°F)," she says.

"You therefore burn more calories just to stay warm."

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Just 10 seconds of cold water exposure could be all it takes to help you stay svelte.

"Pharmaceutical companies are actively seeking ways to increase the activity of brown adipose tissue in adults to combat obesity – vitamin sea in pill form," says Dr Brewer, who has swum almost every day since her first ocean dip on 8 September, 2020.

Brown fat is activated by cold temperatures, causing it to produce heat to help maintain your body temperature.

As the coronavirus pandemic continues to unfold, immune health is at the forefront of many people's mind.

The odd "cold water immersion" will do little to help you fight off infections. Regular exposure, however, may keep your immune system strong.

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"Regular cold water immersions (three times a week for six weeks) significantly increases numbers of immune cells and increases levels of powerful antioxidants as an adaptive response to improve tolerance to environmental stress," says Dr Brewer.

"Swimming club members report increased immunity and fewer colds," she adds.

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An ice cream on the beach leaves many people in a good mood, but cold water immersion – when done safely – may also boost your emotional wellbeing.

"Cold water immersion stimulates release of endorphins and other brain chemicals to improve mood and help combat stress, anxiety and depression," says Dr Brewer.

"Cold water also helps keeps you in the moment, the ultimate form of mindfulness.

In addition, "swimming can help you achieve a calm meditative state as you focus on your breathing", adds Dr Brewer.

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More than two in five (43%) people who swim regularly claim it makes them happier, while 26% feel more motivated and 15% say life is more manageable, according to a study commissioned by Swim England.

As if all that wasn't enough, sea water may even give our skin a healthy glow.

"Sea water is used in spas worldwide to treat dermatological conditions, such as eczema and psoriasis," says Dr Brewer. "This is known as thalassotherapy and the best known example is bathing in the Dead Sea."

Watch: Swimming safety precautions everyone should know

Safety first

Before venturing to the beach, check it is safe to swim.

"Always check weather reports and ocean conditions before attempting an open water swim, especially if you've never done it before," warns personal trainer David Sautter, on behalf of Island Cottage Holidays.

Many of sea swimming's benefits come down to its invigorating, if bracing, temperature.

"When entering cold water, below 15°C (59°F), you will react with an uncontrollable gasp reflex if you are not acclimatised," says Dr Brewer. "This is followed by hyperventilation, which you can't control."

Always enter the sea feet first, to avoid inhaling cold water. Slowly ease yourself into the water, splashing it onto your face. Only start swimming once your breathing has calmed, which can take several minutes.

Repetition is also key when starting off, with Dr Brewer recommending people acclimatise by taking an ocean dip at least once a week, but preferably twice or three times every seven days.

"Adaptation occurs so that after just five or six swims, the duration of your cold shock response can halve," says Dr Brewer. "This adaptation is preserved even if you miss a couple of weeks of cold water swimming."

Nevertheless, "one study found the cold water shock reduction was still partly present after 14 months," adds Dr Brewer.

When starting off, always swim with a companion, stay close to the shore and wear the right kit. Costumes, a hat, socks, shoes and gloves made from the synthetic rubber neoprene will help to keep you warm, particularly during winter.

Mature female swimmers on early morning open water swim
Swim with a companion or two for safety's sake. (Stock, Getty Images)

It is particularly important to ease yourself into the sea during the cold months, only staying in the water for a few minutes initially.

Unlike in a pool, sea swimmers have to contend with currents, which can be dangerous. To stay safe, choose a beach with a lifeguard and take notice of the flags flying that day.

For those who are new to exercise, Sautter recommends building up your fitness in a swimming pool, before venturing into the ocean.

When it comes to cold exposure, get out if you start shivering or cannot feel the tip of your second finger – a sign of cold incapacitation, leaving a person unable to swim despite their physical capability.

Post-swim, focus on "rewarming": dry off and remove wet swimming gear as soon as possible. Change into warm dry clothes, including a hat, gloves, thick socks and even an insulated robe.

Get moving to generate heat, have a hot drink, snuggle up to a hot water bottle and have a warm shower.

And finally: "Enjoy the glow and endorphin high!," says Dr Brewer.