Polar plunge: Here are the benefits and risks of a winter swim

On the first day of 2022, Canadians across the country will jump into icy lakes and rivers as participants in local polar dip events.

Events like the Polar Plunge and the Polar Bear Dip take place in cities throughout Canada on Jan. 1 each year, often to raise funds for local, provincial or national charitable organizations.

In addition to supporting a good cause, habitual cold plungers can also benefit from immersion in icy water, according to Lee Hill.

Hill is a research co-ordinator at McMaster University, a post-doctoral fellow at McGill University, a former Olympic-level swimming coach and a member of the International Ice Swimming Association. Having participated in several of his own ice swims, he said the activity can be safe and fun when done carefully.

Here are some of the benefits and risks of polar plunging, as well as some tips for doing it safely.

BENEFITS

According to Hill, humans have praised the benefits of cold dunking since as far back as 400 BC, when the Greek physician Hippocretes prescribed it as a cure for fatigue. Thousands of years later, various forms of cold therapy have found their way into sports medicine, hospitals and the feeds of social media influencers.

“I think the most well-known benefit to any sort of cold water cleanse is pain relief,” Hill told CTVNews.ca in a phone interview on Friday.

Similarly to icing an injury, Hill said cold water can ease pain and reduce swelling by constricting blood vessels and reducing circulation to the affected area.

“It’s been used in a couple of conditions like carpal tunnel syndrome and fibromyalgia, even rheumatism to help with pain, tissue volume and even stiffness of the joints,” he said.

That’s not all. Hill said icy dips raise adrenaline, dopamine and norepinephrine levels to generate a feeling of euphoria. Plus – for some people – it’s fun.

“Putting yourself in harm’s way, so to speak, floods your body with feel good hormones,” he said. “And for some folks there are bragging rights involved.”

RISKS

In order to enjoy the benefits of cold plunging, swimmers first need to make sure they’re mitigating the risks associated with the activity.

Those risks include drowning, hypothermia and cold shock severe enough to cause cardiac arrest in some people, according to the Canadian Red Cross and the American Heart Association.

“One of the first major risks is drowning, because that initial cold shock causes a 600 to 1,000 per cent increase in your breathing rates,” Hill explained. “When you go in there’s that sudden gasp and struggling to get air, and that’s often when people get into trouble initially from that cold shock response.”

According to the American Heart Association, that initial gasp can cause a person to drown “within seconds” if it happens while their head is submerged. Cold shock also places stress on the heart and makes it work harder. People with heart conditions who take medication to lower their blood pressure could have a harder time adapting to the shock of a sudden temperature drop.

Hill said plungers are also at risk of developing mild to severe hypothermia, since water takes heat from the body 25 times faster than air. And the danger doesn’t necessarily go away once a person is back on dry land, thanks to a form of hypothermia called secondary drop.

After a swimmer leaves cold water, all the cooled blood in their arms and legs – which are large reservoirs for blood – eventually returns to central circulation via the heart. Depending on how cold that blood is, it can cause problems when it reaches the heart.

“We know cold blood reduces heart rates and can reduce your blood pressure,” Hill said.

“So some folks up to 10 minutes to an hour after cold water immersion, can then also have a large drop in blood pressure, or your heart can stop.”

HOW TO DO IT SAFELY

Because the risks associated with cold water immersion can be so serious, Hill said it’s important to follow safety protocol. First, he said, anyone planning to take a polar dip should get the approval of their physician. People with a history of asthma or underlying heart conditions should probably avoid the activity altogether.

When the time comes to take the plunge, Hill said to make sure there are other people around to spot you – preferably lifeguards – and a way to dry off and re-warm safely once it’s over. Enter the water slowly, if you can, giving yourself plenty of time to acclimatize to the cold. And don’t drink alcohol before going in.

“Alcohol is a vasodilator, so you can have a large drop in blood pressure,” Hill explained. “It also reduces your ability to re-warm afterwards.”

To avoid the risk of hypothermia, the Canadian Red Cross recommends limiting time spent in the water to two minutes. The organization also recommends wearing socks, water shoes, neoprene surf boots or running shoes to protect your feet and prevent them from sticking to snowy or icy rocks on the shore.