Sept. 29, 2022 -- Every Sunday from November to April Dennis Thomas starts his day by hitting the beach at Coney Island for a dip in the frigid Atlantic Ocean -- no matter how low the mercury plummets.

Thomas, president of the Coney Island Polar Bear Club, says these winter swims offer more than just a bracing rush of adrenaline. He believes they’re the reason that, at age 67, he is fiddle-fit physically, tack-sharp mentally, and rarely catches so much as a winter cold.

“I’ve been doing this for 35 years,” says Thomas, a brand manager for a software company who bikes 5 miles a day. “Physically, I will say I get less winter colds than I used to. Mentally, it clears my head. It’s kind of a purge and a cleansing of the mind because you can’t think of anything that’s troubling you when you’re in water that cold.”

New research out of Norway appears to confirm what Thomas and his fellow Polar Bears have long believed to be true.

A systematic review of 104 studies, by researchers from UiT The Arctic University of Norway and from the University Hospital of North Norway, found strong evidence that cold-water swims and therapies based on them offer significant physical and mental health benefits.

Taking a dip in icy-cold water cuts “bad” body fat in men, according to the analysis published in the peer-reviewed International Journal of Circumpolar Health. It also boosts the development of “good” fat that helps burn calories and combats obesity, cardiovascular disease and diabetes, the authors concluded.

James Mercer, PhD, a thermal physiology specialist from UiT who led the new research, says that many small studies over the years have hinted at the benefits of cold-water immersion. But the new review is one of the most comprehensive assessments of the benefits of cold-water swimming, bathing, showering and therapies based on exposing the body to low temperatures.

“It’s very rarely that you’ll meet a cold-water swimmer who thinks it’s a negative activity. They all swear by it,” Mercer says. 

Over the years there has been evidence that cold-water swimming can boost  your health, Mercer says. Among those benefits: Everything from increased libido to improved heart health, mental health, and more. 

Mercer says more research will help solidify the connection, “but we have to start somewhere, and what we’re seeing right now, I think without doubt, is that in some areas ... indeed, there may be some potential positive effects.”

Not a New Trend

Cold-water swims and therapies have been practiced for centuries in many countries with colder winter climates. 

“Ice swimming,” where the frozen ice over a lake or pond has been removed to expose the water below, is so common that global organizations have sprung up around the practice: the International Ice Swimming Association and the International Winter Swimming Association.

Ice swimmers typically take the plunge into waters that are under 50 degrees F and may even be near or just below freezing temperatures, Mercer’s team reports.

Many people who engage in these activities say they believe the practice has helped them lose weight, have better mental health (and less depression), improve their immune system function, boost their circulation, and even increase their libido, among other benefits.

 

But the new study gives greater scientific insight into how icy-water swimming, cold showers, ice baths, and exposure to cooler water and air temperatures might drive health benefits.

For the review, Mercer’s team conducted a detailed search of scientific literature on the issue, excluding studies where participants wore wet suits, experienced accidental cold-water immersion and water temperatures greater than 68 degrees. 

Among their findings:

  • Some studies showed solid evidence that cold-water swimmers often experience significant improvements in overall cardiovascular health. 
  • Cold-water immersion triggers a “shock response” that stresses the cardiovascular system and elevates the heart rate – a chief goal of high-intensity heart-healthy exercise. 
  • Ice baths and other hydrotherapies can reduce cholesterol, boost the immune system, help treat autoimmune inflammation, ease pain and speed recovery from sports injuries.
  • Cold-water swimming boosts the body’s stores of so-called “brown adipose tissue” (BAT), a type of “good” body fat activated by low temperatures. BAT burns calories to maintain body heat, which can lead to weight loss, unlike “bad” white fat which stores energy and hikes obesity risks.
  • Exposure to cold water or air boosts BAT’s production of adiponectin, a protein that helps protect against insulin resistance, diabetes and other diseases. 
  • Cold-water immersions greatly increase insulin sensitivity and decrease insulin concentrations. This is true for both inexperienced and experienced swimmers. 
  • Winter-weather swimmers typically describe feeling “joyful” in the water, suggesting the practice has “a positive effect on mental health and brain development.”

The researchers note the participants in the 104 studies varied widely. They ranged from elite swimmers and regular winter bathers to those with no previous winter swimming experience. Others were not strictly ice bathers but used cold-water immersion as a treatment after exercise. 

They added that other factors – beyond simply cold-water exposure – may play a role in the health benefits the studies observed. For instance, cold-water swimmers may be “naturally healthier” as a group and tend to live active lifestyles. They experience positive social interactions from such activities, have learned how to handle stress (often through meditation, breathing techniques and mindfulness practices), eat healthy foods and demonstrate “a positive mindset,” the authors report. 

Beyond icy-water swims, Mercer says his findings also apply to cold-water therapies, such as using ice baths after sports activities, cold showers and related treatments. 

Tips to Get Started

If you’d like to give cold-water immersion a shot,  you don’t need to jump in an icy lake, pond or the ocean during the winter. Amanda Alexander, ND, a naturopathic doctor with Sonoran University of Health Sciences in Tempe, AZ, and other experts recommend the following ways:

  • When showering, gradually turn the temperature of the water down, ending with cold water for 30-60 seconds. This can help blood circulate to the surface where cold water is applied and may also relieve congestion and boost energy.
  • You can also skip the warmup and go straight to a cold shower, particularly after a vigorous workout.
  • Wearing cold, wet socks also help improve blood and nutrient circulation by stimulating a pump-like effect within the circulatory and lymphatic systems, increasing vitality and speeding recovery from an acute illness with fever. 
  • Try an ice bath. Add ice to water until the temperature is 50-59 degrees F. Athletes have used ice baths for years, particular for sore muscles. Aim to stay submerged for no more than 10 to 15 minutes.
  • Swim in an unheated pool but not icy-cold water, at least for starters. 

If you do decide to give cold-water immersion a shot, Alexander, Mercer and other experts recommend talking to your doctor first if you have a heart condition or other health concerns.

It’s also a good idea for beginners to ease into the practice, keep your initial experiences to just a few minutes and gradually increase your time in the water as your cold tolerance increases. In addition, be sure to warm up after any cold-water immersion to eliminate the risk for hypothermia.

“Before anyone should get involved in this they have to be aware of the negative effects and the dangers, if you’re not used to this kind of activity,” Mercer says. “What I’m afraid [of] is people will think they should go and jump into icy-cold water without being used to it, perhaps not realizing they might have some underlying health problem.”

Even so, Mercer says he would not hesitate to recommend cold-water swimming, based on his own research.

“But with a proviso: If you do it, at least when you’re starting out, don’t go into the coldest water and perhaps do it with other people who know what they’re doing ... because there are some risks and people could die. Ice swimming is quite high stress on the body. But all in all, we do have some clear indications that there are indeed benefits.”

Lessons From a Polar Bear

Thomas, the Coney Island Polar Bear Club president, acknowledges that cold-water swimming isn’t for everyone and that it’s important for beginners and anyone with a pre-existing health condition to be careful.

But he’s known only a few individuals who have had negative experiences or health problems during the club’s regular Sunday winter swims. 

“We do encourage someone who’s new to this [or] has any concerns to consult with their physician first,” he says. “But in all these years, I’ve seen only a couple cases where people had a reaction, mild hypothermia, and I haven’t seen any heart attacks.”

Thomas took his first winter plunge in the 1980s after watching a group of Polar Bear swimmers jump into the ocean one wintry Sunday morning. Like many of the club’s 130 members, he did it on a lark, thinking it would be a one-and-done experience only. But he enjoyed it so much he decided to keep coming back, Sunday after Sunday.

So how does he stand the cold temperatures of the water?

“People ask me that all the time -- is it mind control that allows you to think it’s not that cold?” he says with a laugh. “And the answer is no, it’s cold every time. But it’s fair to say I know what to expect, and [now] I do it for fun, to be honest.” 

Thomas adds that Mercer’s study findings are heartening in that they support what Polar Bear members have long suspected to be true.

“We’ve heard a lot of anecdotal evidence through the years, small research studies and such,” he says. “Anyone who does this truly believes it brings them some sort of benefits in it, whether it’s physical, mental, spiritual ... or something like that. So I’m not surprised that science is starting to back that up.”

Show Sources

SOURCES:

Dennis Thomas, president, Coney Island Polar Bear Club. 

James Mercer, PhD, thermal physiology specialist, UiT The Arctic University of Norway.

International Journal of Circumpolar Health: “Health effects of voluntary exposure to cold water – a continuing subject of debate.”

Amanda Alexander, ND, associate professor of naturopathic medicine, Sonoran University of Health Sciences, Tempe, AZ. 

Taylor & Francis Group: “An icy swim may cut ‘bad’ body fat, but further health benefits unclear – review of current science suggests.”

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