Cold water plunges are the rage. But does the science back up the devotion?

When Dafydd Snowdon-Jones was offered the chance to immerse himself in a container filled with frigid ice water, he was confident he would be able to follow instructions, breathe through the experience and not panic.

“I get in this thing and I really do feel like I’m going to die,” he recalled. “You go into survival mode.”

He stayed in the freezing cold temperature for two minutes and was hooked.

“You feel amazing — you feel energized for hours on end,” said Snowdon-Jones, an architect who lives in Orient. “It became addictive, to be honest.”

Cold water immersion is having its moment, with celebrities posting about their ice baths and year-round swimming groups becoming more popular.

Devotees swear by its physical and emotional benefits. But researchers are still trying to determine if the benefits touted by adherents, ranging from improving a person’s mood and immune system to reducing inflammation and hastening exercise recovery, are backed by science. In addition, some doctors warn the practice could be unsafe for people with cardiac conditions and other underlying illnesses.

‘Visceral’ cold plunge demand up

Several sites on Long Island offer cold plunge tubs, with water generally between 39 and 48 degrees, for people who want the immersion experience. Isar Castaneda’s introduction to cold water swimming led him to offer the therapy to his clients at Bayport Athletic Recovery. But the Patchogue resident admits he was more than a little reluctant to do it himself at first.

“I’m from Belize,” Castaneda told his buddy who suggested a Halloween jump in the ocean in Montauk several years ago. “I don’t do cold.”

But the former Marine gave it a go in the bone-chilling waters.

“It is very visceral,” he said. “It feels like everything you are doing is going to kill you and you should not be doing it.”

But, he added: “After the initial shock, it was amazing.”

Castaneda started a regular practice of cold water swimming and noticed it put him in a better mood, had him bouncing back quicker after workouts and led to better sleep.

More people are asking to try the cold plunge tubs, he said. Newcomers are monitored by staff who also make sure clients have discussed the therapy with their physicians. Castaneda, who said the treatment falls under hot and cold therapies as a licensed massage therapist, suggests sometimes they should start with cold showers at home.

Christine Moloney, of Blue Point, a retired teacher who works at the facility, said she does the immersion four times a week.

“When you first get in, it makes you feel like you are crazy, like ‘Why am I doing this?’ But after 60 seconds, you feel calm, relaxed and your mood is boosted and you have more energy.”

Cardiologist: Cold strains body

For people with heart problems, high blood pressure and other conditions, the strain cold water immersion puts on their bodies could be dangerous, said Dr. Hal Skopicki, chief of cardiology and co-director of the Stony Brook Heart Institute.

“If I submerge your whole body, your blood pressure shoots up because all those blood vessels have tightened,” he said. “Now your heart has to push against an incredibly high blood pressure. If your heart is weak, it is going to have trouble pushing the blood out in the forward direction.”

Exposing an entire body to deep cold is “demanding that the heart function at its highest level and be under its greatest strain,” he said.

These days, when Skopicki speaks to the public, he often is asked about cold water immersion.

He pointed out that actor Chris Hemsworth was recently filmed swimming in arctic waters, while singers Lady Gaga and Harry Styles have posted about ice water baths on social media. Add to that images of professional athletes icing their strained muscles, and some people start to wonder if they are missing out on something, he said.

“But the thing I will point out is these are relatively healthy people without known heart disease or high blood pressure, and their body’s ability to withstand this huge stress is far above the ability of those who are not as healthy as they are,” he said. “But it has not been conclusively demonstrated that cold immersion provides them with any additional health benefits.”

Skopicki added: “If you think about evolution, we got out of the cold water as quickly as we could not only to preserve body heat but also to allow our warm-blooded bodies to operate at peak efficiency while conserving energy. We lack the fur or blubber other aquatic or semiaquatic mammals have.”

People who are interested — and who are young and healthy — should try out a cold shower first, he suggested, before venturing into ice water, which could cause them to get disoriented or experience breathing difficulties and impaired motor function.

“If you are trying to improve your overall heart functions, there’s literally thousands of other things you can do with known benefits,” Skopicki said. “Top of the list is aerobic exercise.”

Help for sore muscles

The science behind cold water immersion, ice baths and polar plunges is still not well understood, said Dr. Brian Cruickshank, sports medicine physician in the Department of Orthopedics at Stony Brook Medicine.

“We do know that some effects to cold water immersion include an association with increase in heart rate, blood pressure, metabolism,” he said. “Ice in general can reduce pain and inflammation by decreasing blood flow, so the thought is that full-body submersion could reduce general inflammation.”

Ice baths long have been a treatment for athletes as a way to soothe aching muscles after a grueling game or workout.

“There is research claiming a lot of different things with ice baths and cold baths,” said Roger Gerland, director of sports medicine and rehabilitation services for Northwell Health and team physical therapist at Hofstra University. “I think the best research has been on decreasing muscle soreness. The other claims … I’m not completely sold on them.”

Gerland said once someone is submerged into the cold water, their peripheral blood vessels constrict, sending the blood to the primary organs such as the heart, lungs and brain. Once they exit the water in a few minutes, that blood rush goes back to the muscles in a flushing action, highly oxygenated and full of nutrients, that helps with recovery and removes the lactic acid that can build up during exercise.

“It’s also a stress load to organs,” Gerland said. “That’s where you have to be careful.”

He reiterated the importance of checking with your doctor before taking part in cold therapy.

“As long as you are OK to do that from a health standpoint, the benefits from this to me include the reduction to muscle soreness and recovery from exercise,” he said.

Devotees’ daily swim

Patricia Garcia-Gomez said she never set out to be a cold-water swimmer. 

“I had been living in Greece working on an art installation and swam every day,” she said. “It really got into my system.”

She moved to Orient and continued the practice, even when the temperature dropped.

Now she can’t imagine not being the water nearly every day. With water temperatures around 44 degrees this time of year, she swims about 18 minutes.

“This is my fitness, my connection to nature and my meditation, my happy place,” she said.

As cold water immersion had become trendy over the last year, Garcia-Gomez has seen a growing interest in the swimming group she joined, called the North Fork Polar Bears.

She said a mentor helped her get sensitized to the water, starting slowly and paying attention to tides and wind speed. She wears a neoprene swimsuit, gloves, a cap and booties.

“I learned my limits and I overstayed a few times,” Garcia-Gomez said. “And I’ve gone blizzard swimming, but if it’s really dangerous we don’t go. The point is not to put yourself at risk, it’s to enjoy it and not be afraid of the elements.”

Garcia-Gomez said her connection to water also has transformed her life.

“I discovered the magic of being out in the ocean by yourself in the winter,” she said. “The birds are swooping in, the seals are popping up. It’s like this intensely private wild space. It’s beautiful.”

A ‘sacred’ place

People hooked on cold water swimming said they are certain of the physical and emotional benefits, even if the scientific community hasn’t caught up yet.

Snowdon-Jones, who is also a member of the North Fork Polar Bears, regularly runs to the beach from his home for a swim. He always brings a thermometer, because when the water temperature dips into the 30s, he doesn’t stay in longer than five minutes.

“It’s so sacred, it’s so magical to be in that water to be held by the water,” he said. “It’s not about getting in or how long am I staying in, it’s really about being there and relaxing.”

Lisa joined Newsday as a staff writer in 2019. She previously worked at amNewYork, the New York Daily News and the Asbury Park Press covering politics, government and general assignment.