The temperature hovered around 35 degrees on a recent winter morning at Seattle's Golden Gardens. A group of friends waded into the water, wearing only their bathing suits, swimming caps and goggles.
“We just wait until we're not in pain anymore,” Andrew Lee said. “And then we slowly start going.”
“And then maybe there’s expletives,” Madison Yamane laughed.
The friends met while open water swimming, and like others who frequent this beach, they dunk in the ocean regularly, even during the coldest winter months. These cold plungers swear doing so helps their physical and mental health.
Some studies back that up, though most have small sample sizes or lack robust control groups. Nevertheless, those researchers have found immersion in cold water helps with inflammation, stress, and sleep. It may even boost plungers’ immune system and mood.
Ben Schreck, 30, stood bare-chested on the beach, shivering with a towel over his shoulders. He tries to dunk weekly; it helps him stay resilient.
“Even if there’s stuff going on in my life, I get in and there’s nothing else that I can think about,” Schreck said. “Other than the fact that it is so cold.”
Gym buddies Darci Cascioppo and Mallory Roth didn’t hesitate as they walked into the Puget Sound wearing knit hats.
“I was in a really stressful job when I started, and it was a way to have a ritual, have something to ground me,” Roth said.
Cascioppo sought out the practice for its purported physical benefits.
“My knees were twingey, and I definitely can tell the difference,” she said.
Perhaps the most robust research on cold plunging comes from athletes who use ice baths between big games, said Chris McMullen, a sports medicine doctor at the University of Washington School of Medicine.
“Cold water is likely reducing inflammation, swelling that may occur after a hard workout or a game,” McMullen said. “By reducing swelling, there's decreased pressure on pain receptors.”
“That’s all that fight-or-flight response. The goal is to keep our vital organs warm, so our organs in the chest, and our heart and lungs and brain.”Chris McMullen, University of Washington School of Medicine
When people enter cold water, the body has immediate physiological responses, McMullen said: adrenaline, endorphins, and a spike in blood pressure, heart rate, and the rate of breathing.
“That’s all that fight-or-flight response,” he said. “The goal is to keep our vital organs warm, so our organs in the chest, and our heart and lungs and brain.”
Given that stress response, it may seem counterintuitive that people report mental health benefits after cold plunging — especially if they dunk on a regular basis. But they do.
“After you warm up, you just feel amazing the whole rest of the day,” said Emily Ausema, from the swimming group.
McMullen, the UW doctor, said some research backs up that feeling.
Researchers in Finland found that after weeks of cold plunging, women who participated had lower cortisol levels, measured 35 minutes after they got out. They published the 2009 study in The Scandinavian Journal of Clinical & Laboratory Investigation.
“There are often folks that report, in the several hours after the cold plunge, they have this feeling of relaxation,” McMullen said.
But he said scientists still haven’t pinned down what’s driving the potential benefits of this practice. It could be the cold water immersion. It could also be exercise, the outdoors, or spending time in a group and doing something enjoyable.
There are risks to plunging in frigid water, too. People with underlying conditions like cardiac issues, high blood pressure or poor circulation could be at risk of cardiac arrest or hypothermia.
But for those who want to try it, McMullen said 30 to 60 seconds in the cold water is plenty when starting out.
At Golden Gardens Park in Seattle, the swimmers advised newbies to go with friends, try it at least twice and to bring warm clothes for after. As their teeth chattered and they donned towel ponchos, one thought rose to the surface for Andrew Lee:
“If we could do it today, we can do it the rest of the year."
