SWIMMING OUTDOORS IN WINTER?
Some people love it, but make sure to bring a swim parka
It's 6:45 a.m. and cold — in the mid30s F or about 1 C — when I step onto the Bethesda-chevy Chase YMCA'S outdoor pool deck, a towel wrapped around my shoulders. Pink streaks punctuate the sky, and I can still see the moon. A canopy of steamy vapour hovers above the heated water. I sink into the pool and start swimming, the contrast of bracing air and warmish water exhilarating.
Think I'm crazy? You're not alone. It's difficult for some to imagine swimming outside when it's near freezing. But outdoor winter swimming in a heated pool is safe, experts say, and good for your health. For the dedicated cadre of outdoor winter swimmers who join me every morning, there's nothing like it.
“It's a pleasure to feel so alive,” says Valerie Campbell a Kensington, Md., massage therapist who swims outside at the Y five mornings a week all year long. “We enjoy the sunlight, the fog over the water, even the brutal wind at times, which can chill the heels of our feet as we kick. Sometimes people from `inside' come out, but they never last long,” referring to indoor swimmers.
An outdoor swim on a cold evening also can be awe-inducing. Robert Judson, a financial consultant from Bethesda, Md., recalls the one time he missed his usual sunrise swim and made it up after work. “It was a pitch-dark cold night with the stars out,” he says. “It began snowing very lightly midway through my usual slow mile. It was perfect. Perhaps too perfect. Maybe it was a dream.”
Non-swimmers and even those who swim inside don't always understand the passion for winter swimming. But they are OK with it, even grateful. “I am delighted that there are so many nuts who love swimming outdoors,” says Kate Macomber Stern, a teacher who swims 45 minutes daily. “That makes the indoor pools much less crowded.”
Although it can feel particularly invigorating, experts say that health-wise, swimming in a heated pool outdoors doesn't provide any more health benefits than indoor swimming.
Cold air doesn't affect the calories you burn, although swimming in cold water can — if shivering is added to swimming, says Mike Tipton, professor of human and applied physiology at the University of Portsmouth's School of Sport, Health and Exercise Science. “This is a miserable experience. The shivering disappears when you exercise at an intensity above `light exercise.'”
In warm waters outdoors, there is little danger of hypothermia — or abnormally low body temperature that can occur from exposure to extreme cold — once a swimmer starts moving, experts say. Unlike in unheated outdoor waters, a swimmer's body fat isn't that important, they say.
“Once you are in the (heated) water, the thermoregulatory aspect” — the body's ability to maintain a safe temperature — “is normal,” says Scott Trappe, director of the human performance laboratory and professor of human bioenergetics at Ball State University. “There is nothing in that scenario that would cause a thermoregulatory risk.”
The risk of hypothermia increases when the water temperature drops into the 70s F or 21 C. This is one reason many competitive open-water lake and river swimmers train in outdoor heated pools during the winter.
“If we're talking only winter, I typically don't swim in open water then,” says Diane Mcmanus a teacher from Upper Darby, Pa., who swims in the Schuylkill River through October. “I like the pool because it's easier to get in and out and still has some closeness to nature — looking up at the stars during night swims, enjoying the sunrise in the dawn swims.”
In February 2022, she made an exception to compete in the Lake Memphremagog Winter Swimming Festival in Newport, Vt., where two lanes are cut into the frozen lake and the event is conducted like a regular swim meet — with spectators dressed in parkas, hats and boots. Mcmanus is an experienced river and lake swimmer, acclimatized to swimming in ridiculously cold conditions. This contest had both, she recalls.
“They had to keep monitoring the water so it wouldn't refreeze,” she says. “I did just 25-metre events,” which are mercifully short. “It was challenging but pretty amazing, too,” she says.
When the water is very cold, below 70 degrees, swimmers must take precautions and adapt, experts say. This means exposing themselves to cold water gradually over time, says Michael J. Joyner, physiologist and anesthesiologist at the Mayo Clinic in Rochester, Minn.
“If the water temperature is really uncomfortable and you're not used to it, you need to be careful,” he says. “If the temperature is below 70, get in for a few minutes today, then a few minutes tomorrow and so on.”
How long does it take? “It's variable,” Joyner says. “But temps that once felt cold can feel not so cold in a matter of days or a week.”