Almost everyone can work out safely in cold weather. In fact, scientists have suggested no temperature is too low to exercise outdoors as long as you suit up to minimize cold-weather risks. American College of Sports Medicine position stand: prevention of cold injuries during exercise. Castellani JW, Young AJ, Ducharme MB. Medicine and science in sports and exercise, 2007, Jan.;38(11):0195-9131. And though it's obvious that high-intensity workouts—like boot camp training or running—are better choices for staying warm than, say, yoga, your body will work to maintain a core temp of 98.6 degrees no matter what you're doing.
"I still remember working out in 9 degrees," says Anthony Burdi, co-founder of The Rise, a year-round outdoor workout group based in New York. "Afterward we said, 'I can't believe what we just did!' But it's not as bad as you think."
Exercising outdoors when the temperature drops below freezing does come with annoyances. But that runny nose is a good sign. The inside of the nose moistens to humidify the air we inhale, and the excess fluids creep out our nostrils. As for that icy air hitting your lungs? It's basically impossible for freezing air to damage your lungs. Try wearing a scarf and keep layers on your chest to feel warmer as you inhale.
There are a few groups of people who should be cautious before trekking outdoors for a mid-winter run. If you have asthma, the cold, dry air can trigger lung tightness and asthma attacks while exercising. And if you've been diagnosed with poor blood circulation or heart problems, it's best to check with your doc first before hitting the frozen pavement.
Your Action Plan
1. When the windchill is in the negatives, skip the outdoors.
"Extreme wind chill can make it unsafe—even if you dress warmly," says Lipi Roy, M.D., an internist at Massachusetts General Hospital and instructor at Harvard Medical School. As a general rule, if it's warmer than five degrees (F), your chances of frostbite are low, Roy says. But when the windchill brings temps down to below -15 degrees, exposed skin can get frostbitten in less than 30 minutes. Translation: The treadmill is calling your name.
2. Know the warning signs.
The first sign of frostbite is numbness, followed by a tingling or burning sensation. If you suspect frostbite, head back inside and warm the area gradually by running it under lukewarm water or wrapping it in a warm blanket, Roy says.
While you can treat superficial frostbite at home, hypothermia is a true medical emergency. If anyone you're working out with has slurred speech, intense shivering, or a loss of coordination, get to a hospital stat.
3. Wear synthetic fabrics, fleece, and wool.
"The first layer should be synthetic—something that will wick moisture away from your skin," Roy says. The second layer should be fleece or wool to help insulate, and the third should be a breathable, waterproof layer to help repel wind. Avoid cotton: It loses its insulating power when we become sweaty.
"The one thing I'm always really adamant about is having something dry to change into," says Chris Lopez, another member of The Rise. "When the workout is over, you don't want to be stuck in wet, sweaty clothes when it's 30 degrees outside."
4. Cover your head, fingers, and toes.
Blood flow stays concentrated in our core, making our limbs more susceptible to the cold. In addition to wearing gloves, consider roomier shoes to accommodate thermal or wool socks. A large percentage of body heat is also lost through the head, so wearing a hat is a must. For extra protection, wear a face mask or scarf. And don't forget sunscreen on your exposed face—especially if you're skiing. "UV rays are just as strong in the winter," Roy says.
Lopez also suggests an unconventional idea: Wear latex gloves under your regular gloves. That way, if you're doing burpees or push-ups on any potentially wet or icy surface, your hands won't end up wet, even if your gloves do. Same goes for your feet. "Put a small plastic bag on each foot, then your socks, then your shoes," Lopez says. Admittedly it can look a little goofy.
5. Avoid the rain and wind.
The body has a hard time managing its temperature when soaked; water draws heat away from the body 25 times faster than air because of its higher density and heat capacity. And freezing windchill can be dangerous (like we mentioned earlier). Not only can it quickly make the outdoors feel much colder than the themometer reads, wind pushes air and moisture through our clothes and removes the layer of warm air that surrounds our body. #Rude.
6. Don't overdress.
Since your body warms up once you get moving, it's OK to feel cold at first. When performing higher-intensity activities, overdressing can lead to excess sweating, which will cause the body to become wet. Damp skin is an unfortunate conductor of heat loss and will lower body temperature and increase risk of hypothermia.
The solution isn't very scientific: "Just experiment [with layers], and see what your body best tolerates," Roy says.
7. Enjoy the scenery.
Don't forget that being outside likely means better views—no matter where you live. "For us, we get time to enjoy New York for New York—enjoy all the beauty," Lopez says. "If you're at the gym, you always see the same thing."
And let's face it: Whenever you want, you really can just head back inside. There's always hot yoga.
Originally published November 2011. Updated January 2016.