What about fitness levels? “You will lose whatever advantages you’ve gained over time and be back down to couch potato status within three to six months, but the effect of inactivity starts within days,” says exercise physiologist J.P. Hyatt, an associate professor in the Department of Human Science in the School of Nursing and Health Studies at Georgetown University. For starters, he points out that cardiopulmonary fitness can decrease by 20 percent within three to eight weeks of stopping your workouts.
For those who worry that being active outdoors in extreme cold also poses a risk to health, sports physiologist Mike Bracko of the Institute for Hockey Research in Calgary, Alberta, offers reassurance: “There is no real danger, whether you’re running, cross country skiing, taking a long trail walk or anything else, as long as you’re prepared and dressed appropriately.”
Delia Roberts, an exercise physiologist who chaired the winter-sport interest group for the American College of Sports Medicine, agrees. “As soon as you start exercising at a reasonably high level — even just walking with purpose — about 40 percent of the energy you consume is lost as heat, and so your body very quickly warms up” she explains.
The key is learning how to keep your overall body temperature at a constant level. “If you lose too much heat, that’s when it becomes problematic,” says Roberts, who says careful layering is key to guarding against the cold, wind, rain, snow and other elements. She suggests always protecting your extremities — head, hands and feet — which lose heat quickly, and using a vest to keep your core toasty.
Many people wonder whether there’s a specific danger temperature, but it’s really all relative. “Everybody’s different — one person may not want to go outside at 32 degrees, while another is okay at zero — so it’s really based on individual comfort level,” says Bracko, who exercises outdoors throughout the Canadian winter and finds it “refreshing and invigorating.”
Roberts says she knows people who are active outside no matter the weather, and she provides some tips that may allow you to do the same.
Avoid overdressing. Though walking out the door for a winter workout can be a shock, it’s important not to load up with too many thick layers, and also to shed clothes when you start warming up. “If you keep heat in too much, you’re going to sweat; and if you’re sweating heavily, it doesn’t matter how good the wicking properties of a material are: You’re going to be saturated,” says Roberts, who notes that damp clothing not only is uncomfortable but also hastens the loss of body heat.
Grab a scarf. Lung tissue is very delicate and can be damaged if it’s exposed to freezing-cold air. A muffler can help you create a space to warm air before you inhale it into your mouth and nose, says Roberts, who suggesting starting “with the scarf wrapped close and tight and then, as body temperature increases and your face is generating more heat and the air is being warmed faster, you can adjust and loosen it.” She adds that this step is especially important for someone with asthma, “whose airway is going to be little more reactive and susceptible to those changes in air temperature that can cause constriction.”
Don’t forget to hydrate. Even though you may not sweat profusely in the cold, you’re still losing fluid through your lungs; thus, drinking water or sports beverages is as important as in the heat, says Roberts. She says some research suggests that people may be more susceptible to frostbite when they are dehydrated.
Keep moving. When you’re jogging, biking or being otherwise active at a pretty good pace, your body will generate enough heat to warm. But if you stop moving, because of fatigue or an injury, “that can be a real problem,” says Roberts. “You cool down very rapidly and may have a problem maintaining your body temperature, which increases the risk of frostbite, hypothermia and other issues.” Always watch out for slick, icy terrain.
If you simply can’t face braving the cold, there are plenty of ways to get a decent workout indoors, whether it’s at a gym or using inexpensive motivators such as workout DVDs, fitness apps or weights at home, says Georgetown’s Hyatt. But he warns that because indoor fitness can be monotonous, people may not exercise long or often enough. That’s okay, he counsels, as long as you increase intensity. “That will challenge your cardiovascular and muscular systems enough to keep moving forward — or at least sustain the initial fitness you had in the summer months — all through the winter.”