Winter Games

Just because the weather outside is frightful, that's no excuse for slacking off on your physical activity. With much of the U.S. in a deep freeze, however, this is probably a good time to review the rules for exercising in cold weather.

1. DRESS IN LAYERS The greatest danger is hypothermia, a condition in which the body's core temperature drops from 98.6F to below 96F. Sports doctors recommend that you wear an inner layer made of a material, such as polypropylene, that wicks away moisture so that your perspiration doesn't chill your body. (Don't use cotton, which retains moisture against the skin.) Choose something like fleece or wool for your middle, insulating layer, and make sure your outer layer protects against the wind.

2. GET A BUDDY It's easier to recognize the signs of hypothermia confusion, trouble speaking or walking in someone else than in yourself.

3. WATCH OUT FOR FROSTBITE The nose, ears, fingers and toes are particularly vulnerable to cold and need to be covered. If the temperature drops low enough or the wind is fierce enough, frostbite can develop on the corneas of the eyes as well, says Dr. William Roberts, president-elect of the American College of Sports Medicine. Men whose pants are too flimsy or who insist on wearing just shorts can develop a very painful condition known as testicular nip. Watch out too for earrings, nose rings and any other metal object that conducts cold right to the skin.

4. DRINK LIQUIDS Just because it's winter doesn't mean you don't sweat or breathe out a lot of moisture. If you're outdoors for more than an hour, take water or a sports drink with you. Avoid caffeine which, besides being a diuretic, will tax your already stressed-out cardiovascular systemand alcohol, which opens up the blood vessels in your limbs, causing you to lose heat from your core.

5. STRETCH Do it both before and after you exercise. This is especially important in winter, when muscles are more likely to be cold.

6. KNOW YOUR LIMITS Pay someone else to shovel the sidewalk if you have a heart condition. Cold air can be particularly hard on your lungs if you have asthma, but it can also trigger problems in folks who don't. Wearing a scarf or mask will reduce the amount of cold air going into your lungs. Call your doctor if you cough a lot and develop shortness of breath after exercising. "Minus 10 is not that bad if you're dressed for it and are used to it," says Dr. Roberts.

Of course, he's from Minnesota. Whatever your comfort zone, don't forget that there is always an alternative: just go indoors to exercise at a mall, at a gym or in your basement. Remember, spring is only nine weeks away.