By Carol Krucoff
If you're heading outdoors to hike, chop wood, skate or do any other physical activity in cold weather, don't bundle up. Overheating can be a serious problem for people who exercise in the cold, note experts, who say it's better to layer on clothing.
"Balance how hard you'll be working out with how cold it is and wear appropriate layers that you can shed like shells as your body heats up with activity," says environmental physiologist Andrew Young, a cold weather specialist with the U.S. Army Research Institute of Environmental Medicine in Natick, Mass.
If you slow down or stop exercising, you can put one or two layers back on.
The Art of Layering
Young instructs soldiers who are dressing for cold weather assignments to remember the acronym COLD, which stands for Clean, avoid Overheating, Layer and Dry. "Clothes should be clean so that oil and dirt doesn't accumulate in the pores of the clothing and interfere with ventilation," he says.
"And it's important to avoid overheating, since that will cause your clothes to get soaked in sweat." If you stop your activity or if a strong wind blows while you're wearing perspiration-soaked clothes, you're likely to get chilled.
In addition, "once your workout clothes get sweat-soaked they can lose as much as 90 percent of their insulating capabilities," notes the Penn State Sports Medicine Newsletter. That's why it's also important to layer on clothes and keep dry.
The key to layering is choosing fabrics that will move perspiration away from your body, while helping retain heat.
Here's a guide to a three-layer system that should keep you comfortable during most cold-weather workouts.
- Inner Layer: The fabric next to your skin should be lightweight, snug-fitting and able to wick perspiration. Look for undershirts made of synthetics, such as polypropylene or acrylic, designed for this purpose. Avoid cotton, which absorbs moisture. On colder days, layer nylon tights or polypropylene leggings under your pants.
- Middle Layer: This is the insulation layer, which should also wick moisture and provide warmth. Choose a slightly thicker fabric that fits loosely over your inner layer to trap the air warmed by exercise-generated heat. Wool is often used because its crimped fibers retain insulating air. If you find it too heavy, try lighter-weight synthetics, such as polyester fleece or therma fleece.
- Outer Layer: Like a protective shell, this layer shields you from wind, rain and snow. A light nylon jacket may suffice, or you may want to choose synthetics designed for this purpose. Zippered garments have the advantage of letting you unzip as much as you want for comfort when you heat up from activity.
Warm in the Middle
It's important to keep your torso warm because your body will keep vital organs comfortable at the expense of your extremities. But don't forget a hat, since at least 40 percent of body heat can be lost through the head.
Protect your fingers with mittens, which will keep your hands warmer than gloves, notes Lorentz Wittmers, Jr., a physiologist at the hypothermia lab of the University of Minnesota at Duluth. "Never wear anything tight on your hands that could restrict blood flow to the fingers," he cautions.
Avoid alcoholic beverages if you're going out in the cold, Wittmers adds. A nip of whiskey may "make you feel warm," he says, "but it's a false stimulation." Alcohol causes peripheral blood vessels to dilate, radiating heat away from the body. "And alcohol can impede your judgement," he notes, "so you might not take the appropriate precautions against hypothermia."
Other drugs also can affect heat regulation, including barbiturates, narcotics and tricyclic antidepressants, notes The Physician and Sportsmedicine journal. Inadequate nutrition can decrease cold tolerance, too, so eat some carbohydrates and drink fluids before being active in the cold.