Resist the temptation to bundle up like Nanook of the North. Exercise generates heat, and if you start to sweat, you'll get cold when that sweat dries. Instead, dress in layers. Start with a thin synthetic layer to wick sweat. Avoid cotton. Pull on a wool or fleece layer next, and top it off with a waterproof, breathable outer layer. If it's really cold, you might want a face mask or scarf to warm air before you breathe it in.
Photo: John Spink
Photo: John Spink

The ins and outs of exercising in cold weather

From runny noses to freezing lungs, questions about cold weather exercise answered

Can you get dehydrated in the cold?

Dehydration doesn't just occur under a hot summer sun. It's one of the biggest problems when exercising in cold weather. Most people don't feel as thirsty when it's cold, and they drink less. That's because cold actually inhibits the thirst sensation, according to a University of New Hampshire study published in Medicine & Science in Sports & Exercise. Blood moves away from the extremities and into the body's core. Since the fluid level in the central body doesn't drop, the kidneys don't get the signal to conserve fluid. The thirst response decreases by about 40 percent.

What's the best temperature for running?

Austin runners already know it's better to run a marathon in February than August. A study from the U.S. Army Research Institute of Environmental Medicine proves it. After studying years of results and weather data from six major marathons, researchers showed that colder temperatures meant faster times. The ideal long-distance running temperature, according to the study, is 41 degrees. The times of top male runners were 2.5 percent slower than the course record when the temperature was between 51 and 59 degrees. Finishing times were even slower at higher temperatures.

Can your lungs freeze in extreme cold?

Nope. People in cold climates used to avoid running outside in the winter, but freezing lungs are a myth, according to Blair Gorsuch at the CardioPulmonary Rehabilitation Center at Proctor Hospital in Peoria, Ill. The body naturally warms air before it enters the lungs.

Why does your nose run in the cold?

The nose's job is to warm and humidify air that you breathe into your lungs. If the air is cold and dry, the nose increases fluid production. Sometimes it makes too much, and your nose runs. There's another factor at work, too. Water in warm air condenses in cold air. When you breathe warm air out your nose, some of it might condense at the tip of your nose, where it's cold. Voilà, runny nose. A runny nose also could be a sign of exercise-induced rhinitis. Physical exercise often triggers the symptoms, which include inflamed nasal mucous membranes that pump out more mucus during exertion.

Do you burn more fat exercising in colder weather?

Probably not. A 1991 study published in Sports Medicine found that "the combination of exercise and cold exposure does not ... enhance metabolism of fats." In fact, some bodily processes involved in fat metabolism slow down in cold temperatures. That slowdown might be because blood vessels in peripheral fatty tissues constrict when it's cold outside. The heart rate is usually lower in cold weather exercise, too.

Do exercisers catch fewer colds?

Yes, according to a 2008 study reported in the British Journal of Sports Medicine. After tracking about 1,000 American adults for 12 weeks, researchers determined that regular aerobic exercise might cut the risk of catching a cold or other upper respiratory infection nearly in half. According to the study, people who exercised at least five times a week had up to 46 percent fewer sick days than those who exercised only one day a week or less. The exercisers had an average of 4.41 sick days versus 8.18 days for the couch potatoes. And when they did get sick, their symptoms were milder.

What about goose bumps?

Goose bumps are the body's way to help keep us warm. Rising hairs trap cold air and form a protective shield so cold air doesn't come into direct contact with sensitive skin, according to "The Odd Body," by Dr. Stephen Juan.

Does cold increase heart attacks?

More heart attacks occur in cold weather than in warm weather. In fact, with each drop of 1 degree Celsius, about 200 extra people have a heart attack within 28 days, according to a study in the British Medical Journal. Researchers say that's because very cold temperatures cause an increase in blood pressure — and a better chance for blood clots.

Is it harder to lose weight swimming in cold water than warm water?

Yes, according to a 2005 study by the University of Florida. In a nutshell, exercising in cold water makes you hungry. The study tracked energy used by students who rode a stationary bicycle submerged in water at 68 degrees and again at 91.4 degrees. They burned roughly the same amount of energy during each session, but ate 44 percent more calories after exercising in cold water.

What should you eat to exercise in the cold?

When it gets cold, your body temperature drops. To stay warm, you need to generate heat. Eat complex carbohydrates two hours before you exercise. Warm foods like soup, whole wheat pasta and baked potatoes are good, but sometimes inconvenient. Other suggestions? Peanut butter, whole wheat bread, whole grain cereal, lean meat or low-fat cheese. During long periods of exercise, eat small amounts at frequent intervals. If you don't replace the energy you're consuming, you'll get tired and chilled more easily.

More tips for exercising in the cold:

1. Layer it: Resist the temptation to bundle up like Nanook of the North. Exercise generates heat, and if you start to sweat, you'll get cold when that sweat dries. Instead, dress in layers. Start with a thin synthetic layer to wick sweat. Avoid cotton. Pull on a wool or fleece layer next, and top it off with a waterproof, breathable outer layer. If it's really cold, you might want a face mask or scarf to warm air before you breathe it in.

2. Protect your extremities: Chilly temperatures mean your body protects its vital organs. Blood flow to your hands and feet is diminished. Wear gloves and warm socks.

3. Avoid frostbite: If temperatures drop below zero degrees or the wind chill is extreme (not likely in Austin, but we know Texans like to ski), exercise outdoors can become unsafe. Exposed skin is prone to frostbite. Consider exercising indoors instead.

4. Choose the right gear: If it's dark when you exercise outside, wear reflective clothing. Wear shoes with enough traction to stop falls on ice or snow. Wear a helmet during snow sports and while cycling.

pleblanc@statesman.com; 445-3994

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