Too Frigid?

For a quality workout, at what temperature should you run on a treadmill or brave the cold?

- John Kortman, Indianapolis

Cold weather brings a number of risks, from exposure to respiratory ailments and reduced performance. According to the National Weather Service, uncovered skin can get frostbite in 30 minutes or less when the wind chill is -15 degrees or below. However, there are no hard-and-fast rules for frostbite risks at different temperatures—risk depends on each person’s physiology and starting core temperature, among other things. Fingers and feet are especially vulnerable.

Fortunately, your lungs aren’t in danger of freezing. By the time air reaches your lungs, it’ll be warm enough to breathe safely. However, cold air, due to its dryness. can irritate the windpipe, especially for people who aren’t acclimated to frigid air. Even for perfectly healthy people, air at temperatures below 0 can contribute to bronchoconstriction.

In addition to bronchoconstriction, cold can reduce performance due to reduced body temperature. Studies show that the legs fatigue more rapidly if body temperature is low, possibly due to less powerful muscle contractions. If your body is not generating enough heat to stay warm, you shouldn’t be running at all, let alone running hard.