Some studies show that "moderate intensity" exercise may cut down the number of colds you get. That type of activity includes things like a 20- to 30-minute walk every day, going to the gym every other day, or biking with your kids a few times a week.
In one study in the American Journal of Medicine, women who walked for a half-hour every day for 1 year had half the number of colds as those who didn't exercise. Researchers found that regular walking may lead to a higher number of white blood cells, which fight infections.
In another study, researchers found that in 65-year-olds who did regular exercise, the number of T-cells -- a specific type of white blood cell -- was as high as those of people in their 30s.
Should You Exercise When You Have a Cold?
It's usually safe to do it as long as you listen to your body. You'll need to watch out for certain risky situations.