Working out regularly doesn't only help tone your body and build muscle — it could also help you avoid catching the common cold, a new study suggests.
People who exercise five or more times a week get fewer and less severe colds than those who work out one or fewer times a week, said Dr. David Nieman, director of the Human Performance Laboratory at Appalachian State University in North Carolina.
"The most powerful weapon someone has during cold season," Nieman told MyHealthNewsDaily, "is to go out, on a near-daily basis, and put in at least a 30-minute brisk walk."
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Nieman and his colleagues found exercising stimulates the movement of immune cells throughout the body about three hours after a workout. The more often a person exercises, the more often their immune cells will be on high-alert for invading pathogens.
"It's the frequency, and getting the cells moving," he said. "That's what provides the top-level protection of the body."
The study was published online today (Nov. 1) in the British Medical Journal.
Researchers tracked the respiratory health of 1,000 people, ages 18 to 85, for 12 weeks during autumn and winter, and asked them questions about how often they exercised and how fit they felt.
The researchers found the length of time cold symptoms lasted was shorter by 43 percent to 46 percent in people who worked out five or more times a week, compared with people who worked out once a week or never. [Related Infographic: Colds, Allergies or Sinusitis? Here's How You Can Tell]
And people who felt the fittest had cold symptoms that were 41 percent less severe than those of people who felt the least fit.
"We looked at diet, we looked at mental stress, weight, education levels, gender, on and on," Nieman said. "The thing that people can do — the way they live — that's head and shoulders above all of them, is physical activity."
People who are older and married are less likely to get a cold than people who are young and single, the study found. Older people may have more antibodies than younger people, Nieman said. And married people may go out less or might have less exposure to other people and their germs, he added.
Confirming past results
Previous studies have suggested a link between exercise and a boosted immune system.
A 2002 study in the journal Medicine & Science in Sports & Exercise found moderate physical activity reduced the risk for an upper respiratory tract infection by 23 percent, compared with low levels of physical activity.
And a 2006 study in the American Journal of Medicine found one year of a moderate-intensity exerciseregimen could reduce the incidence of colds in postmenopausal women who were overweight or obese.
"From animal data to multiple human trials, we've kind of reached a point now where there's enough evidence that this has to be real," Nieman said.