A new study shows postmenopausal women who exercised regularly lowered their risk of coming down with colds compared with more sedentary women.
Researchers found the protective effects of moderate exercise, like brisk walking, on preventing colds also appeared to increase over time. By the end of the yearlong study, nonexercisers had three times the risk of colds than women who exercised regularly.
"This adds another good reason to put exercise on your to-do list, especially now that cold season is here," says researcher Cornelia Ulrich, PhD, of the Fred Hutchinson Cancer Research Center in Seattle, in a news release.
It's the first yearlong clinical trial to look at the effects of moderate exercise on fighting the common cold and suggests regular physical activity can boost the body's immune system and prevent infection. But experts say further research will be needed to confirm these results.
Walk Away From Colds
In the study, published in The American Journal of Medicine, researchers divided 115 previously overweight or obese and sedentary postmenopausal women into two groups. They were all nonsmoking women.
One half was asked to engage in moderate exercise at home or at a gym for 45 minutes a day, five days a week. Among the exercise group, brisk walking was the activity of choice for most of the women. The other half of the women acted as a comparison group and participated in a 45- minute stretching session once a week.
During the study, the women recorded their exercise habits and any episodes of allergies, colds, and other upper respiratory infections, such as flu.
The results showed that over the course of the year, the risk of colds decreased among exercisers and increased modestly among the nonexercisers. Overall, 48% of stretchers had at least one cold during the study compared with 30% of exercisers.
By the last three months of the study, the risk of colds was three times higher among nonexercisers.
"The enhanced immunity was strongest in the final quarter of the yearlong exercise intervention," says Ulrich. "This suggests that when it comes to preventing colds, it's really important to stick with exercise long term."
Ulrich says regular exercise in moderation, such as 30 to 45 minutes of brisk walking, appears to be the key. Other studies have shown that excessive, exhaustive exercise can deplete the immune system and increase the risk of colds.
"It's been shown that just a 30-minute walk can increase levels of leukocytes, which are part of the family of immune cells that fight infection," Ulrich says, which may help explain the protective effect found in the study.
SOURCES: Chubak, J. American Journal of Medicine, November 2006; vol 119: pp 937-942. News release, American Journal of Medicine. News release, Fred Hutchinson Cancer Research Center.
By Jennifer Warner
Reviewed by Louise Chang