You know that regular exercise is good for your health, but did you know that it can also be a suprisingly potent vaccine?

Here's what they had to say in a recent article in O Magazine, "Outrun a Cold," March 2007):

"In the first randomized clinical trial to investigage the connection between physical activity and colds, sedentary, postmenopausal women were about twice as likely to get sick as those who worked out regularly for a year. Most of the exercisers chose brisk walking as their activity and averaged 30 minutes five days a week.

'Increased blood flow stimulates the immune system,' says Cornelia Ulrich, PhD, senior author of the study (published in The American Journal of Medicine). Each bout of exercsie, the researchers hypothesize, may boost virus-fighting cells called leukocytes."

Take it from a girl who has gotten the Erie Times-News "perfect attendance" award for five years running (not counting maternity leave) -- exercise makes your body more ready to fight germs from the common cold and flu. Despite living with two young children who go to school (and bring home all kinds of bugs), I can count on one hand how many colds I've had this year (knock on wood).