Can Exercise Stave Off Colds?

Can exercise stave off colds? The answer, according to New York Times health columnist Gretchen Reynolds, is very possibly. Reynolds’ opinion comes from a new study conducted at Chosun University in Gwangju, South Korea, that found that regular exercise strengthens the body’s immune system in part by repeatedly stressing it. The researchers worked with mice, not people, testing the blood and the fat cells (for markers of inflammation) in 28 mice, half of whom did a 30-minute swimming five days a week for three weeks. At the end of that time period, all of the mice were inoculated with Staphylococcus germs, which can cause serious health problems in mice and in people. Reynolds reports that the infected swimmers had much lower levels of these pro-inflammatory cells, a natural response to invading germs, lower even than in the uninfected swimmers. The swimmers also produced an antimicrobial immune cell that kills germs. “Over all,” writes Reynolds, “the infected swimmers did not become as sick as the infected sedentary mice.” How did that work? The researchers don’t really know, but they suggest that the exercise reduced fatness, which, diminished the likelihood of excessive levels of pro-inflammatory substances produced by fat cells. They also think the exercise caused small amounts of continuous tissue damage and inflammation, which could have familiarized the animals’ bodies with trauma and encouraged healing. Read more in the New York Times.