Running is a popular topic among my circle of friends. I don’t run personally, but I know a surprisingly large number of crazies who run marathons, and a few other aspiring crazies who run recreationally and occasionally hint at training for a marathon.
Many people see running a marathon as symbol that they’ve “arrived” at physical fitness. And yet, the same people often comment on how bad marathon training is for the body. Sure, you might have zero body fat, but you’ll also have put a lot of stress on your bones and joints. Not only that, but lots of people I know seem to more apt to catch colds while training. Can this really be good for you?
Tim pointed me out to this interesting article in yesterday’s New York Times about exercise and immunity. Recent studies suggest that moderate exercise may boost immunity, but push your body too far and exercise has the opposite effect.
Why exercise effects your susceptibility to cold and flu is still unclear, but the studies suggest why, once you’ve caught the bug, intense exercise can make it worse.
… viruses evoke an increase in what are called T1-type helper immune cells. These T1-helper cells induce inflammation and other changes in the body that represent a first line of defense against an invading virus. But if the inflammation, at first so helpful, continues for too long, it becomes counterproductive.
And here’s an interesting statistic:
1,694 runners at the 2000 Stockholm Marathon informed researchers about any colds or other infectious illness they developed in the three weeks before or three weeks after the race. Nearly one-fifth of the runners fell ill during that time period. That’s higher than the rates in people generally, but it still means that the overwhelming majority of runners didn’t get sick.