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.
I’d like to hope it boosts immunity–I’ve a ridiculously weak immune system, and I haven’t gotten as sick this year since I started swimming in addition to cycling!
Could also be all the apples you’ve been eating. =)
It’s an interesting, thought provoking article that you cite, but I think you mistated it slightly with your pasting regarding the T-1 cells. The article actually goes on to say that in moderate exercise the T-2 helper cells moderate the T-1 cells to reduce inflammation and actually increase the immune response. In the case of intense/long-duration exercise the T-1 cells are suppressed too much and the immune response is suppressed.
“In the mice at the University of Illinois, moderate exercise subtly hastened the shift from a T1 response to a T2-style immune response — not by much, but by just enough, apparently, to have a positive impact against the flu. “Moderate exercise appears to suppress TH1 a little, increase TH2 a little,” Woods says.
On the other hand, intense or prolonged exercise “may suppress TH1 too much,” he says.”
You make an excellent point! So many people are scared away by the thought of all the hard work that comes with regular exercise, but it’s actually moderate exercise, just a few times a week, that packs the most punch. That, combined with a general healthy lifestyle, can work wonders to boost immunity.