Exercise & Our Immune System
As I'm still in recovery mode from my 50K run, I think it's a good time to write about exercise and our immune systems again. I'm thinking about this because marathon runners often develop colds or respiratory infections after a race. Many athletes are more susceptible to viruses after extreme exertion.
So what's the story - is exercise good for our immune system, or does it make us more susceptible to disease?
It all depends on the amount and intensity. Moderate exercise has been shown in studies (notably, a study by David Nieman, PhD, FACSM, in 1997: Moderate Exercise Boosts the Immune System, Too Much Exercise Can Have the Opposite Effect, published in ACSM Health & Fitness Journal) to boost the immune system. It's a temporary boost, lasting just a few hours. It is cumulative, however, so regular exercise prolongs the boost.
Researchers aren't totally clear on how it helps. It could be that the slight rise in temperature from exercise may inhibit bacterial growth. The activity and deep breathing may help to flush bacteria from the lungs. Or the immunity boost could come from white blood cells and antibodies being sent throughout the body during exercise. Exercise also inhibits stress hormones; stress hormones lower our immunity. Whatever the reason, moderate exercise helps our immune system.
But the key is moderation. Don't go and knock yourself out with a super-hard workout.
That same important study by David Nieman found that very intense or extended exercise lowers immune function. The same short-term boost in immunity happens, but then immune function plummets. That's why marathoners and other endurance athletes are more susceptible to colds after a big event.
And that's one reason why I'm making sure to take good care of myself: eat well, stay warm, get lots of rest, and drink plenty of fluids. But for the rest of you, add a little exercise to your cold-fighting regimen - extra vitamins, garlic, tea with honey, ginger, echinacea, golden seal.... Whatever it is, add in a walk.
- BY Julie | 01.11.2011
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