How exercise keeps you from getting sick

Josef Brandenburg
WTOP Fitness Contributor

WASHINGTON — Cold and flu season is here, and one of the most powerful tools to keep from getting sick is exercise.

The average American gets two to four colds each year, and each one sticks around for seven to 10 days — leaving you feeling miserable for 14 to 40 days each year. But working out just three days a week could prevent this.

How does exercise support the immune system? The experts have several theories:

  • The deep and full breathing that occurs during exercise might help to flush out your lungs and make you more resistant to respiratory infections.
  • Exercise helps balance stress hormones such as cortisol. When cortisol is too high, it suppresses your immune function. (This is why workouts that are too intense or too long undermine your immune system.)
  • Regular exercise changes T-cells, a type of white blood cell, to the ones that are better at fighting disease.

While exercise keeps you in top mental and physical shape, too much of it can make you sick. There is a fad in fitness in which working out until you collapse or are so exhausted you can’t keep going, is considered a good thing. Besides being dangerous and ineffective over time, this kind of exercise suppresses your immune system because it stimulates the secretion of too much cortisol.

In fact, this kind of exercise is worse than no exercise, since it makes it more likely that you will get sick. Long exercise sessions — anything at moderate intensity or higher that lasts 90 minutes or more — also seems to suppress the immune system.

So, if you are preparing for a marathon, take extra care after your long runs by washing your hands frequently and replenishing your body with the proper nutrients.

Should you exercise when you’re sick?

Yes! (Probably.) If the illness is above the neck, then yes. The exercise (if not excessive) will probably boost immune function, help suppress bacterial growth and get you better faster. Listen to your body, and tone down your efforts to match your energy levels.

However, if you have a fever, diarrhea, vomiting and/or other below-the-neck issues, wait until all of those symptoms have gone away. After you feel better, wait a few days, and take it easy when you come back.

Regular, reasonable exercise is very important when it comes to keeping your immune system in tip-top shape, but it’s not the only important factor. Getting quality sleep, getting enough vitamin D, managing stress and avoiding sugar and other highly processed carbs also contribute to staying healthy.

Editor’s Note: Josef Brandenburg is a D.C.-area fitness expert with 14 years of experience and co-author of the international best-selling book “Results Fitness.” In 2004, he started The Body You Want personal training program, which specializes in helping you get the body you want in the available time you have. You can also check out his blog, follow him on Twitter, or check out his fitness videos on YouTube.

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