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Exercise & the immune system

As we move into the cold and flu season, I’ve been thinking about exercise and its connection to the immune system. Does exercise improve your resistance to infection? Is it possible to exercise too much? Let’s take a closer look at these questions as we brace for winter.

Exercise does improve your immunity to infections, but researchers do not agree on why. One current theory states that when you exercise, you increase the speed at which the body removes waste products through the lungs and the sweat glands. It seems logical that a body overburdened with toxins that don’t get removed on a regular basis is more prone to infection.

Another idea about exercise and immunity states that because your heart rate increases during exercise, disease-fighting white blood cells circulate more rapidly through the blood stream. With increased blood flow, white blood cells can start working sooner to start destroying those bacteria, viruses and fungi.

Exercise increases your body temperature. Many infectious organisms cannot survive an increase of a few degrees, and will die in a hotter environment. This rise in temperature is the same strategy that the body uses when it produces a fever, with the goal of creating a hostile environment for invaders within the body.

Exercise decreases stress. We now know that stress contributes to a weakened immune system. By managing stress through exercise, you create a stronger fortress in your body, less prone to infection.

Studies done with marathoners and other endurance athletes show that many of them have a suppressed immune system. The extreme strain of training places a huge burden on their body’s ability to fight infection. People who run several marathons a year of work out more than two hours a day put themselves at risk. No need to worry if you are following a more standard workout regimen. In most cases, exercise will keep your immune system strong for cold and flu season.

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