"Exercise not only helps your immune system fight off simple bacterial and viral infections, it decreases your chances of developing heart disease, osteoporosis, and cancer.” The National Institute of Health
The above quotation, used on our page about the immune system, is from an excellent article published by the National Institute of Health entitled, “Exercise and immunity.”
They go on to mention that, although it is known that exercise does boost the immune system, there are different theories as to why it does. Here’s their list of possibilities:
- Physical activity may help by flushing bacteria out from the lungs (thus decreasing the chance of a cold, flu, or other airborne illness) and may flush out cancer-causing cells (carcinogens) by increasing output of wastes, such as urine and sweat.
- Exercise sends antibodies and white blood cells (the body's defense cells) through the body at a quicker rate. As these antibodies or white blood cells circulate more rapidly, they could detect illnesses earlier than they might normally. The increased rate of circulating blood may also trigger the release of hormones that "warn" immune cells of intruding bacteria or viruses.
- The temporary rise in body temperature may prevent bacterial growth, allowing the body to fight the infection more effectively. (This is similar to what happens when the body has a fever.)
- Exercise slows down the release of stress-related hormones. Stress increases the chance of illness.