If you want to protect yourself from infections, exercise regularly and lose weight if you are overweight. A new study on mice shows how exercise helps to strengthen your immunity (Sci Rep, November 6, 2015;5:16364). When germs get into your body, you produce certain cells and proteins that attack the germs and try to kill them. When you exercise vigorously enough to damage muscle cells, your body uses these same cells and proteins to help heal your muscle cells. Exercise that is vigorous enough to damage muscles stimulates the same immune cells that heal muscles to help your immunity respond to and kill invading germs.
The Study
Mice were divided into two groups. The first group stayed inactive in their cages and the second group swam vigorously for 10 minutes per day, five days a week for three weeks. At the end of three weeks, the second group had much stronger immunities as evidenced by increased pro-inflammatory cytokines TNF-α and IL-1β, nitric oxide, the antimicrobial peptide cathelicidin, and a reduction in belly fat.
After three weeks, half of the swimmers and half of the inactive mice were infected with Staphylococci bacteria. Mice in both groups got sick, but the sedentary mice were much sicker, had far more lung damage, had more proteins of cell damage in their damaged lungs and had lower levels of the protective immune proteins that kill germs. The muscles damaged by swimming had caused the mice’s bodies to produce muscle-healing proteins that were also more effective in killing germs. The swimming mice were able to heal much faster than the sedentary mice.
How Excess Weight Damages Your Cells
If your immunity stays active all the time, the same cells and proteins that kill germs can attack your own cells. This is called inflammation. Full fat cells can cause inflammation by producing the proteins that turn on and keep your immunity overactive, even when you have no infections (Proc Nutr Soc, Aug 2001;60(3):349-56). The same cells and proteins that you use to kill germs can punch holes in your arteries to cause plaques to form and increase your risk for a heart attack. They can damage your DNA to increase your risk for cancer cells to form. They can attack your own cells to cause so-called auto-immune diseases such as rheumatoid arthritis or lupus.
Full fat cells also weaken your ability to fight infections by making immune cells less able to kill germs. Full fat cells in your liver weaken your immunity by preventing your liver from responding to insulin and increasing your risk for diabetes (Eur Cytokine Netw, Mar 2006;17(1):4-12). Diabetics suffer from a markedly increased risk of suffering infections. Losing weight strengthens your immunity and your ability to kill germs.
My Recommendations
Exercise helps to improve your ability to kill germs and to control your weight. It also helps to prevent diabetes, heart attacks and many types of cancers. I recommend that you try to exercise every day and avoid being overweight.
Gabe Mirkin, M.D., is a sports medicine doctor and fitness guru. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin has run more than 40 marathons and is now a serious tandem bike rider with his wife, Diana. His website is http://drmirkin.com/. Click to read Gabe’s full bio.
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