InformationBattling another cough or cold? Feeling tired all the time? Taking a daily walk or following a simple exercise routine a few times a week may help you feel better.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.We dont know exactly how exercise increases your immunity to certain illnesses, but there are several theories.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 bodys 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.While exercise is beneficial, be careful not to “overdo” it. People who already exercise regularly are cautioned not to develop too vigorous a workout program in the hopes of increasing the immunity benefits. Heavy, long-term exercise (such as marathon running and intense gym training) could actually decrease the amount of white blood cells circulating through the body and increase the presence of stress-related hormones.advertisementStudies have shown that the people who benefit most from starting (and sticking to) an exercise program are those who go from a sedentary (“couch potato”) lifestyle to a moderately energetic lifestyle. A moderate program can consist of:Bicycling with the children a few times a weekDaily 20 – 30 minute walksGoing to the gym every other dayPlaying golf regularlyExercise can help us feel better about ourselves, just by making us feel more energetic and healthier. So go ahead, take that aerobics class or go for that walk — and feel better and healthier for it.There is not strong evidence that taking any immune supplements along with exercising lowers the chance of illness or infections.ReferencesIvker RS. Chronic sinusitis. In: Rakel D. Integrative Medicine. 2nd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 19.Barrett B. Viral upper respiratory infection. In: Rakel D. Integrative Medicine. 2nd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 20.Hewitt MJ. Writing an exercise prescription. In: Rakel D. Integrative Medicine. 2nd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 90.Johnson R, Knopp W. Nonorthopaedic conditions. In: DeLee JC, Drez D Jr, Miller MD, eds. DeLee and Drez’s Orthopaedic Sports Medicine. 3rd ed. Philadelphia, Pa: Saunders Elsevier; 2009:chap 3.Woods JA. Exercise, inflammation, and innate immunity. Immunol Allergy Clin North Am. 2009;29(2):381-393.Review Date:5/15/2012Reviewed By:Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.