Exercise and the Immune System

Depending on the intensity of exercise, the duration, and your physical condition, exercise can boost your immune system or impair your immune system. Several studies have shown that physical activity may help flush bacteria out from the lungs and may flush out carcinogens by increasing output of wastes, such as urine and sweat. Exercise also allows the body to transport antibodies and white blood cells at a faster rate. This along with a temporary rise in body temperature may prevent or stop bacterial growth. This is similar to a fever when the body is fighting an infection.  Light to moderate exercise also slows the release of cortisol and adrenaline. These hormones are stress-hormones and stress is a major contributor to illness, as it lowers the immune system. Resistance training and cardiovascular training increase your body’s ability to recover from illness, such as colds and flus.

Light to moderate exercise on a daily basis, not only helps your immune system, but also decreases your chances of developing heart disease, osteoporosis, and cancer. The immune enhancing effects return to normal after a few hours, but consistent exercise makes these effects last longer. When moderate exercise is repeated on a daily basis, there is an improvement in long-term immune response. The more fit you are, the less likely you are to develop a cold and when you do, it will be less severe. While sick, moderate exercise can actually boost your immune system. Intense exercise, while sick, can make things worse or extend your illness.

Studies have shown than intense exercise (extreme) can lower your immunity for a few hours post exercise. Intense exercise consists of more than 90 minutes of high-intensity, much like marathons or triathlons. Unlike light-moderate exercise, during extreme events, the body increases production of cortisol and adrenaline, temporarily suppressing immunity. These suppressing immune changes can last between three and 72 hours post-exercise.

The most important factors in training are rest and recovery. Recovery not only allows your muscles to recover, but also your immune system. Good immune function can be maintained by regular physical activity, eating a well-balanced diet, keeping life stresses to a minimum, avoiding chronic fatigue, and obtaining adequate sleep.