Exercise & Immunity

By Elizabeth Quinn, About.com
Updated: January 9, 2008

The average adult has two to three upper respiratory infections each year. We are exposed to viruses all day long, but some people seem more susceptible to catching colds or the flu. The following factors have all been associated with impaired immune function and increased risk of catching colds:
· old age
· cigarette smoking
· stress
· poor nutrition
· fatigue and lack of sleep
· over-training

Regular Moderate Exercise Boosts ImmunityHowever, there are some things that seem to protect us from picking up colds. One of those things appears to be moderate, consistent exercise. More and more research is finding a link between moderate, regular exercise and a strong immune system.

Early studies reported that recreational exercisers reported fewer colds once they began running. Moderate exercise has been linked to a positive immune system response and a temporary boost in the production of macrophages, the cells that attack bacteria. It is believed that regular, consistent exercise can lead to substantial benefits in immune system health over the long-term.

More recent studies have shown that there are physiological changes in the immune system as a response to exercise. During moderate exercise immune cells circulate through the body more quickly and are better able to kill bacteria and viruses. After exercise ends, the immune system generally returns to normal within a few hours, but consistent, regular exercise seems to make these changes a bit more long-lasting.

According to professor David Nieman, Dr. PH., of Appalachian State University, when moderate exercise is repeated on a near-daily basis there is a cumulative effect that leads to a long-term immune response. His research showed that those who walk at 70-75 percent of their VO2 Max for 40 minutes per day had half as many sick days due to colds or sore throats as those who don't exercise.

Link to entire article:
http://sportsmedicine.about.com/od/injuryprevention/a/Ex_Immunity.htm