Research shows that several positive changes occur in the immune system as a result of regular exercise:

**Moderate exercise keep stress hormones low; that's good because stress hormones can suppress immunity.

**People who exercise report fewer colds than those who are sedentary.

**Near daily exercise cut the number of sick days in half during a 12-15 week period.

Although the immune system returns to pre-exercise levels very quickly after exercise, each workout represents a boost to the immune system that appears to reduce the risk of infection over the long term.