January 13, 2010
While more research is needed to fully understand the effects of exercise on the immune system, existing studies have established a link between moderate, regular exercise and a strong immune system.
Research conducted by Dr. David Nieman concluded that individuals who perform a moderate-intensity walk for 40 minutes per day had half as many sick days due to colds or sore throats as those who don’t exercise.
What’s happening internally?
During moderate intensity exercise, immune cells circulate through the body at a more rapid pace, and are better able to kill viruses and bacteria due to a temporary boost in the production of macrophages. Although the immune system generally returns to normal within a few hours, consistent regular exercise is believed to make these positive changes in the immune systems last a little bit longer.
Is more better?
While moderate exercise has been linked to a positive immune system response, there is also evidence to suggest that too much intense exercise can reduce immunity. During intense physical activity, stress hormones cortisol and adrenaline raise blood pressure and cholesterol levels and suppress the immune system. Research has shown that more than 90-minutes of high intensity endurance exercise can actually make individuals more susceptible to illness for up to 72 hours following the conclusion of the exercise session.
Tips to improve your immune system
Engaging in moderate intensity exercise (on a scale of 1-10, moderate intensity would be about a 6) 30 minutes per day, at least five days per week. Remember, exercise can also be accumulated in shorter bouts (e.g., three 10-minute bouts) over the course of the day.
In addition to regular exercise, eating a well-balanced diet, obtaining adequate sleep, and reducing stress will also help to ensure optimal immune system function.