Stress, like the kind created when training up for and running races, can reduce the defenses provided by your immune system. In a study of three groups, sedentary, recreation, and elite athlete runners, the groups on each end had about the same rate of upper respiratory illnesses; however, the recreational runners had fewer instances of sickness.

The conclusion was that moderate exercise reduced the risk of infection while no exercise or intense training seem to increase the risk of getting sick. In fact, light to moderate training seem to even provide a boost to the immune function.

But where is the break between recreational and elite? The study showed 20 miles and over per week seem to be the optimal point at which the immune system was affected.

To keep your immune system running at an optimal level, keep an awareness of these three things:

1) Avoid overtraining:
Overtraining results when recovery between workouts on a repeated basis does not happen or is not long enough. Generally, most training plans have enough recovery time built into them, but if you skip parts of your plan or push too hard, it can happen.

Symptoms include elevated heart rate when at rest, moodiness, susceptibility to sickness and trouble sleeping.

2) Get adequate sleep:
Chronic sleep deprivation is linked to a drop in one’s immune system as a result of several studies. With less sleep over time, metabolic and hormonal levels start to change, Cortisol increases and glucose tolerance decreases, both affecting how the body processes food to glycogen – a really important function when competitive running.

3) Eat a healthy diet:
Most seasoned runners know they have unique nutritional needs, however, this may be strange territory to runners new to the sport. What competitive runners eat before, during and after running at various stages in their training plan not only affects performance, but their health.

A diet rich in complex carbohydrates (at the rate of 3 to 5 grams per pound of body weight) replaces and builds up the glycogen stores while protein (1.4 to 1.7 grams per kilogram of bodyweight) is necessary to rebuild and repair muscle.

Finally, be sure to keep properly hydrated by monitoring the color of your urine. It should be a light yellow. Be cautious of clear urine as it could indicate over-hydrating which can cause an imbalance of electrolytes.

Statistically, your risk for catching more colds and upper respiratory illnesses increases when you move from recreational to competitive running, however, by following the tips in this article, you should be able to keep it at a manageable level.