Cooler weather brings with it an increasing threat of colds and upper respiratory viruses. Not what you wanted to hear, right? It's no fun to be sidetracked by sneezing, coughing, and a sore throat! Plus, the cough can stick around even after the virus has cleared.


Of course, we'd like to avoid getting those pesky viruses in the first place. Eating a healthy diet, not smoking, and getting enough sleep can help, but what about exercise? No one can deny it's a healthy habit, but can moving your body regularly lower your risk of developing a cold?


Does Regular Physical Activity Lower the Risk of Colds?


No amount of physical activity you do will guarantee you'll never succumb to an upper respiratory infection. But there is evidence that regular workouts lower the risk. In fact, a study published in the British Journal of Sports Medicine supports this idea. The study showed that healthy people who worked out at least 5 days of the week enjoyed 46% fewer days of illness due to respiratory viruses. Studies also suggest that exercise may reduce the severity of cold symptoms and shorten their duration. Those are all good things!


How Does Exercise Reduce Cold Risk?


It's good news that exercise helps keep colds at bay, but how? According to some studies, exercise boosts the activity of immune cells called macrophages that destroy unwanted invaders like respiratory viruses. After a bout of moderate exercise, you get a temporary bump up in the immune response after a moderate workout, but it's usually short lived. However, exercising regularly leads to a more sustained, virus-fighting immune response.


Other studies show moderate exercise boosts the activity of natural killer cells, a type of immune cell that fights viruses and also helps keep tumor cells from gaining a foothold in the body. But, as with everything, there's a "sweet spot." Too much exercise, especially when combined with inadequate nutrients and too little sleep, can have the opposite effect. Overdoing it can increase your susceptibility to catching a cold. In fact, some studies show marathon runners have a higher incidence of colds after running the big race. Even training for a marathon can temporarily weaken the immune response if it's overdone. Running a marathon isn't exactly moderation!


Too Much Exercise Increases the Body's Stress Response


One reason training too hard increases the risks of catching a cold is it boosts the release of cortisol, a stress hormone that dampens the immune response. The cortisol response is higher after very intense exercise and exercise of long duration. For example, a study found that intense exercise for 90 minutes led to a suppression of the immune system and increased susceptibility to infection. Some studies suggest that eating a meal that contains protein and carbs after a workout can dial back the body's cortisol response.


What Type of Exercise is Best?


Moderate-intensity exercise, like brisk walking or cycling, for 30 to 45 minutes several times per week is conducive to a healthy immune system. Shorter, high-intensity workouts can cause temporary suppression of immunity right afterward, but the immune cell activity usually returns to normal quickly, as long as you're allowing enough recovery time. If you do high-intensity workouts, balance vigorous training with low-intensity workouts for recovery.  



The Bottom Line?


Exercise is good medicine for your immune system and a healthy immune system helps protect against viruses that cause colds and upper respiratory infections. However, training too long and too often, especially at a high intensity may have the opposite effect. Exercise of long duration, especially if it's intense, can transiently suppress immune function and increase the risk of catching a cold.


Recovery is an important part of the equation. During cold and flu seasons, it's important to get enough sleep too, as inadequate sleep can dial up the body's stress response and increase susceptibility to colds. So, keep your workouts balanced, but make sure you're moving your body!



Short Summary:


Exercise is for more than fitting into a smaller clothing size. It also helps you stay healthy! We know that working out benefits your heart, but can it also lower your risk of catching a cold or upper respiratory virus? Find out what research shows about the link between colds and exercise.




Br. J. Sports Med. 2010.

American Council on Exercise. "Can Exercise Reduce Your Risk of Catching a Cold?"

USA Today. "Exercise Fights the Common Cold, Study Finds"

Sports Medicine 28(3):177-95 · September 1999