You know exercise is good for your health, but you might be wondering—can exercise can help ward off respiratory illnesses? And should you continue exercising during a global pandemic, or should you give your immune system a rest?
As it turns out, continued physical activity can actually help boost your immune system—but just don’t overdo it.
A recent review published in the Journal of Sport and Health Science found that obesity and and inactivity can lower the function of the immune system, but engaging in a healthy lifestyle can help improve the immune system’s surveillance activity (when immune cells are in the bloodstream looking for infection) and may even reduce mortality rates from respiratory illnesses.
So, how can you make exercise work in your favor, and how much do you need? The review found that 30 to 60 minutes of near daily brisk walking (at least 3.5 miles per hour, or a 17-minute mile) can improve your body’s defense against germs.
“[Exercise] improves the surveillance activity of the immune system,” review author David Nieman, Dr. PH., health professor at Appalachian State University and director of the Human Performance Lab at the North Carolina Research Campus told Runner’s World.
That’s because each time you exercise, the activity increases the exchange of important white blood cells between peripheral tissues—which help with the body’s immune response—and the circulation (blood and lymph vessels). This increases the activity of immune cells in the bloodstream looking for viruses, Nieman said.
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Though hard to say without much current data specific to COVID-19, when people adopt a healthier lifestyle, especially those who were previously sedentary, it may help improve their chances of recovery from upper respiratory tract infections, Nieman explained. The same is true of those, like runners, who are currently active.
On the flip side, overtraining can lower your immune system function.
“Overtraining that leads to chronic fatigue, performance decline and mood disturbances can decrease immune function, resulting in increased odds for respiratory infections,” Nieman said.
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And while overtraining looks different for everyone, Nieman cautions against pushing too hard during exercise training without adequate rest and recovery, as this can lead to chronic fatigue, performance decline, and mood disturbances, which decrease immune function.
As for increasing your mileage during marathon training or adding in more tough workouts? You’ll want to be careful you don’t push too hard.
“I recommend keeping exercise training at normal levels until this pandemic gets under control,” Nieman said.
Bottom line: If are already an avid exerciser—keep it up, but remember everything is multifactorial, Nieman says. Physical activity is just one important factor that helps the immune system do its job better. Other factors include high flavonoid intake from berries and other fruits, low mental stress, regular sleep, and a nutrient-rich diet. And if you haven’t previously been active, making healthy changes in your diet and exercise routines will be beneficial to your health, just be sure to check in with a doctor.