Pandemic or not, a runner’s gotta run, right? Here’s some news that may let you breathe more easily during this pandemic: Exercise can keep you healthy from respiratory illness. But before you go pouring on the miles, know this, too: more miles doesn’t necessarily equate to more immunity.
“The research actually goes back a long time,” says Dr. Karan Shukla, “as far back as the early 1900’s.” Dr. Shukla is a physician at Novant Health Randolph Family and Sports Medicine in uptown Charlotte. If the name sounds familiar to runners, it’s because he’s also served in the medical tent at the Novant Health Charlotte Marathon for the past three years. He knows medicine, and he knows runners.
Dr. Shukla says some of the first research about exercise and immunology came from the Boston Marathon more than a century ago, but great advances were made during the onset of another worldwide health crisis — the AIDS epidemic.
“We were able to look really deeply into people’s responses from a molecular standpoint, and understand its effects on how people feel,” says Dr. Shukla. So should we stay active? “Yes,” he replies emphatically. We’ll tell you why, but be sure to stick around for his corollary explanation of more-is-not-better, too.
First: Get moving. The research supports it, and it has immediate effects.
“With daily exercise, we see enhanced immune systems to defend against pathogens,” says Dr. Shukla. “It stimulates your circulation and distribution of immune cells, and increases anti-pathogenic cells in your system.” He references the “J Curve” effect in studies of respiratory illness, where results on a graph briefly fall, then rise quickly and steeply.
“With moderate to vigorous exercise, you see dramatic decrease in respiratory illness,” he says. “We see an increase of our bodies to perform immuno-surveillance — to be on guard.” Dr. Shukla says research shows exercise has a profound effect on cells in our mucus and saliva, and our respiratory tract. “This is an important cell to defend against illness,” he says, especially flu-like and respiratory illness.
So exercise is good; modern science again confirms what your mom said all along. But all the way back in the 1600’s, Shakespeare warned us, “you can have too much of a good thing.” Research shows that’s true, too. The takeaway? Don’t go beyond what you are currently conditioned to do, at least at first, says Dr. Shukla, or you may do more harm than good.
“There needs to be a fine line drawn between a healthy amount of activity, and an unhealthy amount of exercise,” says Dr. Shukla.
Studies of ultramarathoners, marathoners, and runners who are logging 26-50 miles a week show an increased risk of upper respiratory infections or flu illnesses after heavy exertion, like a race. This is caused by an interplay of factors, says Dr. Shukla, like increases in the stress hormones epinephrine and cortisol, and a disfunction in the ability of the immune system to circulate its fighter cells to the body’s tissue compartments like skin, muscles, and respiratory tracts under duress.
In some runners, an increase in heavy or intense exercise, like running a marathon, led to between 2 and 6 times the upper respiratory infections 1-2 weeks after the race. Another study found a statistically significant difference in respiratory illness between marathoners and those who walked at a moderate or intense pace for 30-45 minutes at a time.
Does this mean you should give up running longer distances, or even building up to more mileage? Nope!
“If you usually run 26 miles a week regularly, you’re conditioned to tolerate those stressors and it shouldn’t have a significantly negative impact on your health,” Dr. Shukla reassures us. “We want people to maintain their level of conditioning.”
So if you’re used to going the distance, go the distance. If you’re just starting out — or starting back — do it gently.
“Pacing yourself and incrementally increasing distance would be the safest way to get to your goals,” he says.
Building mileage is a practice in patience. The old “10 Percent Rule” (increasing mileage 10 percent each week) may not be for everyone. If you’re new to running, shoot for consistency first; such as a month or two of running 3 or 4 days per week before adding mileage. More experienced runners may have the foundation to safely add more than 10 percent each week. Experts agree – and so do we – that all runners should add supplemental strength and stretching exercises to their routines, no matter their mileage goals.