She said that’s because running could potentially increase your likelihood of spreading the virus, should you be infected.
"If you're running and you happen to be infected, you might release more virus into the air than if you're walking because you're breathing harder," she told NPR.
Marr says its best to always run alone.
Change up your routine
Here in Atlanta, officials are encouraging folks to get outside at different times than they may be used to, especially in high-traffic areas like the Beltline.
On social media, the Beltline asked people to avoid the trail at peak hours.
"Do us all a favor and avoid peak hours if you have to get out on the trail. Before 9:45 a.m. and after 7 p.m. may be less enticing, but it's a whole lot safer... for you and the rest of us," the post reads.
When it comes to staying safe on your walks and runs, changing up your routine may help keep you safe. Try getting up early to run at less popular times or take a route that will be less populated.
Should runners wear masks?
Since the CDC made the recommendation that Americans wear cloth masks when going outside earlier this month, it has raised the question if that applies when exercising outside.
"Really, what these announcements should mean to athletes, and to everyone, is that the situation we are in is very serious. And that we all need to consider the consequences of our individual actions on the community around us," biology professor Matt Ferrari told Runner's World.
For the most part, experts agree: If you’re going to be in a crowded area outside, you should wear a mask regardless of what you’re doing, including exercising.
"The purpose of the mask is not to protect you, but to protect other people from you," professor Brian Labus told Runner's World. "If that is the goal, going out solo and avoiding other people altogether is the best thing you can do."
Consider indoor options
Ultimately, looking to indoor workout options is one of the best ways to protect yourself and others.
Michael Capiraso, the president and CEO of New York Road Runners, told NPR that he’s encouraging people to take it easy right now.
There are a variety of ways to stay active inside your own home, from cross training to yoga, he notes.
"I've been advocating to just give yourself a break and back off a little bit," he told NPR. "It's OK. We'll run another day."