If you've started running, or gotten back into it, in the last few weeks, you're not the only one.

Cities across the country have seen a surge in the number of people running, walking and biking outside as social distancing guidelines take hold.

As more people turn to running, there are a lot of questions about how to do it safely. We talked to researchers and runners alike to answer some of the biggest questions.

6 Feet Is Not Enough

For starters, national experts aren't telling people to avoid exercising outside — even if you're under a shelter-in-place mandate. Health experts say your risk of infection from outdoor exercise is low.

You do have to practice social distancing. The Centers for Disease Control and Prevention recommends that you stay at least 6 feet away from other people when you're outside your home.

But that may not be enough for runners.

New research suggests that standard social distancing guidelines might be insufficient to stop the spread of the virus when it comes to strenuous activities.

Linsey Marr, a professor of civil and environmental engineering at Virginia Tech with an expertise in airborne disease transmission, says that 6 feet may not be enough.

"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," Marr tells NPR.

But by moving fast, you're also disturbing the air around you and effectively diluting the virus, says Marr. This makes it hard to determine whether there's a greater risk of spreading the virus if you're running versus walking.

Regardless, Marr says runners can reduce the risk of transmission by staying farther apart from other people than the recommended 6 feet. She suggests that runners increase that distance to at least 10 feet, and other experts have suggested doubling CDC guidelines to 12 feet.

Maintaining this level of distance requires that runners not only run alone, but run far away from other people. Runners should avoid places with high pedestrian traffic or run at off-peak times like early in the morning or late at night.

Last week, for instance, Paris banned running, and all other outdoor sports, between 10 a.m. and 7 p.m.

To Mask Or Not To Mask?

Another question on runner's minds has been whether to wear a cloth face covering.

The CDC recommends wearing cloth face coverings in "public settings, where other social distancing measures are difficult to maintain" in order to avoid community-based transmission of the virus.

So just as you'd wear a mask to the grocery store or pharmacy, you should wear one if your run is likely to bring you into close contact with other people.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, has noted that as many as 50% of people who have the virus may be asymptomatic. Runners who feel well enough to go on a regular run may still be infecting those they come into contact with.

According to the CDC, your mask should fit snugly over your nose and mouth, which can be difficult to maintain while running. Some runners use neck gaiters — a tube of fabric, usually moisture-wicking — to cover their mouth and nose in lieu of a mask.

Don't Push Too Hard

Many running groups are encouraging their members to keep active for their physical and mental health, but they've stressed that staying safe may mean running less.

Michael Capiraso is the president and CEO of New York Road Runners, a running nonprofit that serves almost 700,000 runners each year through local outreach and events, including the TCS New York City Marathon.

He says the group has been encouraging its runners to take it easy.

Backing off can mean a few things. First, run outside only when you know you'll be able to keep your distance from others. And, when you do, slow your pace. If you push too hard, you might forget to maintain proper social distancing or injure yourself.

Stress and anxiety are also bad for your body, so try not to worry too much about keeping up a certain training regimen. Capiraso urges people to consider running by minutes rather than miles so that they can settle into whatever pace feels comfortable.

He's also telling runners to take more days off, and to spend less time running outside and more time training indoors, either running on the treadmill or cross-training — you can lift weights or do yoga, for instance — to build strength and flexibility.

Ways To Stay Connected While Apart

Running is a solitary activity, but has become more community-driven in recent years. And running groups and online platforms make it easier than ever for runners to stay connected while running apart.

Running clubs around the country are using social media to keep in touch and gathering online for events.

Pamela Skaufel is a long-distance runner in Houston, Texas. Her running club, the Houston Harriers, canceled group meetings back in March, but is staying in touch on Facebook and holding online training workshops on topics like nutrition.

Capiraso says New York Road Runners is meeting virtually with people in its training programs and launching new resources online, such as a new website designed to help keep kids active at home.

Individual runners are also relying on tracking apps, like Strava, to share their runs with friends and motivate one another.

Competition In The Age Of Coronavirus

Apps can also be used for virtual competition, while real-world races are canceled for the foreseeable future.

Some virtual races serve as replacements for those canceled due to the coronavirus. But others, like those hosted by iRunFar and the Quarantine Backyard Ultra, were created in response to the pandemic and were never meant to be in-person events.

These online races allow runners to sign up for a particular distance and then run on their own time outdoors or on a treadmill. You can run anywhere — literally. People are logging miles in their driveways, in stairwells and on balconies.

You log your time once you've done the miles; some virtual races even come with all the goodies of an in-person race, like leaderboards, T-shirts and medals.

Bottom line, says Capiraso of the New York Road Runners, is that runners are usually a regimented bunch.

But these are not normal times.

"I've been advocating to just give yourself a break and back off a little bit," he says. "It's OK. We'll run another day."

Lauren Hodges contributed reporting this story.

Copyright NPR 2020.