"You have to make your own assessment of how risky it is based on knowing your medical situation and whether you are someone who's at high risk for an infection," Griffith-Howard says.

So if you fall in a high risk category, Griffith-Howard says it may not be worth the risk.

"If it was someone in my family [who was high risk] I would suggest that they not go to a gym," she says.

If you want to exercise indoors, it's safer to do it at home, says Doug Reed, an immunologist and aerobiologist at the University of Pittsburgh.

There are things gyms can do to help mitigate the risk of infection, so Griffith-Howard suggests making a checklist before you go.

And, if people are breathing heavily, "it would be preferable to double that to 12 feet," says Dr.

That's because we don't know exactly how far virus particles travel when people are breathing heavily," says Doug Reed, an immunologist and aerobiologist at the University of Pittsburgh.

"And so the potential for being infected or spreading the infection would be that much higher," says Reed.

"You may be breathing harder, people may be coughing, it may be hard to keep on masks," she says.

This is especially important because there's increasing evidence to suggest "that people who are not symptomatic are, in fact, transmitting the infection," says Reed.

But of course, when you're working out hard and breathing heavily it can be difficult to keep a mask on

"Physical exercise doesn't lend itself well to the idea of wearing a mask," says Reed, because it can make it harder to breathe

"If you're doing aerobic type exercises on an aerobic type machine, you probably are not wearing a mask," says Bruno-Murtha of the Cambridge Health Alliance in Cambridge

And even if people don a mask when they enter the gym, Bruno-Murtha still highly recommends maintaining at least a minimum 6-foot physical distance, "because I suspect at some points people may inadvertently remove their mask," she says which can be risky for others

Exercising indoors in hot spots where cases are surging is more risky than in areas with low infection rates says Bruno-Murtha