With almost all of us spending a lot of time at home because of the coronavirus pandemic and some under edicts to shelter in place and avoid going out at all, those of us who are used to regular exercise naturally have pressing questions and concerns about how best to stay in shape.

To get answers, I spoke with virologists, physiologists and other scientists about what we do and do not know about exercising during the coronavirus crisis. Here is what they had to say.

If I live in a community that is under a shelter-in-place order, can I run or walk outside?

This answer is easy: yes. The San Francisco County health department’s order, which is likely to be a model for similar announcements, says that people may leave their homes “to engage in outdoor activity, provided the individuals comply with social distancing requirements as defined in this section, such as, by way of example and without limitation, walking, hiking, or running.” So, as long as you remain six feet away from other people (not counting those in your household), you can exercise outside.

Does the sun sterilize surfaces outside?

A trickier question. “It is possible to inactivate viruses using U.V. light in laboratory settings,” says Akiko Iwasaki, a professor of immunology at the Yale University School of Medicine. “However, whether and to what extent natural sunlight kills SARS-CoV2,” the official name of the new coronavirus, “is not yet known.”