Coronavirus FAQ: How Safe Is It To Work Out In A Gym Or Play Indoor Sports?

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I have been playing tennis outdoors and would like to play indoors now that winter is coming. How safe is it to exercise, work out and play sports indoors? Or in an outdoor tent next to a gym or sports facility?

In the pandemic, it's much riskier to do these types of activities indoors, according to guidance from the Centers for Disease Control and Prevention. But as winter temperatures set in, exercising or playing sports outside may not be feasible for everyone.

While some fitness studios and indoor sports facilities are rolling out coronavirus safety plans that include upgraded air filtration systems and meticulous cleaning, our experts say this isn't enough to keep you safe from infection.

You still have to practice social distancing and wear a mask while gathering indoors, says Dr. Thomas Tsai, a professor at the Harvard T.H. Chan School of Public Health.

Indoor exercise has resulted in recent clusters of infections.

In Hamilton, Ontario, over 60 positive coronavirus cases were linked to one spin studio last month. In Massachusetts, the governor had to shut down indoor ice rinks in October after at least 30 coronavirus clusters were tied to youth ice hockey. It reopened this month after two weeks of closure.

But not all indoor activities carry the same risk level, Tsai says, and assessing that risk is not a simple matter of checking off boxes. It depends on many different factors, including the facility, your community and your own health.

A facility can do a lot to mitigate the risk of transmission, says Dr. William Schaffner, an infectious disease professor at Vanderbilt University. He points out that masks were not worn during exercise in most transmissions linked to indoor activity, including the Hamilton outbreak.

"If you walk into a place and see people not wearing masks," Schaffner says. "Turn around and walk out."

Facilities must be strict with enforcing mask-wearing and social distancing at all times, even during exercise. Staff should be regularly disinfecting high-touch surfaces and conducting COVID-19 screenings on patrons and employees.

A crucial indoor variable is airflow, says Richard Corsi, an air quality expert and dean of engineering at Portland State University. Outside air must be exchanged frequently and at the right amount. Air filtration systems help if proper filters are used and replaced properly, but nothing comes close to being outside, where coronavirus droplets disperse more quickly into the air.

Unfortunately, there are no surefire ways of determining if you're in a well-ventilated space, Corsi says, other than asking a staff member at the facility and taking the staffer's word for it. And a tent set up outside to exercise in, once all the flaps are closed, is just another room with walls and a ceiling that offers no more significant ventilation than exercising indoors, he says.

Large indoor spaces – such as a stadium-size gymnasium or domed indoor tennis courts – with only a few people playing far apart, are less risky, Tsai says. But basketball and hockey, in those same types of environments, with players so close together is much riskier.

You should also consider who else is indoors. If the local infection rate in your community is high, that's a risk factor, Tsai says. There's more of a chance of you encountering the virus. To find out how risky being indoors is in your community, Georgia Tech maintains an interactive map that assesses your risk based on location and the size of the gathering.

Think of your own personal risk before you decide to exercise indoors, Schaffner says. Everyone is susceptible to being infected, but it is much more likely to affect the elderly severely. According to the CDC, 8 out of 10 coronavirus-related deaths reported in the U.S. have been among adults 65 and older. But you can be of any age and be at a high risk of being hospitalized if you have serious health problems such as diabetes or are immunocompromised. If you're in a vulnerable group, you may not want to put yourself in a higher-risk situation.

How far you are from other people while doing indoor activities is crucial, experts say.

Exercising without social distancing is risky especially when it involves sweating and heavy breathing, says Lisa Lee, a population health sciences professor at Virginia Tech. Heavy breathing means more breath is coming out of your mouth with more force. That's more virus in the air travelling farther.

"The harder we exhale, the greater the risk," Lee says.

For this reason, we should go well beyond the 6-foot distance and keep masks on even during physical activity, Schaffner says, and don't forget to wash your hands. Although chances are slim, touching equipment or picking up a ball could transmit the virus.

There are ways to take matters in your own hands and reduce the risk of infection. Exercise at home or outdoors, and if you do go to a gym or an indoor court, spend less time exercising there. You can decrease your risk by reducing exposure time, says Dr. Todd B. Ellerin, director of infectious diseases at South Shore Health in Weymouth, Mass.

At a time when COVID-19 cases are rising worldwide, our experts say it's best to avoid playing or exercising in an indoor facility for now.

"You really do have to ask yourself is this something so important to me that I need to do this," Schaffner says.

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