How to make your gym workout less risky during the pandemic - CNN

That means "the increased respiratory exertion that occurs in the enclosed spaces of indoor exercise facilities facilitates transmission" of the virus, the US Centers for Disease Control and Prevention has reported.

Infection risk while inside gyms is lower for fully vaccinated people, but unvaccinated people remain unprotected -- so both groups, if they go, should take the same precautions.

Mask wearing while exercising hasn't been found to be harmful for healthy people, according to the CDC -- but those with a lung disease or heart disease should talk with their health care provider before trying to work out while wearing a mask.

High-intensity indoor classes need "to have very good ventilation with people spaced at least 10 feet apart," said CNN Medical Analyst Dr.