The researchers also collected data on known risk factors for severe Covid disease, including age, smoking habits, weight and history of cancer, diabetes, organ transplants, kidney problems and other serious conditions susceptible to the disease.
The investigators then checked the numbers with arresting results. People in the least active group, who almost never played sports, were hospitalized for Covid with twice the percentage of people in the most active group and were subsequently about twice and a half more likely to die. Even compared to people in the less active group, they were hospitalized about 20 percent more often and were about 30 percent more likely to die.
Of the other common risk factors for severe disease, only old age and organ transplants have increased the likelihood of hospitalization and mortality from Covid more than being inactive, the researchers found.
“Being stuck is the biggest risk factor” for a serious illness, “unless someone is elderly or has had an organ,” says Dr. Robert Salis, a family and sports doctor at Kaiser Permanente Fontana Medical Center. who is leading the new study. And while “there’s nothing you can do about these other risks,” he says, “you can play sports.”
Of course, this study, as it has been observed, does not prove that exercise causes severe risks to Covid, but only that people who exercise often are people at low risk for serious illness. The study also did not go into depth on whether exercise reduced the risk of coronavirus infection in the first place.
But Dr. Salis said the associations in the study were strong. “I think based on that data,” he says, “we can tell people that brisk walking for half an hour five times a week should help protect them from heavy Covid-19.”
The walk – or five – can be especially helpful for people waiting for their first vaccine, he added. “I would never assume that someone who does regular exercise should consider not getting the vaccine. But until they get it, I think regular exercise is the most important thing they can do to reduce their risk. And regular exercise is likely to be protective against new variants or the next new virus. “