More exercise means less risk of developing severe Covid, according to a compelling new study of physical activity and coronavirus hospitalizations. The study, which involved almost 50,000 Californians who developed Covid, found that those who had been the most active before falling ill were the least likely to be hospitalized or die as a result of their illness.
The data were gathered before Covid vaccines became available and do not suggest that exercise can substitute in any way for immunization. But they do intimate that regular exercise — whether it’s going for a swim, walk, run or bike ride — can substantially lower our chances of becoming seriously ill if we do become infected.
Scientists have known for some time that aerobically fit people are less likely to catch colds and other viral infections and recover more quickly than people who are out of shape, in part because exercise can amplify immune responses. Better fitness also heightens antibody responses to vaccines against influenza and other illnesses.
But infections with the novel coronavirus are so new that little has been known about whether, and how, physical activity and fitness might affect risks for becoming ill with Covid. A few recent studies, however, have seemed encouraging. In one, which was published in February in The International Journal of Obesity, people who could walk quickly, an accepted gauge of aerobic fitness, developed severe Covid at much lower rates than sluggish walkers, even if the quick striders had obesity, a known risk factor for severe disease. In another study of older adults in Europe, greater grip strength, an indicator of general muscle health, signaled lowered risks for Covid hospitalizations.