The study, which involved almost 200,000 men and women in South Africa, found coronavirus vaccination effectively prevented severe illness in most of them. But it worked best in people who exercised regularly. They wound up about 25 percent less likely to be hospitalized with covid than sedentary people, although everyone received the same vaccine.

“I think this study adds to the growing evidence that, along with vaccination, daily physical activity is the single most important thing you can do to prevent severe COVID-19 outcomes,” said Robert Sallis, a family and sports medicine doctor at the Kaiser Permanente Fontana Medical Center in California and former president of the American College of Sports Medicine. He has researched covid and exercise but was not involved with the new study.

A wealth of research in the past year has shown that being active and fit substantially lowers your risk of becoming seriously ill if you develop covid. Sallis led a study, for instance, of almost 50,000 Californians who tested positive for the coronavirus before vaccines were available. Those who had regularly walked or otherwise worked out before falling ill were about half as likely to need hospitalization as sedentary people.

So, for the new study, which was just published in the British Journal of Sports Medicine, researchers in Johannesburg gathered anonymized records of almost 200,000 men and women from the nation’s largest health insurer.

The records included information about people’s vaccinations, covid outcomes and exercise habits, gleaned from activity trackers and gym visits. Because the health insurer gave people points and prizes for being active, the study subjects tended to scrupulously record each workout.

The researchers first broadly compared the vaccinated and unvaccinated. (The Johnson & Johnson vaccine was the only available option then.) As expected, the unvaccinated developed covid and became seriously ill in much larger numbers than the vaccinated.

This study was associational, though, meaning it shows links between activity and covid outcomes. While it does not prove that being active causes vaccines to be more effective, the links were consistent and the effects large, Patricios said.

Perhaps most encouraging, “I do not think it is ever too late” to start exercising, he said. Been inactive? A stroll today should begin prepping your immune system to respond with greater fervor to your next vaccination or covid exposure. “Plus,” he pointed out, “you don’t need a prescription, and it’s free.”

This content was originally published here.