“I think this study adds to the growing evidence that, along with vaccination, daily physical activity is the most important thing you can do to prevent serious outcomes from COVID-19,” said Robert Sallis, a sports and family medicine physician. of the Kaiser. Permanent Fontana Medical Center in California and past president of the American College of Sports Medicine. He has researched covid and exercise, but was not involved in the new study.
However, the study findings raise questions about how much (or little) exercise might best increase the benefits of the vaccine, and whether it’s too late to benefit if you’ve already been fully vaccinated or will be soon.
A lot of research in the last year has shown that being active and fit substantially reduces the risk of getting seriously ill if you develop covid. Sallis led a to study, for example, of nearly 50,000 Californians who tested positive for the coronavirus before vaccines were available. Those who had walked or exercised regularly before getting sick were about half as likely to need hospitalization as sedentary people.
Similarly, an August revision of 16 previous studies involving nearly 2 million people concluded that active people were much less likely than inactive people to be infected, hospitalized or killed by covid.
These connections between exercise and protection against Covid make sense, Sallis said. We know that “immune function improves with regular physical activity,” she said, as do lung health and levels of inflammation, which can otherwise contribute to a spiral of poor outcomes with Covid.
But the studies had not looked at whether active people get additional benefits from their coronavirus vaccines and boosters.
So for the new study, just published in the British Journal of Sports Medicine, Johannesburg researchers collected anonymous records from nearly 200,000 men and women from the country’s largest health insurer.
The records included information about people’s vaccinations, Covid results and exercise habits, gleaned from activity trackers and gym visits. Because the health insurer gave people points and rewards for being active, the study subjects tended to scrupulously record each workout.
The researchers first extensively compared the vaccinated and the unvaccinated. (The Johnson & Johnson vaccine was the only option available at the time.) Unsurprisingly, the unvaccinated developed covid and became seriously ill in much higher numbers than the vaccinated.
But even among the fully vaccinated, exercise made a significant difference in Covid outcomes, said Jon Patricios, a professor of clinical medicine and health sciences at the University of the Witwatersrand in Johannesburg-Braamfontein, who supervised the new study.
Vaccinated people who walked or exercised moderately for at least 150 minutes a week were nearly three times less likely to be hospitalized if they developed Covid than those who were vaccinated but sedentary.
In more concrete terms, their vaccines protected them 25 percent better than the same injections in sedentary people.
These people’s exercise habits met or exceeded the standard exercise guidelines promoted by the World Health Organization and the Centers for Disease Control and Prevention, Patricios said, which call for a half hour or so of moderate activity at least five times a week.
But even vaccinated people who moved less, exercising as little as one hour a week, were 1.4 times less likely to be hospitalized than the sedentary vaccinated group, suggesting that their vaccines were about 12% more effective than those of people who did not exercise.
“Doing something mattered, even if people didn’t meet all the guidelines,” Patricios said. “It’s an idea we call ‘small steps, strong shield.’ ”
If you can’t do a 30-minute walk today, he said, a 10-minute walk is better than skipping exercise altogether.
However, this study was associative, meaning it shows links between activity and covid outcomes. While it doesn’t prove that being active makes vaccines more effective, the links were consistent and the effects were large, Patricios said.
He also thinks the relationship would be similar for exercise and other coronavirus vaccines, such as the Moderna and Pfizer versions, and in people who don’t live in Johannesburg.
It is not yet clear how regular activity increases the response to the vaccine. But Patricios suspects that the muscular immune system of athletes causes the creation of additional battalions of covid antibodies after each vaccination. Lifestyles can also affect the response, including people’s diets and incomes.
Perhaps most encouragingly, “I don’t think it’s ever too late” to start exercising, he said. Have you been inactive? A walk today should start preparing your immune system to respond more fervently to your next vaccination or covid exposure. “Plus,” she noted, “you don’t need a prescription and it’s free.”
Do you have a fitness question? Email [email protected] and we may answer your question in a future column.
