Is it true that exercise strengthens the immune system?

Special for Infobae of The New York Times.

(Science Times)

You’ve probably heard this advice: One of the best things you can do to stay healthy—especially as cold and flu season approaches—
is to be physically active.

This conventional wisdom has been around for a long time, but until recently researchers didn’t have much data to support such a notion. Now, scientists studying risk factors related to COVID-19 have found some preliminary clues regarding the link between regular exercise and better immune defenses once morest disease.

When researchers reviewed 16 studies of people who were physically active during the pandemic, they found that exercising was associated with a lower risk of infection, as well as a lower chance of suffering from COVID complications. The analysis, published last month in The British Journal of Sports Medicine, has generated great enthusiasm among exercise scientists, who say the findings might lead to updated guidelines on physical activity and health policy that consider exercise as medicine.

Experts who study immunology and infectious diseases are more cautious in interpreting the results. But they do agree that exercise helps protect health through several different mechanisms.

Exercise might improve immunity in several ways.

For decades, scientists have observed that people who are fit and physically active appear to have lower rates of various respiratory tract infections. Also, when people who exercise get sick, they tend to have less severe illness, said David Nieman, a professor of exercise and health sciences at Appalachian State University, who was not involved in the recent COVID research. .

“The risk of complications and death from the common cold, influenza and pneumonia is greatly decreased,” Nieman said. “I call it the vaccine-like effect.”

The new meta-analysis, which looked at studies conducted between November 2019 and March 2022, found that this effect extends to COVID. People around the world who exercised regularly had a 36% lower risk of hospitalization and a 43% lower risk of death from COVID compared to those who were not active. They also had a lower chance of getting COVID at all.

People who followed recommendations to get at least 150 minutes of moderate activity or 75 minutes of vigorous activity per week seemed to get the most benefit. But even those who exercised less were more protected once morest the disease than those who did nothing.

Researchers theorize that exercise may help fight off infectious bacteria and viruses by increasing the circulation of immune cells in the blood, for example. In some small studies, researchers also found that muscle contraction and movement release signaling proteins known as cytokines, which help direct immune cells to find and fight infection.

Although the levels of cytokines and immune cells decline two to three hours following you stop exercising, Nieman explained, your immune system becomes more receptive and able to catch pathogens more quickly if you exercise every day. “Your immune system is primed and in better shape to deal with a viral load at any given time,” he said.

In healthy humans, physical activity has also been linked to lower chronic inflammation. Widespread inflammation can be very damaging and even cause the immune cells themselves to turn once morest the body. This is a known risk factor for COVID, Nieman noted. He also said that therefore it stands to reason that reducing inflammation improves the chances of fighting infection.

Research also shows that exercise is capable of amplifying the benefits of some vaccines. For example, people who exercised right following receiving the COVID-19 vaccine seemed to produce more antibodies. And in studies of older adults who got vaccinated early in the flu season, those who exercised had antibodies that lasted through the winter.

Exercise provides a number of health benefits that help reduce the incidence and severity of disease, says Stuart Ray, an infectious disease specialist at Johns Hopkins University School of Medicine. Incorporating a walk, a jog, a trip to the gym or the sport of your choice into your routine is known to help reduce obesity, diabetes and heart disease, for example, all of which are risk factors for the complications produced for the flu and COVID. Exercising can help you get more restful sleep, boost your mood, and improve insulin metabolism, as well as your cardiovascular health, which improves your chances in fighting the flu and COVID. It’s hard to tell, Ray says, whether the benefits come from direct changes in the immune system or simply better overall health.