- Exercising regularly can help your immune system fight off infections, such as Covid-19.
- This idea is supported by a review that combed through multiple studies from 2019 and 2022.
- However, future studies are needed to back up the current findings, the authors say.
When it comes to powering up the immune system, people have been debating the positive impact of exercise for the longest time.
But research looking into whether working out truly strengthens the immune system and in turn, helps fight off infections, was scarce – until recently.
Last year, a review by 11 researchers supported this notion. During the pandemic, they combed through data comprising nearly 48 500 adult patients and found that physical inactivity was associated with a higher risk for Covid-19 hospitalisation.
Regular physical activity boosts your immunity, they write, which reduces your risk of falling ill and dying from infectious disease by more than a third.
Now, a more recent study – also looking at risk factors for Covid-19 – has come to a similar conclusion: after reviewing 16 studies between November 2019 and March 2022, the team has found that this positive effect extends to Covid-19. Data from over 1.8 million adults were included in their study.
To date, Covid-19 has claimed the lives of more than 6.5 million people globally.
"Our findings highlight the protective effects of engaging in sufficient physical activity as a public health strategy, with potential benefits to reduce the risk of severe Covid-19," they write.
The findings were published in the British Journal of Sports Medicine last month.
Why the protective effect?
Our immune function is complex, and for decades, scientists have been trying to figure out its nuts and bolts.
In the 2021 systematic review, the researchers found consistent evidence across 35 trials that regular exercise led to elevated levels of the antibody immunoglobulin IgA, one arm of the immune system.
"This antibody coats the mucosal membrane of our lungs and other parts of our body where viruses and bacteria can enter," explains Professor Sebastien Chastin from Glasgow Caledonian University.
Regular physical activity also increases the number of CD4+ T cells, which are another arm of the immune system. Their job is to find infected cells in the human body and destroy them, thereby preventing a virus from spreading and causing severe illness.
It was already known that regular physical activity has a protective effect against the severity of respiratory infections, and that being active is associated with a multitude of beneficial health effects. However, the value this study brings is that it uncovers that regular workouts are linked to a lower risk of severe infections, such as Covid-19, including hospitalisation and death.
The latest findings are promising in that it could help guide physicians and healthcare policymakers in developing guidelines that include physical activity, the authors say.
But, as the New York Times reports, immunologists and infectious diseases experts say we must urge caution when interpreting the studies. Nonetheless, they agree that exercise has benefits for a person's health.
"Due to limitations of the studies, our findings need to be interpreted with caution," add the authors.