Exercise May Help Restore Immune Health After Severe COVID-19

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Regular, guided exercise may help the immune system recover after severe COVID-19 and support overall recovery from post-COVID syndrome, according to findings presented at the European Respiratory Society Congress in Amsterdam.

Although most people who have contracted COVID-19 — a virus that has resulted in at least 778.7 million infections and is responsible for 7 million deaths — recover from their illness, many experience the lasting effects of long COVID (or post-COVID syndrome). The risk of developing long COVID can vary depending on individual factors, just as the severity of the initial infection differs from person to person.

“Research suggests that those with post-COVID syndrome are at an increased risk of immune dysregulation where, instead of protecting the body, the immune system can become overactive or misdirected, attacking the body’s own healthy cells or reacting strongly to things that are not harmful,” said researcher Enya Daynes, Ph.D., senior specialist physiotherapist in the Pulmonary and COVID Rehabilitation team at the National Institute for Health and Care Research Leicester Biomedical Research Centre in the U.K., who presented the study at the congress. “This can lead to ongoing inflammation and symptoms such as fatigue, joint pain and generally feeling unwell, many of which overlap with what people experience in post-COVID syndrome.”

A significant portion of patients — around one-third — develop long COVID despite having only mild or even asymptomatic initial cases. These patients often experiencing symptoms that arise later and persist confusingly without clear triggers. In addition to joint pain and fatigue, over 200 different symptoms have been connected to the condition. Other common issues include cognitive problems often called brain fog, heart palpitations, ongoing respiratory symptoms and lingering loss of taste or smell. It can also manifest as difficulty regulating blood sugar or blood pressure.

The current study explored whether an eight-week exercise-based rehabilitation program could help restore immune balance in people recovering from severe COVID-19. The team included 31 participants who had been hospitalized with COVID-19. Half followed a supervised exercise and education program, while the rest received usual care.

After eight weeks, those in the exercise program showed significant increases in healthy “naive” and memory T cells compared with controls, suggesting their immune systems were recovering.

“We found improvements in central memory CD4+ T cells,” said Daynes. “These are responsible for providing a quick response to any infections that the body has encountered before, which could include COVID. We also found that central and effector memory CD8+ T cells improved throughout the body. These cells can identify and fight future infections more rapidly, providing a crucial systemic immune response, and long-term immunity.”

The results indicate that structured exercise may help improve immune function in post-COVID patients. The team believes this is likely due to improvements in blood flow, mobilizing immune cells and helping their ability to monitor the body for potential threats. Chronic inflammation is also reduced because an improved communication between immune cells can help with immune response and production and turnover of cells. This in turn helps with creating a balanced environment for immune function.

Future research will focus on whether these benefits can be replicated among people who were not hospitalized for their COVID infection.