Rockville, Md. (May 13, 2021)—A new study suggests the lungs may not be the main factor that reduces exercise ability in people recovering from severe COVID-19. Anemia and muscle dysfunction also play a role. The study is published ahead of print in the Journal of Applied Physiology. It was chosen as an APSselect article for May.

“We found that exercise capacity after COVID-19 was reduced as a consequence of muscular factors and anemia.” – Sergio Caravita, MD, PhD

COVID-19, the disease caused by the SARS-CoV-2 virus, was described primarily as a respiratory disease in early 2020. People who are hospitalized with severe forms of the disease, including “COVID pneumonia” and breathing difficulties, often have a reduced capacity for physical activity when they continue to recover at home. SARS-CoV-2 can also cause cardiovascular complications in hospitalized patients. More recently, the medical community has expressed concern about detrimental muscle changes associated with COVID-19. Emerging research explores, in part, how decreased muscle function affects recovery.

Researchers in Italy studied 18 people who were hospitalized for COVID-19 infection. Immediately before being released from the hospital, the volunteers participated in exercise tests that included riding a semi-recumbent stationary bicycle. During the activities, the research team monitored the volunteers’ blood oxygen levels, heart function and lung volume.

Compared to healthy people of the same age, sex and weight, “exercise capacity was roughly reduced by one-third in the [COVID-19] survivors,” explained Sergio Caravita, MD, PhD, corresponding author of the study. “However, despite some persistent lung abnormalities, the great majority of [the volunteers recovering from COVID-19] did not stop exercise due to lung impairment. … Instead we found that exercise capacity after COVID-19 was reduced as a consequence of muscular factors and anemia.”

Inflammatory anemia caused by SARS-CoV-2 and muscle loss from prolonged bedrest during hospitalization, contributed to muscle fatigue, the researchers explained. These factors also caused many of the recovering volunteers to hyperventilate during exercise, which exacerbates the breathing problems commonly associated with COVID-19.

The study’s findings might help reassure those who had COVID-19 that these residual symptoms are, in most cases, not dangerous, the research team explained.

Read the full article, “Impact of COVID-19 on exercise pathophysiology. A combined cardiopulmonary and echocardiographic exercise study,” published ahead of print in the Journal of Applied Physiology. It is highlighted as one of this month’s “best of the best” as part of the American Physiological Society’s APSselect program. Read all of this month’s selected research articles.

NOTE TO JOURNALISTS: To schedule an interview with a member of the research team, please contact the APS Communications Office or call 301.634.7314. Find more research highlights in our Newsroom.

Physiology is a broad area of scientific inquiry that focuses on how molecules, cells, tissues and organs function in health and disease. The American Physiological Society connects a global, multidisciplinary community of more than 10,000 biomedical scientists and educators as part of its mission to advance scientific discovery, understand life and improve health. The Society drives collaboration and spotlights scientific discoveries through its 16 scholarly journals and programming that support researchers and educators in their work.

Journal Link: Journal of Applied Physiology