WEDNESDAY, May 31, 2023 (HealthDay News) — Lack of energy for exercise is a common problem for people with so-called long-term COVID.
New research pinpoints the most likely reason why: reduced ability to get the heart pumping fast enough to sustain exertion. The name for this is chronotropic incompetence.
The amount of aerobic exercise an individual can do is largely limited by the supply of oxygen by the heart, lungs, and blood and its utilization by muscles, noted the study’s first author, Dr. Matthew Durstenfeld, cardiologist and assistant professor of medicine at the University of California, San Francisco.
If the heart can’t pump that fast, you can’t train that hard,” Durstenfeld said.
Chronotropic incompetence wasn’t the only reason people with long COVID had lower-than-expected exercise capacity in the new study, but it was surprisingly common among people with long COVID, he added.
Some people infected with COVID-19 can develop a variety of ongoing health problems. These conditions can last for weeks, months or years and have been labeled long COVID.
Using biomarker testing, the researchers found inflammatory biomarkers early in patients with long COVID.
They also found that all of the patients who struggled with reduced exercise capacity also experienced reactivation of a previous Epstein-Barr virus (EBV) infection. Epstein-Barr is linked to mononucleosis and multiple sclerosis.
EBV reactivation is common after SARS-CoV-2 infection in general, Durstenfeld noted, so it’s hard to tell whether this is a chance finding or a significant clue from our study.
For this study, researchers looked at 60 adults who had had COVID-19 and evaluated them about 18 months after their initial infection. The mean age was 53 years. Participants underwent MRI scans and aerobic exercise tests, as well as heart rhythm monitoring, while on stationary bikes. Blood samples were also taken.
Exercise tests revealed that nearly half with symptoms suffered from markedly reduced exercise capacity, versus 16 percent without symptoms.
The findings suggest that chronotropic incompetence — failure to achieve 80 percent of predicted maximum heart rate during exercise — contributes to exercise limitations in the long run of COVID, Durstenfeld said.
The average capacity decline was approximately equivalent to 10 years. A 40-year-old woman can only exercise as much as a 50-year-old woman, Durstenfeld noted.
In other words, the same person who could have played doubles tennis before COVID would now be able to manage golf with just a cart, he explained.
So what explains the link between long COVID and chronotropic incompetence?
Durstenfeld said there’s no clear answer yet, though he suggested it could have something to do with inflammation or the autonomic nervous system.
For now, long-term COVID patients who find it difficult to exercise, especially those with severe long-term COVID, may need to adjust the pace of their activity with guidance from a rehabilitation expert if possible, Durstenfeld said.
My hope is that treatments for long-term COVID will be discovered that will help people regain lost exercise capacity, Durstenfeld noted. But we don’t have any proven treatments yet.
Dr. Leslie Rydberg is an attending physician at the Shirley Ryan AbilityLab in Chicago.
Rydberg, who was not part of the study, suggested that the best way to help people with long-term COVID increase their ability to be active is to figure out what activities or exercises they can do without exacerbating their symptoms and build them into their daily routine.
Then they can very slowly and gradually increase the amount of time they do that activity, she added, cautioning that patients should decrease activity levels if and when symptoms increase.
The results were recently published in Journal of Infectious Diseases.
More information
US Centers for Disease Control and Prevention has more on long COVID.
SOURCES: Matthew Durstenfeld, MD, MAS, assistant professor, medicine, University of California, San Francisco, and cardiologist and clinical research physician-scientist, Zuckerberg San Francisco General Hospital; Leslie Rydberg, MD, attending physician, Shirley Ryan AbilityLab, Chicago; Journal of Infectious Diseases, May 11, 2023
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