The findings add to mounting evidence, both from experiments and people’s experiences, that “something is going on” in many people who develop prolonged Covid that makes exercise challenging, if not impossible, he said. Matthew Durstenfeld, a cardiologist at Zuckerberg San Francisco General Hospital and a professor in the Department of Medicine at the University of California, San Francisco, who led the new study.
That possibility has implications for the length of the definition of Covid and for the health and well-being of patients with prolonged Covid, months or years from now.
Long covid, the name for persistent, even worsening, symptoms of illness that continue for months after a covid-19 infection, affects millions of Americans and others around the world. A published study earlier this week indicates that at least one in 20 people sick with coronavirus will develop covid for a long time.
Long-term covid is typically diagnosed based on a constellation of symptoms including headaches, fatigue, brain fog, joint pain, and others. Many people with prolonged covid also report anecdotally that they can’t exercise or even walk around the block without feeling breathless and exhausted.
But this inability to be active, known as exercise intolerance, hasn’t generally been considered a formal symptom of prolonged Covid, Durstenfeld said, in part because doctors and researchers thought it was likely due to a lack of conditioning. That is, they thought that people’s resistance decreased while they were bedridden with covid, and that they would recover it once they got up and started moving again.
But anecdotally, many people with prolonged Covid did not regain their fitness, and in the past year, published science began to suggest that their bodies responded uniquely, and poorly, to exercise. During the exercise tests, their hearts, breathing, muscles and other biological systems struggled much more than in healthy people.
But most of these studies were small, sometimes involving a single patient, and usually focused on those who had been hospitalized, often for weeks or more, making it difficult for researchers to separate the effects of being bedridden and inactive for a prolonged period. COVID-19.
So, for the new study, Durstenfeld and colleagues decided to aggregate and reanalyze data from all relevant recent studies, to give any findings more weight by including as many patients as possible.
To achieve this, they identified nine experiments that compared the exercise tolerance of people with long-term covid with that of people who had been infected but recovered. Combining the data from the studies, they ended up with results for 464 people with prolonged covid and 359 without covid. These groups were similar in age, between 39 and 56 years old, and all had completed a clinical test of their aerobic capacity and heart rate on a treadmill or exercise bike, along with some additional medical tests.
Their results, however, were markedly different. In general, those who had overcome covid showed normal exercise capacity for their age. But those with prolonged covid had the resilience of someone 10 years older. Forty-year-olds jogged or biked like “someone in their fifties,” Durstenfeld said.
An unusual response to exercise
They also harbored a number of unusual internal responses to exercise, previous studies showed. Many people’s muscles drew less oxygen from the bloodstream than normal, hindering the muscles’ ability to contract. People’s heart rates also often didn’t rise as high as would be expected during exercise, slowing blood flow throughout the body and causing some people to hyperventilate.
These are not common physiological reactions after someone has lost form due to illness and bed rest, Durstenfeld said. “This is more than deconditioning.”
Other scientists agree. “I think the main and correct point in this review is that deconditioning alone” is not what makes exercise so challenging for many people with long-term Covid, said David Systrom, a pulmonary physician at Brigham and Women’s Hospital. in Boston and professor of medicine at Harvard. Medicine School. He was not involved in the new study, but has studied and treated patients with prolonged covid.
People with prolonged Covid are likely to develop molecular changes within their muscles and some nerves and blood vessels, he said, that may influence how well their bodies handle the physical demands of exercise. These changes and challenges occur despite the fact that most people with prolonged covid do not show obvious abnormalities in the lungs or heart.
A new symptom of long covid.
However, to compound the complexities, few people with prolonged covid showed precisely the same patterns of physiological changes, and some seemed much less affected by exertion than others.
Still, one takeaway from the new study is that exercise intolerance “should be considered a symptom” of prolonged Covid, Durstenfeld said.
Another is that people with prolonged Covid may want to consider exercise testing, said Stephen J. Carter, a cardiovascular physiologist at the Indiana University Bloomington School of Public Health, who has studied people with prolonged Covid but was not involved in the study. new review.
“If people are having trouble exercising, talking to their doctor about cardiopulmonary exercise testing would be an important starting point,” he said. “These tests offer a non-invasive way to identify where exercise limitation may be coming from.”
It might also be worth visiting a clinic that specializes in prolonged Covid and is familiar with exercise intolerance, Durstenfeld said.
“We still don’t know the trajectory” of prolonged covid and exercise intolerance, he continued, or how long the condition lasts, whether it can be treated or whether it can slowly resolve on its own. But the long-term goal of her and others’ research, she said, is to help people with long-term Covid find ways to get active again.
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