Long COVID-19 is perhaps best known for the “brain fog” it causes in infected people, but it's not the only symptom. Physical symptoms can be debilitating as well, such as prolonged and extreme fatigue, especially after exercise. Thanks to new research in Amsterdam, we now know why.
“There are clear changes in the muscles of these patients,” Michel van Vugt, professor of internal medicine at UMC Amsterdam and co-author of the study, said in the paper. statement. “The causes of fatigue are truly biological.”
“This discovery means we can begin researching appropriate treatments for long-term patients with COVID-19,” she added.
To find out what was going on, researchers asked 46 participants (25 patients with long-term COVID-19 infection and 21 non-coronavirus control subjects) to cycle for 15 minutes. I requested it. While that shouldn't be a huge ordeal for most of us, it has definitely been taxing for long-term COVID-19 patients. The group had “severely impaired motor performance,” the study says, including some fairly serious consequences later on.
“We found a variety of abnormalities in the musculature of the patients,” explains study co-author Rob Wust, assistant professor in the Department of Human Movement Sciences at Vrije Universiteit Amsterdam. “At the cellular level, we found that muscle mitochondria, also known as the cellular energy factory, were less functional and produced less energy.”
This difference was not only apparent after exercise. Biopsies of participants' skeletal muscles taken one week before exercise showed that the muscles of patients with long-term COVID-19 infection had a higher proportion of glycolytic fibers compared to controls. . That ismany of their muscles relied on sugar rather than oxygen to produce energy, making them more susceptible to fatigue.
But biopsies taken after exercise sessions confirmed that the situation for long-term coronavirus patients is actually even worse than that. Not only was their mitochondria functioning worse than before, but their muscles were showing signs of more severe tissue damage, which their bodies were struggling to repair.
Even more concerning, especially for those who believe that their current health allows them to overcome the potential effects of contracting COVID-19, is that all participants were infected with COVID-19. The fact is that he was of working age, fit and healthy before that. No one became sick enough to be hospitalized, and everyone's heart and lungs remained healthy after the exercise.
“It confirms that there is something wrong inside the body with this disease,” Wust said. guardian.
“[Long COVID] “It damages your muscles, impairs your metabolism, and explains why you feel sore and tired for weeks after exercise,” he says.
There were also some surprises. Contrary to what some people have suggested, long-term infection with the new coronavirus does not appear to be caused by coronavirus particles that remain in the body. “We don't see any signs of that in the muscles at this point,” Van Vugt noted. The research team found accumulations of amyloid protein in the patients' skeletal muscles, and some scientists theorize that these deposits could clog capillaries and immune cells in long-term coronavirus patients. No evidence was found that it was.
“Postexertional fatigue cannot be explained by the hypothesis that these deposits impede vascular perfusion and cause local tissue hypoxia,” the paper concludes. “The underlying reasons for increased intramuscular accumulation of amyloid-containing deposits during post-exercise fatigue remain unknown.”
So what advice would you give to people suffering from the after-effects of COVID-19, months after the virus has left their bodies? Unfortunately, not much. “Specifically, we advise these patients to stick to their physical limits and not exceed them,” said UMC Amsterdam researcher and co-author of the study. said one Brent Appelman.
“Consider light exercise that doesn't make your symptoms worse,” he added. “Walking or riding an electric bike is a good way to stay fit. Keep in mind that each patient has different limits.”
The research will be published in a journal nature communications.
