"The groundwork of all happiness is health." - Leigh Hunt

Researchers link fatigue from long-COVID to changes in muscles

January 10, 2024 – People with long COVID experience persistent fatigue, which latest research from Amsterdam attributes to changes within the muscles.

Scientists at Amsterdam UMC and Vrije Universiteit Amsterdam (VU) say the fatigue is brought on by mitochondria in muscle cells, which produce less energy than in healthy people, in keeping with a press release EurekAlert.

The results of the study were published in Nature communication.

Michèle van Vugt, professor of internal medicine at Amsterdam UMC, said: “We see clear changes in the muscles in these patients.”

25 individuals with long COVID and 21 healthy people took part within the study. They were asked to cycle for quarter-hour, which resulted in worse symptoms in patients with long COVID or post-exertional malaise (PEM).

National Public Radio reports that while most individuals experience pain after exercise, PEM is different. “It’s not just pain,” said study co-author Braeden Charlton NPR. “For many people it is completely debilitating for days or weeks.”

Scientists examined blood and muscle tissue per week before cycling and a day after.

“We saw various abnormalities within the patients’ muscle tissue. At the cellular level, we saw that the muscle's mitochondria, also called the cell's energy factories, function less well and produce less energy,” said Rob Wüst, assistant professor of exercise science at VU. “So the reason for fatigue is definitely biological… This discovery means we will now start researching an acceptable treatment for individuals with long COVID.”

Researchers said their findings contradict a theory about long COVID – that coronavirus particles remain within the body. They also said that the guts and lungs were functioning well, meaning long-term effects on fitness aren’t brought on by problems with the guts and lungs.