Even months after recovering from COVID-19, around one in four sufferers suffers from muscle pain and premature muscle fatigue. Recent study results indicate that anomalies in the muscles at the microstructural level play a role.
The term “post-COVID” covers a number of different symptoms that appear within three months after a SARS-CoV-2 infection, last for at least two months and cannot be explained by another diagnosis. These include severe tiredness (fatigue), shortness of breath, cognitive disorders and pain. At least 25 percent of those affected develop muscle pain (myalgia) and premature muscle fatigue.
Leg muscles examined in 20 people with post-COVID diagnosis
The underlying mechanisms have not yet been elucidated. A research team from the Ruhr University Bochum has now, as part of a Case-Control-Study looked for changes in the skeletal muscles that could be the cause. To do this, they examined the leg muscles of 20 people with a post-COVID diagnosis and 20 healthy controls using quantitative magnetic resonance imaging (MRI).
The results were compared to the results of a 6-minute walk test and standardized questionnaires assessing quality of life, fatigue and depression. Furthermore, all participants underwent a clinical examination, nerve conduction studies and determination of serum creatine kinase.
No evidence of neurogenic or myopathic changes
Participants with post-COVID performed significantly worse than controls in the 6-minute walk test. Although the majority of them complained of motor and cognitive fatigue, no evidence of neurogenic or myopathic changes could be found. With one exception, all of them had serum creatine kinase values in the normal range.
Quantitative muscle MRI showed neither signs of progressive inflammation nor a dystrophic process in the post-COVID group. Compared to the control group, however, the leg muscles of those affected showed microstructural differences. The study authors suspect that this could be a sign of reversible muscle fiber hypotrophy as a result of deconditioning.
However, this hypothesis must first be tested in longitudinal and intervention studies. If it turns out to be true, the changes could potentially be reversed as part of a muscle-building rehabilitation program.
