In this amazing study, Dutch researchers used muscle biopsies in long COVID patients suffering from post-exertional malaise. They found that the muscle phenotype had changed, resulting in lower exercise capacity. They also found mitochondrial function issues and local amyloid accumulation. Macrophages and CD3+ T cells were also infiltrated in the muscle tissues.
The clinical takeaways are to keep inflammation under control, utilize light exercises and not stressful ones, and optimize mitochondrial health.