Nature communicationsAug 26, 2026

Muscle changes in long COVID and ME/CFS differ from those caused by bed rest

Long Covid Weekly Brief ↗PubMed ↗DOI ↗OA ↗

Updated Aug 27, 2026

Abstract

Bed rest for 60 days leads to muscle atrophy in patients with long COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).

Patients with long COVID and ME/CFS exhibit unique respiratory and cardiovascular responses to maximal exercise compared to healthy individuals.
Both patient groups show an increase in glycolytic muscle fibers after bed rest.
ME/CFS patients specifically demonstrate atrophy in type I muscle fibers.
Changes in skeletal muscle characteristics suggest that physical inactivity alone does not fully account for the reduced exercise capacity in these patients.
Oxidative phosphorylation capacity is linked to maximal oxygen uptake only after periods of bed rest.

Simplified

Patients with long COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) suffer from post-exertional malaise. The accompanying physical inactivity may contribute to a lower aerobic capacity and may explain skeletal muscle adaptations in these patients. Here, we compare whole-body exercise responses and skeletal muscle adaptations after strict 60-day bed rest in healthy people with those in long COVID and ME/CFS patients, and healthy age- and sex-matched controls. Bed rest alters respiratory and cardiovascular responses to maximal exercise, which are dissimilar in patients. Bed rest causes muscle atrophy without altering fiber type. Both patient groups have more glycolytic fibers, and ME/CFS patients display type I-specific atrophy. Only after bed rest is oxidative phosphorylation capacity associated with maximal oxygen uptake. As skeletal muscle characteristics differ between patients and healthy individuals after bed rest, physical inactivity cannot solely explain the lower exercise capacity and skeletal muscle adaptations in long COVID and ME/CFS patients.

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Long CovidIssue #52

Long COVID muscle changes look nothing like what happens after 60 days of bed rest

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Muscle changes in long COVID and ME/CFS differ from those caused by bed rest

Abstract

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