Functional and Morphological Differences of Muscle Mitochondria in Chronic Fatigue Syndrome and Post-COVID Syndrome.
Level 4 - case-series / case-control
Cross-sectional comparative case-control study using human muscle biopsy samples
PubMed 38338957 · doi:10.3390/ijms25031675
What was done
Mitochondrial oxidative phosphorylation (OXPHOS) capacity was measured using high-resolution respirometry in permeabilized muscle fibers across chronic fatigue syndrome (CFS) patients, post-COVID syndrome (PCS) patients, and healthy controls (HC). Electron microscopy was used to evaluate mitochondrial morphology (cristae, diameter, circumference, area) and content (number, proportion per cell) in subsarcolemmal and intermyofibrillar compartments, comparing CFS directly with PCS.
What was found
Complex I OXPHOS capacity was reduced in PCS compared to HC. Subsarcolemmal area, volume per cell, diameter, perimeter, and both subsarcolemmal and intermyofibrillar cristae integrity were higher in PCS compared to CFS. No differences were observed between PCS and CFS in intermyofibrillar mitochondrial dimensions. The abstract reports directional findings only and omits exact numerical values, sample sizes, and p-values.
Why it matters
This study differentiates the pathophysiology of PCS and CFS, suggesting distinct mechanisms: direct or acute viral-induced Complex I respiratory impairment in PCS versus advanced structural cristae and morphological degradation in CFS.
Limits
The abstract does not report participant sample sizes, demographic characteristics, or quantitative values. Morphological comparisons were restricted to CFS vs. PCS without inclusion of healthy controls. Confounding by variable disease duration and physical deconditioning cannot be ruled out.