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Research Study: Overlaps between Long Covid and ME/CFS

Long-term neuromuscular consequences of SARS-Cov-2 and their similarities with myalgic encephalomyelitis/chronic fatigue syndrome: results of the retrospective CoLGEM study | Journal of Translational Medicine | Full Text


SARS-Cov-2 infection is well documented and often includes fatigue and myalgia [1,2,3,4]. A meta-analysis by Bornstein et al. [5] showed that a large number of individuals infected with SARS-CoV-2 complain of continuing fatigue many months after the onset of the disease. This phenomenon has been termed “post-COVID syndrome” or “long-COVID” and defines a series of chronic symptoms that patients experience after resolution of acute SARS-Cov-2 infection.


Patients with long-COVID often complain of continuous fatigue, myalgia, sleep problems, cognitive dysfunction, and post-exertional malaise. No data are available on EMG recording of evoked myopotentials (M-waves) or exercise-induced alterations in long-COVID patients, providing evidence of muscle membrane fatigue. Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) develops in more than half of patients after an infectious disease, particularly viral diseases. A large proportion (around 70%) of these patients have neuromuscular disorders with M-wave alterations during and after exercise. Our hypothesis was that M-wave alterations would be also found in long-COVID patients, in association with neuromuscular symptoms, similar to ME/CFS.


This retrospective observational ColGEM (Covid LonG Encéphalomyelite Myalgique) study compared 59 patients with long-COVID and 55 ME/CFS patients with a history of severe infection who presented before the COVID pandemic. All of these patients underwent the same protocol consisting of a questionnaire focusing on neural and neuromuscular disorders and M-wave recording in the rectus femoris muscle before, during, and 10 min after a progressive cycling exercise. Maximal handgrip strength (MHGS) and maximal exercise power were also measured. The frequency of symptoms and magnitude of M-wave changes in the two groups were compared using non-parametric and parametric tests.


The frequency of fatigue, myalgia, sleep problems, cognitive dysfunction, and post-exertional malaise as well as the magnitude of exercise-induced M-wave alterations were the same in the two groups. By contrast, digestive problems were less present in long-COVID. M-wave alterations were greater in ME/CFS patients as in those with long-COVID when the highest muscle strength and highest exercise performance were measured.


These high clinical and biological similarities between long-COVID and ME

MEA Comment

Dr Charles Shepherd, Honorary Medical Adviser to the ME Association comments:

Yet another paper on the pathological overlaps between ME/CFS and Long Covid.

Interesting to note that this study on nerve-muscle abnormalities comes from researchers in France – where there is very little recognition of ME/CFS by both health professionals and researchers.

Dr Charles Shepherd,
Trustee and
Hon. Medical Adviser
to the ME Association.

Dr Charles Shepherd
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