Thread by @RobWust

1/10 I am incredibly proud to share our latest study, published today in @NatureComms, a follow-up to our 2024 paper on skeletal muscle abnormalities in long COVID. Open access:

#LongCOVID #MECFSnature.com/articles/s4146…

2/10 People with long COVID and ME/CFS are often told that their reduced exercise capacity and muscle abnormalities simply result from physical inactivity or “deconditioning.”
We directly tested this assumption.

3/10 We compared people with long COVID and ME/CFS with healthy individuals who underwent 60 days of strict bed rest, an extreme and carefully controlled model of prolonged physical inactivity, in close collaboration with @esa and @DLR_en.

@esa @DLR_en 4/10 Although all groups had a lower exercise capacity, compared to healthy controls, the underlying changes were clearly different. After bed rest, healthy participants showed substantial and rapid muscle loss. This pattern was not observed in people with long COVID or ME/CFS.

@esa @DLR_en 5/10 Both patient groups had fewer slow-twitch muscle fibres, which are important for endurance, and relatively more fast-twitch fibres, which fatigue more quickly. This does not occur after bed rest. People with ME/CFS also showed specific atrophy of their slow-twitch fibres.

@esa @DLR_en 6/10 We also found signs of impaired energy production in the muscles of people with long COVID and ME/CFS.

In ME/CFS, we additionally observed fewer muscle capillaries, potentially limiting oxygen delivery during exercise.

@esa @DLR_en 7/10 Our main conclusion: physical inactivity alone cannot explain the reduced exercise capacity and skeletal muscle abnormalities in long COVID and ME/CFS. This helps explain why “just exercise more” does not reflect the underlying biology, especially for those with physical PEM

@esa @DLR_en 8/10 At the same time, deconditioning can occur in sedentary patients. Complete inactivity causes muscle loss, increased fat mass and reduced insulin sensitivity. The challenge is finding the individual balance between too little and too much activity.
pubmed.ncbi.nlm.nih.gov/38232697/

@esa @DLR_en 9/10 Huge thanks to our participants, patient representatives, co-authors, collaborators all over the world

@esa @DLR_en And a special shout-out to all the funders of this work: @ZonMw, @patientled @PlzSolveCFS @MEResearchUK @StLongCOVID @amsterdamumc @VU_FGB @AMSmovement @esa. Thanks a lot for your continued support!