Kent-Braun, J A, Sharma, K R, Weiner, M W et al. · Neurology · 1993 · DOI
Researchers tested whether muscle fatigue in ME/CFS patients was caused by problems within the muscle itself or in the brain's ability to control muscles. They found that the muscles worked normally and used energy normally during exercise, but the patients' brains were unable to fully activate their muscles during hard, sustained work. This suggests the primary problem may be in how the nervous system controls muscles rather than in the muscles themselves.
This study provides early evidence that ME/CFS fatigue may originate from a central (brain and nervous system) control problem rather than muscle damage, which has important implications for understanding disease mechanisms and potential treatment approaches. Understanding whether fatigue is central versus peripheral helps researchers focus on the correct biological system and may guide development of more effective interventions.
This study does not prove what causes the central activation failure or whether it is primary to ME/CFS or secondary to other disease processes. The findings are limited to one muscle group and acute exercise responses, so they may not generalize to whole-body fatigue or post-exertional malaise patterns. The study also cannot determine whether this activation deficit is reversible or permanent.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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