van Campen, C Linda M C, Rowe, Peter C, Visser, Frans C · Journal of translational medicine · 2021 · DOI
This study examined whether being physically deconditioned (out of shape) causes the dizziness and fainting symptoms that many ME/CFS patients experience when standing up. Researchers tested 199 ME/CFS patients and 22 healthy people using exercise tests and a tilt table test that measures blood flow to the brain. The results showed that ME/CFS patients had significant problems with blood flow to their brain when tilted upright, but this problem occurred regardless of how deconditioned they were.
This finding challenges the common assumption that ME/CFS patients' orthostatic symptoms result primarily from deconditioning, suggesting instead a distinct underlying physiological mechanism affecting cerebral blood flow regulation. Understanding that these symptoms are independent of fitness level may shift clinical management approaches and validate patients' experiences as arising from disease-specific pathophysiology rather than lifestyle factors.
This study does not prove what causes the abnormal cerebral blood flow reduction in ME/CFS, only that deconditioning is not the primary driver. It also does not establish whether improving fitness through rehabilitation would or would not benefit patients, as the relationship between exercise capacity and orthostatic symptoms appears mechanistically distinct. Additionally, the findings are correlational and cannot exclude deconditioning as a contributing factor in individual cases.
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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