Popkirov, Stoyan · European journal of neurology · 2025 · DOI
This study looked at handgrip strength tests in ME/CFS patients and healthy people to understand why grip strength varies so much in ME/CFS. Researchers found that ME/CFS patients showed more inconsistency in their grip strength measurements compared to healthy controls, suggesting their bodies aren't producing maximum force even when asked to do so. This pattern indicates the problem may be related to how the brain controls muscles rather than the muscles themselves being permanently damaged.
This research challenges the assumption that ME/CFS causes permanent muscle damage, instead suggesting the nervous system may be protecting the body by limiting force production. Understanding the true mechanism of weakness is essential for developing appropriate treatments and for validating reliable biomarkers that accurately reflect ME/CFS pathophysiology.
This study does not prove that peripheral muscles are completely unaffected in ME/CFS, only that reduced grip strength involves central nervous system factors. The cross-sectional design cannot establish causation or explain why higher-order motor control is altered. The findings also do not rule out other potential mechanisms contributing to weakness beyond those measured.
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 →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Popkirov, Stoyan (2025). Variation in Repeated Handgrip Strength Testing Indicates Submaximal Force Production in Patients With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.. European journal of neurology. https://doi.org/10.1111/ene.70273
BibTeX
@article{mecfsatlas-popkirov-2025-variation-repeated,
author = {Popkirov, Stoyan},
title = {Variation in Repeated Handgrip Strength Testing Indicates Submaximal Force Production in Patients With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.},
journal = {European journal of neurology},
year = {2025},
doi = {10.1111/ene.70273},
note = {PubMed: 40923211},
url = {https://www.mecfsatlas.com/evidence/popkirov-2025-variation-repeated},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-26. https://www.mecfsatlas.com/evidence/popkirov-2025-variation-repeated
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