Variation in Repeated Handgrip Strength Testing Indicates Submaximal Force Production in Patients With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. — CFSMEATLAS
Variation in Repeated Handgrip Strength Testing Indicates Submaximal Force Production in Patients With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.
Popkirov, Stoyan · European journal of neurology · 2025 · DOI
Quick Summary
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.
Why It Matters
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.
Observed Findings
ME/CFS patients showed significantly higher coefficients of variation in handgrip strength compared to healthy controls
Most ME/CFS patients had CV values exceeding 15%, a threshold associated with submaximal voluntary effort
In participants with normal fatigability indexes, female ME/CFS patients still demonstrated significantly elevated CV
Male patients with normal fatigability showed elevated CV that approached but did not reach statistical significance (p=0.06)
Variation in grip strength suggests inconsistent force production rather than maximal neuromuscular output
Inferred Conclusions
Loss of grip strength in ME/CFS involves alterations in higher-order motor control, not solely peripheral neuromuscular dysfunction
Handgrip strength may not be a reliable biomarker of ME/CFS because it reflects central nervous system control mechanisms rather than peripheral disease
Motor fatigue in ME/CFS may result from reduced implicit self-efficacy in the context of chronic dysregulation and disability
The pattern of submaximal force production suggests a protective mechanism rather than primary muscle damage
Remaining Questions
Why do female and male patients show different patterns in CV with respect to fatigability status, and what role does sex play in central motor control in ME/CFS?
What This Study Does Not Prove
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.