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J Neurol Neurosurg Psychiatry. 2014 Dec;85(12):1354-8. doi: 10.1136/jnnp-2014-307598. Epub 2014 Mar 21.

Is overwork weakness relevant in Charcot-Marie-Tooth disease?

Author information

  • 1IRCCS Foundation, C. Besta Neurological Institute, Milan, Italy.
  • 2MRC Centre for Neuromuscular diseases, UCL Institute of Neurology, London, UK.
  • 3Department of Neurology, Ophthalmology and Genetics, University of Genoa, Genoa, Italy.
  • 4Department of Neurological, Neuropsychological, Morphological and Motor Sciences, University of Verona, Verona, Italy.
  • 5Federico II University Department of Neurological Sciences, Naples, Italy.
  • 6Department of Neurosciences, University of Messina, and Clinical Centre NEMO SUD, Fondazione Aurora Onlus, Messina, Italy.
  • 7Neurology Clinic, Magna Graecia University, and Neuroimaging Research Unit, National Research Council, Catanzaro, Italy.
  • 8Department of Neurosciences, Catholic University and Don Gnocchi Foundation, Rome, Italy.
  • 9Department of Neurosciences, University of Parma, Parma, Italy.
  • 10Department of Pharmacological Sciences, University School of Pharmacy, Milan, Italy IMDEA-Food, Madrid, Spain.
  • 11Department of Epidemiology and Biostatistics, European Institute of Oncology, Milan, Italy.



In overwork weakness (OW), muscles are increasingly weakened by exercise, work or daily activities. Although it is a well-established phenomenon in several neuromuscular disorders, it is debated whether it occurs in Charcot-Marie-Tooth disease (CMT). Dominant limb muscles undergo a heavier overload than non-dominant and therefore if OW occurs we would expect them to become weaker. Four previous studies, comparing dominant and non-dominant hand strength in CMT series employing manual testing or myometry, gave contradictory results. Moreover, none of them examined the behaviour of lower limb muscles.


We tested the OW hypothesis in 271 CMT1A adult patients by comparing bilateral intrinsic hand and leg muscle strength with manual testing as well as manual dexterity.


We found no significant difference between sides for the strength of first dorsal interosseous, abductor pollicis brevis, anterior tibialis and triceps surae. Dominant side muscles did not become weaker than non-dominant with increasing age and disease severity (assessed with the CMT Neuropathy Score); in fact, the dominant triceps surae was slightly stronger than the non-dominant with increasing age and disease severity.


Our data does not support the OW hypothesis and the consequent harmful effect of exercise in patients with CMT1A. Physical activity should be encouraged, and rehabilitation remains the most effective treatment for CMT patients.

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