Muscle endurance deficits in myositis patients despite normal manual muscle testing scores

David R. Amici, Iago Pinal-Fernandez, Ruben Pagkatipunan, Albert Mears, Rebecca de Lorenzo, Eleni Tiniakou, Jemima Albayda, Julie J. Paik, Thomas E. Lloyd, Lisa Christopher-STINE, Andrew L. Mammen, Tae Chung

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Introduction: It is unclear whether quantitating muscle endurance adds nonredundant information useful for the care of patients with muscular disease. Methods: Records were retrospectively reviewed for all Johns Hopkins Myositis Center patients with a muscle endurance assessment (n = 128, 226 patient-visits). Muscle endurance and strength were quantitated with the Myositis Functional Index-2 (FI2) and manual muscle testing (MMT), respectively. Results: Composite FI2 muscle endurance scores were comparable in inclusion body myositis (n = 58), dermatomyositis (n = 31), and polymyositis (n = 39). Overall, muscle endurance correlated with and evolved similarly to strength, inversely to serum creatine kinase. However, in patients with normal or near-normal strength (mean MMT > 9.75/10), muscle endurance was typically abnormal and highly variable (mean FI2, 5.6/10; interquartile range, 3.3-7.8/10). Discussion: Muscle endurance testing may identify muscle impairment inadequately described by MMT, particularly in patients with high MMT scores. Muscle Nerve 59:70–75, 2019.

Original languageEnglish (US)
Pages (from-to)70-75
Number of pages6
JournalMuscle and Nerve
Issue number1
StatePublished - Jan 2019


  • functional index
  • muscle strength
  • myositis
  • neuromuscular diseases
  • physical endurance

ASJC Scopus subject areas

  • Physiology
  • Clinical Neurology
  • Cellular and Molecular Neuroscience
  • Physiology (medical)


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