title: "Skeletal muscle function deficit" in a nationally representative British birth cohort in early old age.
abstract: BACKGROUND
  Recommendations for identifying age-related muscle dysfunction have recently been published. We aimed to compare definitions for clinically relevant weakness and low lean mass proposed by the Foundation for the National Institutes of Health (FNIH) Sarcopenia project with the definition of sarcopenia proposed by the European Working Group on Sarcopenia in Older People (EWGSOP).
  
  
  METHODS
  A total of 1566 men and women from a British birth cohort had measures of appendicular lean mass, grip strength and timed up, and go speed at ages 60-64. Prevalence of low lean mass, weakness and slowness, identified using the FNIH and EWGSOP recommendations were estimated and compared: using kappa statistics and; by testing cross-sectional associations of both definitions of low lean mass and weakness with slowness and self-reported difficulties walking.
  
  
  RESULTS
  The combined prevalence of low lean mass and weakness ranged from 1.1% in men using FNIH criteria to 6.4% in women using EWGSOP criteria. There was limited overlap between the groups identified using the different criteria, driven by limited agreement between the two definitions of low lean mass. Using FNIH criteria, both low lean mass and weakness were associated with higher odds of slowness and difficulties walking; whereas low lean mass classified using EWGSOP criteria was not associated with these markers of mobility impairment.
  
  
  CONCLUSIONS
  At relatively young ages, signs of skeletal muscle function deficit with potential clinical relevance are already identifiable in the general population. This suggests that implementation of strategies to prevent mobility limitations, related to age-related muscle dysfunction, may need to start at least as early as midlife.
authors.affiliation: MRC Unit for Lifelong Health and Ageing, University College London, London, UK. rachel.cooper@ucl.ac.uk.
authors.forename: Rachel
authors.initials: R
authors.lastname: Cooper
authors.affiliation: MRC Unit for Lifelong Health and Ageing, University College London, London, UK.
authors.forename: David
authors.initials: D
authors.lastname: Bann
authors.affiliation: MRC Unit for Lifelong Health and Ageing, University College London, London, UK.
authors.forename: Elizabeth G
authors.initials: EG
authors.lastname: Wloch
authors.affiliation: Clinical Radiology and Academic Health Science Centre, Manchester Royal Infirmary, Central Manchester University Hospital NHS Foundation Trust, Manchester, UK.
authors.forename: Judith E
authors.initials: JE
authors.lastname: Adams
authors.affiliation: MRC Unit for Lifelong Health and Ageing, University College London, London, UK.
authors.forename: Diana
authors.initials: D
authors.lastname: Kuh
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology*; D015995:Prevalence; D055948:Sarcopenia / Q000453:epidemiology* / Q000503:physiopathology*; D006113:United Kingdom / Q000453:epidemiology
keywords: Epidemiology; Life course; Physical capability.