title: Insulin resistance and muscle strength in older persons.
abstract: BACKGROUND
  The functional consequences of an age-related insulin resistance (IR) state on muscle functioning are unknown. Because insulin is needed for adequate muscle function, an age-related insulin-resistant state may also be a determining factor. We evaluated the relationship between IR and handgrip muscle strength in men and women from a large population-based study (n = 968).
  
  
  METHODS
  The degree of IR was evaluated by the homeostasis model assessment (HOMA) and muscle strength was assessed using handgrip.
  
  
  RESULTS
  Simple sex-stratified correlations demonstrated that, in men, body mass index-adjusted handgrip strength correlated positively with physical activity (r = 0.321; p < .001), muscle area (r = 0.420; p < .001), muscle density (r = 0.263; p = .001), plasma albumin (r = 0.156; p = .001), insulin-like growth factor-1 (r = 0.258; p < .001), calcium (r = 0.140; p = .006), and testosterone (r = 0.325; p < .001) concentrations, whereas a negative association was found for age (r = -0.659; p < .001) and myoglobin plasma levels (r = -0.164; p =.001). In women, body mass index-adjusted handgrip strength correlated positively with physical activity (r = 0.280; p < .001), muscle area (r = 0.306; p < .001), muscle density (r = 0.341; p = .001), plasma albumin (r = 0.140; p =.001), and insulin-like growth factor-1 (r = 0.300; p < .001), whereas a negative association was found for age (r = -0.563; p < .001), myoglobin levels (r = -0.164; p = .001), and IR (r = -0.130; p = .04).
  
  
  CONCLUSIONS
  Sex-stratified analyses adjusted for multiple confounders showed that the relationship between IR and handgrip strength was found significant in women, whereas it was negligible and not significant in men.
authors.affiliation: Department of Geriatric Medicine and Metabolic Diseases II, University of Naples, Italy.
authors.forename: Angela M
authors.initials: AM
authors.lastname: Abbatecola
authors.forename: Luigi
authors.initials: L
authors.lastname: Ferrucci
authors.forename: Gianpaolo
authors.initials: G
authors.lastname: Ceda
authors.forename: Cosimo R
authors.initials: CR
authors.lastname: Russo
authors.forename: Fulvio
authors.initials: F
authors.lastname: Lauretani
authors.forename: Stefania
authors.initials: S
authors.lastname: Bandinelli
authors.forename: Michelangela
authors.initials: M
authors.lastname: Barbieri
authors.forename: Giorgio
authors.initials: G
authors.lastname: Valenti
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Paolisso
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002118:Calcium / Q000097:blood; D005260:Female; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D008297:Male; D008875:Middle Aged; D009132:Muscles / Q000502:physiology*; D009211:Myoglobin / Q000097:blood; D012709:Serum Albumin / Q000032:analysis
chemical_list: D009211:Myoglobin; D012709:Serum Albumin; D007334:Insulin-Like Growth Factor I; D002118:Calcium