title: Bioimpedance vector analysis as a measure of muscle function.
abstract: BACKGROUND
  The impedance vector produced by an alternating current in the bioimpedance analysis can be seen as a standardised test of cellular mass and function since reactance is believed to reflect the mass and integrity of cell membranes. This study investigated the association between resistance and reactance normalised for height (R/H and Xc/H), and muscle function as assessed by hand grip strength.
  
  
  METHODS
  363 patients (172 male, 191 female) from Berlin and Copenhagen were included in the analysis. Whole body impedance was determined by BIA 2000M (Berlin) or EFG2.0 (Copenhagen). Hand grip strength was measured with Digimax electronic hand dynamometer (Berlin) or Jamar dynamometer (Copenhagen). The general linear model was used to assess the association between R/H, Xc/H and hand grip strength.
  
  
  RESULTS
  We observed a significant association between the impedance parameters R/H and Xc/H and hand grip strength after adjusting for confounding variables (hand grip strength= -36.9 - 0.063 x R/H + 0.573 x Xc/H + 40.7 x Height + 0.115 x Weight - 0.09 x Age + 3.41 (gender=male) + 1.87 (Centre Berlin); Weight: P=0.04, all other coefficients: P<0.0005. r(2)=0.708).
  
  
  CONCLUSIONS
  The impedance parameters R/H and Xc/H are related to hand grip strength and might therefore be used as a cooperation-independent method to reproducibly assess muscle function.
authors.affiliation: Charité-Universitätsmedizin Berlin Campus Mitte, Department of Gastroenterology, Berlin, Germany.
authors.forename: Kristina
authors.initials: K
authors.lastname: Norman
authors.forename: Matthias
authors.initials: M
authors.lastname: Pirlich
authors.forename: Janice
authors.initials: J
authors.lastname: Sorensen
authors.forename: Pia
authors.initials: P
authors.lastname: Christensen
authors.forename: Martin
authors.initials: M
authors.lastname: Kemps
authors.forename: Tatjana
authors.initials: T
authors.lastname: Schütz
authors.forename: Herbert
authors.initials: H
authors.lastname: Lochs
authors.forename: Jens
authors.initials: J
authors.lastname: Kondrup
mesh_terms: D000375:Aging / Q000502:physiology; D001823:Body Composition; D001824:Body Constitution; D017097:Electric Impedance; D005260:Female; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*