title: Comparison of three segmental multifrequency bioelectrical impedance techniques in healthy adults.
abstract: BACKGROUND
  The analysis of segmental or limb bioimpedance has gained importance in human population biology. However, standardized measurement techniques are needed.
  
  
  OBJECTIVE
  This study compared three techniques for segmental analysis (T1, conventional electrode measurement; T2, use of a novel additional switching unit; T3, equipotentials instead of switching unit) which are often used in population biology.
  
  
  METHODS
  The techniques were compared in 124 healthy adults (19-83 years) using a tetrapolar bioimpedance analyser (Nutriguard-M) at multiple frequencies (5, 50, 100 kHz) to gain whole-body and segmental resistances, reactances and phase angles.
  
  
  RESULTS
  Repeated measures ANOVA yielded a significant technique effect for most variables (26/27), a significant interaction technique ×  sex for half (13/27), and a significant interaction technique ×  age for a quarter (7/27) of variables.
  
  
  CONCLUSIONS
  Differences exist between the three techniques which are primarily caused by inconsistent current pathways. A comparison with literature data showed that, in addition, subject's posture during measurement, electrode contact and electrode site may lead to inconsistent resistance and reactance values. This makes comparisons between different populations difficult. Therefore, this study recommends generally using the T2 technique which is standardized, easy to use and, thereby, well suited for field studies in large population groups.
authors.affiliation: Department of Human Biology, Zoological Institute, Christian-Albrechts-University , Am-Botanischen-Garten-9, Kiel, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Mally
authors.forename: Manuela
authors.initials: M
authors.lastname: Dittmar
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000886:Anthropometry / Q000379:methods*; D001823:Body Composition; D015992:Body Mass Index; D017097:Electric Impedance; D004566:Electrodes; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011187:Posture; D012737:Sex Factors; D055815:Young Adult