title: Total body water changes after an exercise intervention tracked using bioimpedance spectroscopy: a deuterium oxide comparison.
abstract: OBJECTIVE
  Bioimpedance spectroscopy (BIS) for the estimation of total body water (TBW) has advantages over isotope dilution techniques, including cost, portability, and ease of use. The aim of the current study was to determine the validity of a BIS device (Imp SFB7) for tracking changes in overfat and obese individuals.
  
  
  METHODS
  Sixty overfat and obese men and women (27+/-8 yr, 33.41+/-3.81%fat) participated in the study. TBW was estimated using BIS and deuterium oxide (D(2)O) before and after the ten-week intervention.
  
  
  RESULTS
  Pre-and post-intervention BIS TBW estimations errors increased as body mass index (BMI), fat mass (FM), and fat-free mass (FFM) increased (p<0.05). Delta values were more accurate than pre- and post-TBW estimations (total error=1.45 L). Age significantly influenced pre- and post-TBW errors (p<0.05). Therefore, a regression equation was developed to correct for the pre- and post-BIS-estimated TBW errors: D(2)O TBW=11.478+0.743(BIS TBW)-2.429(Gender), (Men=1, Women=2).
  
  
  CONCLUSIONS
  BIS can be considered an accurate tool for tracking changes in TBW regardless of variations in BMI, FM, FFM, or age in both overfat and obese men and women (BMI>24). Employing a BIS TBW equation is suggested over the development of resistivity coefficients based on BMI, FM, FFM or age.
authors.affiliation: Metabolic and Body Composition Laboratories, University of Oklahoma, Norman, OK 73019, USA.
authors.forename: Jordan R
authors.initials: JR
authors.lastname: Moon
authors.forename: Abbie E
authors.initials: AE
authors.lastname: Smith
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Tobkin
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Lockwood
authors.forename: Kristina L
authors.initials: KL
authors.lastname: Kendall
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Graef
authors.forename: Michael D
authors.initials: MD
authors.lastname: Roberts
authors.forename: Vincent J
authors.initials: VJ
authors.lastname: Dalbo
authors.forename: Chad M
authors.initials: CM
authors.lastname: Kerksick
authors.forename: Joel T
authors.initials: JT
authors.lastname: Cramer
authors.forename: Travis W
authors.initials: TW
authors.lastname: Beck
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Stout
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D001823:Body Composition / Q000502:physiology*; D015992:Body Mass Index; D001834:Body Water / Q000378:metabolism*; D041961:Deuterium Exchange Measurement; D017097:Electric Impedance; D015444:Exercise / Q000502:physiology*; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D015596:Nutrition Assessment; D009765:Obesity / Q000208:ethnology / Q000628:therapy*; D050177:Overweight / Q000208:ethnology / Q000628:therapy*; D057185:Sedentary Behavior; D013046:Specific Gravity; D055815:Young Adult