title: Assessment of total body water and its compartments in elite judo athletes: comparison of bioelectrical impedance spectroscopy with dilution techniques.
abstract: Bioelectrical impedance spectroscopy (BIS) is an inexpensive and non-invasive technique to measure total body water (TBW), extracellular water (ECW), and intracellular water (ICW). The purpose of this study was to validate TBW, ECW and ICW assessed by BIS, using dilution techniques as the reference method (REF) in elite judo athletes. Thirty-two Portuguese elite male judo athletes were evaluated during a period of weight stability. TBW, ECW and ICW were assessed by BIS (Xitron 4000). Deuterium and bromide dilution techniques were used as the criterion method for measuring TBW and ECW, while ICW was calculated as the difference between the two. BIS explained 96%, 77% and 94% of the total variability from REFs for TBW, ECW and ICW, respectively. BIS also demonstrated high precision (ρ ≥ 0.88) and accuracy (Cb = 0.98), with a minimum concordance coefficient correlation of 0.87 for ECW. The mean bias demonstrated that BIS slightly overestimated the REF in 1.1 kg (2.3%), 0.3 kg (1.6%) and 0.8 kg (2.7%) for TBW, ECW and ICW, respectively. The 95% limits of agreement ranged from -1.2 to 3.3 kg in TBW, from -1.8 to 2.4 kg in ECW and from -1.0 to 2.6 kg in ICW. A non-significant trend was found between the difference and the mean of reference and alternative methods. These findings highlight the efficacy of BIS as a valid non-biased tool for the assessment of TBW and its compartments in elite male judo athletes, during a period of weight stability.
authors.affiliation: a Growth and Development Lab - Center for Investigation in Pediatrics (CIPED), Faculty of Medical Sciences , State University of Campinas , Campinas , Brazil.
authors.forename: Ezequiel M
authors.initials: EM
authors.lastname: Gonçalves
authors.forename: Catarina N
authors.initials: CN
authors.lastname: Matias
authors.forename: Diana A
authors.initials: DA
authors.lastname: Santos
authors.forename: Luis B
authors.initials: LB
authors.lastname: Sardinha
authors.forename: Analiza M
authors.initials: AM
authors.lastname: Silva
mesh_terms: D000328:Adult; D001834:Body Water; D001965:Bromides; D017666:Deuterium Oxide; D058266:Dielectric Spectroscopy; D005110:Extracellular Space; D006801:Humans; D007201:Indicator Dilution Techniques; D042541:Intracellular Space; D008297:Male; D016139:Martial Arts / Q000502:physiology*; D012015:Reference Standards; D015203:Reproducibility of Results; D017670:Sodium Compounds; D055815:Young Adult
chemical_list: D001965:Bromides; D017670:Sodium Compounds; D017666:Deuterium Oxide; C027938:sodium bromide
keywords: body composition; deuterium oxide; dilution techniques; extracellular water; sodium bromide