title: Density of the fat-free mass and estimates of body composition in male weight trainers.
abstract: The purpose of this study was to determine whether the assumed density and composition of the fat-free mass (FFM) and estimates of percent fat (%Fat) from body density by use of the Siri equation (%Fatd) are valid in weight trainers with high musculoskeletal development. Measures of body density by underwater weighing (Db), body water by deuterium dilution, and bone mineral by whole body dual-energy X-ray absorptiometry were obtained in young white men: 14 weight trainers with high musculoskeletal development and 14 non-weight-training controls with average musculoskeletal development. %Fatd was significantly higher (P < or = 0.05) than %Fat estimated from body density, water, and mineral (%Fatd,w,m) by use of a four-component model in weight trainers (17.3 +/- 4.6 vs. 13.2 +/- 5.1%) but not in controls (14.8 +/- 3.1 vs. 14.2 +/- 3.6%). The greater discrepancy between %Fatd and %Fatd,w,m was explained by lower density of fat-free mass (Dffm) in weight trainers (1.089 +/- 0.005 g/ml) than in controls (1.099 +/- 0.007 g/ml). The lower Dffm in the weight trainers was due to higher water (74.8 +/- 1.2 vs. 72.6 +/- 20%) and lower mineral (5.3 +/- 0.6 vs. 5.9 +/- 0.4%) and protein (19.9 +/- 1.4 vs. 21.5 +/- 1.9%) fractions of the FFM. We conclude that, in young white men with high musculoskeletal development, Dffm is lower than the assumed value of 1.1 g/ml and %Fat is overestimated from Db by use of the Siri equation.
authors.affiliation: Department of Exercise Science, University of Georgia, Athens 30602, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Modlesky
authors.forename: K J
authors.initials: KJ
authors.lastname: Cureton
authors.forename: R D
authors.initials: RD
authors.lastname: Lewis
authors.forename: B M
authors.initials: BM
authors.lastname: Prior
authors.forename: M A
authors.initials: MA
authors.lastname: Sloniger
authors.forename: D A
authors.initials: DA
authors.lastname: Rowe
mesh_terms: D000328:Adult; D001823:Body Composition / Q000502:physiology*; D015992:Body Mass Index; D001834:Body Water / Q000502:physiology*; D001835:Body Weight / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005223:Fats; D006801:Humans; D008297:Male
chemical_list: D005223:Fats