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.

Body fat measurement in adolescent athletes: multicompartment molecular model comparison

“…Also, a higher FFM density was found in adult female middle -distance runners (Withers et al, 1998). The higher FFM density found in our female sample, caused by the lower TBW/FFM than assumed, differed from the pattern observed in other sports, namely in adult body builders (Modlesky et al, 1996;Withers et al, 1997), football players and swimmers (Prior et al, 2001) which showed values of FFM density smaller than 1.1 g/cm 3 , as a result of the higher FFM hydration. The lower TBW/FFM found in our adolescent female athletes could have reflected dehydration.…”

“…Studies on a few small groups of adult athletes have found differences in estimates of body density (Bd) (Modlesky et al, 1996;Withers et al, 1997Withers et al, , 1998Prior et al, 2001), indicating that FFM density may vary by 1.1 g/cm 3 , whereas studies of other groups have not reached the same conclusion (Penn et al, 1994;Arngrimsson et al, 2000). Therefore, uncertainties remain about FFM composition in growing athletes and the resulting complications on body fat estimates, and efforts to overcome methodological limitations using robust multicompartment models are warranted.…”

Impact of indexing resting metabolic rate against fat-free mass determined by different body composition models

“…Some investigators have found that hydrodensitometry significantly over-and underestimated %BF in older (Baumgartner et al, 1991;Smith et al, 1999) and younger (Withers et al, 1998a) subjects, respectively. Two other studies (Modlesky et al, 1996;Withers et al, 1997) have reported significant overestimations in hydrodensitometrically determined %BF in weight-trained subjects. While other investigators (Friedl et al, 1992;Cote & Adams, 1993;Penn et al, 1994;Siconolfi et al, 1995;Prior et al, 1997;Visser et al, 1997;Goran et al, 1998;Clasey et al, 1999) have not found significant mean differences, their data have displayed large individual differences between two-and multicompartment techniques.…”

“…Three-compartment models involving the measurement of body density and TBW generate body composition values that closely approximate those of four-compartment models (Friedl et al, 1992;Siconolfi et al, 1995;Modlesky et al, 1996;Withers et al, 1998a). However, dual-energy X-ray absorptiometry (DXA), which also divides the body into three compartments (FM, BM and bone mineral free lean), may display significant deviations from four-compartment-derived FFM values (Friedl et al, 1992;Modlesky et al, 1996;Withers et al, 1998a).…”

Critical Appraisal of Data Acquisition in Body Composition: Evaluation of Methods, Techniques and Technologies on the Anatomical Tissue-System Level

“…However, various degrees of inaccuracy exist and systematic error is substantial for most individuals and groups of children, adolescents and athletes. In other words, the possibilities and limitations are or should be known and more definitive reviews and studies quantifying the inaccuracy of the method are available (Brodie et al, 1998;Clarys et al, 2010a;Ellis, 2000;Lohman, 1981;Modlesky et al, 1996;Roemmich et al, 1997;Visser et al, 1997). The cause of these inaccuracies is complex and not only a reflection of musculoskeletal development (Prior et al, 2001).…”