Use of Allometry and Skinfold Thicknesses to Estimate the Fat Mass of Circumpubertal Boys

Background: In the pubertal period, each part of the body grows at different rates. This makes the relationship between the parts nonlinear. Particularly, the fat mass (FM) of boys tends to decrease, further exacerbating the issue of linearity in growth. Aim: To propose predictive models of FM from skinfolds (SF) adjusted allometrically. Subjects and methods: 75 pubertal boys (14.4 +/- 0.9 years) composed the sample by self-selected pubic hair. FM was determined by DXA (FMDXA) (kg), stature (cm), body mass (kg) and nine SF (mm) by anthropometric measurements. The SF were individually adjusted allometrically. FMDXA (Y) values and each anthropometric independent variable-IV (X) underwent logarithmic transformation. Linear regressions were used. The significance of the prediction of the FMDXA of each model (ANOVA) and the concordance analysis (Bland-Altman) were performed. Results: Predictive allometric models of FMDXA showed high determination coefficients (r(2)) and reduced standard errors of estimation (SEE). The adjusted model involved reduced agreement limits, demonstrating its accuracy. Conclusions: It was possible to propose models with allometric adjustments to estimate FM of pubertal boys. Allometry may aid in the development of predictive linear models of body composition, since it has an indicative capacity of the variables for estimation.