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Document Type

Article

Abstract

The stability across sex and ethnic groups of fat patterns defined by Principal Components Analysis of multiple skinfold thicknesses was evaluated using Transformation Analysis of component loadings for a sample of 184 White males, 103 Black males, 114 White females, and 80 Black females between 7 and 30 years of age. It was found that, after removing effects of size prior to PCA, a trunk-extremity contrast was the only fat pattern that was homogeneous across all four sex and ethnic groups, and that it accounted for 34 to 57% of the total variance in subcutaneous adipose tissue distribution. Analyses of variance of scores for the trunk- extremity component by sex, ethnicity, and maturation stage showed that a “centripetal” distribution, in which trunk skinfold thicknesses were rela­tively larger than skinfold thicknesses on the extremities, developed in males during adolescence, but not in females, regardless of ethnicity. Main effects for sex, ethnicity and maturation stage were statistically significant (p<.001), and the interaction of sex and maturation stage was significant (p<.001). Regression analyses controlling for sex, ethnicity and maturation stage showed that this pattern was marginally associated with total body fat (R2=1.7%, p<.001) and somewhat more closely associated with fat-free mass (R2 = 8.1%, p<.0001). These findings indicate that measurement errors, as well as biological differences, may confound definitions of fat patterns, other than a trunk-extremity contrast, from PCA of skinfold thicknesses. Also, they suggest that a “centripetal fat pattern” is a masculine characteristic associated with sex-hormone levels; and, that this pattern is part of a constellation of factors including increased internal fat deposition, as well as greater muscle and bone mass.

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