Prediction of Body Density from Skinfolds in Black and White Young Men

The purpose of this study is to compare the relation of skinfold thickness measures to body density in Black and White young men. Body density determined by underwater weighing, and selected anthropometric variables were measured on a sample of 319 males, 140 Blacks and 179 Whites, aged 18 to 32 yrs. Mean measured body density was significantly higher (p \u3c .05) in Blacks (1.075 gm/cc) than in Whites (1.065 gm/cc), but the mean sum of 7 skinfolds was not significantly different (79.3 vs 88.0 mm, respectively). When body density was predicted from sum of 7 skin- folds, sum of 7 skinfolds squared and age in the total group, measured body density was significantly underpredicted in Blacks by an average of 0.004 gm/cc, whereas measured body density was overpredicted in Whites by 0.003 gm/cc, indicating that the measured body density corresponding to a given skinfold sum and age averaged 0.007 gm/cc higher in Blacks than in Whites. Addition of an independent dummy variable denoting Black or White increased the R significantly (p \u3c .05) from .862 to .896, and de­creased the SEE from 0.0072 to 0.0063 gm/cc. The effect of race (Black vs White) was not accounted for by differences in somatotype. The results indicate that the relation of skinfolds to body density is different in Black and White men. To obtain accurate estimates of body density from skinfolds in Blacks, equations developed on Blacks, or Blacks and Whites (including race as an independent variables) should be utilized. If the different relation of skinfolds to body density in Black and White men is due to variation in the composition of the fat-free body, the data also suggest a need to use an alternate equation for estimating % fat from measured body density in Black men

A Comparison of Densitometric, Potassium-40 and Skinfold Estimates of Body Composition in Prepubescent Boys

Densitometric, 40K and skinfold estimates of per cent total body fat were obtained on 49 prepubescent boys, 8 to 11 years of age, to evaluate the relative applicability of these procedures to this age group. No significant differences were found between the mean % fat estimates obtained by different methods on the total group of boys, but 40K estimates of fatness in certain individuals underestimated those obtained using the other methods. Associations between the % fat estimates were only moderate with correlations ranging from .74 to .77. Much of the discrepancy between methods was found to be due to technical rather than biological variation. Technical errors of 3.0, 1.6 and .5% fat were estimated for per cent fat based on body potassium, body density and skinfold thickness measures, respectively.A closer association was found between the density and 40K estimates of fat-free weight (rzz.94) and fat weight (r = .91) than to % fat, due primarily to the larger range of values of the absolute as compared to the percentage estimates. In general, the procedures for estimating body composition utilized in this study appear to be applicable to children, but sizable differences in individual estimates warrant caution when applying these methods to individual children

Exercise and Obesity: Etiology, Physiology, and Intervention

Discusses the relation between exercise and obesity in terms of etiology, physiology, and treatment outcome. It is considered that the role of activity level and caloric intake in the development of obesity is currently unclear because of the methodological limitations of past research. Salutary physiological effects of exercise on caloric intake, metabolic rate, and body composition are noted, and it is concluded that these changes may significantly affect energy output. Methodological problems with previous exercise treatment studies include failure to (a) use body composition measures as dependent variables, (b) report specifics regarding exercise tasks and participation rates, and (c) divide Ss into homogeneous populations based on qualitative aspects of body-fat type. Specific treatment guidelines, based primarily on the physiological data, are provided