Scott B Going

Abstract:

Criterion methods of measuring body composition are often limited to a laboratory setting. An alternative to criterion methods are the more mobile field methods, which are simple techniques for measuring body composition. Cross-validation of prediction equations for specific athletic populations can be used to determine prediction accuracy for estimates of percent body fat (%BF). This study compares two field methods [skinfolds (SKF), bioelectrical impedance analysis (BIA)] to two criterion methods [dual energy x-ray absorptiometry (DXA) and a multi-component model (MULTI-Lohman, 1986)]. Prediction equations used for both field methods were developed for young athletic women. The subjects were 18 elite female heptathletes participating in a USA Track and Field Development Project. Standard protocols and tetrapolar placement for whole body BIA were used and the prediction equations include: A) Lohman, 1992, B) Lohman, active women 1992, and C) Valhalla, model 1990b. Standard procedures were used for skinfold measurement and the prediction equations include: A) Jackson & Pollock, 1985 (3 site), and B) Jackson & Pollock, 1985 (4 site). Correlation analysis between criterion methods and field methods were significant (p0.001) for DXA vs SKF-A (r O 70) and SKF-B (r 0.72); MULTI vs SKF-A (r 0.78) and SKF-B (r 0.75), (p0.000); and MULTI vs BIA-C (r 0.48), (p0.04). These data suggest that the use of skinfold measurement for the estimation of %BF using prediction equations A and B will more accurately estimate %BF relative to the criterion methods DXA and MULTI within this population than estimates of %BF from BIA equations.

PMID: 17557994;Abstract:

Objective: To examine differences in body size, composition, and distribution of body fat among Hispanic, white, and Asian adolescents. Research Methods and Procedures: This included crosssectional data from the baseline sample of the Adequate Calcium Today trial. Participants included 180 Asian, 234 Hispanic, and 325 white girls 11.8 ± 0.05 years of age from Arizona, California, Hawaii, Indiana, Ohio, and Nevada. Anthropometric and DXA measurements (Lunar Prodigy) were standardized across sites. Tanner pubertal stage was self-selected from line drawings. Physical activity was assessed by a validated questionnaire. Comparisons between ethnic groups were examined using contrasts in the context of a general linear model. Results: Controlling for pubertal stage and study site only, Asians weighed less than Hispanics and were shorter than Hispanics and whites. Controlling for pubertal stage, height, weight, and study site, Asians had shorter leg lengths, smaller waist circumference, longer trunk lengths, more lean mass, less total fat mass, and less gynoid fat mass than Hispanics and whites; Asians had larger bitrochanteric width than whites; Asians had smaller DXA-derived android fat mass than Hispanics; and whites had smaller mean android/gynoid fat ratio than Hispanics. However, whites had a smaller android/gynoid fat ratio than both Asians and Hispanics in a model that adjusted for ethnicity, pubertal stage, bitrochanteric width, waist circumference, trunk length, log of physical activity, and study site, which explained 77% of the variation. Discussion: Ethnic differences in fat distribution are partially explained by differences in skeletal dimensions. Copyright © 2007 NAASO.

PMID: 23076447;PMCID: PMC3496253;Abstract:

The extent to which nutrient intake may influence bone structure and strength during maximal rates of skeletal growth remains uncertain. We examined the relationship of dietary intake of micronutrients and bone macroarchitectural structure in young girls. This cross-sectional analysis included baseline data from 363 fourth- and sixthgrade girls enrolled in the Jump-In study. Nutrient intake was assessed using the Harvard Youth/Adolescent Food Frequency Questionnaire. Volumetric BMD (vBMD), bone geometry, and strength were measured by peripheral quantitative computed tomography. Correlations and regression modeling assessed relations between usual nutrient intake and bone parameters. In fourth-grade girls, metaphyseal and diaphyseal area and circumferences as well as diaphyseal strength were associated with vitamin C intake (r = 0.15-0.19, p0.05). Zinc intake was correlated with diaphyseal vBMD (r = 0.15-0.16, p0.05). Using multiple linear regression to adjust for important covariates, we observed significant independent associations for vitamin C and zinc with bone parameters. For every milligram per day of vitamin C intake trabecular area increased by 11 %, cortical strength improved by 14 %, and periosteal and endosteal circumferences increased by 5 and 8.6 %, respectively. For every milligram per day of zinc intake, cortical vBMD increased by 1 %. No significant associations were observed in sixth-grade girls. Results of this study suggests that vitamin C and zinc intake are positively associated with objective measures of bone geometry, size, and strength in fourth-grade girls. This indicates that potential differences in micronutrient and bone associations at various age-associated stages of bone maturation may be indicative of competing hormonal influences. © Springer Science+Business Media New York 2012.

PMID: 12462956;Abstract:

Accurate prediction of weight loss success and failure has eluded researchers for many years. Thus, we administered a comprehensive psychometric battery before a 4-month lifestyle behavioral weight reduction program and analyzed weight changes during that period to identify baseline characteristics of successful and unsuccessful participants, among 112 overweight and obese middle-aged women (age, 47.8 ± 4.4 years; BMI, 31.4 ± 3.9 kg/m²). Mean weight and percentage fat losses among the 89 completers were -5.4 kg and -3.4%, respectively (p .001). A higher number of recent dieting attempts and recent weight loss, more stringent weight outcome evaluations, a higher perceived negative impact of weight on quality of life, lower self-motivation, higher body size dissatisfaction, and lower self-esteem were associated with less weight loss and significantly distinguished responders from nonresponders among all participants. These findings are discussed as to their usefulness (i) to screen individuals before treatment, (ii) to provide a better match between interventions to participants, and (iii) to build a weight loss readiness questionnaire.