Search Results

You are looking at 1 - 6 of 6 items for

  • Author: Timothy G. Lohman x
Clear All Modify Search
Restricted access

Timothy G. Lohman

The assessment of body composition in children has taken on greater significance because of the need to study the prevalence of obesity in children and youth, the need to better document the tracking and genetics of body fatness, the need to relate fat patterning in childhood and fat patterning in adults, and the need to assess changes in the prevalence in obesity over time in a given population. This paper reviews methods of estimating body composition in children and youth. The use of body mass index, anthropometry, body density, and bioelectric impedance methodologies is emphasized, as well as the need to use multicomponent models for validation studies of new methods. Also explored in this article is the relationship between body composition and health related fitness.

Restricted access

Timothy G. Lohman, Melanie Hingle and Scott B. Going

Restricted access

Scott B. Going, Daniel P. Williams, Timothy G. Lohman and Michael J. Hewitt

This paper reviews age related changes in body fat, fat-free body mass, and the subcomponents of FFM including protein, mineral, and body water. It gives an overview of common methods and their limitations in the elderly and reviews the effects of physical activity on body composition in middle-aged and older individuals. Surprisingly little information is available on this important topic in men and women >80 years of age. Although research to date has described a number of qualitative trends with aging and shown the correlations between changes in fat and FFM with disease risk, quantification of rate of change has proven difficult. This is partly because changes in the aging body affect the indicators of body composition, leading to estimation errors, and because few long-term longitudinal studies have been completed. The increasing awareness of the important relationships among health, nutrition, and body composition, and the profound change in population demographics projected for the next 25 to 50 years, has focused attention on this problem and will undoubtedly stimulate additional research in this area.

Restricted access

Linda B. Houtkooper, Veronica A. Mullins, Scott B. Going, C. Harmon Brown and Timothy G. Lohman

This study characterized body composition profiles of elite American heptathletes and cross-validated skinfold (SKF) and bioelectrical impedance analysis (BIA) field method equations for estimation of percent body fat (%Fat) using dual energy x-ray absorptiometry (DXA) as the criterion. Weight, height, fat mass (FM), fat-free mass (FFM), bone mineral density (BMD), and %Fat were measured in 19 heptathletes using standard measurement protocols for DXA, SKFs and BIA. The ages, heights, and weights were respectively 25.5 ± 3.5 years, 175.0 ± 6.6 cm, 67.3 ± 7.1 kg. DXA estimates of mean ± SD values for body composition variables were 57.2 ± 6.1 kg FFM, 10.1 ± 2.6 kg FM, 114 ± 7% BMD for age/racial reference group, and 15 ± 3.0 %Fat. Ranges of bias values for %Fat (DXA minus SKF or BIA) were, respectively, −0.5 to 1.6% and −5.5 to −1.2%. Ranges for standard errors of estimate and total errors were, respectively, SKF 2.4–2.5%, 2.4–2.8% and BIA 3.0%, 5.0–6.5%. Regression analyses of the field methods on DXA were significant (p < .05) for all SKF equations but not BIA equations. This study demonstrates that elite American heptathletes are lean, have high levels of BMD, and that SKF equations provide more accurate estimates of %Fat relative to DXA than estimates from BIA equations.

Restricted access

Constance B. Christ, Mary H. Slaughter, Rachel J. Stillman, Timothy G. Lohman and Richard A. Boileau

Variability associated with the effects of gender, race, maturation (ML), and age on the potassium content of the fat-free body (K/FFB) was investigated in 163 males and 112 females ages 8 to 30 years. Measures of body density (hydrostatic weighing), bone mineral content (single photon absorptiometry), total body water (modified deuterium dilution), and whole body potassium (40K spectroscopy) were obtained. FFB was calculated using a multicomponent equation which accounted for the variability in FFB mineral and water content. Subjects were classified by maturation as prepubescent, pubescent, postpubescent, and adult (Tanner stages). Least-squares multiple regression analysis revealed significant (p<.05) effects of gender and maturation as well as an interaction between whites and blacks with maturation. The significant increase in K/FFB across maturation and age was most evident in the male sample for both racial groups, with K/FFB increasing from 2.37 in prepubescents to 2.54 in adults. The magnitude of increase in K/FFB across maturation was smaller and not statistically significant within the female sample. Hence, consideration of gender, maturation, and age is important in estimating FFB from total body potassium.

Restricted access

Mary H. Slaughter, Constance B. Christ, Rachel J. Stillman, Timothy G. Lohman and Richard A. Boileau

This study was designed to determine the association of selected circumferences with height among black and white, male and female, prepubescent and postpubescent children. Volunteers (N = 232) were grouped according to gender, race, and maturation level. Regression of the logs of the circumferences on the log of height revealed regression coefficients ranging from .74 to 1.3, except for the upper arm circumference (1.7), thus confirming the theoretical expectation of a linear relationship between circumference and height. Within-gender relationships of each circumference with height were determined using regression analysis. In general the prepubescent circumferences deviated below the within-gender line while the postpubescent circumferences typically deviated above it; however, there were exceptions in both sexes. Moreover, the racial differences in the circumference deviation scores were not consistent within either the male or female samples. The consideration of gender, race, and maturation is important in determining the association of circumference with height. The use of circumferences adjusted for height can be useful in studying muscle development in children.