Showing papers by "Gaston Beunen published in 2002"
TL;DR: Although the cross-validation meets statistical standards for acceptance, caution is warranted with regard to implementation and it is recommended that maturity offset be considered as a categorical rather than a continuous assessment.
Abstract: Purpose: The range of variability between individuals of the same chronological age (CA) in somatic and biological maturity is large and especially accentuated around the adolescent growth spurt. Maturity assessment is an important consideration when dealing with adolescents, from both a research perspective and youth sports stratification. A noninvasive, practical method predicting years from peak height velocity (a maturity offset value) by using anthropometric variables is developed in one sample and cross-validated in two different samples. Methods: Gender specific multiple regression equations were calculated on a sample of 152 Canadian children aged 8-16 yr (79 boys; 73 girls) who were followed through adolescence from 1991 to 1997, The equations included three somatic dimensions (height, sitting height, and leg length), CA, and their interactions. The equations were cross-validated on a Combined sample of Canadian (71 boys, 40 girls measured from 1964 through 1973) and Flemish children (50 boys, 48 girls measured from 1985 through 1999). Results: The coefficient of determination (R2) for the boys' model was 0.92 and for the girls' model 0.91 the SEEs were 0.49 and 0.50, respectively, Mean difference between actual and predicted maturity offset for the verification samples was 0.24 (SD 0.65) yr in boys and 0,001 (SD 0.68) yr in girls. Conclusion: Although the cross-validation meets statistical standards or acceptance, caution 1, warranted with regard to implementation. It is recommended that maturity offset be considered as a categorical rather than a continuous assessment. Nevertheless, the equations presented are a reliable, noninvasive and a practical solution for the measure of biological maturity for matching adolescent athletes.
1,791 citations
TL;DR: Genetic effects explained a considerable amount of variation in SPI and LTPA, which were greater in males than in females, and the relevance of shared environmental factors and nonshared environmental factors in females is particularly evident in females.
159 citations
TL;DR: Birth weight accounts for some of the differences in adult body composition between twins, and twins who were heavier at birth were taller and slightly heavier as adults than were lighter twins.
140 citations
TL;DR: It is concluded that the principal anthropometric determinant of BMD in middle‐aged men is lean mass or muscle, and not fat mass or the fat component, were independent predictors of B MD.
Abstract: The association between bone mass, body structure, and body composition was explored in 156 men, 40 years of AGE. Bone mineral density (total body, lumbar spine, left arm, and left leg) was obtained by dual-energy X-ray absorptiometry (DXA; Hologic QDR 4500A). Body structure was determined from a battery of anthropometric dimensions with a principal components analysis. Body composition was estimated with DXA. From the 24 anthropometric dimensions, three components were extracted and identified as muscle, fat, and skeletal length. Significant correlations between the muscle component and all BMD measurements (r = 0.28–0.44) were obtained. Except for BMD of the left arm, which correlated significantly, but negatively, with the fat component (r = −0.16), no significant relations were found between the fat component and BMD. There were significant correlations between lean mass, fat mass, and BMD measurements. The correlations were higher between lean mass and BMD (r = 0.22–0.44) than between fat mass and BMD (r = 0.08–0.24). The multiple regression analysis revealed that except for BMD of the left arm only lean mass or the muscle component, and not fat mass or the fat component, were independent predictors of BMD. It is concluded that the principal anthropometric determinant of BMD in middle-aged men is lean mass or muscle. Am. J. Hum. Biol. 14:735–742, 2002. © 2002 Wiley-Liss, Inc.
57 citations
TL;DR: Peak VO2 is largely explained by body mass, but activity level and its interaction with maturity status contribute independently to peak VO2 even after adjusting for body mass.
Abstract: Purpose: The aims of this study are two-fold: first, to analyze intraindividual allometric development of aerobic power of 73 boys followed at annual intervals from 8 to 16 yr, and second, to relate scaled aerobic power with level of habitual physical activity and biological maturity status. Methods: Peak (V) over dot O-2 (treadmill), height, and body mass were measured. Biological maturity was based on age at peak height velocity (PHV) and level of physical activity was based on five assessments between 11 and 15 yr and at 17 yr. Interindividual and intraindividual allometric coefficients were calculated. Multilevel modeling was applied to verify if maturity status and activity explain a significant proportion of peak (V) over dot O-2 after controlling for other explanatory characteristics. Results: At most age levels, interindividual allometry coefficients for body mass exceed k = 0.750. Intraindividual coefficients of peak (V) over dot O-2 by body mass vary widely and range from k' = 0,555 to k' = 1,178. Late maturing boys have smaller k' coefficients than early maturing boys. Conclusion: Peak (V) over dot O-2 is largely explained by body mass, but activity level and its interaction with maturity status contribute independently to peak (V) over dot O-2 even after adjusting for body mass.
54 citations
36 citations
01 Jan 2002
TL;DR: In this article, the authors explored the pattern of genetic and environmental determination of the variation in Heath-Carter somatotype components from early adolescence into young adulthood and found that more than half of the variance in all three components for both sexes at all time points is explained by factors the three components have in common.
Abstract: Background : Several studies with different designs have attempted to estimate the heritability of somatotype components. However they often ignore the covariation between the three components as well as possible sex and age effects. Shared environmental factors are not always controlled for. Aim : This study explores the pattern of genetic and environmental determination of the variation in Heath-Carter somatotype components from early adolescence into young adulthood. Subjects and methods : Data from the Leuven Longitudinal Twin Study, a longitudinal sample of Belgian same-aged twins followed from 10 to 18 years ( n = 105 pairs, equally divided over five zygosity groups), is entered into a multivariate path analysis. Thus the covariation between the somatotype components is taken into account, gender heterogeneity can be tested, common environmental influences can be distinguished from genetic effects and age effects are controlled for. Results : Heritability estimates from 10 to 18 years range from 0.21 to 0.88, 0.46 to 0.76 and 0.16 to 0.73 for endomorphy, mesomorphy and ectomorphy in boys. In girls, heritability estimates range from 0.76 to 0.89, 0.36 to 0.57 and 0.57 to 0.76 for the respective somatotype components. Sex differences are significant from 14 years onwards. More than half of the variance in all somatotype components for both sexes at all time points is explained by factors the three components have in common. Conclusions : The finding of substantial genetic influence on the variability of somatotype components is further supported. The need to consider somatotype as a whole is stressed as well as the need for sex- and perhaps age-specific analyses. Further multivariate analyses are needed to confirm the present findings.
36 citations
TL;DR: Novel findings suggest that in twin pregnancies, maternal factors are more important than fetoplacental factors in determining glucose-insulin metabolism in the offspring.
Abstract: OBJECTIVE —There is strong evidence that low birth weight is associated with glucose intolerance and diabetes in adults. We have carried out a twin study to distinguish among maternal influences, which affect both twins; fetoplacental influences, which are unique to each twin; and the genetic factors that may underlie this association. RESEARCH DESIGN AND METHODS —We identified a sample of 423 twin pairs (250 monozygotic and 173 dizygotic) from the East Flanders Prospective Twin Survey who were born between 1964 and 1982. Data collected in this study included the mother’s body composition and weight gain during pregnancy, the twins’ birth weights, and gestational age. The twins (aged 18–34 years) attended a research center for measurement of height, weight, and waist-to-hip ratio as well as fasting glucose, proinsulin, and insulin concentrations. RESULTS —Among twin pairs discordant for birth weight, we found little evidence that the lighter twin had abnormal glucose-insulin metabolism in adult life. However, both a low prepregnancy maternal BMI and older maternal age at delivery were associated with hyperinsulinemia and evidence of insulin resistance in the offspring. Fasting insulin increased by 1.3% (95% CI 0.1–2.6%) per unit fall in maternal BMI and by 1.1% (0.02–2.0%) per year increase in maternal age. These associations were independent of the twins’ BMI and waist-to-hip ratio and their zygosity. CONCLUSIONS —These novel findings suggest that in twin pregnancies, maternal factors are more important than fetoplacental factors in determining glucose-insulin metabolism in the offspring.
19 citations
01 Jan 2002
3 citations