B. Vanden Eynde

Age-specific correlation analysis of longitudinal physical fitness levels in men

SummaryThis study investigated the age-specific tracking of adult health- and performance-related fitness scores. In addition, the independent contribution of adolescent physical characteristics to the explanation of adult fitness scores was also studied. The sample consisted of 173 adults observed at age 30 years. These subjects had been followed at annual intervals from age 13 to age 18 years and were remeasured at age 30 years. At each age nine fitness tests were administered together with the recording of anthropometric dimensions, biological maturation, sports participation and family characteristics. Tracking was measured by the inter-age correlations at each age between 13 and 18 years and the performance scores at 30 years. The independent contribution of characteristics observed during adolescence to the explanation of adult fitness was investigated through stepwise multiple regression analysis and discriminant analysis with the adult fitness scores as the dependent variables and the fitness, maturation, anthropometric characteristics, sports participation and family background as the independent variables. Tracking between age 13 and age 30 years was moderately high (46% of variance explained) for flexibility, low to moderate (between 19% and 27% of variance explained) for the other fitness parameters and low for pulse recovery and static strength (70% to 11% of variance explained). Between age 18 and age 30 years the tracking was high for flexibility, moderately high for explosive and static strength, and moderate for the other fitness parameters except for pulse recovery. The amount of variance of adult fitness levels explained increased significantly when other characteristics observed during adolescence entered the regressions or discriminant functions. This indicated that in addition to fitness scores, anthropometric dimensions, and skeletal maturation, behavioural characteristics also added significantly to the prediction of adult fitness levels.

Heritability of somatotype components from early adolescence into young adulthood: a multivariate analysis on a longitudinal twin study.

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.

Associations between physical activity, nutritional practices and health-related anthropometry in Flemish males: a 5-year follow-up study

OBJECTIVE: To examine the extent to which extent health-related anthropometric characteristics such as body mass index, waist–hip ratio, waist girth, percentage of body fat and weight gain are associated with physical activity and nutritional habits in a prospective follow-up study.DESIGN: A 5-y prospective follow-up study.SUBJECTS: 132 healthy men from The Leuven Longitudinal Study on Lifestyle, Physical Fitness, and Health.MEASUREMENTS: The main outcome measures in this study were body mass index, waist–hip ratio, waist girth, percentage of body fat and significant weight gain at the ages of 35 and 40 y. An unhealthy body composition was defined as a body mass index above 26, a waist–hip ratio above 0.95, a waist girth and body fat percentage above percentile 75 at the end of the 5-y follow-up period and a significant weight gain of 5 kg or more between the two examination periods. Anthropometric characteristics were derived from clinical examination. Physical activity at the age of 35 and 40 and nutritional habits at the age of 40 were determined from questionnaires.RESULTS: Physical activity was the most important predictor for the waist–hip ratio in this sample. In contrast, nutritional habits show a stronger relationship with body mass index. The absolute amount of energy intake is not as important as the dietary factors in predicting subjects with overweight or an unhealthy body composition. The index of occupational activities appears to be the most important physical activity variable.CONCLUSION: The relative contribution of physical activity and nutritional habits in health-related anthropometry varies with the characteristic considered. It is important to include all components of physical activity, and occupational activities in particular, in determining these relationships in a general population sample.