A Genetic Epidemiological Mega Analysis of Smoking Initiation in Adolescents.

Introduction: Previous studies in adolescents were not adequately powered to accurately disentangle genetic and environmental influences on smoking initiation (SI) across adolescence.

Methods: Mega-analysis of pooled genetically informative data on SI was performed, with structural equation modeling, to test equality of prevalence and correlations across cultural backgrounds, and to estimate the significance and effect size of genetic and environmental effects according to the classical twin study, in adolescent male and female twins from same-sex and opposite-sex twin pairs (N = 19 313 pairs) between ages 10 and 19, with 76 358 longitudinal assessments between 1983 and 2007, from 11 population-based twin samples from the United States, Europe, and Australia.

Results: Although prevalences differed between samples, twin correlations did not, suggesting similar etiology of SI across developed countries.

Skeletal maturation, fundamental motor skills and motor coordination in children 7-10 years.

Relationships between skeletal maturation and fundamental motor skills and gross motor coordination were evaluated in 429 children (213 boys and 216 girls) 7-10 years. Skeletal age was assessed (Tanner-Whitehouse 2 method), and stature, body mass, motor coordination (Körperkoordinations Test für Kinder, KTK) and fundamental motor skills (Test of Gross Motor Development, TGMD-2) were measured. Relationships among chronological age, skeletal age (expressed as the standardised residual of skeletal age on chronological age) and body size and fundamental motor skills and motor coordination were analysed with hierarchical multiple regression.

Role of intensive training in the growth and maturation of artistic gymnasts.

Short stature and later maturation of youth artistic gymnasts are often attributed to the effects of intensive training from a young age. Given limitations of available data, inadequate specification of training, failure to consider other factors affecting growth and maturation, and failure to address epidemiological criteria for causality, it has not been possible thus far to establish cause-effect relationships between training and the growth and maturation of young artistic gymnasts. In response to this ongoing debate, the Scientific Commission of the International Gymnastics Federation (FIG) convened a committee to review the current literature and address four questions: (1) Is there a negative effect of training on attained adult stature? (2) Is there a negative effect of training on growth of body segments? (3) Does training attenuate pubertal growth and maturation, specifically, the rate of growth and/or the timing and tempo of maturation? (4) Does training negatively influence the endocrine system, specifically hormones related to growth and pubertal maturation? The basic information for the review was derived from the active involvement of committee members in research on normal variation and clinical aspects of growth and maturation, and on the growth and maturation of artistic gymnasts and other youth athletes.

Functional fitness and bone mineral density in the elderly.

Unlabelled: Bone quality has been associated with genetic factors and several environmental influences. This study suggests that although functional fitness should be considered in clinical assessments of bone health, body composition appears to have a higher relevance in the explanation of bone health/strength in older people.

Purpose: This study aims to describe the association between functional fitness (FF), other constitutive factors, and bone health/strength in a large community-dwelling sample of elderly active Portuguese.

Short-term tracking of performance and health-related physical fitness in girls: the Healthy Growth in Cariri Study.

The main purpose of this study was to track the performance and health-related physical fitness of girls from Brazil's Cariri region. In the "Healthy Growth in Cariri Study", 294 girls from public and private schools were divided into four age cohorts--8, 10, 12, and 14 years--and followed for three consecutive years, with an assessment every 6 months. Shuttle run, hand grip, standing long jump, trunk lift, curl-up, 12-min run, and fatness were used to rate physical fitness performance and health-related components on each of six occasions.

[Evaluation of physical fitness levels in children and adolescents: establishing percentile charts for the central region of Peru].

Objectives: Construct percentile charts and physical fitness (PF) reference values stratified by age and sex of children and adolescents from Peru's central region.

Materials And Methods: The sample was comprised of 7,843 subjects (4,155 females and 3,688 males) between the ages of 6 to 17 years old. Physical fitness was assessed using six tests developed by EUROFIT, FITNESSGRAM and AAPHERD.

Functional fitness and physical activity of Portuguese community-residing older adults.

The purposes of this study were to generate functional-fitness norms for Portuguese older adults, to determine age and sex differences, and to analyze the physical activity-associated variation in functional fitness. The sample was composed of 802 older adults, 401 men and 401 women, age 60-79 yr. Functional fitness was assessed using the Senior Fitness Test.

Heritability of body mass index in pre-adolescence, young adulthood and late adulthood.

Increased body mass index (BMI) is a worldwide health issue. Individual differences in the susceptibility to increased BMI could be related to genes or environment. We performed a systematic review of genetic studies on BMI in pre-adolescence, young adulthood and late adulthood.

Interrelationships among invasive and non-invasive indicators of biological maturation in adolescent male soccer players.

The relationships among indicators of biological maturation were evaluated and concordance between classifications of maturity status in two age groups of youth soccer players examined (11-12 years, n = 87; 13-14 years, n = 93). Data included chronological age (CA), skeletal age (SA, Fels method), stage of pubic hair, predicted age at peak height velocity, and percent of predicted adult height. Players were classified as on time, late or early in maturation using the SA-CA difference, predicted age at peak height velocity, and percent of predicted mature height.

Prediction of adult height in girls: the Beunen-Malina-Freitas method.

The purpose of this study was to validate and cross-validate the Beunen-Malina-Freitas method for non-invasive prediction of adult height in girls. A sample of 420 girls aged 10-15 years from the Madeira Growth Study were measured at yearly intervals and then 8 years later. Anthropometric dimensions (lengths, breadths, circumferences, and skinfolds) were measured; skeletal age was assessed using the Tanner-Whitehouse 3 method and menarcheal status (present or absent) was recorded.

Tracking of fatness during childhood, adolescence and young adulthood: a 7-year follow-up study in Madeira Island, Portugal.

Aims: Investigating tracking of fatness from childhood to adolescence, early adolescence to young adulthood and late adolescence to young adulthood.

Subjects And Methods: Participants from the Madeira Growth Study were followed during an average period of 7.2 years.

Growth references for Brazilian children and adolescents: healthy growth in Cariri study.

Aim: To construct reference values for height, body mass and BMI of children and adolescents from the Cariri region, Brazil; to compare the growth of Cariri children with those from CDC (Centers for Disease Control and Prevention) and with references from other Brazilian regions; to verify the associations between socioeconomic status and height, body mass and BMI in children and youth from both sexes.

Subjects And Methods: The sample comprised 3311 girls and 3280 boys aged 7-17 years, participating in the study 'Healthy Growth in Cariri'. Socioeconomic status was defined according to school attendance: private and public.

Agreement in activity energy expenditure assessed by accelerometer and self-report in adolescents: variation by sex, age, and weight status.

The agreement between self-reported and objective estimates of activity energy expenditure was evaluated in adolescents by age, sex, and weight status. Altogether, 403 participants (217 females, 186 males) aged 13-16 years completed a 3-day physical activity diary and wore a GT1M accelerometer on the same days. Partial correlations (controlling for body mass) were used to determine associations between estimated activity energy expenditure (kcal · min(-1)) from the diary and accelerometry.

Identification and prioritization of NUAK1 and PPP1CC as positional candidate loci for skeletal muscle strength phenotypes.

Muscle strength is an important determinant in elite sports performance as well as in the activities of daily living. Muscle metabolism also plays a role in the genesis, and therefore prevention, of common pathological conditions and chronic diseases. Even though heritability estimates between 31 and 78% suggest a significant genetic component in muscle strength, only a limited number of genes influencing muscle strength have been identified.

The contribution of prenatal environment and genetic factors to the association between birth weight and adult grip strength.

Low birth weight has been associated with reduced hand grip strength, which is a marker of future physical function and disease risk. The aim of this study was to apply a twin pair approach, using both 'individual' data and 'within-pair' differences, to investigate the influence of birth weight on hand grip strength and whether this association may be mediated through fat free mass (FFM). Participants from the East Flanders Prospective Twin Survey were included if born without congenital abnormalities, birth weight >500 g and ≥22 weeks of gestation.

Comprehensive fine mapping of chr12q12-14 and follow-up replication identify activin receptor 1B (ACVR1B) as a muscle strength gene.

Muscle strength is important in functional activities of daily living and the prevention of common pathologies. We describe the two-staged fine mapping of a previously identified linkage peak for knee strength on chr12q12-14. First, 209 tagSNPs in/around 74 prioritized genes were genotyped in 500 Caucasian brothers from the Leuven Genes for Muscular Strength study (LGfMS).

Prevalence of overweight, obesity and physical activity levels in children from Azores Islands.

Background: Childhood overweight and obesity are increasing all over the world and have been associated with low levels of physical activity (PA).

Aims: To determine the prevalence of overweight, obesity and PA levels in Azorean children according to age and sex; and to determine the association between levels of PA and prevalence of overweight and obesity.

Subjects And Methods: Weight, height and PA levels were measured in 3699 children aged 6-10 years, from the Azores Islands, Portugal.

Physical activity assessed by accelerometry in rural African school-age children and adolescents.

Physical activity (PA) in children/adolescents of both genders from a rural community in Mozambique was estimated by accelerometry and by questionnaire and was compared with PA of Portuguese youth. Total PA, moderate (MPA), vigorous (VPA) and very vigorous (VVPA) were evaluated. Mozambican boys were more active than girls.

Cross-validation of the Beunen-Malina method to predict adult height.

The purpose of this study was to cross-validate the Beunen-Malina method for non-invasive prediction of adult height. Three hundred and eight boys aged 13, 14, 15 and 16 years from the Madeira Growth Study were observed at annual intervals in 1996, 1997 and 1998 and re-measured 7-8 years later. Height, sitting height and the triceps and subscapular skinfolds were measured; skeletal age was assessed using the Tanner-Whitehouse 2 method.

Timing of adolescent somatic maturity and midlife muscle function: a 34-yr follow-up.

Unlabelled: Midlife muscle function is associated with disability and premature mortality later in life. Biological maturity is associated with muscle function during growth; however, it is unknown whether biological maturity during adolescence is associated with muscle mass and function in middle-aged healthy men.

Purpose: The purpose of this study is to evaluate if late maturation during adolescence is associated with better muscle function in middle-aged men.

Anthropometry, carbohydrate and lipid metabolism in the East Flanders Prospective Twin Survey: linkage of candidate genes using two sib-pair based variance components analyses.

Insulin resistance and obesity are underlying causes of type 2 diabetes and therefore much interest is focused on the potential genes involved. A series of anthropometric and metabolic characteristic were measured in 240 MZ and 112 DZ twin pairs recruited from the East Flanders Prospective Twin Survey. Microsatellite markers located close to ABCC8, ADIPOQ, GCK, IGF1, IGFBP1, INSR, LEP, LEPR, PPARgamma and the RETN gene were genotyped.

Genome-wide linkage scan for contraction velocity characteristics of knee musculature in the Leuven Genes for Muscular Strength Study.

The torque-velocity relationship is known to be affected by ageing, decreasing its protective role in the prevention of falls. Interindividual variability in this torque-velocity relationship is partly determined by genetic factors (h(2): 44-67%). As a first attempt, this genome-wide linkage study aimed to identify chromosomal regions linked to the torque-velocity relationship of the knee flexors and extensors.

Heritabilities of somatotype components in a population from rural Mozambique.

There have been few genetic studies of normal variation in body size and composition conducted in Africa. In particular, the genetic determinants of somatotype remain to be established for an African population. (1) To estimate the heritabilities of aspects of somatotype and (2) to compare the quantitative genetic effects in an African population to those that have been assessed in European and American populations.

Clustering of metabolic risk factors in young adults: genes and environment.

Objective: Evidence of a genetic basis of metabolic risk factors (MRFs) is growing. Studies examining the genetic and environmental basis of the clustering of MRFs, grouped together in the metabolic syndrome (MetS), are however sparse. The aim of this study therefore was to study the heritabilities of the MRFs and the genetic and environmental correlations between the MRFs.

Selection of genes and single nucleotide polymorphisms for fine mapping starting from a broad linkage region.

Fine mapping of linkage peaks is one of the great challenges facing researchers who try to identify genes and genetic variants responsible for the variation in a certain trait or complex disease. Once the trait is linked to a certain chromosomal region, most studies use a candidate gene approach followed by a selection of polymorphisms within these genes, either based on their possibility to be functional, or based on the linkage disequilibrium between adjacent markers. For both candidate gene selection and SNP selection, several approaches have been described, and different software tools are available.