Changes in the Genetic Variance and Heritability of the Body Mass Index and Skinfolds among Polish Twins Aged 8–18 Years

Body Mass Index (BMI) and skinfolds are common indicators of adiposity. Many studies have shown relationships between the BMI in childhood and adolescence and the BMI in adulthood. Similar correlations were observed for the skinfolds, although they tend to be lower. The aim of this study was to estimate changes with age in the genetic variance and heritability of the BMI and skinfolds among Polish twins born between 1959 and 1965. Observations involved male and female monozygotic (MZ) and dizygotic (DZ) twins, who were measured annually between 8 and 18 years of age. Body Mass Index and skinfold thicknesses at the triceps (TSF), subscapular (SSF) and suprailiac (SIF) sites were measured. Genetic variance and heritability were estimated for individual skinfold thicknesses, the sum of three skinfolds (SUMSF) and BM, separately by age classes for both sexes. Intraclass correlations were significantly higher for MZ twins than for DZ twins in both sexes and across all ages. Heritability estimates were significant for all indicators of adiposity, but varied with age and had different ranges for boys and girls. Estimates of genetic variance were significant for all indicators of adiposity and were higher for girls than for boys

Variation in sport participation, fitness and motor coordination with socioeconomic status among Flemish children

Socioeconomic status (SES) is often indicated as a factor that influences physical activity and associated health outcomes. This study examined the relationship between SES and sport participation, morphology, fitness and motor coordination in a sample of 1955 Flemish children 6-11 years of age. Gender, age and SES-specific values for morphologic dimensions, amount and type of sport participation and fitness and motor coordination tests were compared. SES was positively and significantly associated with sport participation and sports club membership in both sexes. Although differences were not consistently significant, morphologic dimensions and tests of fitness and motor coordination showed a trend in favor of children from higher SES. The results suggest that public and local authorities should consider providing equal opportunities for children in all social strata and especially those in the lower SES to experience the beneficial effects of sport participation through which they can enhance levels of physical fitness and motor coordination

Assessment of reliability in isokinetic testing among adolescent basketball players

Background. The reproducibility of day-to-day testing of isokinetic concentric and eccentric muscular actions among adolescent basketball players aged 14 to 16 years and relationships of mean within-subject variation in two isokinetic testing sessions with chronological age, biological maturation (estimated age at peak height velocity), training experience, body size, lower-body morphology, and initial strength performance were evaluated. Material and Methods. The sample included 27 basketball players who completed replicate test sessions of 5 repetitions of reciprocal concentric and eccentric knee extensions and flexions at 60 degrees s(-1). A randomly selected subsample of 8 players completed a third testing session to confirm reliability estimates. Results. Coefficients of variation (CV) between sessions 1 and 2 ranged from 8.1% to 17.4%, and intraclass coefficients (ICCs) ranged from 0.72 to 0.89. For sessions 1 and 3, CVs ranged from 3.9% to 6.0%, and ICCs ranged from 0.95 to 0.99. The initial level of strength of eccentric knee flexion (r=-0.43) and eccentric knee extension (r=-0.42) were correlated (P<0.05) with eccentric knee extension within-variation between two sessions. Training experience (r=-0.37, P<0.05) and initial values of concentric knee flexion (r=-0.62, P<0.01) were correlated with concentric knee flexion within-subject differences. Within-subject variation of eccentric knee extension was correlated (P<0.05) with chronologic age (r=0.41), estimated age at peak height velocity (r=-0.38), body size (r=0.41 to 0.47), and leg volume (r=0.39). Conclusions. Familiarization sessions may improve the reliability of concentric and eccentric knee isokinetic strength testing at 60 s(-1) in adolescent basketball players. Age, maturity status, and training experience of young athletes should be considered when testing knee isokinetic strength at 60 degrees s(-1)

Relative Age and Maturation Selection Biases in Academy Football

This study examined the simultaneous effects of relative age and biological maturity status upon player selection in an English professional soccer academy. A total of 202 players from the U9 to U16 age groups, over an eight-year period (total of 566 observations), had their relative age (birth quarter) and biological maturity (categorised as late, on-time or early maturing based upon the Khamis-Roche method of percentage of predicted adult height at time of observation) recorded. Players born in the first birth quarter of the year (54.8%) were over-represented across all age groups. A selection bias towards players advanced in maturity status for chronological age emerged in U12 players and increased with age; 0% of players in the U15 and U16 age group were categorised as late maturing. A clear maturity selection bias for early maturing players was, however, only apparent when the least conservative criterion for estimating maturity status was applied (53.8% early and 1.9% late maturing in the U16 age group). Professional football academies need to recognise relative age and maturation as independent constructs that exist and operate independently. Thus, separate strategies should perhaps be designed to address the respective selection biases, to better identify, retain and develop players

Developmental fitness curves: Assessing sprint acceleration relative to age and maturity status in elite junior tennis players

Background The influence of maturity-status on athletic performance is reasonably well-documented. Methodological and practical issues of assessment and lack of longitudinal data have impacted the success of various models. Aim To develop age- and sex-specific developmental curves for sprint acceleration in elite youth tennis players and to address variation in performance relative to chronological and biological age. Subjects and methods Measures of acceleration were available for 3120 elite youth tennis players aged 8–15 years attending National and Regional Talent Identification days. Variation in acceleration by chronological and estimated biological ages was evaluated in corresponding data for an independent sample of elite youth players 8.9 to 15.1 years of age. Results Acceleration varied as a function of chronological and biological age relative to developmental curves. Early maturing males and females had significantly poorer performances when acceleration was considered relative to biological age. Significant discrepancy in percentiles relative to biological versus chronological ages was also evident between early and late maturing players of each sex. Conclusion Evaluating performance relative to developmental curves and maturity status may be a practical means of monitoring long-term athlete development in tennis

Motor coordination, physical activity and fitness as predictors of longitudinal change in adiposity during childhood

The purpose of this study was to examine the influence of motor coordination (MC), physical fitness (PF) and physical activity (PA) on the development of subcutaneous adiposity in a sample of children followed longitudinally from 6 to 10 years of age. Participants were 142 girls and 143 boys. Height, weight, and the triceps and subscapular skinfolds were measured annually between the ages of 6 and 10 years. PA was estimated with the Godin–Shephard questionnaire. MC was evaluated with the Körperkoordination Test für Kinder (KTK) test battery, and PF was assessed with four Fitnessgram tests: curl-ups (CU), push-ups (PU), trunk-lifts (TL) and one mile run/walk (MRW). Hierarchical linear modelling with MC, PF items and PA as predictors of the sum of two skinfolds (SKF) was used. The results showed that boys and girls differed significantly in SKF at baseline (girls: 19.7 mm; boys: 16.6 mm). Three PF items (CU, PU and MRW) and MC had a positive influence on SKF. For each unit improvement in CU, PU, MRW and MC, SKF was reduced by 0.06, 0.04, 0.06 and 0.12 mm, respectively. In conclusion, motor coordination, muscular strength and endurance, and aerobic endurance attenuated the accumulation of subcutaneous adipose tissue during childhood

Physical activity patterns during school recess : a study in children 6 to 10 years old

The aims of this study were to characterize the spontaneous physical activity of children during school recess, and to estimate variation in physical activity associated with gender and age. A MTI actigraph (Model 7164) was used with a sample of 140 boys and 131 girls, 6 to 10 years of age. MTI counts were converted to METs using a regression equation developed for children. The number and average duration of periods of activity by intensity were calculated for each child during a 30 minute recess: rest or mild physical activity (≤ 2.9 METs), moderate physical activity (3.0-5.9 METs,), vigorous physical activity (6.0-8.9 METs) and very vigorous physical activity (≥ 9.0 METs). Boys and girls spent about 50% of the recess in physical activity. Physical activity was characteristically done in very short bursts with intervals of rest or mild physical activity. The number of episodes of physical activity of all intensity levels was lower in older children while the inverse occurred at rest or mild physical activity. Boys engaged in higher intensity activity than girls and in general spent more recess time in physical activity

Changes in the Genetic Variance and Heritability of the Body Mass Index and Skinfolds among Polish Twins Aged 8–18 Years

Body Mass Index (BMI) and skinfolds are common indicators of adiposity. Many studies have shown relationships between the BMI in childhood and adolescence and the BMI in adulthood. Similar correlations were observed for the skinfolds, although they tend to be lower. The aim of this study was to estimate changes with age in the genetic variance and heritability of the BMI and skinfolds among Polish twins born between 1959 and 1965. Observations involved male and female monozygotic (MZ) and dizygotic (DZ) twins, who were measured annually between 8 and 18 years of age. Body Mass Index and skinfold thicknesses at the triceps (TSF), subscapular (SSF) and suprailiac (SIF) sites were measured. Genetic variance and heritability were estimated for individual skinfold thicknesses, the sum of three skinfolds (SUMSF) and BM, separately by age classes for both sexes. Intraclass correlations were significantly higher for MZ twins than for DZ twins in both sexes and across all ages. Heritability estimates were significant for all indicators of adiposity, but varied with age and had different ranges for boys and girls. Estimates of genetic variance were significant for all indicators of adiposity and were higher for girls than for boys

Weight status, BMI and physical fitness in polish youth: relationships between 1986 and 2016

One of the components affecting the level of health is physical fitness and diets, which is also considered the foundation of a healthy lifestyle. Methods: Samples by survey ranged from 871 to 1,417 (boys) and from 843 to 1,326 (girls). Speed (5 m run), agility (figure-8-run), explosive power (vertical jump), flexibility (stand and reach) and cardiovascular fitness (step test) were measured. The Body Mass Index (BMI) of each student was classified as Thin, Normal weight or Overweight/Obese (Owt/Ob) relative to International Obesity Task Force (IOTF) criteria. Fitness items were compared among weight status groups and across surveys with sex-specific analyses of covariance. Regressions of each fitness item on the BMI in the four surveys were done using linear and nonlinear quadratic models. Results: Performances on all fitness tests except flexibility were poorer among Owt/Ob compared to Normal and Thin youth, but performances on fitness tests within weight status groups did not differ consistently across surveys. Conclusions: Relationships between the BMI and fitness tests varied across surveys, but suggested reasonably consistent curvilinear relationships between fitness tests and the BMI among boys more so than girls.info:eu-repo/semantics/publishedVersio