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The study aimed to evaluate the mediating effect of biological maturation on anthropometrical measurements, performance indicators and subsequent selection in a group of academy rugby union players. Methods: 51 male players 14-17 years of age were assessed for Height, weight, and BMI and percentage of predicted mature status attained at the time of observation was used as an indicator of maturity status. Following this, initial sprint velocity (ISV), wattbike peak power output (PPO) and initial sprint momentum (ISM) was assessed. Results: A bias towards on-time (n = 44) and early (n = 7) maturers was evident in the total sample and magnified with age cohort. Relative to UK reference values, weight and height were above the 90th and 75th centiles, respectively. Significant (P ≤ .01) correlations were observed between maturity status and BMI (r = .48), weight (r = .63) and height (r = .48). Regression analysis (controlling for age) revealed that maturity status and height explained 68% of ISM variance; however, including BMI in the model attenuated the influence of maturity status below statistical significance (p=.72). Height and BMI explained 51% of PPO variance, while no initial significant predictors were identified for ISV. Conclusion: Results indicate a clear selection bias towards earlier maturers within this sample of rugby union players. This was attributable in part, to the mediating effect of maturation on body size, which, in turn, predicted performance variables.

The summer Olympic Games dominates the headlines every 4 years. The 2016 Games in Rio de Janeiro are no exception, although non-sport issues presently dominate headlines—political, economic and soc...

Physical changes associated with puberty may conflict with functional and aesthetic ideals for a career in ballet. The dance teacher is in a position to guide young dancers through the pubertal transition, although dancers rather than teachers are often the focus of research. This study explores the social stimulus value of the female body in ballet as perceived by the dance teacher and how value may change during puberty. Ten UK dance teachers were interviewed; interpretative phenomenological analysis was used. Four main themes perceived by dance teachers emerged as central to the social stimulus value of the body among adolescent dancers: the ideal body; teacher approaches to managing puberty in the dance environment; puberty as a ‘make or break’ stage in ballet; and teacher awareness of pubertal onset and the implications of timing. Dance teachers can play an important role in moderating external and individual expectations during the pubertal transition.

Objective This study tests the hypothesis that natural selection is associated with type 2 diabetes (T2D)-associated mortality and fertility in a rural isolated Zapotec community in the Valley of Oaxaca, southern Mexico. Participants and Methods Mortality data and related demographic and genealogic information were linked with data for fertility, prereproductive mortality and family history of mortality attributed to T2D. Physician verified T2D mortality (n = 27) between 1980 and 2009 and imputed T2D (n = 70) from cardiovascular mortality (68% random sample) and renal failure (44% random sample). Bootstrapping was used to obtain a robust variance estimate in survival analysis and multivariate analysis of variance. Results Estimated maximum natural selection by Crow's Index occurred circa 1930 and was relaxed after this time in the study population. Cox-regression survival analysis of T2D mortality with covariates (family history of T2D, cardiovascular disease, renal failure) indicated a significant hazard ratio (HR = 5.95, 95% CI: 1.38–25.67, p < .008) for the increase in T2D in 2000 to 2009. Survival analysis of imputed T2D resulted in a significant HR of 2.03 (95% CI: 1.08–3.85, p = .01) for the increase in T2D in the 2000 to 2009 cohort (reference group: 1980–1989). Mean number of live born offspring was lower among T2D (n = 27, 4.04 ± 3.85 SD) compared to non-T2D (n = 199, 5.30 ± 3.48) groups (p < .08). Mean number of live born offspring was lower (p = .003) among imputed T2D compared to non-T2D groups (4.10 ± 3.44 vs. 5.62 + 3.50). Discussion T2D-associated mortality increased in frequency as natural selection decreased, and favored offspring survival of non-T2D descedants. The results indicated statistically significant directional selection against T2D and imputed T2D to this population isolate.

Public service obligations (PSOs) are used by governments in many countries, including the United States and 11 countries in Europe, to mandate a minimum level of commercial air transportation service, especially for small or rural communities. This paper analyzes PSOs in these 12 countries for the year 2010 using the recently proposed Global Connectivity Index to measure direct and indirect market access and a novel subsidy database covering 90% of PSO movements in these countries to assess value-for-money. We show that PSO services represent about 2.5% of all commercial movements in the 12 countries analyzed, generating about 1% of these countries' total air transport connectivity. Over all routes for which data was available, approximately USD $900 million was earmarked for PSO and air service discount provision in 2010, with average subsidies per movement ranging from about $700 to $3500. PSO market access and efficiency outcomes vary across the countries analyzed. Some countries, such as Germany and the United States, focus on providing network access for smaller communities, thereby creating not only point-to-point, but also onward connectivity, while others such as Norway, Sweden, and Ireland, predominantly aim at providing "lifeline services" that connect remote regions to a nearby economic center without providing onward connections. (C) 2016 Elsevier Ltd. All rights reserved. Michael Wittman thanks the MIT Airline Industry Consortium for financial support. Florian Allroggen gratefully acknowledges funding from the German Research Foundation under grant no.: AL 1814/1-1. The authors are also grateful for the valuable feedback of two anonymous reviewers.

Growth and maturation impact the selection, development and progression of youth athletes. Individual differences in the growth and maturity may afford a performance advantage, clouding coaches and practitioners’ perceptions regarding current ability and future potential. This may result in the exclusion of talented, yet less physically gifted athletes. Participants were 91 male (n = 47) and female (n = 44) elite British Junior tennis players, 8–17 years of age (12.5 ± 1.9 years). Height and body mass were measured and compared to growth charts; hand-wrist radiographs were taken. Skeletal age (SA) was estimated with the Fels method and contrasted to chronological age (CA). Mean height and body mass of individual players ranged between the 50th and 90th centiles for age and sex. Females were advanced in SA relative to CA (0.3–0.89 years.) from 8 years. Males were average to delayed in maturation from 8 to 12 years, but advanced in SA from 14 to 16 years (0.75–1.23 years). Individual differences in growth and maturation appear to contribute towards the selection of elite junior tennis players, with a bias towards males and females who are advanced in maturation and comparatively tall and heavy for their age. This has important implications for talent identification and development.

BACKGROUND Research on relationships between lifestyle behaviors and adiposity in school youth is potentially important for identifying subgroups at risk. This study evaluates the associations between waist circumference (WC) and objective measures of sedentary behavior (SB) in a sample of rural school adolescents. METHODS The sample included 254 students (114 boys, 140 girls), 13-16 years of age, from rural regions of the Portuguese midlands. Height, weight, and WC were measured. Cardiorespiratory fitness (CRF) was assessed with the 20-m shuttle-run test. An uniaxial GT1M accelerometer was used to obtain 5 consecutive days of physically activity (PA) and SB. Multiple linear regression was used to test associations between WC and SB, adjusted for several potential confounders (age, sex, PA, CRF, parental education). RESULTS SB was not significantly associated with the WC, neither in the unadjusted model nor after adjustment for all potential confounders. In the final model, the unique significant predictor of the WC was cardiorespiratory fitness (β = −0.82; 95% confidence interval [CI], −1.02 to −0.62). CONCLUSION WC was not independently associated with SB time in rural school adolescents. Future research is claimed among rural adolescents in different geographic contexts to try to clarify recent findings of less studied communities.

The body goes through remarkable changes from birth through childhood and adolescence into adulthood. Biological growth and maturation, along with behavioral development, are important aspects “growing up.” These three processes, growth, maturation, and development, dominate the daily lives of children and adolescents for approximately the first two decades of life. This chapter will focus predominantly on growth and maturation, and how timing and tempo of these may affect sports involvement and injury risk in young female athletes.

Physically active and physically inactive behaviors are important in the daily lives of children and adolescents. Both have implications for fitness and health, learning, enjoyment, social interactions, and physical and psychological development. Physically active behaviors are also essential to subsistence in many parts of the developing world, and children and adolescents contribute to these efforts on a regular basis. In these contexts, several aspects of physical activity and inactivity among children and adolescents are discussed: assessment and measurement; current levels of physical activity and inactivity among youth; recent trends in physical activity across time; recent trends in physical inactivity across time; correlates of physical activity and inactivity; and fitness and health benefits of regular physical activity. There is a need for more detailed understanding of meanings attached to and motivations for physically active and sedentary behaviors, and of potential correlates – demographic, biological, psychosocial and cultural, and their interactions.

Physical activity is important in obesity prevention, but the effectiveness of different physical activity modalities remains to be determined among children. The main purpose of this study was to compare the effects of a 6-month soccer programme and a traditional physical activity programme on changes in body composition, cardiometabolic risk factors, inflammatory and oxidative markers, cardiorespiratory fitness and perceived psychological status in obese boys. Eighty-eight boys (8-12 years; BMI > +2 standard deviations of WHO reference values) participated in one of three groups: soccer, traditional activity and control. Soccer and traditional activity programmes involved 3 sessions per week for 60-90 min at an average intensity of 70-80% of maximal heart rate. Control group participated in activities of normal daily living. All boys participated in school physical education, two sessions per week of 45-90-min. Measurements were taken at baseline and after 6 months, and included body size and composition, cardiometabolic risk factors, inflammatory and oxidative markers, cardiorespiratory fitness and perceived psychological status. Physical activity and dietary intake were assessed before and immediately following the intervention. The three groups had similar characteristics at baseline. After 6 months, both intervention groups had significantly lower relative fatness (% fat), waist circumference and total cholesterol, and higher cardiorespiratory fitness, self-esteem, perceived physical competence and attraction to physical activity compared with control group. In conclusion, physical activity interventions over 6 months positively influenced several indicators of health status among obese boys. The results also suggested that soccer has the potential as an effective tool for the prevention and reduction of childhood obesity and associated consequences.

Context: Evidence indicates higher prevalence of obesity in rural American youth. The present study evaluates the growth status and estimates the prevalence of overweight and obesity among rural school children in Texas. Methods: Heights and weights were measured in a sample of 1,084 school youth (545 males, 539 females) 5–19 years of age, in rural north central Texas in 2010. body mass index (BMI) was calculated. Growth status was plotted relative to US reference data. Weight status (underweight/thin, overweight, and obesity) was classified relative to age- and sex-specific Centers for Disease Control (CDC) and International Obesity Task Force (IOTF) criteria. Concordance of classifications was evaluated. Results: Mean heights of the rural children approximated reference medians, while median weights exceeded reference medians and approximated 75th percentiles with increasing age. Median BMIs of boys and girls were below the 75th percentiles except among late adolescent girls. Prevalence of underweight/thinness was low (

Secular changes in body size, estimated fatness, skeletal maturation, and functional characteristics of youth soccer players on entry into an elite academy between 1992 and 2003 were compared. Annual selections grouped across time (1992-1995, 1996-1998, 1999-2003), playing position (goalkeeper, defender, midfielder, forward), and by eventual status in the sport (professional, non-professional) were compared. Data for 158 players (age 13.4 ± 0.4 years) at entry into the academy included skeletal age (Greulich-Pyle method), height, weight, relative fatness, four field tests of functional capacities (aerobic, anaerobic, power, speed), and quadriceps concentric strength of the dominant and non-dominant legs. MANCOVA with age as the covariate and chi square were used for comparisons across years. With few exceptions (but notably estimated [V·]O(2max)), results for player size, functional characteristics, and skeletal maturation did not differ among years. Distributions of players by skeletal maturity status and within each playing position also did not differ between years. Although related research has suggested that the anthropometric characteristics of professional players and demands of contemporary professional soccer competition increased over this period, the size, maturity, and functional characteristics of youth players on entry to an elite academy and of graduates who eventually played soccer as professionals generally did not change across annual selections from 1992 to 2003. The results suggest a lack of change in selection philosophies and practices of coaches involved in recruiting players for the academy, which in turn is reflected in consistency of specific evaluation criteria employed over the decade considered.

This study evaluates the contributions of age, growth, skeletal maturation, playing position and training to longitudinal changes in functional and skill performance in male youth soccer. Players were annually followed over 5 years (n = 83, 4.4 measurements per player). Composite scores for functional and skill domains were calculated to provide an overall estimate of performance. Players were also classified by maturity status and playing position at baseline. After testing for multicollinearity, two-level multilevel (longitudinal) regression models were obtained for functional and skill composite scores. The scores improved with age and training. Body mass was an additional predictor in both models [functional (late maturing): 13.48 + 1.05 × centered on chronological age (CA)—0.01 × centered CA2—0.19 × fat mass (FM) + 0.004 × annual volume training—1.04 × dribbling speed; skills (defenders): 7.62 + 0.62 × centered CA—0.06 × centered CA2 + 0.04 × fat-free mass—0.03 × FM + 0.005 × annual volume training—0.19 × repeated-sprint ability + 0.02 × aerobic endurance]. Skeletal maturity status was a significant predictor of functional capacities and playing position of skill performance. Sound accuracy of each multilevel model was demonstrated on an independent cross-sectional sample (n = 52).

Anthropometric characteristics, physical fitness and technical skills of under-19 (U19) soccer players were compared by competitive level (elite, n=95; non-elite, n=85) and playing position (goalkeeper, central defender, fullback, midfield, forward). Fitness tests included 5- and 30-m sprints, agility, squat jump (SJ) and countermovement jump (CMJ), strength and Yo-Yo intermittent endurance test level 2 (Yo-Yo IE2). Soccer-specific skills included ball control and dribbling. Independent of position, elite players presented more hours of training per year than non-elite players (d>1.2). Stature and body mass discriminated elite from non-elite players among goalkeepers and central defenders (d>0.6). Major differences were noted between elite and non-elite goalkeepers for SJ, CMJ, Yo-Yo IE2, and ball control (d>1.2). Elite central defenders performed better than their non-elite counterparts in SJ and ball control tests (d>1.2). Elite players presented better agility and Yo-Yo IE2 performances than non-elite players within all positional roles (d>0.6). In conclusion, U19 players differed in anthropometric characteristics, physical fitness and technical skills by competitive level within field positions.

Relations among body size, stress coping strategies, and mental health were examined in female high-school gymnasts (n=44) and basketball players (n=105), aged 14–18 years (M = 15.8, SD = 1.1), through hierarchical regression analyses. Athletes completed the Revised Ways of Coping Checklist prior to the season and the Mental Health Inventory at the end of the season. Body mass index (BMI) was also calculated. The use of adaptive over maladaptive coping strategies was associated with more positive mental health and less distress in both sports. In gymnasts, BMI was inversely related to psychological well-being and the interaction between height and less adaptive coping strategies significantly predicted psychological distress.

The purpose was to evaluate a hypothesized model of change during a training and competition macrocycle in a sample of elite field hockey players. Subjects were 11 members of the Polish national team. Players were measured and tested four times through a complete macrocycle. Variables included body mass, %Fat (BIA), aerobic endurance, maximal running speed, speed-endurance and blood lactate concentrations after the endurance, speed and speed-endurance tests. Significant changes occurred in %Fat, aerobic endurance and blood lactate concentrations at different phases of the macrocycle. Mean changes for the total sample did not follow the hypothesized model for speed, aerobic endurance and speed-endurance between specific periods of the macrocycle. Variability among individual players was considerable and emphasized the importance of individualizing training protocols during a macrocycle. The results highlighted the need to consider specific functional capacities (speed, aerobic endurance, speed-endurance) of individual athletes in addition to technical and tactical skills.

The 2011 Pennington Biomedical Research Center's Scientific Symposium focused on adiposity in children and adolescents. The symposium was attended by 15 speakers and other invited experts. The specific objectives of the symposium were to (i) integrate the latest published and unpublished findings on the laboratory and clinical assessment of depot-specific adiposity in children and adolescents, (ii) understand the variation in depot-specific adiposity and related health outcomes associated with age, sex, maturation, ethnicity and other factors and (iii) identify opportunities for incorporating new markers of abdominal obesity into clinical practice guidelines for obesity in children and adolescents. This symposium provided an overview of important new advances in the field and identified directions for future research. The long-term goal of the symposium is to aid in the early identification of children and adolescents who are at increased health risk because of obesity and obesity-related conditions.

This study examined differences in physical activity and physical self-concept between the least and most biologically mature female adolescents within chronological age and academic year groups. A total of 252 British female adolescents (M age = 12.9 years; SD = .7) in Years 7-9 completed self-report measures to assess physical activity and physical self-concept. Percentage of predicted adult (mature) stature served as the index of biological maturation. Univariate analyses of covariance, controlling for decimal age, revealed that the least mature girls generally held higher perceptions of physical self-concept but were no more, or less, active than the most mature girls. A subsequent meta-analysis suggested, however, that across age and year groups the least mature girls were more active than the most mature girls.

Background:Sport has high social valence and is a primary context for physical activity for the majority of youth. The aim of this study was to estimate the contribution of participation in organized sport to the total daily energy expenditure and also to its moderate-to-vigorous portion in male adolescents.Methods:The sample comprised 165 Portuguese male youth, aged 13 to 16 years. Physical activity was assessed with a multi-method approach (Actigraph GT1M accelerometer plus 3-day diary record). Differences in the intensities of physical activity and sedentary behavior of male sport participants and nonsport participants were compared using independent sample t-test.Results:Male participants in organized sports spent significantly more time in moderate-to-vigorous activities than nonparticipants, although the P-value for the 15 to 16 years age-group was marginal (P = .08) on the weekend days. In addition, male adolescents spent 11% to 13% of total daily energy expenditure in organized sports which corresponded to 35% to 42% of the moderate-to-vigorous portion of daily energy expenditure.Conclusion:Organized sport appears to be a relevant component of daily activity energy expenditure to promote healthy lifestyles among male adolescents.

The purpose of this study was to assess the agreement of lower-limb volume estimates based on anthropometry and dual-energy X-ray absorptiometry (DXA) as a reference method in male rugby athletes. Predictive models using body mass and skinfolds were tested to improve the relative agreement between protocols (anthropometry, DXA). Rugby players (n = 41; 19.9 ± 2.2 years) volunteered for the study. Lower-limb total and fat-free volumes were estimated by anthropometry and also derived using DXA. Cross-validation between the anthropometry technique and DXA was then performed. Lower-limb volume estimates by anthropometry overestimated reference values and tended to be further from the reference values with the increase of scale. For the total sample, standard errors of measurement for volume estimates by anthropometry were 1.99 L and 1.34 L for total and fat-free volumes, respectively. Correlations with reference values were 0.81 for lower-limb volume and 0.90 for lower-limb fat-free volume. Correlations between estimated prediction equations and reference values showed higher correlations (r = 0.96 for lower-limb volume and r = 0.93 for lower-limb fat-free volume) compared with anthropometric estimates. Overall, the agreement of anthropometry method to quantify lower-limb volumes with DXA as a reference in young adult rugby players is acceptable and is a practical method when more expensive and complex techniques are not available. The consideration of body mass and lower-limb skinfolds increases the precision of lower-limb volume estimates using anthropometry in the young adult rugby players.

Many factors in the natural, man-made and social environments can influence the physical growth and maturation and behavioral development of children and adolescents. Improved environmental conditions over the past century or so have contributed to positive secular changes in growth and maturation. More recently, however, technological advances have increased opportunities for sedentary behaviors and contributed to reductions in physical activity, both of which have potentially negative implications for the health of youth. Pollutants associa-ted with some industries also have implications for health. Children with elevated lead levels are at increased risk for impaired growth and maturation and for impairments in fine motor coordination. The impact of elevated lead on gross motor coordination in several tests of physical fitness is mediated through the influence of lead on growth in body size. Similarly, emissions from coal-fired power plants and other industries are associated with asthma, which has implications for the physical activity and fitness of youth.

Objectives: To evaluate short-term secular change in menarche and associations with blood lead level in Polish girls between 1995 and 2007. Methods: Menarcheal status of school girls 7–16 years from villages in southwestern Poland was surveyed in 1995, 2001, 2004, and 2007. Blood lead was sampled in 1995 and 2007. Median ages and variance statistics for menarche were estimated with probit analysis. Associations between blood lead level and menarcheal status in 1995 and 2007 were analyzed with logistic regression using blood lead level as an independent binary variable: 2.00–5.00 and ≥5.10 μg/dl. Results: Median ages at menarche declined slightly from 1995 (13.36 ± 0.06 years) to 2001 (13.20 ± 0.04 years), was stable in 2004 (13.20 ± 0.05 years), and declined to 2007 (12.81 ± 0.05 years). Blood lead levels declined from 6.57 ± 0.13 μg/dl in 1995 to 4.24 ± 0.14 μg/dl in 2007. With age, height, and BMI controlled, probability of attaining menarche was not associated with blood lead in 1995, but was decreased with increased blood lead in 2007 (OR 0.31, 95% CI 0.09–1.06, P = 0.057). Conclusion: Ages at menarche and blood lead levels declined between 1995 and 2007. Higher blood lead levels were not associated with menarche in 1995, suggesting that nutritional and health conditions and perhaps somewhat unstable social and economic conditions in the 1980s and early 1990s may have masked the influence of lead on sexual maturation. Elevated blood lead was associated with the probability of later menarche in 2007, although the association was of borderline (P = 0.06). Am. J. Hum. Biol., 2012. © 2012 Wiley Periodicals, Inc.

In jurisdictions including the US and the EU ground transportation and marine fuels have recently been required to contain lower concentrations of sulfur, which has resulted in reduced atmospheric SO(x) emissions. In contrast, the maximum sulfur content of aviation fuel has remained unchanged at 3000 ppm (although sulfur levels average 600 ppm in practice). We assess the costs and benefits of a potential ultra-low sulfur (15 ppm) jet fuel standard ("ULSJ"). We estimate that global implementation of ULSJ will cost US$1-4bn per year and prevent 900-4000 air quality-related premature mortalities per year. Radiative forcing associated with reduction in atmospheric sulfate, nitrate, and ammonium loading is estimated at +3.4 mW/m(2) (equivalent to about 1/10th of the warming due to CO(2) emissions from aviation) and ULSJ increases life cycle CO(2) emissions by approximately 2%. The public health benefits are dominated by the reduction in cruise SO(x) emissions, so a key uncertainty is the atmospheric modeling of vertical transport of pollution from cruise altitudes to the ground. Comparisons of modeled and measured vertical profiles of CO, PAN, O(3), and (7)Be indicate that this uncertainty is low relative to uncertainties regarding the value of statistical life and the toxicity of fine particulate matter.

A model for adolescent involvement in physical activity (PA) that incorporates individual differences in biological maturation is presented. The biocultural model of maturity-associated variance in physical activity recognizes PA as a complex and multifaceted behaviour that exists in multiple contexts (e.g., transport, vocation, sport, exercise) and can be viewed from multiple perspectives (e.g., energy expenditure, movement counts, performance outcomes, fitness). The model holds that biological maturation can exert both direct and indirect effects on PA during adolescence. Direct effects imply a direct and unmediated effect of individual differences in maturation on PA. Indirect effects imply influences of individual differences in maturation on PA that are mediated by psychological constructs (e.g., self-perceptions, beliefs) and/or are moderated by exogenous factors (e.g., social interaction, culture) associated with pubertal maturation.

In adults, fatness and low cardiorespiratory fitness are associated with a higher prevalence of chronic disease risk and mortality. The association between measures of physical fitness and fatness upon cardiovascular risk in youth, however, is less clear. The effects of adiposity and physical fitness upon cardiovascular disease risk factors in youth are receiving increasing attention but studies that have examined their independent associations are sparse. The purpose of this study thus was to investigate relationships among cardiovascular disease risk factors, four indicators of physical fitness and three indicators of fatness in a healthy adolescent cohort. Forty-eight boys and ten girls, 16.4±0.7 years, volunteered to participate in this cross-sectional study. Measurements included Blood Pressure (BP), three indicators of fatness and fat distribution Body Mass Index (BMI), waist-to-hip ratio, waist circumference), four measures of physical fitness (aerobic fitness, muscular fitness, sprinting speed, agility), weekly food intake and Physical Activity (PA) levels. Metabolic CVD risk factors included Total Cholesterol (TC), insulin, High-Density Lipoprotein (HDL), Low-Density Lipoprotein (LDL), high-sensitivity C-Reactive Protein (CRP), glucose, fibrinogen, interleukin-6, adiponectin, triglyceride and Plasminogen Activator Inhibitor-1 (PAI-1). Relationships between cardiorespiratory fitness and adiponectin (r = 0.443) and between muscular power and glucose (r = 0.430) were significant and moderate. Significant inverse correlations were also noted between adiponectin, sprint (r = -0.456) and agility (r = -0.399) performance. Adiponectin was also significantly and inversely correlated with waist circumference (r = - 0.514) and BMI (r = -0.434). From the regression models, a significant percentage of the variance in cardiorespiratory fitness, muscular fitness, agility and sprint performance (about 74, 53, 46 and 59%) was explained by traditional covariates. The results indicate that adiponectin is independently associated with different indicators of physical fitness and adiposity. Future studies may need to consider implementing interventions that improve all measures of physical fitness to ensure enhanced CVD risk profiles of youth.

Relationships among weight status (body mass index [BMI]), cardiorespiratory fitness (CRF) and objective measures of sedentary behaviour and physical activity (PA) were considered in a cross-sectional sample of Portuguese adolescents. The sample included 362 youth aged 13-16 years (165 males, 197 females) from urban and rural regions of the Portuguese midlands. CRF was assessed with the 20-m shuttle-run test. An uniaxial accelerometer was used to obtain five consecutive days of activity behaviours including time being sedentary. Pearson correlations and logistic regression analysis were used to examine relationships among variables. Rural adolescents were less active than their urban peers over the weekend. Both rural and urban youth with higher levels of CRF had a lower relative risk of being overweight/obese. The observations indicate important associations between weight status and CRF in both rural and urban Portuguese adolescents. In addition, place of residence has an important impact on weight status of this sample of adolescents.

Problem statement: Approximately 70% of the total ethnic minority population of Scotland is of South Asian ancestry, although relat ively little is known about their cardiovascular ri sk profile. Determining the risk profiles of Scottish youth of South Asian ancestry may inform the creation of interventions to reduce risk and improv e the quality of life in this population. Approach: The purpose of this pilot investigation was to exam ine the Cardiovascular Disease (CVD) risk profiles of Scottish youth of South Asian ancestry. A sample of 48 South Asian adolescents (26 females, 22 males, 16±2 years of age) resident in the city of G lasgow participated in this study. Stature, mass, waist circumference, physical activity, blood press ure, diet and 10 metabolic markers of CVD risk were recorded. Results: Boys had a significantly (p≤0. 01) greater body mass, stature and were more physically active than girls. The boys also had sig nificantly (p≤0. 05) higher fasting levels of glucose, LDL and C-Reactive Protein (CRP) and recorded lower levels of HDL than girls. High fat diets, low physical activity, elevated CRP, glucose and insuli n levels and low HDL levels were the risk factors most often identified as being as non-desirable. Ab out 88% of the cohort had between 2 and 6 CVD risk factors while 40% of boys and 20% of girls pre sented with 5 or more risk factors. Conclusion/Recommendations: Results suggest that preventive measures, includin g increased physical activity and dietary management may be warranted for the youth of South Asian ancestry.

The objective of the research was to prepare longitudinal percentile curves for the BMI (kg/m2) relative to time before and after peak height velocity (PHV) in Japanese boys and girls born between 1989 and 1991. Stature and weight were measured in every April from 6.5 to 16.5 years for 283 boys and 480 girls. Age at PHV was estimated by the proportional allotment method. The 50th percentile curves for the BMI of Japanese boys and girls born between 1989 and 1991 were similar to the corresponding curves for Japanese boys and girls born between 1972 and 1974. However, the 97th percentiles of children born between 1989 and 1991 were higher and the corresponding 3rd percentiles were lower compared to children born between 1972 and 1974. The differences can be attributed to the influence of early maturing children born between 1989 and 1991 on the 97th percentiles and of late maturing children born between 1989 and 1991 on the 3rd percentiles. The results highlight the need to consider the timing of maturity, in this case, age at PHV, when interpreting the BMI of adolescents.

Background:This study tested a mediated effects model of psychological and behavioral adaptation to puberty within the context of physical activity (PA).Methods:Biological maturity status, physical self-concept, PA, and health-related quality of life (HRQoL) were assessed in 222 female British year 7 to 9 pupils (mean age = 12.7 years, SD = .8).Results:Structural equation modeling using maximum likelihood estimation and bootstrapping procedures supported the hypothesized model. Maturation status was inversely related to perceptions of sport competence, body attractiveness, and physical condition; and indirectly and inversely related to physical self-worth, PA, and HRQoL. Examination of the bootstrap-generated bias-corrected confidence intervals representing the direct and indirect paths between suggested that physical self-concept partially mediated the relations between maturity status and PA, and maturity status and HRQoL.Conclusions:Evidence supports the contention that perceptions of the physical self partially mediate relations maturity, PA, and HRQoL in adolescent females.

The purpose of this study was to examine the effects of exercising at different intensities over 7 weeks on components of physical fitness and CVD risk factors. Forty-seven boys and 10 girls, (16.4±0.7 years of age) were divided into a moderate, high intensity, or a control group. All participants had indices of obesity and blood pressure recorded in addition to four physical performance measures pre- and post-intervention. In addition, the intervention groups repeated the physical performance measures at the 4th week phase of the intervention. Following the intervention, significant improvements (P

This study evaluates the validity and reliability of the line-drill (LD) test of anaerobic performance in 76 male basketball players 14.0-16.0 years of age. The Wingate Anaerobic Test (WAnT) was used as the reference for anaerobic performance. Wingate Anaerobic Test and LD test were moderately correlated (0.39 and 0.43, p < 0.01). Estimated age at peak height velocity (APHV) was moderately, negatively, and significantly (p < 0.01) correlated with WAnT peak (r = -0.69) and mean power (r = -0.71); earlier-maturing players had greater anaerobic power. Training experience was not associated with anaerobic performance, but chronological age (CA) and estimated APHV were significant covariates of the LD test (p < 0.05). National players were better than local players on the LD test (p < 0.01) after controlling for CA and body size. Short-term reliability of the LD test (n = 12, 1-week interval) was good: technical error of measurement = 0.44 seconds (95% confidence interval [CI] 0.31-0.75 seconds), intraclass correlation coefficient = 0.91 (95% CI 0.68-0.97), and coefficient of variation = 1.4% (95% CI 1.0-2.3%). Although the relationship between the LD test and WAnT was moderate, the LD test effectively distinguished local- and national-level adolescent basketball players. In contrast to WAnT, the LD test was not influenced by estimated biological maturity status. Thus, the LD test may be suitable for field assessment of anaerobic performance of youth basketball players.

The objective of this study is to compare the growth and physical fitness of normal, stunted and overweight/obese (owt/ob) Oaxaca children 6-13 years.This study was a cross-sectional, included 688 school children (grades 1-3, 4-6), aged 6-13 years, from an indigenous rural community (n=361) and colonia popular (n=327) in Oaxaca, southern Mexico.Anthropometry-weight, height, sitting height, limb circumferences, skinfolds. Derived-body mass index, sitting height/height ratio, leg and step lengths, limb muscle areas, sum of skinfolds. Physical fitness-sit and reach, sit-ups, distance run, grip strength, standing long jump, 35 yard dash. Physical activity-steps to and from school, household chores, sports participation.Normal-not stunted, not owt/ob; stunted-not owt/ob; and owt/ob-not stunted were compared with multivariate analysis of covariance controlling for age. Two children were stunted and owt/ob, and were excluded.Age-adjusted means for body size, muscularity, adiposity and grip strength showed a gradient, owt/obnormalstunted in both sexes and grade levels (P0.001). Relative position of stunted and owt/ob children was reversed for strength per unit mass. Stunted and normal children ran a greater distance than owt/ob children (P0.05). Normal, stunted and owt/ob children did not differ consistently in other fitness items and indicators of activity and inactivity.Size, muscularity, fatness and strength differed significantly, owt/obnormalstunted, but owt/ob children had less strength per unit mass and poorer endurance. Normal and stunted children did not differ consistently in fitness. Physical activity and television time did not differ among the three groups.

This study examined the association between demographic [age, sex, socioeconomic status (SES)] and socio-cultural [father, mother, sibling physical activity (PA); peers and physical education teacher influences] correlates and low, moderate and high levels of PA among Portuguese adolescents aged 10–18 years. A total of 3352 males and females attending basic and secondary schools, their parents and siblings were sampled across four regions of Portugal. PA was assessed with a psychometrically validated questionnaire. Multinomial logistic regression was used. Age was positively related with moderate and high PA. Boys and adolescents of high SES were more likely to participate in moderate and high PA. Adolescents were more likely to participate in high PA when theirs mother and sibling(s) also participated. Peers had a positive influence on participation in moderate and high PA, while physical education teachers did not have an influence. The results indicated that demographic and socio-cultural correlates – in particular age, sex, SES, mother and sibling PA, and peer influence – were significantly associated with adolescent PA. These results also suggested that interventions should focus on girls and low SES adolescents who face higher risk of inactivity.

Improving physical fitness is often an objective of programmes aimed at preventing obesity among youth.To evaluate the association between cardiorespiratory fitness (CRF) and area of residence controlling for several correlates in adolescents.CRF was assessed with the progressive aerobic cardiovascular endurance run (PACER) test in a cross-sectional sample of 362 Portuguese adolescents (165 males, 197 females) of 13-16 years of age. Youth were classified by area of residence as urban or rural. Gender, age, weight status, parental education, screen time (inactivity) and moderate-to-vigorous physical activity (MVPA) were statistically controlled. Logistic regression analysis was used.Adolescents of both sexes from rural settings were 76% more likely to be classified as aerobically fit compared to those from urban areas. The odds ratio for CRF in the final model was similar in boys (OR = 0.24, 95% CI 0.06-0.99, p0.05) and girls (OR = 0.24, 95% CI 0.07-0.76, p0.05). MVPA and weight status were important predictors of CRF in Portuguese adolescents of 13-16 years of age. Maternal education was an additional predictor in girls.CRF and rural/urban settings were significantly related in this sample of Portuguese adolescents of both sexes.

Absolute and relative components of body mass are a primary focus in studies of body composition. Components change with growth and maturation, requiring care in selecting methods of assessment in children and adolescents. Although sex differences are apparent in fat-free mass (FFM), fat mass (FM), and relative fatness (% Fat) during childhood, they are more clearly defined during adolescence and adulthood. Body composition is one of many determinants of sport performance, but % Fat tends to be the primary focus of discussion in young athletes. The influence of training for sport on bone mineral has received more attention in recent years because of methodological advances in assessment and concern for potential negative effects of altered menstrual function on bone. Relative fatness of young athletes in several sports is summarized, and issues related to sport training and body composition in young athletes are considered. Suggestions for dealing with body composition in young athletes are provided.

The purpose of this study is to compare estimates of physical activity and physical inactivity in urban Mexican school youth. A cross-sectional survey was conducted with 1085 school youth (525 males, 560 females), 9-18 years of age resident in Mexico City. Socioeconomic status (SES) was estimated. The Physical Activity Questionnaire (PAQ) was used to estimate activity over the past week. Television and video game time were noted. Height and weight were measured; the BMI was calculated. Youth were classified as normal weight, overweight or obese using international criteria. MANOVA was used to compare physical activity and inactivity by SES, age group (9-10, 11-13, and 14-18 years) within and between sexes, and by weight status. The most common non-sport physical activities are walking and jogging in girls and jogging, walking and bicycling in boys. Frequent (≥3 times per week) participation in sport activities is more common among boys than girls. Within each age group and sex, PAQ scores and screen time do not differ by SES, and boys are more physically active than girls. Boys spend more time playing video games than girls at all ages. Younger males and females have higher activity scores than the oldest group. Correlations between the BMI and the PAQ score are low. Estimated physical activity and screen time do not differ among youth by weight status. The majority of urban Mexican youth in this sample had insufficient physical activity and seemingly too much inactivity, both of which have negative implications on health status.

In this study we tested for differences in physical activity (PA), physical self-concept, and health-related quality of life (HRQoL) between the least and most biologically mature adolescent females within their respective chronological and academic year groups. A total of 222 British female adolescents aged 10 to 14 years ([Formula: see text] age = 12.7 years; SD = .8) completed a series of instruments assessing PA, physical self-concept, and HRQoL. Percentage of predicted adult stature was used as an index of biological maturation. A series of univariate analyses of covariance (ANCOVA), controlling for chronological age, revealed that the most mature girls within the chronological and academic year groups generally reported lower levels of physical self-concept and, to a lesser extent, PA and HRQoL when compared to the least mature girls. The findings provide partial support toward the contention that maturity-associated variance in health-related outcomes is accentuated at the extreme ends of the biological maturity continuum.

Differential investment in offspring by parental and progeny gender has been discussed and periodically analyzed for the past 80 years as an evolutionary adaptive strategy. Parental investment theory suggests that parents in poor condition have offspring in poor condition. Conversely, parents in good condition give rise to offspring in good condition. As formalized in the Trivers-Willard hypothesis (TWH), investment in daughters will be greater under poor conditions while sons receive greater parental investment under good conditions. Condition is ultimately equated to offspring reproductive fitness, with parents apparently using a strategy to maximize their genetic contribution to future generations. Analyses of sex ratio have been used to support parental investment theory and in many instances, though not all, results provide support for TWH. In the present investigation, economic strategies were analyzed in the context of offspring sex ratio and survival to reproductive age in a Zapotec-speaking community in the Valley of Oaxaca, southern Mexico. Growth status of children, adult stature, and agricultural resources were analyzed as proxies for parental and progeny condition in present and prior generations. Traditional marriage practice in Mesoamerican peasant communities is patrilocal postnuptial residence with investments largely favoring sons. The alternative, practiced by ∼25% of parents, is matrilocal postnuptial residence which is an investment favoring daughters. Results indicated that sex ratio of offspring survival to reproductive age was related to economic strategy and differed significantly between the patrilocal and matrilocal strategies. Variance in sex ratio was affected by condition of parents and significant differences in survival to reproductive age were strongly associated with economic strategy. While the results strongly support TWH, further studies in traditional anthropological populations are needed. Am J Phys Anthropol 143:501–511, 2010. © 2010 Wiley-Liss, Inc.

Relationships between growth, maturation and maximal short-term power outputs were investigated in 94 youth basketball players aged 14-16 years. Data included chronological age (CA), skeletal age (SA), years of training; body dimensions, estimated thigh volume, a running based short-term exercise assessed by the line drill test (LDT), the Bangsbo sprint test (BST) and short-term muscle power outputs with the Wingate anaerobic test (WAnT). Multiple linear regression analyses were used to estimate the effects of CA, skeletal maturity (SA/CA), years of training experience, body size and lower-limb volume on short-term performance in the LDT, BST and WAnT, respectively. Explained variances differed between cycle-ergometry outputs (52-54%) and running test performances (23-46%). The independent effects of predictors were small in the fatigue scores of the WAnT (4%) and the BST (11%). Skeletal maturity, body mass and leg length were primary predictors for all maximal short-term power output measures. Leg length was more relevant as a predictor than stature in the WAnT outputs, while stature and body mass appeared in the model with the running tests as dependent variable. Maximal short-term running abilities were also sensitive to years of training. In summary, skeletal maturation, body size and thigh muscle mass explained moderate to large proportions of the variance on maximal short-term performances of adolescent basketball players. The results highlight the importance of considering maturity status in evaluating the maximal short-term power outputs of adolescent athletes.

To evaluate the relationship between body mass index (BMI) and four components of physical fitness in a national cross-sectional sample of Taiwanese youth.A subsample of 102 765 youth (50 940 girls, 51 825 boys) 9-18 years was selected from a nationwide sample. Height, weight and four fitness items were measured: sit and reach (flexibility), standing long jump (power), sit-ups (abdominal muscular strength/endurance), and 800/1 600 m run/walk (cardiorespiratory endurance). BMI was calculated. Sex-specific regressions using a non-linear quadratic model of each fitness item on BMI were done in four age groups: 9-10, 11-12, 13-15, 16-18 years.The relationship between BMI and fitness varied among tests. Lower fitness in three items (sit-ups, jump, distance run) was evident in boys and girls with higher BMIs in each age group. Slopes of decline with increasing BMI varied by age group and sex. Relationships became parabolic for the three fitness items with age and peaks of the parabola were sharper in adolescent boys than girls. Relationships for the sit and reach contrasted with the other tests and differed among age groups and between sexes.BMI significantly and differentially influenced individual fitness tests, but effects varied with age and sex. Higher BMIs were generally associated with lower fitness.