Carlos E. Gonçalves

Characteristics of youth soccer players who drop out, persist or move up

Abstract In this study, we compared the growth, maturity status, functional capacity, sport-specific skill, and goal orientation of 159 male soccer players, aged 11–12 (n = 87) and 13–14 years (n = 72) years, who at follow-up 2 years later discontinued participation (dropout), continued at the same standard (club) or moved to a higher level (elite). Age group-specific multivariate analysis of variance was used for comparisons. Among 11- to 12-year-old players at baseline, a gradient of elite > club > dropout was suggested for size and function, although differences were not consistently significant. Elite players performed significantly better in only two of the four skills, dribbling and ball control. A gradient of elite > club > dropout was more clearly defined among 13- to 14-year-old players at baseline. Elite players were older chronologically and skeletally, larger in body size and performed better in functional capacities and three skill tests than club players and dropouts. Baseline task and ego orientation did not differ among dropouts and club and elite players at follow-up in either age group. The results suggest an important role for growth and maturity status, functional capacities, and sport-specific skills as factors in attrition, persistence, and moving up in youth soccer.

Youth soccer players, 11–14 years: Maturity, size, function, skill and goal orientation

Background: Participants in many youth sports are commonly combined into age groups spanning 2 years. Aim: The study compared variation in size, function, sport-specific skill and goal orientation associated with differences in biological maturity status of youth soccer players within two competitive age groups. Methods: The sample included 159 male soccer players in two competitive age groups, 11–12 years (n=87) and 13–14 years (n=72). Weight, height, sitting height and four skinfolds, four functional capacities, four soccer skills and goal orientation were measured. Skeletal maturity was assessed using the Fels method. Each player was classified as late, on time or early maturing based on the difference between skeletal and chronological ages. ANOVA was used to compare characteristics of players across maturity groups. Results: Late, on time and early maturing boys are represented among 11–12-year-olds, but late maturing boys are under-represented among 13–14-year-olds. Players in each age group advanced in maturity are taller and heavier than those on time and late in skeletal maturity, but players of contrasting maturity status do not differ, with few exceptions, in functional capacities, soccer-specific skills and goal orientation. Conclusion: Variation in body size associated with maturity status in youth soccer players is similar to that for adolescent males in general, but soccer players who vary in maturity status do not differ in functional capacities, soccer-specific skills and goal orientation.

Cross-validation and Reliability of the Line-drill Test of Anaerobic Performance in Basketball Players 14–16 Years

Carvalho, HM, Coelho e Silva, MJ, Figueiredo, AJ, Gonçalves, CE, Castagna, C, Philippaerts, RM, and Malina RM. Cross-validation and reliability of the line-drill test of anaerobic performance in basketball players 14-16 years. J Strength Cond Res 25(4): 1113-1119, 2011-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.

Age-related variation of anaerobic power after controlling for size and maturation in adolescent basketball players

Background: Adolescence is characterized by increments in body size and physical performance. Short bursts of maximal intensity, requiring anaerobic metabolism, are important in many team sports including basketball. Aim: Variation of anaerobic power of adolescent basketball players (n = 93, 14–16 years) in relation to years before and after estimated age at peak height velocity (PHV) and variation in body size was considered. Methods: The cross-sectional study included chronological age, estimated age at PHV, training experience; stature, body mass (BM), free-fat mass (FFM) and estimated lower-limb volume (LLV) by anthropometry; and short-term power outputs derived from the Wingate Anaerobic Test (WAnT). Based on proportional allometric modeling, power outputs were partitioned for biological maturity status and size variables. Pearson correlations were used to estimate the associations between distance to PHV (maturity offset) and training experience with absolute and scaled estimates of short-term power. Results: Absolute WAnT increased linearly (PP, r = 0.72; MP, r = 0.74) through the interval of rapid growth of the adolescent spurt. Increments were related mainly to BM and muscle mass. Nevertheless, a residual significant positive influence of chronological age per se on maximal short-term power outputs remained independent of body size. Conclusion: Allometric modelling to partition size may reveal other potentially meaningful factors in the development of short-term performance in adolescent athletes.

Prenatal administration of vitamin A alters pulmonary and plasma levels of vascular endothelial growth factor in the developing mouse

Vitamin A and the retinoids play a unique role in mammalian embryonic and foetal development and are essential for both cellular differentiation and the establishment of normal morphogenesis. Vascular endothelial growth factor (VEGF) is a known potent mitogenic factor that plays a key role in lung development and function maintenance. In order to contribute to a better knowledge of the modulating effects of vitamin A in lung development, we investigated the effects of the antenatal administration of vitamin A on VEGF expression in lungs and plasma from foetuses and neonates. Pregnant mice were subjected to subcutaneous administration of vitamin A on the 12th gestational day. The lungs and plasma from foetuses and neonates were collected daily from the 15th gestational day till the day of birth. Our results show that vitamin A modulates VEGF concentrations both in lungs and plasma. Statistically significant differences were observed at gestational days 15 (P = 0.004 for lungs; P < 0.0001 for plasma), 16 (P < 0.0001 for lungs and plasma) and 18 (P < 0.0001 for lungs; P < 0.05 for plasma). Vitamin A tends to increase the expression of this factor in the lung, particularly during the critical period of perinatal adaptation to postnatal life. These effects seem to be spatial and temporally regulated, and point out to the important role of vitamin A during lung development.

Growth, functional capacities and motivation for achievement and competitiveness in youth basketball: an interdisciplinary approach

ABSTRACT The interaction of multiple influences on the path to sport success is not yet fully understood by sport scientists. In this study, we examined variation in body size, functional capacities and motivation for achievement, competitiveness and deliberate practice of youth basketball players associated with differences in biological maturity status, chronological age and years of training experience. Reflecting the importance of interactive effects, we examined the relationships between the psychological variables and functional capacities. Fifty-eight male basketball players aged 9.5 to 15.5 years were considered. Variables included chronological age, estimated age at peak height velocity, stature, body mass and sitting height by anthropometry; the Work and Family Orientation and Deliberate Practice Motivation Questionnaires were also used. Finally, the Line Drill test and Yo-Yo Intermittent Recovery level 1 (Yo-Yo IR1) tests were used as functional capacities indicators for basketball. Variance components models derived from series of multilevel linear regression models revealed a substantial variation by maturity status for body size, functional capacities indicators, mastery and will to excel. The influence of estimated maturity status on mastery and will to excel was independent of age and years of experience. In contrast, no relationships were observed between psychological variables and functional capacities indicators. We conclude that growth-related changes are relevant to understanding players´ motivations for achievement, competitiveness and deliberate practice. This should be of interest to those involved in the selection and development of youth basketball players.

Validity and usefulness of the Line Drill test for adolescent basketball players: a Bayesian multilevel analysis

ABSTRACT The study examined the validity of the Line Drill test (LD) in male adolescent basketball players (10–15 years). Sensitiveness of the LD to changes in performance across a training and competition season (4 months) was also considered. Age, maturation, body size and LD were measured (n = 57). Sensitiveness of the LD was examined pre- and post-competitive season in a sub-sample (n = 44). The time at each of the four shuttle sprints of the LD (i.e. four stages) was modelled with Bayesian multilevel models. We observed very large correlation of performance at stage 4 (full LD protocol) with stage 3, but lower correlations with the early LD stages. Players’ performance by somatic maturity differed substantially only when considering full LD protocol performance. Substantial improvements in all stages of the protocol were observed across the 4-month competitive season. The LD protocol should be shortened by the last full court shuttle sprint, remaining sensitive to training exposure, and independent of maturity status and body size.

The path to expertise in youth sport: using a retrospective interview in three different competitive contexts.

The goal of this study was to identify contextual factors in the path to excellence in youth sport. 48 male athletes under 17 years of age (M = 15.7 yr., SD = 1.0) from a soccer academy (n = 20), a volleyball club (n = 14), and an elite volleyball center (n = 14) participated in the study. A standardized, retrospective interview was administered. Demographic information, training loads, and incidence of injuries were also collected. Male soccer players had more years of practice in sport than their male volleyball peers, but elite male volleyball players practiced more hours per week than the other athletes. The perception of intensity of training, physical effort, and concentration in male soccer players was higher than in male volleyball players. The high demands of expertise in professional soccer leads young athletes to begin training at early ages. The results showed that the environment specificity shapes the way young male athletes perceive their participation and commitment in sport.

Quantification of Mouse Lung Elastin During Prenatal Development

Elastic fibres play a crucial function during the process of lung alveolisation. During the perinatal period, any changes in the elastogenic process during foetal development may result in permanent lifetime defects. In pre-natal life, well-developed pulmonary elastic fibres should favor the pre-natal maturation of the lung and an enhanced alveolisation, which in many species, such as humans begins only after birth. The authors present a quantitative study by image analysis and by high-pressure liquid chromatography (HPLC) of the mouse lungs’ elastic fibre content from the 15th till the 19th gestational day.

Contemporary trends and issues in youth sports in Portugal

Na medida em que todas as obras da UC Digitalis se encontram protegidas pelo Código do Direito de Autor e Direitos Conexos e demais legislação aplicável, toda a cópia, parcial ou total, deste documento, nos casos em que é legalmente admitida, deverá conter ou fazer-se acompanhar por este aviso. Contemporary trends and issues in youth sports in Portugal Autor(es): Gonçalves, Carlos E; Silva, Manuel Coelho e Publicado por: Coimbra University Press URL persistente: URI:http://hdl.handle.net/10316.2/32585 DOI: DOI:http://dx.doi.org/10.14195/978-989-26-0412-1_1