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Nikki Rommers Mireille Mostaert Lennert Goossens Roel Vaeyens Erik Witvrouw Matthieu Lenoir 《Journal of sports sciences》2019,37(2):196-203
This study investigated differences in generic and soccer specific motor coordination, as well as speed and agility depending on age and maturity in elite youth soccer players (U10-U15, N = 619). Measurements included body height, body weight and sitting height to estimate age at peak height velocity (APHV); three Körperkoordinationstest für Kinder subtests (i.e. jumping sideways (JS), moving sideways (MS), balancing backwards (BB)) to assess generic motor coordination; the UGent dribbling test for soccer specific motor coordination; a 5m/30m sprint and T-test for speed and agility, respectively. Age specific z-scores of the predicted APHV identified players as earlier, on time or later maturing. (M)ANOVA analyses showed significant age by maturity interaction effects for the speed and agility test cluster, revealing maturity related differences in U14 and U15 players. Next to an overall higher performance with age for all test clusters (η2 0.080–0.468), earlier maturing players outperformed their later maturing peers in 5m/30m sprinting. The opposite was seen for JS and BB. So, players’ maturity status should be taken into account to adequately value performance in talent identification. Also, the focus on characteristics that appear to be minimally biased by an earlier maturational timing (i.e. motor coordination) should be increased. 相似文献
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Abdallah Rejeb Amanda Johnson Roel Vaeyens Cosmin Horobeanu Abdulaziz Farooq Erik Witvrouw 《European Journal of Sport Science》2017,17(4):495-502
The present investigation was carried out to examine the incidence and pattern of injuries in adolescent multisport athletes from youth sports academy. Injury data were prospectively collected from 166 athletes during the seasons from 2009 to 2014. A total of 643 injuries were identified, 559 (87.0%) were time-loss injuries. The overall injury incidence was 5.5 (95% confidence interval CI: 5.1–6.0), the incidence of time-loss injuries was 4.8 (95% CI: 4.4–5.2), the incidence of growth conditions was 1.2 (95% CI: 1.0–1.4) and incidence of serious injuries was 0.6 (95% CI: 0.5–0.8) per 1000?h of exposure. The prevalence of overuse injuries was 50.3%. Growth conditions represented 20.0%. Most of the injuries (67.0%) involved the lower extremities, and both foot and ankle were the most predominant injured body parts (22.0%). Knee injuries were mostly from overuse (50 vs. 23, p?=?.02), whereas foot and ankle injuries resulted from an acute mechanism (94 vs. 31, p?<?.0001). Minor and moderate injuries accounted for 87.0%. Muscle, tendon and osteochondrosis injuries accounted for 52.0% of all injuries. Comparing groups, squash sport was having the highest injury incidence (8.5 injuries per athlete). Higher exposure was associated with greater overuse relative risk (RR?=?1.03, 95% CI: 1.01–1.014, p?<?.001). In conclusion, the results of this study identified a high incidence of injuries in this youth sports population. Striking was the prevalence of overuse injuries of 50%, which suggests the need for injury prevention protocols for adolescent highly trained athletes. 相似文献
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Roel J. Bosker 《International Journal of Educational Research》1998,29(8):763-778
Primary schools in the Netherlands are autonomous in their decisions on grouping of pupils, and therefore on class size matters, because the state may not interfere in pedagogical-didactical issues according to the constitution. Surveys indicate that both across as well as within schools (across grades) class sizes consequently vary quite a lot. Capitalizing on this situation, a randomly drawn sample of 416 schools was used to collect data on class sizes and pupil achievement in grades 2, 4, 6 and 8. Social-ethnic status, IQ and gender also were examined. Using multi-level statistical models the strongest size effects were obtained in grade 2 in classes below 25 and above 35. Interaction effects between socio-ethnic status, sex and IQ with class size on achievement showed inconsistent trends. In three out of ten cases the achievement gap widened with decreasing class size. 相似文献
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The relationship between peak height velocity and physical performance in youth soccer players 总被引：1，自引：1，他引：0
Philippaerts RM Vaeyens R Janssens M Van Renterghem B Matthys D Craen R Bourgois J Vrijens J Beunen G Malina RM 《Journal of sports sciences》2006,24(3):221-230
Longitudinal changes in height, weight and physical performance were studied in 33 Flemish male youth soccer players from the Ghent Youth Soccer Project. The players' ages at the start of the study ranged from 10.4 to 13.7 years, with a mean age of 12.2 +/- 0.7 years. Longitudinal changes were studied over a 5 year period. Peak height velocity and peak weight velocity were determined using non-smoothed polynomials. The estimations of peak height velocity, peak weight velocity and age at peak height velocity were 9.7 +/- 1.5 cm x year-1, 8.4 +/- 3.0 kg x year-1 and 13.8 +/- 0.8 years, respectively. Peak weight velocity occurred, on average, at the same age as peak height velocity. Balance, speed of limb movement, trunk strength, upper-body muscular endurance, explosive strength, running speed and agility, cardiorespiratory endurance and anaerobic capacity showed peak development at peak height velocity. A plateau in the velocity curves was observed after peak height velocity for upper-body muscular endurance, explosive strength and running speed. Flexibility exhibited peak development during the tear after peak height velocity. Trainers and coaches should be aware of the individual characteristics of the adolescent growth spurt and the training load should also be individualized at this time. 相似文献
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Young adult soccer players often encounter difficulty progressing from youth competition to being regularly selected for high-level, open-age competition. In an attempt to increase the playing opportunities of semi-professional and amateur under-21 players in first teams, the Royal Belgian Football Association required national division teams to include at least two players younger than 21 in their match selection (under-21 rule). Over four seasons, the following variables were analysed across 2138 semi-professional and amateur soccer players aged 16?–?39 years: (1) the number of times a player was selected to be in the first team squad; (2) the number of times a player was selected to play in the starting line-up; and (3) the number of minutes played. Chi-square analysis demonstrated that second and third division teams had complied with the new selection regulations. However, two-way analysis of variance of individual player data revealed no increase in the number of playing minutes in the under-21 group. It would appear that many teams had complied with the new regulations by selecting young players as substitutes. The results highlight the difficulties that talented young soccer players experience progressing from youth to senior competition. We conclude that the rule imposed by the Royal Belgian Football Association has failed to improve the playing opportunities of young adult soccer players. Alternative strategies for increasing playing opportunities for young talented players are required. 相似文献
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Hetty P.J.M. Dekkers Roel J. Bosker Geert W.J.M. Driessen 《Educational Research and Evaluation》2013,19(1):59-82
It is well documented that stratification in education precedes social stratification. Many authors hypothesise that the stratification patterns in education may be related to background characteristics of students in a more complex way than researched so far in this field. Therefore, in this article the interactive effects of social class, ethnicity and gender on various indicators for school success are analysed and discussed. A large-scale longitudinal database offered the possibility to establish the complex relations between the three student background variables and school careers, measured by educational attainment 6 years after entering secondary education and by technical or science related choices. Results show that school success is not always predicted by expected additive or multiplicative effects of the different background variables. For example the situation of girls from ethnic minorities is better than expected, while that of indigenous boys from low socio-economic backgrounds is worse when compared to similar boys from ethnic minorities. Inequalities arising from different choice patterns regarding technical and science subjects can only partly be deduced from differences present at the age of 12, whereas in terms of general educational attainment secondary schools even reduce arrears of ethnic minority female students as these can be observed at the age of 12. 相似文献
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The value of a non-sport-specific motor test battery in predicting performance in young female gymnasts 总被引：3，自引：2，他引：1
Vandorpe B Vandendriessche JB Vaeyens R Pion J Lefevre J Philippaerts RM Lenoir M 《Journal of sports sciences》2012,30(5):497-505
Gymnastics talent identification focuses on the identification of young gymnasts who display characteristics for potential success in the future. The aim of this study was to identify which current performance characteristics are related to performance in competition 2 years later. Twenty-three female gymnasts aged 7-8 years completed a multidimensional test battery measuring anthropometric, physical, and coordinative characteristics and were technically evaluated by expert coaches. Two years later, the all-around competition results of those gymnasts now participating in elite (n = 12) and sub-elite (n = 11) competition were obtained. None of the initial measurements significantly correlated with the results of the sub-elite gymnasts 2 years later. For the elite gymnasts, a non-sport-specific motor test battery correlated strongly with the competition result, with more than 40% of the variation in competition performance being explained by the result on that test 2 years earlier. Neither the coaches' judgement nor the anthropometric and physical characteristics were sensitive enough to predict performance. A motor coordination test might be valuable in the early identification of gymnasts, as its discriminative and predictive qualities might be sufficiently powerful for selection within a relatively homogeneous population of gymnasts exhibiting similar anthropometric and physical profiles. 相似文献
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Krijnen Eke van Steensel Roel Meeuwisse Marieke Jongerling Joran Severiens Sabine 《Reading and writing》2020,33(1):207-238
Reading and Writing - Based on the Home Literacy Model, this study explored a refined model of home literacy activities and their relations with children’s emergent literacy skills in a... 相似文献