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   

Development and validation of the Perceived Game-Specific Soccer Competence Scale     

Hannele Forsman  Arto Gråstén  Minna Blomqvist  Keith Davids  Jarmo Liukkonen  Niilo Konttinen 《Journal of sports sciences》2016,34(14):1319-1327

ABSTRACT

The objective of this study was to create a valid, self-reported, game-specific soccer competence scale. A structural model of perceived competence, performance measures and motivation was tested as the basis for the scale. A total of 1321 soccer players (261 females, 1060 males) ranging from 12 to 15 years (13.4 ± 1.0 years) participated in the study. They completed the Perceived Game-Specific Soccer Competence Scale (PGSSCS), self-assessments of tactical skills and motivation, as well as technical and speed and agility tests. Results of factor analyses, tests of internal consistency and correlations between PGSSCS subscales, performance measures and motivation supported the reliability and validity of the PGSSCS. The scale can be considered a suitable instrument to assess perceived game-specific competence among young soccer players.  相似文献   

Development of perceived competence,tactical skills,motivation, technical skills,and speed and agility in young soccer players     

Hannele Forsman  Arto Gråstén  Minna Blomqvist  Keith Davids  Jarmo Liukkonen  Niilo Konttinen 《Journal of sports sciences》2016,34(14):1311-1318

ABSTRACT

The objective of this 1-year, longitudinal study was to examine the development of perceived competence, tactical skills, motivation, technical skills, and speed and agility characteristics of young Finnish soccer players. We also examined associations between latent growth models of perceived competence and other recorded variables. Participants were 288 competitive male soccer players ranging from 12 to 14 years (12.7 ± 0.6) from 16 soccer clubs. Players completed the self-assessments of perceived competence, tactical skills, and motivation, and participated in technical, and speed and agility tests. Results of this study showed that players’ levels of perceived competence, tactical skills, motivation, technical skills, and speed and agility characteristics remained relatively high and stable across the period of 1 year. Positive relationships were found between these levels and changes in perceived competence and motivation, and levels of perceived competence and speed and agility characteristics. Together these results illustrate the multi-dimensional nature of talent development processes in soccer. Moreover, it seems crucial in coaching to support the development of perceived competence and motivation in young soccer players and that it might be even more important in later maturing players.  相似文献   

Notes on the role of functional language in contemporary culture and education     

Jacques R. Pauwels 《Interchange》1989,20(3):1-16

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Toward a set of measures of student learning outcomes in higher education: evidence from Brazil     

Tatiana Melguizo  Jacques Wainer 《Higher Education》2016,72(3):381-401

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Guidelines for Establishing Undergraduate Bioinformatics Courses     

Cohen  Jacques 《Journal of Science Education and Technology》2003,12(4):449-456

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European Dissertation Summaries     

Jean‐Jacques Dupin 《International Journal of Science Education》2013,35(2):249-255

Over the past decade, Donald Schön's conceptualization of professional practice as reflection‐in‐action has gained wide currency. This paper reports on a seminar, based on Schon's ideas, to assist elementary teachers in making Science a more significant part of their instructional programmes. A detailed analysis of the efforts of two of the experienced teachers involved points to problems related to: (i) the efficacy of reflection‐on‐action in facilitating reflecting‐in‐action; (ii) disjunctions between conceptual and action components of teachers' frames; and (iii) the role of substantive teacher intervention in assisting children in learning to use non‐common‐sense ways of knowing such as Science.  相似文献   

Searching strategies for the Bulgarian language     

Jacques Savoy 《Information Retrieval》2007,10(6):509-529

This paper reports on the underlying IR problems encountered when indexing and searching with the Bulgarian language. For this language we propose a general light stemmer and demonstrate that it can be quite effective, producing significantly better MAP (around + 34%) than an approach not applying stemming. We implement the GL2 model derived from the Divergence from Randomness paradigm and find its retrieval effectiveness better than other probabilistic, vector-space and language models. The resulting MAP is found to be about 50% better than the classical tf idf approach. Moreover, increasing the query size enhances the MAP by around 10% (from T to TD). In order to compare the retrieval effectiveness of our suggested stopword list and the light stemmer developed for the Bulgarian language, we conduct a set of experiments on another stopword list and also a more complex and aggressive stemmer. Results tend to indicate that there is no statistically significant difference between these variants and our suggested approach. This paper evaluates other indexing strategies such as 4-gram indexing and indexing based on the automatic decompounding of compound words. Finally, we analyze certain queries to discover why we obtained poor results, when indexing Bulgarian documents using the suggested word-based approach.  相似文献   

Notes on cellophane     

Jacques E. Brandenberger 《Journal of The Franklin Institute》1938,226(6):797-801

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Finite Memory Observers for linear time-varying systems: Theory and diagnosis applications     

Guillaume Graton  Frédéric Kratz  Jacques Fantini 《Journal of The Franklin Institute》2014

Fault detection and diagnosis are important issues in process engineering. Hence, a considerable interest exists in this field now from industrial practitioners as well as academic researchers, as opposed to 30 years ago. The literature on process fault diagnosis, ranging from analytical methods to artificial intelligence and statistical approaches, is largely widespread. In this paper, the modeling of the real process is known, and the state-space representation is used. The properties of the Finite Memory Observer (FMO) are studied from a global point of view for the class of linear time-varying (LTV) systems with stochastic noises. The FMO performances are framed by the study of their properties, and that of their influences on diagnosis results. Fundamentally, the generation of residuals is an essential procedure in diagnosis. So, the determination of the optimal window length of the observer is resolved, and the generation of residuals for diagnosis completed. In the first part, the design of the observer and the residual generation are shown. The second part is devoted to the study of the sensitivity and robustness of the observer and of residuals generated from the observer.  相似文献