Field dimension and skill level constrain team tactical behaviours in small-sided and conditioned games in football

Abstract

This study analysed the influence of field dimension and players’ skill level on collective tactical behaviours during small-sided and conditioned games (SSCGs). Positioning and displacement data were collected using global positioning systems (15 Hz) during SSCGs (Gk+4 v. 4+Gk) played by two groups of participants (NLP- national-level and RLP-regional-level players) on different field dimensions (small: 36.8 × 23.8 m; intermediate: 47.3 × 30.6 and large: 57.8 × 37.4 m). Team tactical performance was assessed through established dynamic team variables (effective playing space, playing length per width ratio and team separateness) and nonlinear signal processing techniques (sample entropy of distances to nearest opponents and the teams’ centroids’ mutual information). Results showed that the effective playing space and team separateness increased significantly with pitch size regardless of participant skill level (P < 0.001, η² = 0.78 and P < 0.001, η² = 0.65, respectively). Playing length per width ratio increased with pitch size for the NLP but was maintained at a relatively constant level by RLP across treatments indicating different playing shapes. There was significantly more irregularity in distances to nearest opponents for the NLP in small (P = 0.003) and intermediate fields (P = 0.01). Findings suggest that tactical behaviours in SSCGs are constrained by field size and skill level, which need to be considered by coaches when designing training practices.     

我国体育教育训练学硕士研究生培养方案的再构建

课程设置与培养方案,决定着研究生培养的质量与规格.本研究依据社会发展的不同需求,按照国家深化研究生教育改革的具体要求,试图对现行的体育教育训练学硕士研究生培养方案进行再分析,阐释现行课程方案及研究存在的问题.从而提出改革的相关对策,并尝试重新构建培养模式,以期培养“供求”对接的体育专门人才.     

Pelé, racial discourse and the 1958 World Cup

The aim of this essay is to map out the racial discourses of the 1950s, particularly those pertinent to the 1958 Soccer World Cup, in order to better understand the main ideas about race, which were in vogue at the time when Edson Arantes do Nascimento (Pelé) became (inter)nationally famous as a great sports star. The essay argues that Pelé’s statements regarding race and race relations in Brazil were inherently based on the discourses prevalent among academics and Brazil’s black activists during the 1950s. Pelé’s professional asceticism and his belief in individualism, cultivated during his youth in the city of Bauru, were further reinforced by the racial discourses of the 1950s. These views led him to believe that any discrimination he might encounter due to his colour and class could be overcome with a disciplined and professional attitude. Today, this sort of ascetic view of the world has been accused by certain segments of Brazil’s black movements as being insufficient to overcome the supposedly irresolvable inequalities that exist between Brazil’s black and white populations. Pelé, however, has not changed his position regarding anti-black discrimination, choosing to continue to emphasize professionalism and discipline as the two most formidable tools in the fight against racial discrimination and inequality.     

The effects of features of examination questions on the performance of students with dyslexia

This research investigated whether features of examination questions influence students with dyslexia differently to others, potentially affecting whether they have a fair opportunity to show their knowledge, understanding and skills. A number of science examination questions were chosen. For some questions two slightly different versions were created. A total of 54 students considered by their teachers to have dyslexia and a matched control group of 51 students took the test under exam conditions. A dyslexia screening assessment was administered where possible and some students were interviewed. Facility values and Rasch analysis were used to compare performance between the versions of the same question and between those with and without dyslexia. Chi‐square statistics found no statistically significant differences in performance between groups or between question versions. However, some tentative implications for good practice can be inferred (e.g. avoiding ambiguous pronouns, using bullet points).     

Evaluating the performance of calculus classes using operational research tools

This paper compares the efficiency of calculus classes. Two kinds of classes are evaluated: the traditional ones and others that use computational methods in teaching. This experiment was performed at Fluminense Federal University, Niterói, Brazil, from 1998 to 2000. The emphasis of this paper is on the quantitative evaluation using two operational research tools: multicriteria decision aid methods (mainly using the MACBETH approach) and data envelopment analysis. The evaluating variables are the level at which students enter the university and the performance of the students after studying calculus.     

Influence of source credibility on students’ noticing and assessing comprehension obstacles in science texts

This study aims to analyse the effect of source credibility on students’ identification and assessment of comprehension obstacles in science texts. Source credibility was manipulated by providing 12th grade students with paragraphs supposedly taken from science textbooks or, alternatively, from students’ reports. The paragraphs contained information expected to be difficult to understand by the participating students. The students were instructed to report any comprehension obstacle they might find and to rate the comprehensibility of the paragraphs. There was no effect of source credibility on noticing and reporting comprehension obstacles in the conditions of our experiments. However, there was a significant finding regarding comprehensibility scores. The students rated the comprehensibility of the paragraphs supposedly taken from science textbooks higher than the comprehensibility of the same paragraphs supposedly taken from peer reports. The finding has implications on the way students approach the understanding of science texts. An enhancement of students’ feelings of competence in dealing with scientific subject matter would have a beneficial effect on students’ assessment and validation of information in science texts.     

Yo-Yo Intermittent Endurance Test-Level 1 to monitor changes in aerobic fitness in pre-pubertal boys

The present study aimed to examine the performance and heart rate responses during the Yo-Yo Intermittent Endurance Test-Level 1 (Yo-Yo IE1) in children under the age of 10. One hundred and seven male children (7–9 years) performed the Yo-Yo IE1 at the beginning (M₁), middle (M₂) and end (M₃) of the school year. Data from individual heart rate curves of the Yo-Yo IE1 were analysed in order to detect the inflection point between an initial phase of fast rise in heart rate values and a second phase in which the rise of the heart rate values is much smaller. The distance covered in the Yo-Yo IE1 improved from M₁ to M₃ (884 ± 496 vs. 1032 ± 596 m; p < 0.05; d = 0.27), with intermediate values for M₂ (962 ± 528 m). Peak heart rate (HR_peak) decreased from M₁ to M₂ and M₃ (204 ± 9, 202 ± 9 and 200 ± 9 bpm, respectively; p < 0.05; d = 0.25–0.42). The 7th shuttle of the test (280 m), corresponding to 2.5 min, was identified as the inflection point between the two phases. Also, absolute heart rate at the 7th shuttle decreased progressively throughout the year (185 ± 9, 183 ± 10, and 179 ± 10 bpm; p < 0.05; d = 0.31–0.61). The present study provides evidence of the usefulness of a maximal as well as a submaximal version of Yo-Yo IE1 as a tool to monitor changes in aerobic fitness in pre-pubertal children.     

Analysis of the body composition of Paralympic athletes: Comparison of two methods

Body composition is a physiological variable associated with physical activity and, in some cases, is related to athletic performance. Our objectives were to describe the body composition of participants in three distinct Paralympic sports and to compare the values of body density and estimated body fat obtained from the Paralympic athletes on the National Team by air-displacement plethysmography (ADP) and by the anthropometric method (skinfolds (SFs)). The sample consisted of 70 volunteers of both genders. The body composition of the volunteers was evaluated using the ADP in a Bod Pod^® and seven SFs. There were no significant differences between the values obtained by ADP and SF for body fat percentage (p?=?.58) and body density (p?=?.49). Analysis by Bland–Altman plots showed mean differences of 0.56?±?4.94 (?9.12–10.23) and ?0.0017?±?0.0113 (?0.024–0.020) for body fat percentage and body density, respectively. In conclusion, body composition analyses of Paralympic athletes by the ADP and SF methods show similar results, and ADP should be used as the first option when available. When the use of ADP is not possible, estimating body density and fat percentage by SF is a viable alternative for Paralympic athletes when future comparisons will use the same analysis method.     

Modelling the relationship between biomechanics and performance of young sprinting swimmers

The aim of this study was to compute a swimming performance confirmatory model based on biomechanical parameters. The sample included 100 young swimmers (overall: 12.3?±?0.74 years; 49 boys: 12.5?±?0.76 years; 51 girls: 12.2?±?0.71 years; both genders in Tanner stages 1–2 by self-report) participating on a regular basis in regional and national-level events. The 100?m freestyle event was chosen as the performance indicator. Anthropometric (arm span), strength (throwing velocity), power output (power to overcome drag), kinematic (swimming velocity) and efficiency (propelling efficiency) parameters were measured and included in the model. The path-flow analysis procedure was used to design and compute the model. The anthropometric parameter (arm span) was excluded in the final model, increasing its goodness-of-fit. The final model included the throw velocity, power output, swimming velocity and propelling efficiency. All links were significant between the parameters included, but the throw velocity–power output. The final model was explained by 69% presenting a reasonable adjustment (model's goodness-of-fit; x²/df?=?3.89). This model shows that strength and power output parameters do play a mediator and meaningful role in the young swimmers’ performance.     

A Method to Increase Student Interaction Using Student Groups and Peer Review over the Internet

A method of peer review for student groups is proposed. In this method, groups of students publish their assignments results over the Internet. A fellow student group reviews their work and publishes their findings (on the Internet). Finally, the two groups debate their points of view in front of the class. The debate and healthy competition among groups give the students a chance to learn how to give and receive criticism in a constructive way. This should increase the students' ability to interact and work in groups, an important skill for computer science professionals.