Validity and reliability of a 6-a-side small-sided game as an indicator of match-related physical performance in elite youth Brazilian soccer players

ABSTRACT

The aims of this study were: (i) to compare the external and internal load during a 6-a-side small-sided game (6v6-SSG) according to age-group; (ii) to relate these parameters between the 6v6-SSG and official matches; and (iii) to test the reliability of the 6v6-SSG. A total of 51 Brazilian youth soccer players participated in this study (U11 [n = 16]; U13 [n = 10]; U15 [n = 9]; U17 [n = 8]; U20 [n = 8]). Three experiments were conducted. Experiment A: fifty-one U11 to U20 players were submitted to 6v6-SSGs (n = 10 games; two for each age-group). Experiment B: thirty-two players were randomized to also play official matches (n = 6 matches). Experiment C: thirty-five youth players played the 6v6-SSG twice for test and retest reliability analysis. External load was obtained using Global Positioning Systems and the internal load parameter was calculated through mean heart rate. Statistical approaches showed progressive increases in all parameters according to categories (U11< U13< U15< U17< U20; p < 0.05; ES = 0.42?23.68). Even controlling for chronological age, all parameters showed likely to almost certain correlations between 6v6-SSG and official matches (r = 0.25?0.92). Collectively, the proposed protocol indicates good reliability (CV% = 2.0?12.6; TE% = 2.3?2.7%; ICC = 0.78?0.90). This research suggests that the 6v6-SSG is an alternative tool to indicate match-related physical performance in youth soccer players.     

A linear optimization approach to the combined production planning model

Two fundamental processes usually arise in the production planning of many industries. The first one consists of deciding how many final products of each type have to be produced in each period of a planning horizon, the well-known lot sizing problem. The other process consists of cutting raw materials in stock in order to produce smaller parts used in the assembly of final products, the well-studied cutting stock problem. In this paper the decision variables of these two problems are dependent of each other in order to obtain a global optimum solution. Setups that are typically present in lot sizing problems are relaxed together with integer frequencies of cutting patterns in the cutting problem. Therefore, a large scale linear optimizations problem arises, which is exactly solved by a column generated technique. It is worth noting that this new combined problem still takes the trade-off between storage costs (for final products and the parts) and trim losses (in the cutting process). We present some sets of computational tests, analyzed over three different scenarios. These results show that, by combining the problems and using an exact method, it is possible to obtain significant gains when compared to the usual industrial practice, which solve them in sequence.     

Understanding the limits of Marxist approaches to sociocultural studies of science education

In the first three sections of this paper we comment on some of the ideas developed in the forum papers, pointing out possible misunderstandings and constructing new explanations that clarify arguments we made in the original article. In the last section we expand the discussion raised in the original paper, elaborating on the limits of the use of Marxist approaches to sociocultural studies of science education. Following insights suggested by Loxley et al. (Cult Stud Sci Edu. doi:10.1007/s11422-013-9554-z, 2013) and detailed by Zuss (Cult Stud Sci Edu, 2014) on the commodification of knowledge, we sketch an analysis of how knowledge is transformed into capital to understand why contemporary scholars are likely to be engaged in a relation of production that resembles capitalist exploitation.     

Using conceptual questions to promote motivation and learning in physics lectures

In the last years, science courses in higher education (HE) have been facing some problems, namely the lack of students’ motivation, the number of students’ failures and drop outs, particular in physics courses. The most probable reason, which has been mentioned in current science education research in HE, is that the level of interaction between teachers and learners in formal instructional settings is very low. In this paper, we describe changes that were introduced in lectures towards the promotion of active learning and analyse its effects in the classroom environment. The introduction of conceptual questions and peer instruction seems to motivate students in the class and help them engage in the learning process. These strategies have been used in the first year of an introductory physics course for engineering students in two different Portuguese HE institutions. The data were collected through questionnaires and student interviews.     

A Bourdieusian analysis of the participation of Polish students in the ERASMUS programme: cultural and social capital perspectives

In this paper we examine the perceptions of ERASMUS agents’ of Polish students’ participation in the EP. We provide a Bourdieusian analyse of the cultural and social capital acquisition of students based on the qualitative data, collected through semi-structured, in-depth interviews with Erasmus agents, of a European research project. We argue that: Polish students’ participation in the EP has a positive impact on their academic achievement, cultural, social and linguistic capital, but, at the same time, it has a negative impact on degree completion of students as they get highly paid jobs, which prevent them from fully developing their cultural capital; ERASMUS Tourism has its value and place in the EP, because it provides students with the opportunity to develop their cultural, social and linguistic capital; and a Bourdieusian analysis of the experiences of ERASMUS students provides a better understanding of the impact student participation in the EP on their development.     

Let’s begin with ourselves: attempting resonance responses in the exchange of researchers’ professional autobiographies

The economic, social, cultural, technological and labour changes experienced by Spanish universities in the last 40?years have had their impact on the professional lives of the university teachers. Our methodological decision to study, through the construction of life histories, how scholars cope with social and institutional changes in their professional lives led us to start by writing our professional autobiographies which were followed by a resonance practice in which each of us wrote a response to a partner’s autobiography. Results show that our responses appeared to have three different functions: give some feedback to our partners, tell our group our position about our partner’s autobiography and make sense of it for us. It became clear that writing about our resonance responses is a difficult task for academics like us and that our texts were bound by the position each one occupied in the research group and at the university. Our experience lets us rethink the interweaving of reflexivity, personal practical knowledge and resonance. The tension between our academic rationality and our efforts to give spontaneous resonance responses shows that even with narrative researchers, changing one’s personal practical knowledge may conflict with a rationalist point of view.     

The European Project Semester at ISEP: the challenge of educating global engineers

Current engineering education challenges require approaches that promote scientific, technical, design and complementary skills while fostering autonomy, innovation and responsibility. The European Project Semester (EPS) at Instituto Superior de Engenharia do Porto (ISEP) (EPS@ISEP) is a one semester project-based learning programme (30 European Credit Transfer Units (ECTU)) for engineering students from diverse scientific backgrounds and nationalities that intends to address these goals. The students, organised in multidisciplinary and multicultural teams, are challenged to solve real multidisciplinary problems during one semester. The EPS package, although on project development (20 ECTU), includes a series of complementary seminars aimed at fostering soft, project-related and engineering transversal skills (10 ECTU). Hence, the students enrolled in this programme improve their transversal skills and learn, together and with the team of supervisors, subjects distinct from their core training. This paper presents the structure, implementation and results of the EPS@ISEP that was created in 2011 to apply the best engineering practices and promote internationalisation and engineering education innovation at ISEP.     

The Development of Dalton’s Atomic Theory as a Case Study in the History of Science: Reflections for Educators in Chemistry

The inclusion of the history of science in science curricula—and specially, in the curricula of science teachers—is a trend that has been followed in several countries. The reasons advanced for the study of the history of science are manifold. This paper presents a case study in the history of chemistry, on the early developments of John Dalton’s atomic theory. Based on the case study, several questions that are worth discussing in educational contexts are pointed out. It is argued that the kind of history of science that was made in the first decades of the twentieth century (encyclopaedic, continuist, essentially anachronistic) is not appropriate for the development of the competences that are expected from the students of sciences in the present. Science teaching for current days will benefit from the approach that may be termed the “new historiography of science”.