Maturity status effects on torque and muscle architecture of young soccer players

ABSTRACT

This study investigated the effects of maturity status on knee extensor torque and vastus lateralis architecture of young soccer players. Thirty-four males aged 13–18 years were divided into two groups: pubescent (PUB, n = 15) and postpubescent (POSP, n = 19). Torque by angle interaction was established for absolute [F(2.649, 84.771) = 9.066, p < 0.05] and relative to body mass [F(2.704, 86.533) = 4.050, p < 0.05] isometric torque with the POSP group showing greater values. Muscle volume torque-angle relationship was similar between groups. Absolute, relative to body mass, and relative to muscle volume concentric and eccentric torque-velocity relationship showed a non-significant interaction but a significant group effect in favour the POSP group for absolute and concentric torque relative to body mass. Torque-angle and torque-velocity relationship normalized by body mass allometric exponents showed a non-significant interactions and group effects. Muscle thickness (3.6 ± 0.6 vs. 3.8 ± 0.6 cm), fascicle length (8.3 ± 1.4 vs. 8.9 ± 1.6 cm) and pennation angle (15.0 ± 2.3 vs. 14.3 ± 3.2 degrees) was similar between PUB and POSP groups, respectively. Maturity status did not show a significant effect on muscle architecture and on isometric and dynamic torques when allometrically normalized.     

Carbon outclasses wood in racket paddles: Ratings of expert and intermediate tennis players

Wooden racket paddles were modified with rubber and carbon fibre laminates and their differences tested in terms of flexural, damping, and coefficient of restitution properties. Four rackets types were designed: a wood reference, wood with rubber, carbon fibre 0°, and carbon fibre 90°. Seven expert and eight intermediate tennis players tested the rackets. To determine which of the four rackets suited the players best, we asked the players to compare the rackets two by two. After each pair tested, participants had to fill out a 4-item questionnaire in which different aspects of the rackets' performance were judged. The most preferred racket was the 0° carbon fibre racket, followed by the 90° carbon fibre racket, the wood racket and, finally, the 1-mm rubber racket. Thus, rackets with the highest stiffness, least damping, and highest coefficient of restitution were the most preferred. Interestingly, although experts and intermediate players overall judged the rackets in very similar ways according to force, vibration, and control, they were sensitive to quite different physical characteristics of the rackets.     

Aussichten der freien Schulwahl

Educational reforms around the world are increasingly converging, and this is reflected in the concept of a global educational reform movement. Although several recent studies have looked at the conditions under which nation states borrow from global educational models, the political mechanisms underlying these processes are not well understood. On the basis of a case study from Switzerland, which has a system of direct democracy which appears to be particularly suitable for an analysis of political transfer processes, this article reconstructs the debate around a series of popular initiatives addressing school choice. The results of the study show that a neo-institutional approach can be useful for understanding the implementation of global educational models in a national context if it is supplemented by a theoretical analysis of the participant and takes the specific features of the local political system into account. Methodologically, the analysis of global harmonisation processes in education should consider four reference points, namely the state, the market, the general public and scientific research.     

Sport as a means of immigrant youth integration: an empirical study of sports,intercultural relations,and immigrant youth integration in Switzerland

The objective of this paper is to examine the role of sport in immigrant youths integration into a host society. The analyses are based on a survey of 454 first-generation immigrant youths from secondary, vocational, and pre-apprenticeship schools located in the German-speaking part of Switzerland. In short, our results indicate that for most immigrant youth, sport is an important part of their free time, even though the proportion of female immigrant youth doing sport in sports clubs is twice as low as that of male immigrant youth. Our findings also illustrate that female and male immigrant youth who do sports in clubs have considerably more personal contact with Swiss peers during these sporting activities. Moreover, the young people who have frequent personal contact with Swiss peers during sporting activities reported having considerably more intercultural contacts in their free time and among their close friends. Finally, immigrant youths’ contacts with Swiss peers during sporting activities increase their feeling of being integrated in Switzerland.     

Assessing the effectiveness of a hybrid-flipped model of learning on fluid mechanics instruction: overall course performance,homework, and far- and near-transfer of learning

To examine the impact of a hybrid-flipped model utilising active learning techniques, the researchers inverted one section of an undergraduate fluid mechanics course, reduced seat time, and engaged in active learning sessions in the classroom. We compared this model to the traditional section on four performance measures. We employed a propensity score method entailing a two-stage regression analysis that considered eight covariates to address the potential bias of treatment selection. First, we estimated the probability score based on the eight covariates, and second, we used the inverse of the probability score as a regression weight on the performance of learners who did not select into the hybrid course. Results suggest that enrolment in the hybrid-flipped section had a marginally significant negative impact on the total course score and a significant negative impact on homework performance, possibly because of poor video usage by the hybrid-flipped learners. Suggested considerations are also discussed.     

Financial Aid and College Persistence: Do Student Loans Help or Hurt?

Using data from two freshmen cohorts at a public research university (N = 3730), this study examines the relationship between loan aid and second-year enrollment persistence. Applying a counterfactual analytical framework that relies on propensity score (PS) weighting and matching to address selection bias associated with treatment status, the study estimates that loan aid exerts a significant negative effect on persistence for students from low-income background (i.e., Pell eligible), and those taking up high amounts of loans in order to meet total cost of attendance, including students who exhausted the available amount of subsidized loan aid. However, no significant incremental effect associated with unsubsidized loan aid, net of subsidized loan aid, could be detected. The estimated effect of loan aid on persistence controls for first-year academic experience and takes into account 26 factors related to loan selection and persistence in order to match students with loan aid to a counterfactual case in covariate adjusted regression. Comparison with results from non-matched-sample analysis suggests selection bias may mask the negative effect of loans detected with matched-sample estimation. Validity of covariates determining the loan selection process and criteria for acceptable balance in the matched data are discussed, and implications for future research are addressed.     

Muscle properties and coordination during voluntary movement

The aims of this review were to provide some insight into the theoretical problems and questions associated with muscle coordination and control of movement, to consider some of the experimental findings on force-sharing among synergistic muscles, and to discuss some of the practical implications of force-sharing and movement control for optimal performance in sports. Theoretically, the distribution problem is introduced and the problems and difficulties of this approach in making quantitative predictions of force-sharing among muscles is discussed. Experimentally, the force-sharing research in the cat ankle extensor muscles is critically evaluated, and a complete force-sharing picture is given for the soleus and (medial) gastrocnemius for tasks covering a large range of speeds and intensities. In the application section, optimal performance criteria in jumping and cycling are considered. Furthermore, the plasticity of skeletal muscle properties is illustrated using examples from high-performance sports. The review ends with a summary of the topics discussed and suggestions for future research.