Differences in the utilisation of active power in squat and countermovement jumps

The aim of this article was to understand how active power is used in squat and countermovement jumps. A simple empirical model comprising a mass, a spring, an active element and a damper, together with an optimisation principle, was used to identify the mechanical factors that maximise performance of jumps without countermovement (squat jumps, SJ) and with countermovement (CMJ). Twelve amateur volleyball players performed SJ from two initial positions and CMJ with two degrees of counterbalancing, while kinematic data were collected (jump height, push-off duration and position of the centre of mass). The model adjusted well to real data of SJ through all the impulse phase, and slightly less adequately at the end of this phase for CMJ. Nevertheless, it provides a satisfactory explanation for the generation and utilisation of active power for both type of jumps. On average, the estimated power of the active elements, the spring, and the damper were greater in the SJ. Based upon the result obtained with this model, we suggest that active power is best evaluated with SJ. The reason for this is that, during this kind of jump, the elements associated with the damper consume much of the energy produced by the active elements. The participation of the elements that consume the energy generated by the active elements is less in CMJ than in SJ, allowing for a better utilisation of this energy. In this way it is possible to achieve a better performance in CMJ with less active power.     

Does regional disadvantage affect health-related sport and physical activity level? A multi-level analysis of individual behaviour

This study examines the role of regional government quality in health-related participation in sport and physical activity among adults (18–64 years) in 28 European countries. The importance of the analysis rests in the relative autonomy that regional and local governments have over policy decisions connected with sport and physical activity. While existing studies have focussed on economic and infrastructural investment and expenditure, this research investigates the quality of regional governments across 208 regions within 28 European countries. The individual-level data stem from the 2013 Eurobarometer 80.2 (n?=?18,675) and were combined with regional-level data from Eurostat. An individual's level of participation in sport and physical activity was measured by three variables reflecting whether an individual's activity level is below, meets, or exceeds the recommendations of the World Health Organization. The results of multi-level analyses reveal that regional government quality has a significant and positive association with individual participation in sport and physical activity at a level meeting or exceeding the guidelines. The impact is much larger than that of regional gross domestic product per capita, indicating that regional disadvantage in terms of political quality is more relevant than being disadvantaged in terms of economic wealth.     

The use of player physical and technical skill match activity profiles to predict position in the Australian Football League draft

This study investigated the extent to which position in the Australian Football League (AFL) national draft is associated with individual game performance metrics. Physical/technical skill performance metrics were collated from all participants in the 2014 national under 18 (U18) championships (18 games) drafted into the AFL (n = 65; 17.8 ± 0.5 y); 232 observations. Players were subdivided into draft position (ranked 1–65) and then draft round (1–4). Here, earlier draft selection (i.e., closer to 1) reflects a more desirable player. Microtechnology and a commercial provider facilitated the quantification of individual game performance metrics (n = 16). Linear mixed models were fitted to data, modelling the extent to which draft position was associated with these metrics. Draft position in the first/second round was negatively associated with “contested possessions” and “contested marks”, respectively. Physical performance metrics were positively associated with draft position in these rounds. Correlations weakened for the third/fourth rounds. Contested possessions/marks were associated with an earlier draft selection. Physical performance metrics were associated with a later draft selection. Recruiters change the type of U18 player they draft as the selection pool reduces. juniors with contested skill appear prioritised.     

Mathematical modelling as a tool to assessment of loads in volleyball player’s shoulder joint during spike

This article deals with kinematic and kinetic conditions in volleyball attack and identifies loads in the shoulder joint. Joint angles and velocities of individual segments of upper limb were measured with the use of the motion capture system XSENS. Muscle forces and loads in skeletal system were calculated by means of mathematical model elaborated in AnyBody system. Spikes performed by players in the best and worst way were compared with each other. The relationships were found between reactions in shoulder joint and flexion/extension, abduction/adduction and rotation angles in the same joint and flexion/extension in the elbow joint. Reactions in shoulder joint varied from 591 N to 2001 N (in relation to body weight [BW] 83–328%).

The analysis proved that hand velocity at the moment of the ball hit (which varied between 6.8 and 13.3 m s^–1) influences on the value of reaction in joints, but positions of individual segments relative to each other are also crucial. It was also proved in objective way, that position of the upper limb during spike can be more or less harmful assuming that bigger reaction increases possibility of injury, what can be an indication for trainers and physiotherapists how to improve injury prevention.     

Is there really an eccentric action of the hamstrings during the swing phase of high-speed running? part I: A critical review of the literature

It is widely assumed that there is an eccentric hamstring muscle fibre action during the swing phase of high-speed running. However, animal and modelling studies in humans show that the increasing distance between musculotendinous attachment points during forward swing is primarily due to passive lengthening associated with the take-up of muscle slack. Later in the swing phase, the contractile element (CE) maintains a near isometric action while the series elastic (tendinous) element first stretches as the knee extends, and then recoils causing the swing leg to forcefully retract prior to ground contact. Although modelling studies showed some active lengthening of the contractile (muscular) element during the mid-swing phase of high-speed running, we argue that the increasing distance between the attachment points should not be interpreted as an eccentric action of the CE due to the effects of muscle slack. Therefore, there may actually be no significant eccentric, but rather predominantly an isometric action of the hamstrings CE during the swing phase of high-speed running when the attachment points of the hamstrings are moving apart. Based on this, we propose that isometric rather than eccentric exercises are a more specific way of conditioning the hamstrings for high-speed running.     

The 'new' politics of education in Britain's changing times

The British Labour Party has continued to make progress on education, following two broad policy paths and adopting a pragmatic approach that does not attempt to force these to cross or converge. One path is that of the quasi market inherited from the previous Conservative administration; the other is characterised as 'intervention' to support those for whom the market remains almost entirely irrelevant. Some observers regard this dual approach as 'opportunism' and Labour's education policy as a 'betrayal' of principle, by which is meant the principle of 'equal opportunity'. Of course, that principle provides equal opportunity to fail as much as to succeed. Rather than leaving education to the market, Labour has focused on the needs of those most likely to be failed by the principle of 'equal' opportunity in a quasi market.     

龙行石上气韵生--永佑寺内乾隆御制石碑的龙形纹饰及保护

保存于避暑山庄永佑寺内的乾隆御制石碑以其装饰精美的龙型纹饰倍受世人瞩目.这些纹饰形象丰富、造型优美、雕刻精致、气韵生动,是不可多得的艺术精品.保护好这笔文化财产,是每一个文博工作者的神圣职责.     

Developing a prototype information system framework to handle pedagogical knowledge in a secondary school modern foreign languages department

This paper reports a small-scale project to develop a prototype web-based information system to support teaching and learning within the modern languages department of a comprehensive secondary school. The system was developed in close consultation with the teaching staff and the work is presented within the broader context of knowledge management systems and their potential use in an educational environment.     

基于多级构架的模拟电路故障诊断实现

本文利用仿真分析软件采集电路各种故障模式的特征数据,后将采集到的数据构造多层次的神经网络来进行诊断,最后使用虚拟仪器LabVIEW完成对整个流程的编程与控制,通过实际验证故障诊断正确率非常好。     

浅谈图形同构在高职高专设计造型基础教学中的作用

图形同构是设计造型基础教学中,尤其是创造性思维训练的一个重要课题。通过图形同构的理论与方法的讲解,使学生较快的建立以图形同构为基础的创意方法,在高职高专设计基础教学中起到重要的作用。