Analysis of lower limb internal kinetics and electromyography in elite race walking

Abstract

The aim of this study was to analyse lower limb joint moments, powers and electromyography patterns in elite race walking. Twenty international male and female race walkers performed at their competitive pace in a laboratory setting. The collection of ground reaction forces (1000 Hz) was synchronised with two-dimensional high-speed videography (100 Hz) and electromyography of seven lower limb muscles (1000 Hz). As well as measuring key performance variables such as speed and stride length, normalised joint moments and powers were calculated. The rule in race walking which requires the knee to be extended from initial contact to midstance effectively made the knee redundant during stance with regard to energy generation. Instead, the leg functioned as a rigid lever which affected the role of the hip and ankle joints. The main contributors to energy generation were the hip extensors during late swing and early stance, and the ankle plantarflexors during late stance. The restricted functioning of the knee during stance meant that the importance of the swing leg in contributing to forward momentum was increased. The knee flexors underwent a phase of great energy absorption during the swing phase and this could increase the risk of injury to the hamstring muscles.     

Reliability and validity of the Yo-Yo intermittent recovery test level 1 in young soccer players

Abstract

The present study investigated the test-retest reliability from the Yo-Yo IR1 (distance and heart rate responses), and the ability of the Yo-Yo IR1 to differentiate between elite and non-elite youth soccer players. A total of 228 youth soccer players (11–17 years) participated: 78 non-elite players to examine the test-retest reliability within 1 week, added with 150 elite players to investigate the construct validity. The main finding was that the distance covered was adequately reproducible in the youngest age groups (U13 and U15) and highly reproducible in the oldest age group (U17). Also, the physiological responses were highly reproducible in all age groups. Moreover, the Yo-Yo IR1 test had a high-discriminative ability to distinguish between elite and non-elite young soccer players. Furthermore, age-related standards for the Yo-Yo IR1 established for elite and non-elite groups in this study may be used for comparison of other young soccer players.     

运动水平和认知风格对网球运动员接发球预判绩效的影响

采用3(运动水平)×2(认知风格)的混合实验。实验被试总人数56人,平均年龄18.68±6.47岁。经过ANOVA、T-test、相关分析、多重比较等方法对实验数据进行分析。结果显示:不同认知风格运动员接发球预判准确性(P=.015)、预判速度(P=.012)存在显著性差异;不同运动水平运动员接发球预判的准确性上的差异具有非常显著性(p=.001),不同运动水平运动员接发球预判速度上的差异具有显著性(p=.017)。得出:场独立型认知风格网球运动员在接发球预判绩效较好于场依存型认知风格的网球运动员;高水平网球运动员在接发球预判准确性和速度上具有绝对的优势,不仅远远高于低水平组,而且也明显高于中水平组。     

江苏省田径赛事市场现状与对策分析

本文以南京、苏州、扬州、无锡四个城市的田径赛事市场为研究对象,客观分析了江苏省田径赛事的现状。本文认为,要提高江苏省的田径赛事市场运作水平,首先必须提高运动员参赛竞技水平,其次是吸引社会力量共同开发田径市场,与此同时还必须培养和引进相关方面的人才,进一步完善田径市场发展的政策法规。     

基于知识图谱的领域新兴主题研究现状分析*

发现和追踪领域新兴主题是研究人员发现和追踪本领域内最新研究趋势和研究方向的一个重要途径。新兴主题探测可以探测、识别、发现这些新兴趋势和新兴主题。本文对ISI Web of Science数据库中收录的关于新兴主题研究的文献进行收集,然后从文献计量学的角度进行定量分析;利用CiteSpaceII对国家、机构、作者的合作关系做出对应的知识图谱;并对共被引文献的关键节点文献进行了研读和分析;最后利用CiteSpaceII生成的本研究领域中的研究主题聚类图、时序图对研究内容及现状进行了分析和预测。     

10kV与110kV混压并架线路带电作业人员安全防护研究

10kV与110kV混压并架输电线路可以有效集约土地资源,充分利用线路走廊。为了评估带电作业人员检修10kV配电线路时,上方110kV输电线路对其安全影响,采用有限元电场计算与电场实测的方法研究混压线路空间电场分布和作业人员体表电场分布规律,在此基础上提出了10kV与110kV混压并架输电线路检修作业安全防护方法。     

中外女子投掷项目发展态势的比较研究

以2003~2012年中外女子投掷项目各单项历年前8名成绩为研究对象,采用文献资料、数理统计等方法,对中外女子投掷项目的发展态势进行了比较分析。结果表明:近10年来,世界女子投掷成绩整体上呈正增长,中国呈负增长;女子投掷项目发展不平衡,顶尖运动员具有挑战世界高水平的实力,但整体水平与世界水平仍有很大差距。     

形如5a2的Fibonacci数的一个性质

在假定存在第3个Fibonacci数,使得Fn=5a2的假设下,讨论下标n的性质,并给出n的一个下界.     

低速带电粒子在均匀电磁场中的运动轨迹

系统地介绍了低速带电粒子在电磁场中的运动规律,并由此分析对此类问题的解决方法,从而加深对此内容的理解.     

On becoming a doctoral student: Chinese doctoral students’ socialization of capital and habitus in academia

Abstract

This study examines Chinese international doctoral students’ academic socialization into TESOL discourses and communities. Rooted in the academic discourse socialization theory, complemented by the notions of Lave and Wenger’s community of practice, and Bourdieu’s capital, habitus, and field, this longitudinal multiple-case study suggest the focal participants’ academic discourse socialization is mediated by their participation in communities of practice, different forms of capital, and habitus in exerting agency. The participants are socialized into academic discourses and communities through their interactions with more experienced colleagues. By participating in the communities of practice, the focal students gain different forms of capital and experience different degrees of competence and memberships. However, due to the inequitable power relations in the TESOL doctoral program field, each participant is socialized to varying levels of central, peripheral, and marginal participation. This study concludes by providing suggestions for action to be taken by university advisors, instructors, and administrators.