Coordination variability and skill development in expert triple jumpers   总被引：1，自引：0，他引：1  

Wilson C  Simpson SE  van Emmerik RE  Hamill J 《Sports biomechanics / International Society of Biomechanics in Sports》2008,7(1):2-9

The aim of this study was to examine the influence of skill of expert triple jumpers on the coordination variability of lower extremity intra-limb couplings. In contrast to the traditional motor learning perspective, we hypothesized that as skill and thus performance increases, movement coordination variability will also increase. Three-dimensional kinematic and ground reaction force data were collected during the hop-step transition phase of the triple jump. Relative motion plots and a modified vector coding technique were used to quantify the coordination variability across the trials. The results were consistent with a U-shaped curve, representing coordination variability, as skill increases. The high coordination variability in less skilled athletes is present while the appropriate characteristics defining the movement coordination patterns are acquired. This coordination variability may not be beneficial to performance. As the refinement of these characteristics is achieved, coordination variability decreases, resulting in a more consistent or regulated performance. In the final stages of developing a skilled performance, a functional variability is accessed that brings flexibility to the system allowing it to cope with perturbations. This study highlights the need to address the learning effect when analysing coordination variability from a dynamical systems perspective.  相似文献   

The energetics and benefit of an arm swing in submaximal and maximal vertical jump performance     

Lees A  Vanrenterghem J  De Clercq D 《Journal of sports sciences》2006,24(1):51-57

The aims of this study were to investigate the energy build-up and dissipation mechanisms associated with using an arm swing in submaximal and maximal vertical jumping and to establish the energy benefit of this arm swing. Twenty adult males were asked to perform a series of submaximal and maximal vertical jumps while using an arm swing. Force, motion and electromyographic data were recorded during each performance and used to compute a range of kinematic and kinetic variables, including ankle, knee, hip, shoulder and elbow joint powers and work done. It was found that the energy benefit of using an arm swing appears to be closely related to the maximum kinetic energy of the arms during their downswing, and increases as jump height increases. As jump height increases, energy in the arms is built up by a greater range of motion at the shoulder and greater effort of the shoulder and elbow muscles but, as jump height approaches maximum, these sources are supplemented by energy supplied by the trunk due to its earlier extension in the movement. The kinetic energy developed by the arms is used to increase their potential energy at take-off but also to store and return energy from the lower limbs and to "pull" on the rest of the body. These latter two mechanisms become more important as jump height increases with the pull being the more important of the two. We conclude that an arm swing contributes to jump performance in submaximal as well as maximal jumping but the energy generation and dissipation sources change as performance approaches maximum.  相似文献   

安拉和电脑     

布瑞吉蒂·罗沙里欧  邓笛  羽狐 《世界儿童(小学生阅读版)》2006,(1)

安拉的父母每天都要工作很长时间。“安拉,今天我要参加一个会议。”爸爸在电话里说,“如果你需要帮助,可以找邻居特威哥太太。”“安拉,我要接待一个重要的客商。”妈妈过了一会儿也打来了电话,“你自己将菜放进微波炉里热一下。”“知道了。”安拉大声答道。又是一个人呆在家  相似文献   

安娜·查克维塔泽双手反拍赏析     

翠茜·奥丝汀  金路 《网球》2008,(9):120-121

21岁的俄罗斯姑娘并不是网球场上最高最壮的选手,但她平稳而有力的双手反拍,打得非常漂亮。1查克维塔泽的对手打来一记球速慢、弹跳高的球(看她眼睛锁定的高度),但她并没有浪费时间,正在积极进行准备——球拍始终放在身后,以便在需要的时候迅速挥出。她的双肩已经转到合适的位置,双膝微微弯曲,并将重心放在后脚。而她离开地面的前脚正在向前上步,准备迎击来球。经常能够看到一些业余选手在面对慢球时,表现得非常放松。他们认为,"哦太好了,我有许多时间来把球打回去"。其实,你应该对每一个来球都一视同仁。查克维塔泽的对手正要送给她一个进攻的机会,她是不会拒绝的。  相似文献   

中国移民在俄国——中国移民对俄国远东发展的贡献   总被引：1，自引：0，他引：1  

亚历山大G·拉宁  李宏为 《历史档案》1994,(2)

本文作者系俄罗斯科学院远东研究所台湾研究部主任、高级研究员。本文译自治湾出版的《近代中国史研究通讯》1993年第16期。本文虽有不少提法和观点，为我们所不能同意，但文内提供了不少有关中国侨民在沙俄及前苏联的情况，有一定的参考的研究价值，故仍全文照译发表。  相似文献   

奥运会体操简史     

约翰V·格罗姆巴奇  李佐惠 《体育文化导刊》1992,(2)

体操曾是世界上宣传最少的运动之一。然而,体操运动员在一个晚会上所作的那些充满着惊险和难度的表演胜过了多数棒球手、足球或田径运动员们在一个季节中的表演。作为一项运动的体操自身证明它比许多别的运动历史悠久。如今它已  相似文献   

新疆伊犁哈萨克自治州民族中小学汉语教学质量现状调查与对策研究     

古丽尼萨·加玛勒 《民族教育研究》1997,(2)

新疆伊犁哈萨克自治州民族中小学汉语教学质量现状调查与对策研究古丽尼萨加玛勒汉语不仅是我国各族人民之间交际的重要工具，而且是联合国五大工作语言之一。８０年代初，我区各民族中小学把汉语作为一门主课列入教学计划，汉语教学已取得了可喜的成绩。但是，由于语言...  相似文献   

上网风波     

理威拉·普里斯克  丁然 《家庭教育》2004,(Z1)

斯科特是凯蒂的儿子,今年12岁。他天真、内向,一直是妈妈心中可爱的孩子。然而凯蒂对孩子却越来越不放心,因为儿子已经进入了青春期,时常睡不醒,跌跌撞撞就像是梦游似的。这天,凯蒂正在收拾房间,忽然听到斯科特的计算机喇叭提醒说收到了邮件。凯蒂心想:这孩子,需要我说多少遍他才能记住关掉计算机呢?凯蒂在一一关闭计算机的程序时,不知怎么一下点到了网络浏览器上的“历史记录”。凯蒂一看,显示器上面显示了好几个刺眼的色情网址……乖乖,凯蒂心想,看来孩子真是到了青春期。凯蒂急急忙忙告诉了丈夫白思。下午,斯科特放学刚回到家,就预感到家…  相似文献   

windows 非法操作详解及常见的小故障修复方法     

肖凯提·买苏提 《和田师范专科学校学报》2004,24(3):142-144

大家肯定都用过Windows的，想必经历过“非法操作”。一般的“非法操作”有两个选项：“关闭”和“详细资料”。可是“详细资料”里面的内容大多数人都看不明白，只好关闭了。现在不用怕了，我来给大家讲解一下非法操作的每个详细资料的具体含义和使用Windows过程中常见的小故障及解决方法。  相似文献   

儿童体育运动的评估方法(上)   总被引：2，自引：0，他引：2  

格雷戈里·韦尔克  查尔斯·科尔宾  戴伦·戴尔  张宝华 《中国体育教练员》2002,(1):43-46

体育运动能促进成人的身心健康发展，这一点已得到证实。(美国健康与人类服务部，1996)由于一些由不健康的行为引发的慢性病具有一定的潜伏期，因而关于儿童的这方面的研究还没有得出确切的结论。然而随着关于儿童肥胖症的报道日益增多，如何评价及推动儿童体育运动的开展已成为人们所关心的问题(戈特麦克，迪茨，索博尔和韦利尔，  相似文献