中外优秀标枪运动员投掷步技术的运动学比较

通过对我国优秀标枪运动员和世界优秀标枪运动员投掷技术的运动学比较研究.结果表明,现阶段我国标枪运动员投掷步技术存在的一些问题,是阻碍我国标枪运动水平进一步提高的主要原因.并针对这些问题,提出相应的训练方法和技术改进措施,使训练更具有针对性与目的性.     

广西壮族高杆投绣球训练调查分析

采用跟踪调查法、文献资料法、体育统计法等研究方法,对广西民族大学绣球队的高杆投绣球训练进行调查分析,得出：台阶跑、上坡跑、追逐跑等练习能有效提高运动员投球次数,合理的运用技、战术能使运动员获得更多的投球次数和有效进球,模拟加赛1min训练、定点投10个球训练赛、使用不同重量、持不同绳长的球和在不同投球点进行测试等练习内容,能有效提高运动员心理素质稳定性,运动员身体素质和心理稳定性的提高与技战术的合理运用能有效提高运动员命中率,并对广西民族大学绣球队的高杆投绣球训练提出相关的建议。     

Kinematic comparison of the seoi-nage judo technique between elite and college athletes

This study sought to identify biomechanical factors that determine fast and skilful execution of the seoi-nage (shoulder throw) technique by comparing kinematics between elite and college judo athletes. Three-dimensional motion data were captured using a VICON-MX system with 18 cameras operating at 250 Hz as three male elite and seven male college judo athletes performed seoi-nage. No significant difference was found in motion phase time of the turning phase between the two groups, indicating that motion phase time is not necessarily a factor contributing quickness in seoi-nage. The maximum relative velocity of the whole body centre of mass along the anterior–posterior direction was significantly greater in the elite athletes (2.74 ± 0.33 m/s) than in the college athletes (1.62 ± 0.47 m/s) during the turning phase (p = 0.023). The overall angular velocity of the body part lines, particularly the arm line, tended to be greater in the elite athletes (p = 0.068). The results imply that the velocity of the thrower relative to the opponent in the forward drive and turning motion reflects high skill seoi-nage. Coaches should recognise the relative forward velocity as a factor that may contribute to a successful seoi-nage when teaching the judo throw technique.     

Three-dimensional glenohumeral arthrokinematics related to internal impingement in throwing athletes: Communication on six clinical cases

Abstract

The aim of this study was to undertake a comparative arthrokinematic evaluation of the shoulder of throwers with internal impingement. The participants were six throwing athletes with internal impingement type I. The intra-articular position of the humeral head on the glenoid in the apprehension test pose was evaluated using three-dimensional reconstructions obtained on medical images. Glenohumeral internal rotation deficit, external rotation gain, and the difference in posterior shoulder tightness were assessed goniometrically. No abnormal translation behaviour of the humeral head on the glenoid could be demonstrated, with a posterior positioning of the humeral head in relation to the centre of the glenoid of ?6.6±0.9 mm and a superior positioning of +2.3±1.5 mm, despite the presence of a glenohumeral internal rotation deficit between the throwing shoulder and the contralateral shoulder of ?26.3±7.2° and a difference in posterior shoulder tightness of ?6.7±2.9 cm. In conclusion, the results do not support the biomechanically based hypotheses relating internal impingement at the end of the late preparatory phase of throwing with an increased posterior-superior or anterior-inferior glenohumeral translation. Instead, the results favour a physiological cause of symptomatic internal impingement.     

Comparison of kinematics in skilled and unskilled arms of the same recreational baseball players

Abstract

We examined mechanisms of coordination that enable skilled recreational baseball players to make fast overarm throws with their skilled arm and which are absent or rudimentary in their unskilled arm. Arm segment angular kinematics in three dimensions at 1000 Hz were recorded with the search-coil technique from the arms of eight individuals who on one occasion threw with their skilled right arm and on another with their unskilled left arm. Compared with their unskilled arm, the skilled arm had: a larger angular deceleration of the upper arm in space in the forward horizontal direction; a larger shoulder internal rotation velocity at ball release (unskilled arms had a negative velocity); a period of elbow extension deceleration before ball release; and an increase in wrist velocity with an increase in ball speed. It is suggested that some of these differences in arm kinematics occur because of differences between the skilled and unskilled arms in their ability to control interaction torques (the passive torque at one joint due to motion at adjacent joints). It is proposed that one reason unskilled individuals cannot throw fast is that, unlike their skilled counterparts, they have not developed the coordination mechanisms to effectively exploit interaction torques.     

Competition and Instructional Set Effects On the Speed and Accuracy of a Throwing Task

Abstract

Two experiments were conducted to investigate the effects of competition and instructional sets on the speed and accuracy of a dart-throwing task. In both experiments individuals competed against another subject on one day, and performed under noncompetitive conditions on a second day. The five distinct instructional sets varied from extreme emphasis on speed to extreme emphasis on accuracy. Multivariate analyses of variance revealed main effects for instructional sets on speed and accuracy in both experiments. Strong tradeoffs occurred with speed slowing and accuracy improving as the instructional emphasis changed from speed to accuracy. A competition by instructional sets interaction in Experiment 2 indicated that competition facilitated speed when speed was important, but when instructions emphasized accuracy, speed was slower in competition than in noncompetition. Accuracy was not affected by competition.     

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。     

Baseball

The purpose of this study was to quantify and compare kinematic, temporal, and kinetic characteristics of American and Korean professional pitchers in order to investigate differences in pitching mechanics, performance, and injury risks among two different cultures and populations of baseball pitchers. Eleven American and eight Korean healthy professional baseball pitchers threw multiple fastball pitches off an indoor throwing mound positioned at regulation distance from home plate. A Motion Analysis three‐dimensional automatic digitizing system was used to collect 200 Hz video data from four electronically synchronized cameras. Twenty kinematic, six temporal, and 11 kinetic variables were analyzed at lead foot contact, during the arm cocking and arm acceleration phases, at ball release, and during the arm deceleration phase. A radar gun was used to quantify ball velocity. At lead foot contact, the American pitchers had significantly greater horizontal abduction of the throwing shoulder, while Korean pitchers exhibited significantly greater abduction and external rotation of the throwing shoulder. During arm cocking, the American pitchers displayed significantly greater maximum shoulder external rotation and maximum pelvis angular velocity. At the instant of ball release, the American pitchers had significantly greater forward trunk tilt and ball velocity and significantly less knee flexion, which help explain why the American pitchers had 10% greater ball velocity compared to the Korean pitchers. The American pitchers had significantly greater maximum shoulder internal rotation torque and maximum elbow varus torque during arm cocking, significantly greater elbow flexion torque during arm acceleration, and significantly greater shoulder and elbow proximal forces during arm deceleration. While greater shoulder and elbow forces and torques generated in the American pitchers helped generate greater ball velocity for the American group, these greater kinetics may predispose this group to a higher risk of shoulder and elbow injuries.     

掷标枪最后用力过程中左侧支撑技术的研究

本文通过分析,揭示了掷标枪技术最后用力过程中如何使左侧支撑起到更好的作用,对教学与训练有一定的参考价值。     

荆南干堤局部河段近岸水下抛石前后冲淤分析

对调关至八十丈河段抛石后局部冲刷进行验证测量 ,结果表明 ,抛石总体效果是明显的 ,但在特殊河段、特殊水流条件下抛石后河床局部有冲刷现象。对长江堤防工程的正常运行提出了安全监测建议。