Cinematographic Analysis of the Handspring Vault

Handspring vaults performed by 10 advanced-level female gymnasts were analyzed using a three-segment model. Kinematic variables and energy changes were measured for the preflight, contact, and after-flight phases. Each vault was scored with regard to kinematic factors only, and a correlation matrix between all of the measured variables was calculated. It was found that even though the preflight variables of the gymnasts as they left the takeoff board were very similar, their vertical velocities at initial horse contact varied considerably, with the poorest vaults showing downward velocities. This appeared to be a principal factor determining the outcome of the vault. All gymnasts lost horizontal speed, angular momentum, and mechanical energy during the contact phase.     

A Cinematographic and Mechanical Analysis of the External Movements Involved in Hitting a Baseball Effectively

Abstract

A controlled, cinematographic study was made of 17 proficient, professional hitters of the Eastern League hitting a baseball effectively, in order to make a qualitative and quantitative analysis of the mechanics of hitting. Angular measurements of the forward-swing bat delineated a sharply increasing rate of velocity as the bat approached the baseball. Responsibility for the generation of the force imparted to the bat was made manifest by the far greater velocity of the hands-and-wrists over the hips, and, similarly, of the hips over the striding foot. Additional analyses were made of the efforts to maintain bodily balance, the judgment time of each hitter, the changing levels of the head, the preparatory movements of the stance, and the extent of arm movement before the follow-through.     

台阶试验结果及准确度影响因素分析

通过实验法、统计法、分析法,对100名体育系学生的台阶试验结果进行分析,分析影响其结果差别的原因以及影响台阶试验准确性的因素。并把两种台阶指数评定标准进行对比,以期对台阶试验进行科学的评价。     

对艺术体操中圈运动的力学原理分析

本文运用力学原理分析了艺术体操中转动圈和地上倒回滚圈的运动性质和成因，为艺术体操的教学和训练提供某些理论依据。     

T球（TeeBall）运动进攻技术分析

文章以T球（TeeBall）初学者为对象,分析了T球运动中的击球与跑垒进攻技术动作。强调在学习和练习的过程中,不仅要掌握击球与跑垒基本的技术要领,更重要的是在实践中发现和开发个性特点技术的重要性。     

我国三级跳远运动员助跑踏跳准确性调查分析

运用观察法、文献资料法、数理统计法等,对参加2007年全国田径特许赛（重庆站）三级跳远决赛的男、女运动员的助跑踏跳犯规情况进行调查和分析,旨在使教练员和运动员充分认识准确踏跳的重要性,进行有针对性的训练,提高踏跳的准确性,从而创造更优异的运动成绩。     

运动影像测量方法的误差研究

在实验研究的基础上,对运动影像测量方法的误差问题进行了讨论.在总结前人研究结果以及实验测试的基础上,以竞走项目为例,提出了对测量过程中各误差源进行误差合成计算的方法,确定了最后测量结果的误差范围以及各误差源的比例构成.研究结果表明:在平面定机拍摄时,图像边缘处的镜头畸变误差会对测量结果产生一定影响;在立体影像定机拍摄时,标定空间与地面垂直方向的测量精度高于其他方向.误差合成的计算结果表明,平面定机拍摄和立体定机拍摄两种方法的测量精度分别为8.1±8.44 mm和8.05±4.9mm,多数被测点的位移量误差百分比在2％以下.     

判罚越位准确性的影响因素分析

2010年第19届世界杯足球比赛在南非举行,来自世界各地32个国家的足球队参加了比赛。共进行了64场比赛,145个进球。本届杯赛的裁判执法是历届杯赛中受到质疑最多的一次,有近10场比赛出现了严重的错漏判,其中有六场关键比赛因为越位进球嫌疑影响了比赛结果,球场上多次出现球员围攻裁判、爆粗口现象,引起了全世界广大球迷的极度不满,国际足联倍感压力,一度引发了足球场上是否使用“鹰眼”（电子录像技术）的争论。本人作为一名足球裁判,世界杯期间,从裁判的角度收看了全部64场比赛,并通过查阅大量文献资料、反复观看有争议的越位进球视频及访谈专家,在收集典型战例的基础上深入地探析一下如何在执法中准确判罚越位。希望对年轻的足球裁判员有所启示,对提高我国足球运动发展及提高裁判员的业务水平能有所裨益。     

竞走技术原述与违背竞走定义技术的成因分析

竞走运动员的技术必须在理解和适应竞走定义过程中完善自己的技术.竞走裁判员主要依据竞走定义对比赛中运动员实施屈腿和腾空的判定,但腾空和屈腿的产生是有缘由的.对常见造成屈腿和腾空的成因进行分析,以利技术的改进和评判.     

辐射式框架进行三维重构的精度分析

使用两部JVC摄像机对爱捷008-D辐射式框架进行定点拍摄,运用直接线性转移 (DLT)方法进行标定框架的三维重构和精度分析。结果表明:辐射式框架的控制点数目足够多且在标定空间内均匀分布时,如果控制点张成空间大于并包含被标定对象,可以达到比较好的标定精度;如果控制点均匀地分布于被标定对象的内侧和外侧,可以达到的标定精度更好。     

Validity of the activPAL and Height-Adjusted Curvilinear Cadence-METs Equations in Healthy Adults

ABSTRACT

The activPAL is a widely-used measure of sedentary time but few studies have evaluated its ability to estimate physical activity intensity. This study determined the accuracy of the algorithm used by the activPAL to predict metabolic equivalents (METs) from cadence and a curvilinear cadence-METs equation individualized for height. Thirty-six healthy adults (25 ± 6 years) completed a progressive walking protocol. Stepping cadence was video recorded and METs were determined via indirect calorimetry. Manually-counted cadence was input into the activPAL and curvilinear equations. The internal activPAL equation overpredicted METs at slower cadences (<120 steps/minute) but underpredicted METs at faster cadences (>120 step/minute) (proportional bias, p < .001). Conversely, the curvilinear equation exhibited neither fixed (p = .37) nor proportional bias (p = .07), and a lower absolute MET difference [0.87 ± 0.65 (range:0.0–3.2) vs. 0.56 ± 0.45 (range:0.0–2.7) METs]. The linear activPAL equation poorly estimates METs from stepping cadence but these inaccuracies may be lessened through the use of an individualized curvilinear equation.     

篮球运动员持球活动系统结构的理论分析

活动在人类生活中占有重要位置。通过活动,人作用于自然界、事务和其他的人,与周围的世界建立现实的联系。文章以人类活动结构一般理论为基础,探讨篮球运动员个人持球活动系统的结构、要素及相互关系,旨在进一步完善篮球专项理论体系,为篮球学科的建设与发展提供理论依据。     

Accuracy and Prediction in Throwing: A Taxonomic Analysis of Children's Performance

Abstract

The throwing and prediction performances of first, third and fifth grade boys and girls were analyzed within the framework of a four-part taxonomy originally conceived by Fitts (1965). Throwing performance was assessed under task conditions which varied the motion states of the thrower's body and the target (stationary or moving) by use of a dual pendulum apparatus. Accuracy scores were highest in a condition where both body and target were stationary, and lowest where both body and target were moving. Task conditions requiring motion of only target or of body were of intermediate difficulty, and scores for these tasks were not significantly different from each other. There was evidence of learning across trial blocks for all tasks, but no indication that rates of acquisition differed for the task types. Likewise, significant main effects were observed for age levels but no age X task type interactions were disclosed. Boys were more accurate than girls across task conditions, most noticeably on the two most difficult tasks. Comparison of subjects' ability to predict, from a stationary body position, the coincidence of the moving target with a standard reference point, and their ability to predict the coincidence of their moving body with the same reference point revealed lower error scores on the former prediction task.     

独竹漂运动的文化特征分析

通过文献资料法、调查法对独竹漂运动进行研究,运用逻辑分析法总结该项运动的文化特征。独竹漂运动在群众体育当中不断实现它的多元文化功能和价值。与现代体育积极的融合,不断继承和创新,走科学化、竞技化、产业化的道路,加大社会力度才是可持续的发展方向。     

划艇运动力学参数检测与分析

研制了一种集划桨力、划桨过程中桨的偏转角度、艇的俯仰角度和倾覆角度、艇速等多个运动力学参数为一体的新型划艇测试评价系统，实现了对这些参数的同步采集。系统通过传感器（力传感器、角度传感器和速度传感器）将采集到的数据无线传输至计算机，利用自行开发研制的软件系统，教练员可以实时地掌握运动员划船过程中的运动状态。整个系统的重量比较轻，并且数据的主要传输采用无线形式，既保证了教练员实时的了解以往单凭眼睛观测和经验判断而很难得到的一些划桨技术细节信息，同时不会对运动员的正常划船技术动作的产生过多的干扰。     

师范大学生三级跳远运动员助跑踏跳准确性分析

现状调查法、文献法、数理统计法等,对年第六全国高等师范大学生田径运动会(甲、乙、丙三个组别)三级跳远决赛中,男、女运动员的助跑踏跳调查分析,旨在给教练员和运动员充分认识到助跑踏跳准确的重要性,科学地进行针对性的训练,稳定助跑踏跳的准确性,提高运动成绩,为读者提供参考。     

多点摄像与解析方法在跳台滑雪技术分析中的应用

在运动影像解析技术领域里,为了准确地获取运动目标的三维空间坐标位置,一般使用定点、定焦摄像方式。对于大范围运动的动作解析,需要多台摄像机在多点位置进行定点、定焦动作捕捉。跳台滑雪运动是一个比较典型的、在较大范围内动作复杂的运动项目。对于优秀跳台滑雪运动员的三维动作解析问题是我国冰雪体育科研领域的前沿研究项目,其中如何捕捉和获取大范围运动信息是分析过程的关键环节之一。通过研究多点摄像解析方法在跳台滑雪运动中的应用,为处理大范围运动的动作捕捉与解析研究提供理论参考。