Acquiring an Attacking Forehand Drive: The Effects of Static and Dynamic Environmental Conditions

Abstract

Two groups of 10 novice subjects each were trained to perform attacking forehand drives in table tennis and land the balls as fast and as accurately as possible onto a target on the opposite side of the net under two different training conditions. Under the static training condition, the balls were to be struck from a constant position, and under the dynamic training condition, balls approached the subjects in a normal way. Both groups were tested under dynamic conditions prior to and after four days of training, during which they received 1,600 practice trials. Both groups of subjects were shown to increase the number of balls that landed on the target, and learning was also evident from an increased consistency of the direction of travel of the bat at the moment of ball/bat contact. However, no increase in consistency was found for the location of the bat at the moment of ball/bat contact and for the movement times. Thus, learning can occur in the absence of externally generated time-to-contact information, but this is not due to the establishment of a consistent movement form. Learning appears to progress from control at the moment of ball/bat contact backward, toward the moment of initiation.     

Fatigue Effects on the Timing Performance of Well-Practiced Subjects

Abstract

In an attempt to extend the laws of fatigue to the performance of highly practiced subjects, 24 college males were trained for four days (50 trials/day) on a coincident timing task prior to manipulation of the fatigue variable. On day 5, motor performance was immediately preceded by either local fatigue (static exercise), general fatigue (treadmill running), or no fatigue. Increased variable error was found for both local and general fatigue subjects as compared with controls on the first block of five trials following fatigue. However, by block 2 this difference had diminished. A constant error analysis on the first and second postfatigue trials revealed transitory overshooting of the criterion timing response for local fatigue subjects and undershooting for general fatigue subjects. The results suggested that local and general fatigue may alter the timing mechanism in different ways and that both are sources of at least transient decrements in the performance of well-practiced subjects.     

不同级别优秀散打运动员鞭腿技术动作特征及其对击打速度的影响

为探求优秀散打运动员的体重差异与鞭腿技术动作特征是否对击打速度产生影响。方法：运用VICON Nexus 3D运动捕捉系统,对小、中、大三个级别15名运动员运用鞭腿技术动作快速击打目标物时的运动轨迹进行采集。依据鞭打动作特点和下肢关节运动特征,将技术动作划分为四个时刻、三个时段,并对四个时刻下肢关节的角度以及三个时段的动作位移、时间、速度、角速度等运用VICON Polygon分析软件进行计算。结果表明：启动时段（P1）小级别运动员的躯干和支撑腿各关节运动幅度呈"上大下小"状态,大级别运动员呈"上小下大"状态;三个级别运动员作用腿下肢关节的运动方向相同,运动幅度却出现差异,小级别运动员启动时段的动作速度相对较快。击打时段（P2）三个级别运动员支撑腿的髋、踝关节回旋运动方向出现差异;作用腿下肢关节运动方向相同,中级别运动员膝关节屈曲角度相对较大、转动半径相对较小,击打时段的动作速度也相对较快。回收阶段（P3）三个级别运动员支撑腿髋关节屈伸、回旋运动方向出现差异;作用腿下肢关节运动方向相同,小级别运动员作用腿下肢关节转动半径相对较小,回收时段的动作速度也相对较快。不同级别运动员鞭腿技术动作特征对击打速度存在显著性差异,相同级别散打运动员减轻体重、改善下肢关节的运动方向和运动幅度,才是提高击打速度的重要途径。     

Effects of Extended Practice and Movement Time on Motor Control of a Coincident Timing Task

Abstract

The present study investigated the extent to which movement time (MT) and practice influenced subjects' use of feedback to make corrections in the spatial-temporal movement pattern of coincident timing responses. Subjects performed 400 coincident timing responses of either 250,500, or 1,000 milliseconds. Schmidt's (1972) index of preprograming (IP) was used to estimate the level of feedback involvement in controlling the movement while the spatial-temporal pattern of the response was characterized by fluctuations in the speed of the movement to the barrier. The analysis of the IP and the spatial-temporal pattern of the responses suggest that MT and not practice limits the extent to which a response is preprogramed, with rapid performance more likely to be preprogramed than slower performance. Indeed, in the 1,000-millisecond response, the movement pattern appeared to be adjusted in the terminal phase (i.e., near the barrier) by accelerating or decelerating the rate of movement.     

快速抛击练习对提高棒球击球能力的探讨

本文就快速抛击练习对提高棒球击球能力的作用及训练方法进行了分析探讨。     

网球运动员动态中击球质量的探究

本文从整体论的角度出发,认为动态中击球质量的好坏并不只是由一个击球动作决定的,它应该是一个完整的预备体系,由此体系中的每一个部分包括重心、步伐、击球技术、击球战术和心智共同影响着。旨在对动态中击球质量有一个全面深入的认识,以期为指导网球运动员动态中击球的训练实践服务。     

Object rotation effects on the timing of a hitting action

We investigated how perturbing optical information affects the guidance of an unfolding hitting action. Using monocular and binocular vision, six participants were required to hit a rectangular foam object, released from two different heights, under four different approach conditions, two with object rotation (to perturb the viewed surface area) and two without. Participants made more misses under monocular conditions, and the presence of rotation had a significant effect on the duration between the arm's peak velocity and its contact with the object. We conclude that binocular information contributes to the timing of interceptive tasks. In addition, the guidance of interceptive actions does not appear to be based solely on object expansion information picked up from the viewed surface area.     

多功能搏击训练机的设计与实现

利用新型压电薄膜传感器输出信号随冲击大小而变化的特性,通过Soc单片机系统,实现了对击打力、击打速度和反应度的准确测量;不但能通过液晶显示器显示测值,而且通过软件实现了对训练机功能的菜单控制;通过语音电路和音箱实现了对测值的语音输出和对训练者的语音提示。经多家武校和跆拳道馆的试用,证明多功能搏击训练机稳定可靠,功能齐全,且造价低廉。介绍了多功能搏击训练机测量原理、结构和软件功能。     

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.     

咖啡因的作用机理及对肌肉代谢和运动能力的影响

对咖啡因在细胞水平上的３种主要作用机理进行了描述。研究表明，咖啡因可增加血浆儿茶酚胺的产生。血浆儿茶酚胺的产生增加，则会依次提高在运动期间作为肌肉底物的自由脂肪酸的利用率，从而节省糖原。咖啡因能够增加肌肉的收缩性和提高长时间极限下强度活动时的运动能力和耐力。运动员若想从咖啡因中获得有利影响，还应考虑个体对甲基黄嘌呤的耐受力和敏感性。     

安徽阜阳国际武术大赛中散打侧踹腿击中次数的调查研究

文章运用录像分析法、实地观察法和教学实验法,对2008安徽阜阳国际武术交流大赛中,运动员侧踹腿技术应用、击中次数、得分、犯规行为等方面的情况进行调查与分析,旨在为今后散打教学与训练以及侧踹腿技战术应用水平的提高和发展方向提供参考依据。     

平衡与核心肌群训练对网球运动员击球稳定性影响的研究

以如何提高网球运动员击球稳定性为目的,探讨平衡与核心肌肉群的训练对提高网球运动员击球稳定性的效果。采用实验研究方法,把网球运动员进行了不同训练项目的分组,在训练前、后均对测试者进行击球稳定性、平衡能力的测验,来评价训练的效果。研究发现经过平衡及核心肌群训练,在两边发球稳定性有了显著的进步,但在正拍与反拍击球则没有改变。     

提高多向飞碟射击首发命中率是主导方向

通过统计分析探讨多向飞碟射击比赛时运动员第一发命中与第二发命中与总成绩的关系，从而得出结论：（１）多向飞碟射击高成绩的取得，必须提高第一发的命中率，它是总成绩的保障，起到至关重要的作用，是主导方向；（２）第二发命中率的提高是建立在第一发命中值基础上且随之提高的，两者间有着不可分割的关系；（３）根据竞赛规则的需要，必须提高第一发命中率。并提出若干建议。     

浅析篮球比赛中的带球撞人与阻挡犯规

带球撞人与阻挡犯规是篮球比赛中裁判员经常碰到的问题,也是裁判员判断和处理犯规问题的一个难点。裁判员能否及时准确地判断出带球撞人与阻挡犯规,对于保护进攻队员、鼓励积极防守,使比赛顺利进行起着十分重要的作用。本文从竞赛规则、裁判方法以及临场实践的角度分析了带球撞人与阻挡犯规的判罚。     

武术散打项目打脚靶训练的生理学分析与研究

文章通过对散打运动员打脚靶时心率变化的情况进行监控,运用实验法和数理统计分析法,进一步掌握运动员在训练时的心率频率及其恢复情况。并利用心率情况客观地了解训练和比赛的激烈程度,分析影响训练效果的主要因素,从而更好地为各个运动队和俱乐部进行有针对性的科学训练提供依据和参考。     

抢篮板球起跳时机探析

在抢篮板球中,选择起跳时机是抢篮板球技术中最重要的部分,通过观察法和文献资料法,得知：篮板球的反弹方向、速度、上升高度等都有一定的规律,认识和掌握其规律有利于运动员在比赛中做出准确判断,选择最佳起跳时机,从而获得更多的篮板球。同时本文提出了提高运动员掌握起跳时机的训练手段,为教学和训练提供辅助参考。     

抗干扰训练对提高投篮命中率的实验研究

篮球技术的飞速发展 ,使比赛过程中的对抗性更加激烈、投篮运动员在完成投篮动作过程中所受干扰程度越来越高。篮球运动员在激烈对抗条件下的抗干扰能力对于提高投篮命中率应成为篮球教学与训练的重点。     

浅析垒球项目中优秀投手的技术动作

文章探讨了垒球比赛中投手在防守体系中的重要作用.通过对美、日传统强队投手的投球技术动作进行分析,着重分析了投球腿部伸踏技术动作与上肢屈臂技术动作,为不断改进和提高我国投手的技术动作提供参考依据.     

提高篮球教练员决策科学化水平的理论探讨

作为篮球教练员的工作,就是在训练和比赛过程中,不断地做出各种决策.研究认为,篮球教练员本身就是一名决策者,同时篮球教练员又是一名决策方案的具体执行者;篮球教练员的决策分为战略性决策和战术性决策两个主要方面;教练员决策过程中信息的获取和分析,对于决策的科学化程度有着直接的关系;自身的综合素养、思维方式、性格特征、经验积累,以及外部环境和条件的客观制约,决定了教练员的决策只能是建立在一种有限性理性的基础上.     

A Kinematic Analysis of the Baseball Batting Swings Involved in Opposite-Field and Same-Field Hitting

Abstract

The purpose of this study was to examine the mechanics of hitting a baseball to the same and opposite fields. Twenty male subjects were assigned to one of two groups according to their baseball hitting abilities. Each subject performed as many trials as were necessary to successfully hit a pitched ball three times to both the same and opposite fields. Each trial was filmed from above. No significant interactions (p < 0.05) were found between subject groups and field hits with selected temporal and kinematic parameters entered as dependent variables. Significant differences (p < 0.05) were found between body landmark and segment component displacements and velocities at the instant prior to ball contact. The maximum resultant linear and angular speed of the examined body and bat landmarks were found to occur prior to ball contact. Based on the results of the study it was concluded that no interactions exist between hitting ability and hitting technique when hitting to defined field areas and that differences in the mechanics of hitting to defined areas are due in part to: (1) differences in the angular displacements of the left wrist and left elbow joints and (2) differences in the temporal characteristics of the swings.