田径投掷项目落地区的三种丈量方法的对比分析

根据国际田联最新规则规定,从2003年1月1日起,田径比赛除标枪外,各投掷项目扇形落地区标志线的内沿延长线的夹角,由40°改为34．92°。对三种丈量方法进行分析对比,即正弦丈量法、余弦丈量法和正切丈量法,指出了它们的优缺点。     

用掷骰子的方法模拟不同类型的测量误差

利用掷骰子的方法模拟了不同类型的测量误差,且通过实例,对均匀分布、三角分布、正态分布的随机误差进行模拟,对其数字特征与对应不确定度进行印证,并提出了用掷骰子的方法产生给定数学期望与方差的正态随机数的模拟法。     

The regulation of release parameters in underarm precision throwing

The aim of this study was to determine if adults spontaneously exploit the laws of physics to achieve better accuracy when throwing at various distances. Eight adults performed 25 underarm throws at five horizontal circular targets located 4, 5, 6, 7 and 8 m away with a constant 5% relative accuracy requirement. Angle and speed of the ball at release were found to increase with throwing distance, while the coordinates of the release point did not change significantly. These results support the idea that people minimize the variability in impact distance by adapting both the angle and the speed at ball release following a mechanical optimum predicted by the laws of physics. Moreover, variability in distance was found to be less than expected because of independent variations in the angle and speed at ball release. Hence, the control of precision throwing seems to imply compensatory variability, as frequently reported in the control of skilled actions.     

Stride length: the impact on propulsion and bracing ground reaction force in overhand throwing

Propulsion and bracing ground reaction force (GRF) in overhand throwing are integral in propagating joint reaction kinetics and ball velocity, yet how stride length effects drive (hind) and stride (lead) leg GRF profiles remain unknown. Using a randomised crossover design, 19 pitchers (15 collegiate and 4 high school) were assigned to throw 2 simulated 80-pitch games at ±25% of their desired stride length. An integrated motion capture system with two force plates and radar gun tracked each throw. Vertical and anterior–posterior GRF was normalised then impulse was derived. Paired t-tests identified whether differences between conditions were significant. Late in single leg support, peak propulsion GRF was statistically greater for the drive leg with increased stride. Stride leg peak vertical GRF in braking occurred before acceleration with longer strides, but near ball release with shorter strides. Greater posterior shear GRF involving both legs demonstrated increased braking with longer strides. Conversely, decreased drive leg propulsion reduced both legs’ braking effects with shorter strides. Results suggest an interconnection between normalised stride length and GRF application in propulsion and bracing. This work has shown stride length to be an important kinematic factor affecting the magnitude and timing of external forces acting upon the body.     

对标枪出手瞬间态势的力学分析

采用文献资料法收集有关统计数据，运用运动生物力学、空气动力学原理，对标枪出手瞬间态势进行了定量和定性分析，系统地阐述了诸多力学因子对成绩的影响以及它们之间的相互关系，对运动训练实践起到指导作用。笔者试通过文献资料法结合统计学、生物力学和空气动力学等知识对标枪出手瞬间态势的力学因子进行较系统全面的综合分析。以进一步提高人们对标枪项目的认识，以更好地指导运动训练的实践。     

对历届奥运会田径男子投掷项目成绩发展变化特征的研究

奥运会田径项目的比赛成绩,为后人对奥运田径史的深入研究和认识有着重要的价值。本文对历届奥运会田径男子投掷项目比赛成绩进行了整理和统计,对其成绩的发展变化过程及成绩水平的递进状况进行了分析和描述,并探讨了历届奥运田径男子投掷项目成绩发展变化的内在特征。     

试论投掷运动中髋关节的功能与作用

对投掷各项技术动作中有关髋关节的动作结构与相应的功能与作用进行了分析和论述，从中发现投掷技术动作中的共性和个性相互差异以及内在的有机联系。