Optimum release angle in the shot put

The aim of the study was to assess the accuracy of a method of calculating the optimum release angle in the shot put. Using the proposed method, the optimum release angle that produces the greatest flight distance is calculated by combining the equation for the range of a projectile in free flight with the relations between release speed, release height and release angle for the athlete. The method was evaluated using measurements of five college shot-putters who performed maximum-effort throws over a wide range of release angles. When the athletes threw with high release angles, the shot was released from a greater height above the ground and with a lower release speed. For all five athletes, the calculated optimum release angle was in good agreement with the athlete's preferred release angle. Each athlete had his own specific optimum release angle because of individual differences in the rate of decrease in release speed with increasing release angle. Simple models of shot-putting were developed to explain the relations between release speed, height and angle in terms of the anthropometric and strength characteristics of the athlete.     

铅球最后用力阶段的数字模型及其解

本文建立了铅球最后用力阶段的数学模型，讨论了决定铅球飞行远度的三要素间的相互关系，分析了速度角θ，力角α和加速角度α’的力学成因，进而为认识和把握现代铅球技术的本质提供了理论指导。     

对推铅球最佳出手角的研究

运用力学原理，经分析和数理推导，提出因助跑速度和最后用力使铅球所产生的速度方向不同，滑步推铅球的出手初速度是随出手角改变而变化的变量，原理论“最佳出手角”是以出手初速度为定量的基础上推算出来的，仅适用于原地推铅球，并推导出随出手角变化，出手初速度和射程的计算公式，分析助跑速度和出手角变化对出手初速度和射程的影响．提出新的最佳出手角。     

Optimum take-off angle in the long jump

In this study, we found that the optimum take-off angle for a long jumper may be predicted by combining the equation for the range of a projectile in free flight with the measured relations between take-off speed, take-off height and take-off angle for the athlete. The prediction method was evaluated using video measurements of three experienced male long jumpers who performed maximum-effort jumps over a wide range of take-off angles. To produce low take-off angles the athletes used a long and fast run-up, whereas higher take-off angles were produced using a progressively shorter and slower run-up. For all three athletes, the take-off speed decreased and the take-off height increased as the athlete jumped with a higher take-off angle. The calculated optimum take-off angles were in good agreement with the athletes' competition take-off angles.     

背向滑步推铅球叠加式教学的实验研究

在背向滑步推铅球教学中采用叠加式教学法与常规教学法进行比较实验研究。研究结果表明,叠加式教学法更能适应背向滑步推铅球技术教学的特点,教学效果较好,具有较好的推广与应用价值。     

改革女生铅球教法程序的探讨

本文通过对部分大、中学女生铅球（包括实心球）测试成绩的抽样调查，进行比较分析和小范围的教学试验，提出发展力量素质与铅球动作技术结构相结合的教法程序，以代替传统教法程序，达到事半功倍的教学效果。     

试论现代篮球中锋投篮技术

现代篮球中锋的投篮技术是一项强对抗的进攻组合技术。它是由抢位、接球和投篮组成的,它的运用主要体现在意识和抢位的对抗性、接球的攻击性和投篮的应变性     

铅球背向滑步技术CAI教学模式的研制与开发

多媒体组合教学(CAI)是将现代科学技术手段运用于课堂教学的一种方法,本文试图通过研究铅球背向式滑步技术CAI教学模式的研制与开发,来探索体育专业田径课多媒体CAI的教学规律和方法。并通过在教学中初步应用,探索在体育教育专业课教学中运用多媒体优化组合教学法的教学模式。     

现代体育科技发展对竞技体育的影响

从竞技体育的发展史入手,分析科学技术的发展对竞技体育形成的推动和影响。     

我国优秀女子铅球运动员巩立姣最后用力技术的运动学分析

选定进入2013年全国田径大奖赛（苏州站）女子铅球决赛运动员巩立姣最后用力阶段技术为研究对象,研究结果显示：右侧技术中,右踝关节蹬伸比较积极,右膝角幅度大整个右侧各关节伸展比较充分;左侧技术中,左膝角偏小,蹬伸幅度、左膝关节缓冲幅度与世界优秀运动员一致;最后用力阶段各环节特征技术中,左脚着地瞬间身体重心速度、右髋速度、右肩速度都低于3位优秀运动员,而铅球出手瞬间右肩速度、右肘速度较强,另外最后用力出手瞬间,出手高度和出手速度都低于我国3位世界级优秀运动员相应指标。     

The effects of increased shooting distance in the basketball jump shot

Three‐dimensional video techniques (50 Hz) were used to obtain images of basketball jump shots from one of three distances ‐ short range (group 1, n = 5); medium range (group 2, n = 5); long range (group 3, n = 5) ‐ from the basket, as performed by members of the men's quarter‐finalist teams at the games of the XVI Universiade in Sheffield in 1991. Fifteen sequences were digitized, beginning 20 frames prior to take‐off to 10 frames after release. To facilitate analysis, the sequences were rotated about the ball position in the final frame so that the shot direction was parallel to one of the pre‐defined orthogonal axes.

Mean (+1 s.d.) ball release speed was found to increase with distance from the basket (group 1 = 3.04±0.65 m s‐¹, group 2 = 4.71+0.74 m s‐¹, group 3 = 6.24 + 0.80 m s‘¹), while mean release angles were similar for all groups (group 1=48.8 + 10.1°, group 2 = 47.8 + 5.8°, group 3 = 51.9 + 5.5°). The increased impulse necessary for the ball to reach the basket at increased shooting distances was derived from both an increase in angular velocity of the elbow joint of the shooting arm and an increased velocity of the centre of mass in the direction of the basket at release. Centre of mass speed at take‐off was found to be influenced to a greater extent by the angular velocity of the ankle joint than that of the knee or hip joints. Rotation of the hip and shoulder axes, facilitated by the forward placement of the foot on the side of the shooting arm (antero‐posterior separation values: group 1 = 0.17 + 0.11 m, group 2 = 0.10 + 0.14 m, group 3 = 0.09 + 0.09 m) was utilized by all except one subject. All subjects also used an amount of medio‐lateral foot separation which, along with antero‐posterior separation, promoted stability.

All the subjects released the ball while airborne. Both the maximum jump height and the height of the jump at release tended to decrease as shooting distance increased. For short‐range shots, release occurred after the peak of the jump, but increasingly prior to the peak as shooting distance increased.     

竞技健美操跳跃类典型难度动作的运动生物力学分析

采用艾立尔系统、FAB系统和肌仪器系统,对竞技健美操C组跳跃类典型难度动作进行运动生物力学分析。结果发现,起跳时髋、膝关节应在一定范围内进行快速的弯曲缓冲,并控制好起跳的方向。在腾空时,当转体度数较小时并不需要通过减少转动惯量来增加角速度。但是随着难度系数的增加,转体度数不断上升,在这样的情况下夹臂抱胸的姿势是很必要的。在落地时,由于膝关节不能弯曲,肩、肘、腕关节起到了主要的缓冲作用。     

对体育文化中若干概念的辩析与思考

按照“文化”的一般定义把“体育文化”概括为三个层次：表层是运动形式（包括身体运动形式及所使用的场地、器材等物质形态）;中层是体育体制（包括体育的社会组织形态和教学训练体制等）;深层体育观念（包括身体观、运动观、价值观、方法观等）。巾此演变而来的体育文化、终身体育、身体文化、身体娱乐、竞技与体育等概念术语具有学术上的不同含义和实践上的不同功能,只有准确界定他们的概念,才能在体育文化实践中广泛交流和应用,并正确指导人们从事和接受不同的体育文化活动,以避免因含糊不清的概念给体育文化实践带来不利的影响。     

对田径理论中几个传统观点的质疑

通过对国内外优秀运动员技术特征的分析，对田径理论中几个传统观点进行了探讨，对几个技术指标作了补充，有利于充实田径理论，促进田径运动技术水平的提高。     

Optimum take-off angle in the long jump

In this study, we found that the optimum take-off angle for a long jumper may be predicted by combining the equation for the range of a projectile in free flight with the measured relations between take-off speed, take-off height and take-off angle for the athlete. The prediction method was evaluated using video measurements of three experienced male long jumpers who performed maximum-effort jumps over a wide range of take-off angles. To produce low take-off angles the athletes used a long and fast run-up, whereas higher take-off angles were produced using a progressively shorter and slower run-up. For all three athletes, the take-off speed decreased and the take-off height increased as the athlete jumped with a higher take-off angle. The calculated optimum take-off angles were in good agreement with the athletes' competition take-off angles.     

我国运动损伤及骨关节病的研究现状及进展

本文从三个方面综述了我国运动损伤及骨关节病的研究现状及进展。旨在抛砖引玉 ,使广大体育科研工作者对这方面有一总体认识 ,进而从中发掘自己的研究方向。     

运动生物力学在田径运动中的应用及前景

对运动生物力学在田径运动中的运用情况进行了针对性地归纳、分析,认为学科自身的特点和研究传统是其在该领域得以广泛应用的主要原因.文章同时从其研究现状、理论方法、研究手段等角度进行了分析、探讨,研究得出测量技术的进步和计算机技术的进一步应用是现阶段运动生物力学取得突破性发展的首要环节;充分利用力学、机能解剖学和生理学等基础学科的研究成果,并形成自己独特的理论与方法是这门学科的发展趋势.     

背向滑步推铅球最后用力阶段足底压力分布特征

使用RSscan足底压力测量和分析软件对山东省田径队的6名优秀铅球运动进行了测量,主要从压力曲线、压力中心轨迹和脚底各区的压力时间积分几个方面描述优秀铅球运动员背向滑步推铅球时脚底压力分布特点.实验结果显示:1)右脚第一峰值(1.52倍体重)大于左脚第一峰值(1.26倍体重),右脚第二峰值(1.04倍体重)很不明显,提示右脚在着地时维持身体平衡、保持动作的顺畅衔接中起着重要作用.2)最后用力阶段,身体旋转和蹬伸主要是以前脚掌为轴,前脚掌肌肉力量强弱,对运动员投掷铅球的技术动作连贯性、稳定性以及成绩有一定作用.建议在运动训练中,有目的地提高身体平衡能力,加强足部小肌群和踝关节稳定性的练习.     

Effects of low-dose caffeine supplementation on early morning performance in the standing shot put throw

Abstract

The purpose of the present investigation was to assess the efficacy of low-dose caffeine use for early morning performance in the shot put event. A double-blind, randomized, crossover design was used to investigate the effects of buccal caffeine supplementation on early morning shot put execution in nine inter-collegiate track and field athletes. In one condition the participants received a piece of caffeinated gum designed to deliver 100 mg of caffeine in a buccal manner, and in a second condition a placebo gum. The gum was chewed for 5 min before being discarded. Participants then completed the first psychomotor vigilance task followed by a series of five warm-up throws, followed by six attempts with a shot put (7.26 kg for males, 4.0 kg for females) measured for distance. The protocol ended with a final psychomotor vigilance task. A repeated-measures analysis of variance (treatment*time) was used to compare performance between the caffeine and placebo treatments over the six measured attempts. A significant difference (treatment×throw) was observed (P=0.030, partial eta-squared = 0.259), indicating that the caffeine treatment produced better performance over the course of the six attempts subsequent to a warm-up. A paired samples t-test (Bonferroni-adjusted for multiple comparisons) revealed that the first attempt in the caffeine treatment (9.62±1.71 m) and in the placebo treatment (9.05±1.69 m) were significantly different (P = 0.050, effect size = 0.996, 95%CI 1.02 to 0.13 m). Repeated-measures analysis of covariance revealed a significant (P=0.016, partial eta-squared = 0.650) interaction effect (treatment×mean reaction time), whereby both at the pre and post time points the mean reaction time on the psychomotor vigilance task was reduced under the caffeine treatment (caffeine: pre 0.306±0.05 s, post 0.316±0.08 s; placebo: pre 0.317±0.06 s, post 0.323±0.06 s). Based on these results, we suggest that caffeine gum can be beneficial for both performance and alertness if used by shot put athletes during early morning sessions.     

王舟舟跳高技术的运动生物力学分析

通过对收集王舟舟在'99上海全国田径冠军赛比赛时的技术参数与第6届世界田径锦标赛男子跳高冠军及前6名运动员进行对比分析时发现:王舟舟助跑倒1步至起跳腿着地时的水平速度损失较大,倒1步摆动腿着地、离地时的身体内倾角变化规律正好与对方相反,呈减小的趋势;在起跳前及起跳开始阶段的水平速度低、起跳过程中支撑腿膝、踝关节蹬伸不充分。另外,过杆动作极不经济实效,这些都有待他在今后的训练和比赛中不断地提高与改进。