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.     

Kinematics,coordination, variability,and biological noise in the prone flutter kick at different levels of a “learn-to-swim” programme

Abstract

The purpose of this study was to establish the characteristics of the movement patterns common to flutter kicking of skilled swimmers and to determine how the movement patterns of swimmers at different levels of a “learn-to-swim” programme differ from those of skilled swimmers. Also, the nature of the skill afforded the opportunity to investigate learning of a cyclical multi-joint task from a motor control perspective. The underwater motion of nine children representing three levels of a “learn-to-swim” programme and 10 skilled swimmers were video-recorded while performing nine cycles of prone flutter kicking. Kinematics including joint angular motion and coordination of joint actions were calculated. Fourier analysis was applied to determine the frequency composition of the vertical undulations of the hip, knee, and ankle and to calculate the velocity of the body wave travelling caudally from hip to ankle. Fourier analysis also enabled investigation of biological noise, as distinct from variability. The results indicated the desired joint angles and coordination towards which learners could be guided. An index based on the ratio of hip – knee and knee – ankle body wave velocities showed that the inter-joint coordination of most learners was not appropriate for effective flutter kicking. There was strong evidence to suggest that skilled performance in flutter kicking is characterized by sequencing of joint actions to produce a single sinusoidal body wave moving caudally with not decreasing and preferably increasing velocity, low biological noise, and small variability.     

A Test of Schmidt's Schema Theory of Discrete Motor Skill Learning

Abstract

Schmidt's (1975) schema theory was tested with subjects who had to emit a rapid aiming response while wearing prism glasses. The glasses enabled them to view the target, but not their responding limb or the outcome of the movement. The problem was to determine the effect of (a) training with variable target practice, and (b) experiencing visual displacement information of the target, prior to training, on performance in transfer to a novel target distance. A 2 × 2 (type of practice × displacement information) factorial design was used, in which four groups of 15 male college subjects performed 60 training trials with verbal knowledge of results. The groups with variable target practice had less error on initial transfer to the novel target and throughout transfer than the groups with nonvariable target practice. No evidence was found to indicate that rate of learning for a novel target distance during transfer in the absence of KR is a positive function of the variability of target practice in training. Nor was any effect found for experiencing visual displacement information on performance in transfer.     

Effect of skill level on cardiorespiratory and metabolic responses during Tai Chi training

Abstract

Nowadays, Tai chi chuan (TCC) is practiced by millions worldwide with a range of skill levels. However, the effect of skill level on physiological response to TCC performance has yet to be clarified. In this study, physiological parameters during practicing simplified 24-form TCC were investigated and compared in 10 young high-level (HL) male TCC athletes and 10 ordinary-level (OL) male TCC practitioners with similar age and body size. Significantly higher energy expenditure, heart rate, oxygen uptake and tidal volume were found in HL group than OL group during TCC performance. The respiratory frequency and exhalation time were similar between the two groups during practicing TC; however, significantly less inhalation time was found in HL group (1.02±0.2 s) than OL group (1.12±0.28 s). Our results suggested that skill level may have considerable impact on metabolic and cardiorespiratory responses to TCC performance. TCC practitioners with different skill levels may practice TCC in different ways, which was supposed to lead to distinguishable response between the two groups.     

公共管理类专业实践教学模式研究

传统实践教学模式存在诸多问题,公共管理类专业实践教学应围绕以下技能训练展开：组织管理、社交沟通、行政执法、调查研究、统计分析、公文写作与处理等。可以借助＂学生科创＂平台,让学生参与管理类项目的研究,培养学生调查研究、统计分析、项目论证和撰写研究报告等方面的技能;可以借助统一实习平台,让学生接触和参与管理活动、解决管理中遇到的具体问题,提高学生组织、协调、沟通、社交等方面的技能。     

体育舞蹈在高尔夫技术教学中的应用研究

作为一项新兴的运动项目,高尔夫技术教学的方法和手段研究不足。为使初学者尽快掌握高尔夫技术关键点,提出了在高尔夫技术教学中引入体育舞蹈的观点。认为将体育舞蹈渗入到高尔夫技术教学过程中的各个环节,能帮助学生建立核心力量观念,体会恰当的重心转移,学会控制动作节奏,还能激发学生的学习兴趣。运用此教法进行的教学实验结果也表明,实验组学生的专项技能测评的平均成绩明显优于对照组,且该差异性具有高度显著性(P<0.01),表明此教学法具有较高的应用与推广价值。     

浅析“教学做一体”教学模式在《韩语写作课程》上的应用

为了打破传统的“一言堂”教学模式,近几年在国内高职院校悄然兴起了“教学做一体”教学模式改革。这是中国学习德国职业教育模式后,对中国高职院校教学方法的深度改革。每个教学方法都有它自己的优点和缺点,本文深度分析了《韩语写作课程》引进“教学做一体”教学模式后的教学效果,探讨这一教学模式的优缺点。     

TGMD-3在中国3~12岁儿童基本运动技能测试中的信效度研究

目的: 验证TGMD-3在中国3~12岁儿童基本运动技能测试中的可靠性和有效性。方法: 选取上海、深圳、重庆、洛阳、长沙的512名3~12岁儿童为研究对象进行TGMD-3测试,对测试的难度、区分度、一致性信度、重测信度和评价者信度、结构效度进行统计检验。结果: TGMD-3的13个项目难度范围为0.27~0.78,区分度范围为0.38~0.49。每个年龄组儿童基本运动技能测试(TGMD-3)的内部一致性系数范围为0.808~0.902,其中男女生的内部一致性系数均为0.95;总体的基本运动技能评价者信度(肯德尔协同系数)w为0.944, 2值为28.331,达到显著性水平;重测检验中,移动式运动技能(组内相关系数)ICC为0.755、球类运动技能(组内相关系数)ICC为0.741、总的基本运动技能(组内相关系数)ICC为0.743,均达到了较高水平。通过探索性因子分析验证了TGMD-3的双因子结构,并通过验证性因子分析支持双因子模型(χ²(64)=103.28,p<0.001,CFI=0.960,TLI=0.952,RMSEA=0.049,SRMR=0.043)。结论: TGMD-3儿童基本运动技能测试具有良好的项目难度、区分度,以及可靠的内部一致性信度、重测信度和结构效度,对我国3~12岁儿童具有良好的适用性,可以作为我国儿童基本运动技能发展评价的有效工具。     

论应用写作教学设计理念的实施策略

应用文写作作为高校普遍开设的一门专业必修课和素质技能课,对于其教学理论与实践的研究层出不穷,尤其致力于其教学方法上的研究和探讨颇多,而教师采用何种教学方法,又受制于对该门课程前期设计理念的构想和实施,本文拟从应用写作课程理念入手,以期抛砖引玉,共同探讨该课教学艺术。     

排球二传手单脚起跳传球技术分析

本文分析了单脚跳起传球的技术，阐述了单脚跳起传球的优越性及其在比赛中地运用．