超等长训练法在投掷运动员爆发力训练中的运用

文章分析了超等长工作原理及其在投掷技术中的具体表现,指出了超等长练习应注意的问题。     

Quiet eye training aids the long-term learning of throwing and catching in children: Preliminary evidence for a predictive control strategy

Abstract

Quiet eye training (QET) may be a more effective method for teaching children to catch than traditional training (TT) methods, but it is unclear if the benefits accrued persist in the long term. Thirty children were randomly allocated into a QET or TT group and, while wearing a mobile eye tracker, underwent baseline testing, training and two retention tests over a period of eight weeks, using a validated throw and catch task. During training, movement-related information was provided to both groups, while the QET group received additional instruction to increase the duration of their targeting fixation (QE1) on the wall prior to the throw, and pursuit tracking (QE2) period on the ball prior to catching. In both immediate (R1) and delayed (R2, six weeks later) retention tests, the QET group had a significantly longer QE1 duration and an earlier and longer QE2 duration, compared to the TT group, who revealed no improvements. A performance advantage was also found for the QET compared to the TT group at both R1 and R2, revealing the relatively robust nature of the visuomotor alterations. Regression analyses suggested that only the duration of QE1 predicted variance in catch success post-training, pointing to the importance of a pre-programming visuomotor strategy for successful throw and catch performance.     

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.     

Differences among fastball,curveball, and change-up pitching biomechanics across various levels of baseball

Controversy continues whether curveballs are stressful for young baseball pitchers. Furthermore, it is unproven whether professional baseball pitchers have fewer kinematic differences between fastballs and off-speed pitches than lower level pitchers. Kinematic and kinetic data were measured for 111 healthy baseball pitchers (26 youth, 21 high school, 20 collegiate, 26 minor league, and 18 major league level) throwing fastballs, curveballs, and change-ups in an indoor biomechanics laboratory with a high-speed, automated digitising system. Differences between pitch types and between competition levels were analysed with repeated measures ANOVA. Shoulder and elbow kinetics were greater in fastballs than in change-ups, while curveball kinetics were not different from the other two types of pitches. Kinematic angles at the instant of ball release varied between pitch types, while kinematic angles at the instant of lead foot contact varied between competition levels. There were no significant interactions between pitch type and competition level, meaning that kinetic and kinematic differences between pitch types did not vary by competition level. Like previous investigations, this study did not support the theory that curveballs are relatively more stressful for young pitchers. Although pitchers desire consistent kinematics, there were differences between pitch types, independent of competition level.     

关于小学体育侧向投掷垒球指导之思

投掷运动是人类会的从小就掌握的基本技能,其可以将人的力量与动作结合在一起完美呈现出来。既然投掷是人类生存的基本技能,所以投掷运动在小学的体育教学中也被赋予其重要的价值,在小学的体育教材中投掷垒球运动主要是锻炼学生手脚协调同时用力的学习,其不仅可以锻炼学生的肩部力量,还可以让学生在自由、同学合作中掌握投掷垒球的方法。     

《投梭记》论

《投梭记》通过对魏晋时期“幼舆折齿”这一文人风流韵事的深刻挖掘和精心提炼,运用现实主义和浪漫主义有机结合的创作手法,深刻揭露了当时朝廷内部奸臣当道、社会动乱不堪的黑暗现实;同时通过展现男女主人公之间悲欢离合的艰苦爱情历程,歌颂了他们对爱情生死不渝的崇高情操;反映着作者对历史和现实的双重思考,寄托着他愤世嫉俗的思想。在艺术上,塑造出了众多生动传神的人物形象,在结构布局上也颇见匠心,语言雅俗共赏,既充满着历史感,又有鲜明的时代特征。是一部比较典型的文人写心剧。     

推铅球速度力量训练手段的优选及应用研究

在文献资料法的基础上,采用问卷调查法,模糊数学法等对推铅球力量训练手段进行优化选择,试图在微观上对推铅球力量训练手段,特别是速度力量训练手段进行深入研究,并采用教学实验对研究结果进行验证,结果显示采用优选手段进行训练,可以有效提高推铅球的速度力量,而且采用优选手段训练后,实验对象的成绩和技术水平也好于对照组。     

Comparison of sequence of trunk and arm motions between short and long official distance groups in javelin throwing

The purpose of this study was to determine the effects of sequences of the trunk and arm angular motions on the performance of javelin throwing. In this study, 32 male and 30 female elite javelin throwers participated and were separated into a short official distance group or a long official distance group in each gender. Three-dimensional coordinates of 21 body landmarks and 3 marks on the javelin in the best trial were collected for each subject. Joint center linear velocities and selected trunk and arm segment and joint angles and angular velocities were calculated. The times of the initiations of the selected segment and joint angular motions and maximum angular velocities were determined. The sequences of the initiations of the selected segment and joint angular motions and maximum angular velocities were compared between short and long official distance groups and between genders. The results demonstrated that short and long official distance groups employed similar sequences of the trunk and arm motions. Male and female javelin throwers employed different sequences of the trunk and arm motions. The sequences of the trunk and arm motions were different from those of the maximal joint center linear velocities.     

核心力量训练在投掷项目最后用力动作链中的应用研究

研究在投掷项目最后用力动作链的深入分析基础上,依据核心力量的理论和核心力量训练的要素,紧密结合核心力量与投掷项目最后用力动作链的内在联系,提出了核心力量训练在投掷项目最后用力动作链中的可行性.     

Development of the Overarm Throw: Movement and Ball Velocity Changes by Seventh Grade

Abstract

Children studied longitudinally from kindergarten through second grade were refilmed in seventh grade as they performed 10 trials of the forceful overarm throw. The horizontal ball velocities of the 22 boys and the 17 girls were compared with predictions made when the children were in second grade. The original estimate of an annual rate of change (a “developmental year”) of 5–8 feet/sec/year (1.52–2.44m) remained accurate for the boys; the original estimate for the girls had to be increased to 2–4.5 feet/sec/year (.61–1.37m). While the gap between the sexes increased throughout elementary school, it increased at a slower rate from second to seventh grade than it had during the primary years. By seventh grade, however, the girls were 5 developmental years behind the boys. The data also suggested a difference in the degree to which the sexes maintained their relative positions within their groups: girls appeared more stable than boys across the elementary years. Change was also assessed in the developmental levels exhibited by the children as they threw. The girls' rate of development was 5–6 years behind the boys' rate. Few boys, however, had reached an advanced level in all movement components by seventh grade. Self-reports suggested that the boys had participated in more overarm throwing than had the girls.