乒乓球运动节奏之功效

节奏是技术动作在时间、空间、力量等方面相互配合的一种综合表现,并存在于一切运动之中。运动节奏的合理与否、精确与否对掌握运动技术和提高运动技术水平以及实战效果均起着非常重要的作用。乒乓球每项技术本身以及与其他技术之间均包含着节奏和节奏变化。因此,正确的节奏对提高乒乓球技术、战术、比赛水平具有非常重要的意义。乒乓球比赛不仅仅需要运动员综合实力强,更要求教练员能够根据实战情况,指导运动员正确而巧妙运用节奏谋略,充分利用节奏变化,这样才能最终赢得比赛。     

论路由器中的路由选择

文章介绍了影响路由器中路由选择的因素,以及路由选择的全过程.     

存储过程在数据库编程中的应用

本文论述了存储过程的优点、创建和使用存储过程的方法,并通过应用实例进一步说明在使用存储过程时如何根据实际需要将存储过程的嵌套调用、游标和临时表等技术结合起来以充分发挥存储过程的性能优势.     

Competitive balance trends in elite table tennis: the Olympic Games and World Championships 1988-2016

ABSTRACT

Competitive balance is important because it enhances outcome uncertainty and therefore it promotes spectator interest, and encourages government investment in a sport. This article analyses the distribution of gold medals, medals, medal points and top eight points amongst nations in table tennis from 1988 to 2016 at the Olympic Games and the World Championships respectively. A normalised version of the Herfindahl-Hirschman Index and a coefficient of variation are calculated for each nation’s share of these performance indicators. The key findings are that China dominates both events, with successful female players being more dominant than their male counterparts. The competitive balance for gold medals has declined, whilst there is a trend towards improved competitive balance for top eight points for women, suggesting that more teams are featuring in the top eight (but not necessarily the top three) placings. This research has implications for the development of table tennis competitions. Compared to other racket sports, the issue of competitive imbalance in table tennis is particularly thorny, which threatens the long-term development of this sport. Accordingly, some measures are recommended for the International Olympic Committee and the International Table Tennis Federation to propel a more balanced development of international table tennis.     

第50届世界乒乓球锦标赛男单冠军王皓技战术分析

王皓在无机胶水之后的首届世锦赛中发挥出色,一举夺得他职业生涯首个世锦赛单打冠军。通过运用文献综述法、录像分析法、数据统计法对王皓在半决赛和决赛中技战术进行分析,试图找出无机胶水之后,王皓技战术的特点和优势,进而为运动员和教练员了解无机胶水之后技战术的变化提供一定的参考依据。     

合作学习教学模式在体育职业技术院校网球教学中的实验研究

为了更好地提高体育职业院校网球课的教学质量,我们在网球技术教学中采用“合作学习教学法”进行实验研究,结果发现“合作学习教学法”不仅利于提高学生学习的积极性、主动性和创造性,还有利于培养学生学习的能力和兴趣,有利于学生比较牢固地掌握网球技术。     

2011年澳网半决赛和决赛李娜技术指标统计分析

运用录像分析法对2011年澳网李娜半决赛、于底线型选手,主动得分能力强,非受迫性失误过多,够,上网成功率高。决赛的技术统计进行分析,研究结果表明：李娜属击球稳定性有待提高;发球成功率较高,攻击力不     

Differences in ball speed and accuracy of tennis groundstrokes between elite and high-performance players

Abstract

The main aim of this study was to identify and compare ball speed and hitting accuracy of forehand and backhand groundstrokes between ATP professionals (elite) and high-performance youth players when shots were played cross-court and down the line to a target square. Six elite and seven high-performance tennis players volunteered to participate in the study. A Doppler-radar device and a digital video camera, operating at 120 frames per second, were used to measure ball speed and accuracy of forehand and backhand groundstrokes in the respective situation (cross-court and down the line). The results of 1040 measured groundstrokes indicate that the ball speed of the forehand and the backhand ground stroke was higher in the elite group when analysing (1) all valid shots, (2) the six fastest shots, and (3) the six most accurate shots (all P < 0.05). In addition, all players achieved a higher forehand speed compared with their backhand when balls were directed cross-court (P < 0.01). The participants demonstrated similar ability when considering accuracy of their groundstrokes (P > 0.05). However, a group difference for accuracy was identified when considering the six fastest forehand shots (P<0.05), and the forehand cross-court stroke was played more accurately than the backhand cross-court stroke by both groups (valid shots and six most accurate shots, P<0.05). Moreover, there was no evidence that players who impacted the ball faster were any less accurate than those who impacted the ball more slowly. Analyses for participants actually revealed a negative correlation between ball speed and mean radial error (accuracy) for the backhand down the line (r= ? 0.77, P<0.01). According to the results of this study, ball speed seems to be the determining factor that separates elite from sub-elite tennis players.     

The importance of the International Tennis Federation's junior boys' circuit in the development of professional tennis players

Abstract

The relationship between junior boys' tennis success, as measured by a top 20 International Tennis Federation's Junior Circuit (ITFJC) ranking, and subsequent ranking accomplishments in professional men's tennis is discussed. The names, countries, and birthdates of all players to achieve a top 20 ITFJC boys' year-end ranking from 1992 to 1998 were recorded. The progress of these players through the professional ranks was then tracked to the end of 2004. Results indicate that 91% of top 20-ranked boys achieved a professional men's ranking, while a stepwise regression analysis revealed junior ranking (JR) to be a predictor of future, professional ranking (β = 0.232, r ² = 0.054, p < 0.05). A regression equation [predicted professional rank = 78.17 + 6.31?(JR)] accounted for a significant amount of variance in professional ranking. For male players, therefore, the achievement of a top 20 junior ranking appears to be a reasonable yardstick for future, professional success. The type of surface upon which junior players develop their games was also shown to influence professional ranking highs, with play on clay courts or a combination of clay and hard courts helping to produce higher, professionally ranked players than hard court play alone (p≤ 0.01).