Vision testing method for diameter,roundness and hardness of table tennis ball

Under the premise of fully respecting current national standard of table tennis ball,this paper presents an integrated and effective method for testing diameter,roundness and hardness of table tennis ball based on vision measurement. Firstly,camera calibration is performed by 40 mm gauge block to capture the images of table tennis ball in static and pressed state in an appropriate lighting condition. Then image binarization and extraction of image contour are carried out. The least square method is used to fit its center. Finally,the diameter,roundness and hardness are calculated. The measurement data are analyzed by using the method presented in this paper for table tennis ball with known parameter data and with unknown parameter data. Experimental results show that this method can improve measurement accuracy and provide a technical basis for the online testing and integration measurement of table tennis ball.

Correlation analysis of national elite Chinese male table tennis players’ shoulder proprioception and muscle strength

BACKGROUND Shoulder is the most injured part in table tennis players,and it takes multiple roles in transmitting power and striking the center of the ball during the stroke.Proprioception is strongly correlated with high level of athletic performance.It is customary to assume that there is a correlation between proprioception and muscle strength and therefore proprioceptive assessment and rehabilitation is often neglected.AIM To investigate the correlation between isokinetic muscle strength and proprioception in the internal and external rotation muscle groups of elite Chinese male table tennis players,to provide reference for physical training and rehabilitation of elite table tennis players.METHODS A total of 19 national elite table tennis players from the Chinese National Table Tennis Team were recruited in this research.All of them had more than 10 years training experience and had participated major competitions such as the National Games and World Youth Championships.IsoMed 2000 was used to test the peak torque of internal and external rotation isokinetic concentric contraction of the athletes'bilateral shoulder joints at low speed(60°/s)and high speed(180°/s)respectively;IsoMed 2000 was used to conduct the Joint Position Reproduction test to evaluate the athletes'proprioceptive ability capacity at low speed(60°/s)and high speed(180°/s)respectively.If the data satisfied the normal distribution,the correlation between the differences in peak torque s and angles in different directions was analyzed using a Pearson simple linear model;otherwise,Spearman correlation analysis was used.The comparison of proprioceptive ability between the table tennis racket-holding hand and non-racket-holding hands was performed using independent samples t-test if the data satisfied a normal distribution;otherwise,the Mann-Whitney U test was used.RESULTS There was no direct linear correlation between the strength and proprioceptive correlation analysis at slow speed(60°/s)and fast speed(180°/s)in the racket-holding hand;At the slow speed(60°/s)and fast speed(180°/s),there was no correlation between muscle strength and proprioception in the non-racket-holding hand except for the internal rotation variable error(VE)and external rotation relative peak torque,which showed a moderate positive correlation(r=0.477,P<0.05),(r=0.554,P<0.05).The internal rotation’s constant error(CE)and VE were 1.06±3.99 and 2.94±2.16,respectively,for the racket-holding hand,and-3.36±2.39 and 1.22±0.93,respectively,for the non-racket-holding hand;the internal rotation’s CE,VE of the racket-holding hand was lower than that of the non-racket-holding hand,and there was a highly significant difference(P<0.01).CONCLUSION There was no correlation between muscle strength and proprioceptive function in the internal and external rotation of the racket-holding hand’s shoulder in elite Chinese male table tennis players.These results may be useful for interventions for shoulder injuries and for the inclusion of proprioceptive training in rehabilitation programs.

Longitudinal trajectories of athlete burnout among young table tennis players: A 3-wave study

Purpose:The purposes of this study were to examine the trajectories of athlete burnout across a 2-month period characterized by high physical,psychological,and social demands to explore(1)whether several subgroups of athletes representing distinct burnout trajectories emerged from the analyses and(2)whether athlete burnout symptoms(reduced accomplishment,sport devaluation,and exhaustion)developed in tandem or whether some burnout dimensions predicted downstream changes in other dimensions(causal ordering model).Methods:One hundred and fifty-nine table tennis players in intensive training centers completed a self-reported athlete burnout measure across 3 time points within a 2-month period characterized by high demands.Data were analyzed through latent class growth analysis.Results:Results of latent class growth analysis showed 3 distinct trajectories for each athlete burnout dimension,indicating not only linear or quadratic change but also stability in longitudinal athlete burnout perceptions.Results also suggested that the 3 dimensions of athlete burnout did not develop in tandem.Rather,the likelihood of belonging to particular emerging trajectories of sport devaluation and physical/emotional exhaustion was significantly influenced by the athletes’perception of reduced accomplishment assessed at Time 1.Thus,reduced accomplishment predicted downstream changes in the 2 other athlete burnout dimensions.Conclusion:As a whole,these results highlighted that the multinomial heterogeneity in longitudinal athlete burnout symptoms needs to be accounted for in future research.

Testing method for veer of table tennis ball

Under the premise of fully respecting Technical Leaflet T3developed by the International Table Tennis Federation(I T T F),this paper proposes an effective method for testing the veer degree of the table tennis ball based on airflow suspension and machine vision.By sequentially capturing the images of the ball in the stable state of spinning and suspension,a set of fitting circle centres from different circular sections can be obtained by circle fitting through the least square method.The minimum circumscribed circle(MCC)diameter of these centres is served as a basic parameter to evaluate the veer degree of the ball.Experimental results show that this diameter can effectively reflect the veer degree of the ball.The method proposed in this papercan provide a technical basis for the veer online testing of the table tennis ball.

Analysis of the Duration and Rest Time of Wheel Chair Para Table Tennis at the Rio 2016 Paralympic Games

The purpose of this study was to analyse and compare the match characteristics of wheelchair PTT （Para table tennis） classes that played in the team tournament at the Rio 2016 Paralympic. Eight PTT matches of each selected class （1, 2, 4 and 5） were analysed.The variables analysed were DR （duration of rally） and RT （rest time）. In observing the characteristics of the matches in Classes 1, 2, 4 and 5, the DR corresponded to 3.4 ± 1.2, 4.2 ± 1.5, 4.5 ± 1.6 and 5.2 ± 1.2 seconds, and RT to 13.8 ± 3.5, 14 ± 3.5, 13.3 ± 3.1 and 12.3± 3.3 seconds. In Classes 1 and 2, significant differences in DR were found, but none in RT （p 〉 0.05）. In the DR and RT of classes 4 and 5 there were significant differences （p 〈 0.05）. The results indicated that the DR in Classes 1 and 2 were different because of sitting balance due to severe reduction of function in Class 1 playing arm, interfering in the rally and rest. In Classes 4 and 5 the differences in DR and RT were caused by little sitting balance in Class 4. These characteristics should be used by coaches to check the disadvantages that Class 1 presents against Class 2, and the physical limitations of Class 4 that can directly influence DR in the team tournament against athletes with normal trunk muscle function （Class 5）. Planned training prescriptions between classes would aim at achieving better sport performance in training and team tournaments.

The Impact of Developing Coordination Abilities on the Skill Abilities for Table Tennis Iuniors

The coordination abilities are closely related to the development of technical motor skills, where the player cannot master the technical skills in the special activity, in case lack of special coordination abilities for this activity. Many of table tennis experts agree on that the special coordination abilities for table tennis include each of： （1） the motor adaptation and adjustment ability; （2） the ability to differentiate; （3） reaction speed ability; （4） orientation ability; （5） balance ability; （6） coupling ability; and （7） the ability to sense the rhythm. The aim of this study is to design a training program to develop the special coordination abilities of table tennis and identify the impact of this program on the general skill ability for table tennis juniors. The researcher used the experimental method in two groups： One group is experimental group and another is the control group. The most important result of this study was the training program led to the improvement of the special coordination abilities of table tennis for the experimental group, which led to higher levels of the general skill ability in table tennis for the experimental group more than the control group.

乒乓球运动者正手弧圈球不同触地模式的下肢生物力学变化

背景:探讨基于步法的足部触地模式对乒乓球运动中下肢关节运动特征的影响,可为指导下肢训练提供科学依据。目的:对比乒乓球运动中不同触地模式下的运动学和动力学差异。方法:使用动作捕捉和三维测力台同步采集17名专业乒乓球运动员在正常触地和全脚掌触地模式下优势侧下肢的运动学和动力学数据。配对样本t检验用于分析关节角度、地面反作用力、关节反作用力和关节力矩等离散指标的统计学差异;统计参数映射用于分析足底压力中心移动轨迹和膝关节力矩等时间序列数据的统计学差异。结果与结论:①正常触地模式下的膝关节内翻、侧向地面反作用力、膝关节垂直反作用力和伸膝力矩峰值显著高于全脚掌触地模式;②在足底压力中心移动距离中的89%-91%运动阶段,正常触地模式压力中心显著远于全脚掌触地模式;③在X轴力矩曲线中的23%-38%运动阶段,正常触地模式的伸膝力矩显著大于全脚掌触地模式;④在Y轴力矩曲线的8%-18%运动阶段,全脚掌触地模式显著大于正常触地模式。通过对比不同触地模式的下肢生物力学特征值和统计参数映射分析结果,认为全脚掌触地模式可能是影响乒乓球运动表现的重要因素。乒乓球运动中需要针对性地对触地模式进行调整和练习,避免使用全脚掌触地模式,提升乒乓球运动者下肢运动能力。

A STUDY ON THE BASIC CHARACTERISTICS OF TABLE TENNIS TECHNIQUES AND THE REGULATIONS GOVERNING THE SAME

The paper applied the literature review,interviews and experimental methods in order to study on the basic characteristics of the table tennis techniques and the regulatrous goverming the same. Results showed that the table tennis technique had the three basic characteristics of opening,diversity and precisenese. The processing of the technique formation mainly reflected the three basic laws of the stage division,sequening and principle. Graspry ots basic characteristics and fllowing to its basic regulation in the tabletennis teaching and training can shorten the teaching process and improve its quality as well as master a variety of tbe techniqueds in short time.

Table Tennis Venus

In addition to Natalie Du Toit, another female athlete has competed in both theBeijing Olympics and Paralympics. She is Natalia Partyka, a table tennis player whowas born without her lower right arm.

高校乒乓球教练员执教能力提升对策

教练员的执教能力直接关系到运动员的训练效果以及在比赛中的表现,也是衡量教练是否合格的关键要素。在高校乒乓球训练中,教练员不可或缺。为了提高教练员的执教能力,促进高校高水平运动队的运动训练更加科学,使队员能够在比赛中取得优异成绩,就需要采取有效的措施确保教练员的执教能力得到提升。

“Table Tennis Mother”

GUAN Yan sat on the blue stand at Tianjin Stadium. Beside her were the members of China’ s National Table Tennis Team in purple sportswear. Looking at her, no one would associate this small, amiable, grey-haired old mother with the brave sportswomen and sportsmen, yet she is physician to China’s National Table Tennis Team. She has worked with them for 34 years, ever since the 26th World Table Tennis Championships. At that time she was 24 years old and a new graduate of

Closer China-Namibia Ties Forged in Table Tennis Training

At the request of the Chinese Embassy in Namibia,the Nanjing Municipal Government invited the Namibian Table Tennis Association to send a delegation to visit the city.Led by association President Ramon Hansen,the Namibian players received table tennis training from Aug 23 to Sept 5,2016.The delegation’s

乒乓球运动员心理素质培养的策略与方法

随着竞技体育水平的不断提高,心理素质已成为决定运动员竞技表现的关键因素之一。通过理论与实证研究,分析了心理训练在提高运动员适应能力、竞技状态和压力管理方面的作用,并提出了具体的心理训练策略。这些策略不仅有助于优化训练效果,还能显著提升比赛中的心理调控能力。通过案例研究和数据分析,旨在为乒乓球教练员和运动员提供一套科学、实用的心理训练指导方案。

碳纤维改性聚酰胺复合材料球拍制备及性能表征研究

乒乓球底板所使用的不同材料间性能差异较大,运动员可以根据自身的技术特长进行选择或个性化定制。文章以碳纤维及改性聚酰胺等为基础材料,经过复合加工制备了一种新型乒乓球拍,从该类型乒乓球底板特殊结构入手,对当前应用较多碳素球拍底板制备方法进行分析,通过与一般芳基纤维底板、玻璃纤维底板等的性能进行对比,总结出碳纤维复合材料乒乓球拍性能方面的优劣势。

基于表面肌电信号对乒乓球运动员挥拍动作的特征研究

通过对乒乓球运动员进行采集上肢表面肌电信号数据的实验,分析其在进行挥拍动作时的肌肉活动特征。实验对象为30名具有一定乒乓球训练经验的运动员,分别进行正手挥拍、反手挥拍的实验任务。通过表面肌电信号采集设备记录运动员挥拍时肌肉的电活动信号,并对信号进行预处理和分析,提取出肌肉活动的特征参数。利用BP神经网络算法比较表面肌电信号时域特征、频域特征以及时频特征对挥拍动作的影响及识别预测。通过比较肌肉活动特征,探讨乒乓球运动员在不同动作中肌肉协调和活动强度的变化,实验中可正确模拟采集上肢挥拍规律,在运动员基础训练中具有应用价值。

乒乓球战术五项指标统计法的建构与应用研究

为更好地提升乒乓球技战术定量分析效果,构建了乒乓球战术五项指标统计法,并与传统三段法的特点和具体运用进行了对比分析。结果表明:五项指标法破解了战术归“段”时固定得失分板数的规约,最大限度确保战术归“段”准确;厘清了由“抢”入“持”的衔接过程,更明确、深入地揭示由“抢”入“持”的衔接特点;战术指标的内涵更精准、贴切,更充分、准确地揭示运动员的技战术运用特点和世界乒乓球技战术发展的最新特点。