辽宁女排队员不同扣球空中击球技术动作的研究

运用三维录像法,对辽宁女排运动员三种不同扣球技术的空中击球动作进行比较分析,揭示辽宁女排运动员三种不同扣球的空中击球姿态的技术特征。研究结果表明,辽宁队女排运动员在三种不同扣球起跳腾空后首先表现为右膝向前屈膝,然后向后伸展摆动,而且后排扣球技术的屈膝幅度最大,髋关节角度的变化幅度也最大。     

中、外优秀男子排球运动员拦网技术的三维动作分析--3号位运动员向2号位移动拦高球技术

采用三维高速摄像方法在比赛中对古巴、中国、波兰、加拿大 4名中外优秀男子排球运动员拦网技术进行现场拍摄 ,以及三维录像动作解析和分析。结果显示 ,古巴和波兰运动员空中动作较好 ,拦网攻击性强 ,拦网击球瞬间重心高度较高 ;从栏网时机上看 ,拦网运动员晚于扣球运动员 0 .17s起跳较为适宜     

现代排球扣球技术研究进展综述

通过对近年来排球扣球技术主要研究成果进行文献资料的梳理与分析探究,结果显示：扣球技术的高度获取与助跑速度最后一步步幅有很大关系,一般运动员运用的是跨步式和并步式两种起跳方式;运动员在扣球时身体呈＂〈＂型和＂[＂型两种姿势,髋角度幅度变化大,挥臂速度就快;手臂肘关节甩直角度越大,指掌关节获得的速度越大,球速越快,且手臂速度的获得与腰的爆发力有关;为了更好地与其他技术动作相衔接,有必要对落地技术进行分析和研究。     

排球强攻空中姿态的运动生物力学分析

我们将排球强攻和扣球的空中姿态主要分为两种，分别称之为“〈”型和“［”型。研究数据表明，空中击球姿态为“〈”型的选手具有髋的移动幅度大、击球点高和球的出手速度快的特点，并且符合运动生物力学特征。本文认为，空中击球姿态是评价强攻扣球技术高下及是否合理的一个表观标准，并据此提出了改进技术训练的建议。     

第27、28、29届奥运会女排运动员身体形态和网上高度的动态研究

运用文献资料调研、数理统计与比较分析等方法对参加第27、28、29届奥运会女排各12支球队,576名运动员的身高、体重、扣球与拦网高度、HS、HB6项指标进行统计比较分析。结果表明：近3届奥运会女排运动员身体形态和网上高度总体上没有大的变化,但运动员身材有大型化发展的趋势;前4名球队各项指标均高于总体水平,非技术性指标优势明显。     

中国女排主要队员

主攻手 孙：担纲国家女排主攻手多年,属“重炮”选手,是队里的核心,扣球线路较长,变化多,但力量稍显不够,有后排进攻。 王丽娜：弹跳好,扣球力量大,但发挥不稳定,逆境时失误较多。 殷茵：篮球运动员出身的殷茵,扣杀力量大,擅长高球高点下手重扣,她是王丽娜的主要“竞争对手”,缺点是发挥不稳定,扣球路线变化少。 副攻手 吴咏梅：可以算是女排的老队员了,她下手快,拦网好,快攻和吊球相结合,在二号位和三号位都能打出好球。 陈静：从身材上来看,她并不符和如今副攻手身材高大的条件,但地打球变化多,速度快。赵蕊蕊：是有…     

对运用前臂负重法提高排球运动员上肢机能的研究

笔者拟对提高上肢机能的训练方法进行研究,并提出“前臂负重练习法”,为提高排球运动员的上肢机能水平,丰富排球训练理论提供较科学的理论依据。1.研究对象:研究对象共24人,八一男排、北航男排和北体大女排各8名队员。2.研究方法:文献资料法、实验法、影片拍摄法。3.结果与分析(1)对实验对象空中击球各关节的角度变化分析①对躯干角度变化的分析击球前后躯干角的变化幅度越大,利用躯干动量传递的效果就越好,但要加大躯干角度的变化幅度,就要求运动员具有良好的腰腹肌协调性和爆发力。提高运动员腰腹肌协调性和爆发力对提高运动员挥臂击球时…     

单脚背飞扣球运动轨迹与速度解析

运用摄影、测试、解析等方法,对两名优秀排球运动员的单脚背飞扣球全程的身体重心、上肢各关节运动轨迹与速度变化的解析,找出单脚背飞扣球较适宜的助跑距离、速度调整方式、起跳方法、起跳角度的控制以及肩、肘、腕关节的鞭打动作方法,使单脚背飞扣球运动技术模式更加完善。     

2010世界女排大奖赛中国队与前3名球队技术统计的比较与分析

采用录像法、文献资料法和比较分析法等,对2010年世界女排大奖赛前4名球队技术统计数据进行了比较与分析。结果发现,中国女排在比赛中表现出遇强则弱,遇弱则强的现象;扣球技术单一,拦网实力不如前3名球队;在防守方面与前3名队也有较大差距。中国女排在今后的训练中还应全面地提高运动员的技术水平以及相互之间配合的默契程度。     

中外优秀女子排球副攻运动员比赛中拦网技术比较研究

运用三维摄像方法对2011年世界女排大奖赛总决赛澳门站美国、巴西、中国3名中外优秀女子排球副攻运动员3号位向2号位移动拦网技术进行现场拍摄,旨在揭示拦网技术动作各环节运动学特征和规律。研究表明:美国和巴西女排运动员拦网技术较好,准备充分,判断准确,移动迅速,摆臂积极,起跳速度快、重心高度高、肩的高度高,拦网击球瞬间其髋角小、肩倾角小,躯干姿势以髋关节为中心呈"<"型,滞空时间长,落地技术动作衔接紧密,呈现出男子排球拦网技术的特点。     

Shoulder and elbow kinematics in throwing of young baseball players

In this study we compared the kinematic features of the throwing motion between young baseball players of different age groups. Forty-four Japanese baseball players aged 6.1 to 12.3 years who regularly played baseball, including pitchers and position players, had their throwing actions analyzed three-dimensionally using high speed videography. Of this sample, 26 players aged above 9 years of age were categorized as the senior group, while the remaining 18 were categorized as the junior group. Senior group throwers had greater height and body mass, and produced a greater ball speed than junior group throwers. The throwing arm movement of senior group throwers was similar to that of adult skilled players. However, in the junior group throwers, the shoulder horizontal adduction angle was larger during the arm acceleration phase, and the maximum angular velocities of elbow extension and shoulder internal rotation occurred later than in senior group throwers. These results indicate that players aged above 9 years can acquire a mature throwing arm movement, while players younger than that will use an immature motion. A possible reason why these differences were shown is that the official baseball is relatively heavy for junior group throwers; they would be better advised to use a lighter ball in throwing practice.     

Reply to Glazier: “Comment on ‘Influence of shaft length on golf driving performance’”

Abstract

In this study we compared the kinematic features of the throwing motion between young baseball players of different age groups. Forty‐four Japanese baseball players aged 6.1 to 12.3 years who regularly played baseball, including pitchers and position players, had their throwing actions analyzed three‐dimensionally using high speed videography. Of this sample, 26 players aged above 9 years of age were categorized as the senior group, while the remaining 18 were categorized as the junior group. Senior group throwers had greater height and body mass, and produced a greater ball speed than junior group throwers. The throwing arm movement of senior group throwers was similar to that of adult skilled players. However, in the junior group throwers, the shoulder horizontal adduction angle was larger during the arm acceleration phase, and the maximum angular velocities of elbow extension and shoulder internal rotation occurred later than in senior group throwers. These results indicate that players aged above 9 years can acquire a mature throwing arm movement, while players younger than that will use an immature motion. A possible reason why these differences were shown is that the official baseball is relatively heavy for junior group throwers; they would be better advised to use a lighter ball in throwing practice.     

Kinetics of the upper limb during table tennis topspin forehands in advanced and intermediate players

The purpose of this study was to determine the significance of mechanical energy generation and transfer in the upper limb in generating the racket speed during table tennis topspin forehands. Nine advanced and eight intermediate table tennis players performed the forehand stroke at maximum effort against light and heavy backspin balls. Five high-speed video cameras operating at 200 fps were used to record the motions of the upper body of the players. The joint forces and torques of the racket arm were determined with inverse dynamics, and the amount of mechanical energy generated and transferred in the arm was determined. The shoulder internal rotation torque exerted by advanced players was significantly larger than that exerted by the intermediate players. Owing to a larger shoulder internal rotation torque, the advanced players transferred mechanical energy from the trunk of the body to the upper arm at a higher rate than the intermediate players could. Regression of the racket speed at ball impact on the energy transfer to the upper arm suggests that increase in the energy transfer may be an important factor for enabling intermediate players to generate a higher racket speed at impact in topspin forehands.     

Variability in clubhead presentation characteristics and ball impact location for golfers' drives

Previous studies on overarm throwing have described a proximal-to-distal segmental sequence. The proximal segments reached their maximal linear velocities before the distal ones. In handball, no study has demonstrated this sequence from the upper torso to the wrist, although a recent study did present a different organization. The aim of this study was to analyse the throwing arm segmental organization during handball throwing. We found that the maximal linear velocity of the shoulder occurred after the maximal linear velocity of the elbow. Moreover, the maximal angular velocity of the upper torso occurred later than that of the elbow. Hence, contrary to other disciplines, the rotation of the upper torso was not suddenly stopped just after the forward arm motion was initiated. These results may apply to handball in general or be specific to the population of handball players studied. It may be advisable in future studies to include international players.     

Do handball throws always exhibit a proximal-to-distal segmental sequence?

Previous studies on overarm throwing have described a proximal-to-distal segmental sequence. The proximal segments reached their maximal linear velocities before the distal ones. In handball, no study has demonstrated this sequence from the upper torso to the wrist, although a recent study did present a different organization. The aim of this study was to analyse the throwing arm segmental organization during handball throwing. We found that the maximal linear velocity of the shoulder occurred after the maximal linear velocity of the elbow. Moreover, the maximal angular velocity of the upper torso occurred later than that of the elbow. Hence, contrary to other disciplines, the rotation of the upper torso was not suddenly stopped just after the forward arm motion was initiated. These results may apply to handball in general or be specific to the population of handball players studied. It may be advisable in future studies to include international players.     

The off-break and “doosra”: Kinematic variations of elite and sub-elite bowlers in creating ball spin in cricket bowling

This study sought to identify kinematic differences in finger-spin bowling actions required to generate variations in ball speed and spin between different playing groups. A 12-camera Vicon system recorded the off-spin bowling actions of six elite and 13 high-performance spin bowlers, and the “doosra” actions of four elite and two high-performance players. Forearm abduction and fixed elbow flexion in the bowling arm were higher for the elite players compared with the high-performance players. The elite bowlers when compared with the high-performance players delivered the off-break at a statistically significant higher velocity (75.1 and 67.1 km/hr respectively) and with a higher level of spin (26.7 and 22.2 rev/s respectively). Large effect sizes were seen between ball rotation, pelvic and shoulder alignment rotations in the transverse plane. Elbow extension was larger for elite bowlers over the period upper arm horizontal to ball release. Compared to the off-break, larger ranges of shoulder horizontal rotation, elbow and wrist extension were evident for the “doosra”. Furthermore, the “doosra” was bowled with a significantly longer stride length and lower ball release height. Although not significantly different, moderate to high effect size differences were recorded for pelvis rotation, elbow extension and elbow rotation ranges of motion.     

Kinematics of preferred and non-preferred handballing in Australian football

In Australian football (AF), handballing proficiently with both the preferred and non-preferred arm is important at elite levels; yet, little information is available for handballing on the non-preferred arm. This study compared preferred and non-preferred arm handballing techniques. Optotrak Certus (100 Hz) collected three-dimensional data for 19 elite AF players performing handballs with the preferred and non-preferred arms. Position data, range of motion (ROM), and linear and angular velocities were collected and compared between preferred and non-preferred arms using dependent t-tests. The preferred arm exhibited significantly greater forearm and humerus ROM and angular velocity and significantly greater shoulder angular velocity at ball contact compared to the non-preferred arm. In addition, the preferred arm produced a significantly greater range of lateral bend and maximum lower-trunk speed, maximum strike-side hip speed and hand speed at ball contact than the non-preferred arm. The non-preferred arm exhibited a significantly greater shoulder angle and lower- and upper-trunk orientation angle, but significantly lower support-elbow angle, trunk ROM, and trunk rotation velocity compared to the preferred arm. Reduced ROM and angular velocities found in non-preferred arm handballs indicates a reduction in the degrees of freedom and a less developed skill. Findings have implication for development of handballing on the non-preferred arm.     

Mechanical energy generation and transfer in the racket arm during table tennis topspin backhands

The ability to generate a high racket speed and a large amount of racket kinetic energy on impact is important for table tennis players. The purpose of this study was to understand how mechanical energy is generated and transferred in the racket arm during table tennis backhands. Ten male advanced right-handed table tennis players hit topspin backhands against pre-impact topspin and backspin balls. The joint kinetics at the shoulder, elbow and wrist of the racket arm was determined using inverse dynamics. A majority of the mechanical energy of the racket arm acquired during forward swing (65 and 77% against topspin and backspin, respectively) was due to energy transfer from the trunk. Energy transfer by the shoulder joint force in the vertical direction was the largest contributor to the mechanical energy of the racket arm against both spins and was greater against backspin than against topspin (34 and 28%, respectively). The shoulder joint force directed to the right, which peaked just before impact, transferred additional energy to the racket. Our results suggest that the upward thrust of the shoulder and the late timing of the axial rotation of the upper trunk are important for an effective topspin backhand.     

Effects of latissimus dorsi length on shoulder flexion in canoeists,swimmers, rugby players,and controls

BackgroundShoulder flexion requires an optimal length of the latissimus dorsi muscle in order to allow full lateral rotation of the humerus and upward scapular rotation. If shoulder flexion (in an externally rotated position) is restricted, this may predispose the individual to shoulder pathology. Sports such as swimming and canoeing have increased shoulder injuries and require high levels of latissimus dorsi muscle activity, which may create muscle hypertrophy and increased stiffness, resulting in a loss of muscle length. The objective of this study was to investigate if differences are present in shoulder flexion in internally and externally rotated positions across different sports (swimming, canoeing, and rugby) and a non-sporting control group.MethodsOne hundred subjects (40 physically active controls, 25 professional Rugby Union players, 20 elite, national-level canoeists (slalom), and 15 elite, national-level swimmers) participated in this study. Shoulder flexion range of motion was measured using a standard goniometer, with the arm elevated in either full external or internal rotation.ResultsA significant difference in shoulder flexion range was observed between canoeists and swimmers, canoeists and controls, rugby players and canoeists, rugby players and swimmers, and controls and swimmers in the external rotation position (p < 0.017), but not between controls and rugby players (p = 0.12). For the internal rotation position, swimmers significantly differed from canoeists, rugby players, and controls (p < 0.017), but there were no significant differences between rugby players, canoeists, and controls (p > 0.07).ConclusionThis study found that the length of the latissimus dorsi differs between sports and controls in accordance with the specific physical demands of their sport.     

Comparison of kinematics in skilled and unskilled arms of the same recreational baseball players

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.