Morphology of the deltoid muscles in elite tennis players

The aim of this study was to examine the deltoid muscle properties of the dominant and non-dominant arm of Greek professional male tennis players. Eight male tennis players (mean age 22.0 years, s = 3.2) were subjected to biopsy of the deltoid muscle of both arms. Adenosine triphosphate (ATPase) histochemistry and myosin heavy chain (MHC) composition were performed on the samples with homogenate electrophoresis. No significant differences were observed in the percentage of types I, IIa, IIab, and IIb muscle fibres between the deltoid muscles of the two arms. Types I, IIa, and IIx muscle fibres of the dominant and non-dominant deltoid muscles did not differ significantly for MHC isoform composition. Type IIab muscle fibres showed a similar cross-sectional area (CSA) percentage distribution between the two arms. The CSA percentage for types I, IIa, and IIb muscle fibers did not differ significantly between the dominant and the non-dominant arm. We conclude therefore that regular tennis training probably does not lead to any significant changes in the muscle fibre types of the dominant and non-dominant arms of elite tennis players.     

Season of birth distribution of elite tennis players

In many competitive sports, the use of a cut-off date for junior competition has been associated with a skewed birth date distribution in junior and senior players. The International Tennis Federation uses a junior competition year that commences on 1 January. The purpose of the current investigation was to describe the birth date distribution of 448 elite senior tennis players and 476 elite junior tennis players. There was a significant season of birth bias among elite senior players (P <?0.001), with 58.9% being born in the first 6 months of the year. There was also a significant season of birth bias among elite junior players (P <?0.001), with 59.5% being born in the first 6 months of the year. This pattern was observed in both male and female players as well as in players from different regions. The results provide evidence that it is the cut-off date for the junior competition year that is responsible for the skewed birth date distribution in tennis rather than regional or climatic factors.     

Myosin heavy chain isoform composition in the deltoid and vastus lateralis muscles of elite handball players

ABSTRACT

The purpose of the present study was to compare the myosin heavy chain (MHC) isoform composition of the deltoid and vastus lateralis muscles of the dominant and non-dominant limbs in handball players. Eleven male Greek elite handball players (age 22.6 ± 1.9 yrs, training experience 10.6 ± 2.1 yrs, height 184.1 ± 4.1 cm, and weight 81.0 ± 12.5 kg) participated in the study. Four muscle biopsies were obtained from the dominant and non-dominant deltoid and vastus lateralis muscles during the in-season period. The MHC composition was determined using SDS-PAGE. No significant difference was found between the dominant and non-dominant muscles; Deltoid muscle: MHC I [(95%CI = ?1.22, 0.33), P = 0.228], MHC ΙΙa [(95%CI = ?0.32, 1.59), P = 0.168] and MHC IIx [(95%CI = ?1.49, 1.10), P = 0.749]; Vastus lateralis muscle: MHC I [(95%CI = ?0.38, 0.63), P = 0.586], MHC ΙΙa [(95%CI = ?0.50, 0.65), P = 0.783] and MHC IIx [(95%CI = ?1.08, 0.42), P = 0.355]. The findings of the present study indicate that the greater use of the dominant limbs for throwing actions and body movements in handball do not lead to altered MHC isoform composition compared to the non-dominant limbs.     

The asymmetry of pectoralis muscles is greater in male prepubertal than in professional tennis players

It is generally accepted that preadolescents have a limited capacity to develop muscle hypertrophy in response to exercise compared with older populations; however, studies are scarce and conflicting. The main aim of the present study was to assess if playing tennis is associated with the hypertrophy of dominant pectoralis muscles (PM) in professional (PRO) and in prepubescent tennis players (PRE). A secondary aim was to assess if the degree of asymmetry of PM is greater in PRO than PRE. The volume of PM of both sides was determined using magnetic resonance imaging in 8 male PRO (21.9 years), 6 male PRE (11 years, Tanner 1–2) and 12 male non-active controls (6 adults: 23.5 years; and 6 prepubescents: 10.7 years, Tanner 1–2). PRO and PRE had 15 and 30% greater volume, respectively, in the dominant than in the contralateral PM (P?P?=?.34 in adults and 5%, P?=?.17 in children). The degree of side-to-side asymmetry in PM volume was greater in PRE than in PRO (P?相似文献   

A comparison of visual search strategies of elite and non-elite tennis players through cluster analysis

Considerable research has documented that successful performance in interceptive tasks (such as return of serve in tennis) is based on the performers’ capability to capture appropriate anticipatory information prior to the flight path of the approaching object. Athletes of higher skill tend to fixate on different locations in the playing environment prior to initiation of a skill than their lesser skilled counterparts. The purpose of this study was to examine visual search behaviour strategies of elite (world ranked) tennis players and non-ranked competitive tennis players (n = 43) utilising cluster analysis. The results of hierarchical (Ward’s method) and nonhierarchical (k means) cluster analyses revealed three different clusters. The clustering method distinguished visual behaviour of high, middle-and low-ranked players. Specifically, high-ranked players demonstrated longer mean fixation duration and lower variation of visual search than middle-and low-ranked players. In conclusion, the results demonstrated that cluster analysis is a useful tool for detecting and analysing the areas of interest for use in experimental analysis of expertise and to distinguish visual search variables among participants’.     

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 effect of ball compression on the match-play characteristics of elite junior tennis players

The purpose of this article was to examine the effect of equipment scaling, through the modification of tennis ball compression, on elite junior tennis players (aged 10 years) within a match-play context. The two types of ball compressions that were compared were the standard compression (the normal ball) and 75% compression (termed the modified ball). Ten boys and 10 girls participated in the study. Participants were stratified into pairs based on their Australian Age Ranking and gender. Each pair played two two-set matches: one match with standard compression balls and one match with modified balls. The characteristics of each match were analysed and compared. The results showed that the use of the modified ball increased rally speed, allowed players to strike the ball at a lower (more comfortable) height on their groundstrokes and increased the number of balls played at the net. Ball compression had no effect on the relative number of winners, forehands, backhands, first serves in and double faults. The results are discussed in relation to skill acquisition for skilled junior tennis players.     

优秀网球运动员身高、体重和克托莱指数特征的研究

对ATP、WTA年终排名前50名的优秀网球运动员的身高、体重和克托莱指数特征进行了统计分析，探讨世界优秀网球运动员身高、体重和克托莱指数置信区间的特点及其身高与体重的回归方程，旨在为网球运动选材与运动训练提供理论参考。     

对世界优秀乒乓球女双选手李恩实/石恩美的技战术分析与研究

世界优秀乒乓球女子双打选手李恩实／石恩美(韩国)近年来在世界大赛保持着较好的战绩，是中国乒乓球队女双的头号劲敌。通过对她们的发球、发球抢攻、接发球段和相持段的技、战术特点进行分析，以期为中国乒乓球女双备战国际大赛提供参考。     

优秀散打运动员专项耐力及训练研究

加强优秀散打运动员专项耐力训练方面的研究是进一步提高散打竞技水平的重要途径之一。通过对部分优秀散打运动员专项耐力调查分析、根据散打运动专项耐力特点,提出散打运动专项耐力训练方法的几点建议,即针对不同队员制订不同的训练方法、合理安排运动负荷、遵循专项训练深化原则和训练形式多样化。     

Match activity and physiological load during a clay-court tennis tournament in elite female players

Abstract

The aim of this study was to determine the match activity and physiological demands of women's tennis during a 3-day clay-court tennis tournament. The activity profile of eight players was determined by filming each competitive match with video cameras. Metabolic-perceptual measurements–blood samples and individual ratings of perceived exertion (RPE)–were taken while the players were sitting during permitted changeover breaks in play. The activity profile of the players was as follows: strokes per rally, 2.5 ± 1.6; rally duration, 7.2 ± 5.2 s; rest time between rallies, 15.5 ± 7.3 s; effective playing time, 21.6 ± 6.1%; work-to-rest ratio, 1:2.1. Blood lactate concentration [2.2 ± 0.9 mmol · l^?1 (n = 50) vs. 2.2 ± 0.7 mmol · l^?1 (n = 48)] and RPE values [12.2 ± 2.4 (n = 57) vs. 12 ± 2.3 (n = 57)] were not significantly different (P = 0.65–0.78) between service and return games. The results highlight the importance of taking these factors (i.e. activity patterns and physiological profile) into account when planning training strategies for competitive females players. As such, tennis training regimes should be adapted to the specific demands imposed by match-play in female players on a clay-court surface.     

我国优秀女排队员移动拦网技术动作解析

1前言近年来世界排球大赛的实践表明，拦网已从单一的防守技术转变为攻防兼备的制胜技术之一。拦网水平的高低不仅直接影响比赛的胜负，而且也是衡量一支球队技战术水平的重要标志之一，因此，备受国内外教练员和科研工作者的关注。长期以来，有关拦网技术的研究，仅限于现场统     

优秀排球运动员比赛效能的评定

介绍运用效能评分法对排球运动员在比赛中进行技术评定的方法。此评定方法既简单易学、易用,又能比较客观地衡量每一个运动员在比赛中技术水平发挥的状况和比赛中的作用,为赛后进行总结和下一步的训练提供可靠的资料     

我国女子乒乓球运动员个性特征研究

我国女子乒乓球运动员16项个性因素具有典型的项目特征，总体状况表现为在乐群性、聪慧性、稳定性等7个方面趋向高分特征，而在有恒性、敏感性、怀疑性等7个方面趋向低分特征。我国女子乒乓球运动员与女篮、女排运动员相比，个性表现更为热情活泼、自信好强，与女大学生相比，其个性特征表现得较为鲜明，性格更为成熟。我国女子乒乓球运动员的双重个性均属于适应型、外向型、安详机警型和果断型。     

Utilization of cues in action anticipation in table tennis players

ABSTRACT

By manipulating the congruency between body kinematics and subsequent ball trajectory, this study investigated the anticipation capabilities of regional-level, college-level, and novice table tennis players using a full video simulation occluder paradigm. Participants watched footage containing congruent, incongruent, or no ball trajectory information, to predict the landing point of the ball. They were required to choose between two potential locations to make their prediction. Percent accuracy and relevant indexes (d-prime, criterion, effect size) were calculated for each condition. Results indicated that experienced table tennis players (both regional and college players) were superior to novices in the ability to anticipate ball trajectory using kinematic information, but no difference was found between regional-level and college-level players. The findings of this study further demonstrate the superior anticipation ability of experienced table tennis players. Furthermore, the present result suggests that there may be a certain “baseline” level of motor experience in racquet sports for effective action anticipation, while the addition of further motor experience does not appear to assist direction anticipation.     

世界优秀男子网球单打选手相持阶段的技术运用分析

对2005～2007年三届上海网球大师杯14名球员的12场单打比赛中相持阶段技术运用情况进行了统计分析,研究结果表明:(1)相持阶段得失分比例较高,占整个竞技过程的1/3,是整个竞技过程的重要组成部分.(2)正、反手抽球具有强烈上旋的底线型选手,具有较好的相持能力.(3)在相持阶段对抗中,正、反手抽球、正手侧身抽球技术的得分效率,得分比例较低,使用率较高.     

Motivational profiles in table tennis players: Relations with performance anxiety and subjective vitality

ABSTRACT

Research has suggested the need to use a person-centred approach to examine multidimensionality of motivation. Guided by self-determination theory (Deci & Ryan, 1985), the primary aim of the present study was to examine the motivational profiles in table tennis players and their composition by gender, country, training status, and competition levels (from recreational to international). The secondary aim was to examine the differences in performance anxiety and subjective vitality across the motivational profiles. Participants were 281 table tennis players from multiple countries, mostly the U.S. and China. Hierarchical and nonhierarchical cluster analyses were conducted and showed three motivational profiles with distinct quantity and quality: “low”, “controlled”, and “self-determined”. Chi-square tests of independence demonstrated significant differences in their cluster membership by country, formal training with a coach, and competition levels, but not gender. MANCOVA results indicated differences in performance anxiety and subjective vitality across the motivational profiles, in which the controlled profile had the greatest anxiety symptoms. These differences are attributed to the quality over quantity of motivation, which have meaningful implications for table tennis coaches and sport psychology consultants to diagnose and intervene with players in order to reduce their performance anxiety and improve their well-being.     

从2007年中网公开赛看中国女网夺取北京奥运单打奖牌的可能性

运用文献资料、录像观察、数据统计和比较等方法,对中国女网在2007年中网单打比赛中的技、战术指标进行统计与分析。结果表明：一发、二发得分率有很大提高,主动得分能力加强,非受迫性失误减少,战术不再单调,心理稳定;网前得分能力仍较差,前三板得分率不占优势,体能上仍存在问题。     

Acute effects of two different tennis sessions on dorsal and lumbar spine of adult players

The aim of the study was to evaluate the dorsal and lumbar spine of expert and recreational tennis players before (pre) and after (post) two different training sessions. The sample consisted of 17 male tennis players, nine expert and eight recreational males (age 21.2 ± 1.6 years). We assessed the back surface by rasterstereography pre and post two different training sessions both lasting 1.5 h: a standard training and a specific over-shoulder shots training session, respectively. Lordotic and kyphotic angle, length, imbalance, inclination for trunk, pelvic torsion, left and right lateral deviation and surface rotation were measured. Tennis expertise (expert versus recreational) significantly affected the surface rotation and right lateral deviation (P < 0.05). Trunk length was affected by intervention (pre versus post) (P < 0.05). Left lateral deviation differed both for type of session (session 1 versus session 2) and intervention (P < 0.001, P < 0.05). Expert tennis players had higher values on surface rotation and right lateral deviation, around or just above physiological values (0–5° and 0–5 mm, respectively). Type of session significantly affected left lateral deviation, indicating that over-shoulder shots lead to a higher stress for the spine; the workload produced by both single sessions led to a shortening effect on trunk length. A single training session can induce acute modifications in some parameters of dorsal and lumbar spine of players.