|
Measurement of table tennis ball rebound using acoustic techniques
Z.D. Al-Kurdi1 and H.A. Al-Nashash2
1Faculty of Physical Education, Yarmouk University, Irbid-Jordan, 2School of Engineering, American University of Sharjah, U.A.E., kurdi11@hotmail.com
It is until the international federation of table tennis has formed the sports science committee few biomechanical studies have been devoted to the analysis of table tennis. Recently a number of researchers focused their work on the science of table tennis (Renfew, 1979; Fukunage et al., 1989; Shaofa, 1980; Huangun, 1980; Zhoughui, 1982; Lokhov and Reznikov,1993; Schiltz 1993; Yutaka and Yoshitsugu, 1998; Toshiko et al., 2000).
Measurement of tennis ball rebound is important for both improving players’ techniques and verifying the uniformity of the table upper surface. Several methods have been developed to measure and present the dynamics of the table tennis. Researchers used the conventional video camera to record the rebound of a ball. In this research, we present a portable, simple to operate electronic system for providing accurate measurement of table tennis ball rebound. It is composed of test specimen, ball release mechanism, bounce detector and a timer. It is believed that such system will be helpful for players, coaches, manufacturers and technical committees.
Muscular activity of the backhand and forehand top spins in top table tennis players : implications for physical training S. Ambrosino, F. Borrani, O. Skénadji, J.P. Micallef and G.P. Millet Faculty of Sports, ave. Pic Saint-Loup, Montpellier, France, ambrosino.stephane@caramail.com Introduction. Until now there has been no study carried out on the muscular activity of top table tennis players. But now muscular training is playing an increasingly important role in the development of the sport and likewise with the contribution of the different muscular groups involved in different shots and when using different levels of intensity. The aim of the present study was to quantify the activity of the biceps, triceps, pectoral muscle, deltoid muscle and latissimus dorsi muscle amongst top level table tennis players - both for forehand (CD) and back-hand (REV) tops spins and in relation to different ball speeds. Methods. 7 subjects (age: 24 ± 5 years ; height : 181 ± 5 cm ; weight : 71,3 ± 3,7 kg) top level (within the French Table Tennis Federation 2346 ± 164 points) carried out 8 exercises of 30 s of backhands and fore-hands at 4 different ball speed levels. The acquisition of electromyographic signals from each muscle was carried out with surface electrodes using the Bagnoli (Delsys, USA) system - at a frequency of 1024 Hz . The average rectified values (ARV) were then worked out and the balls speeds measured accordingly (radar Speed Check, Canada). Results. The 4 ball speeds were different . (V1 : 27 ± 5 vs 31 ± 6 ;V2 : 43 ± 3 vs 40 ± 7 ; V3 : 57 ± 6 vs 53 ± 7 ; V4 : 92 ± 8 vs 88 ± 11 km.h-1 for backhand or forehand, respectively). Yet no difference was observed between backhand and forehand. The ARV of the 5 muscles studied in both forehand and backhand is shown in table 1.
The sum of ARV is not different to an equivalent speed between forehand and backhand. The relative participation of each muscle is different according to the different speeds used. The sum of ARV is significantly different between V1 and V4 in the pectoral muscle (CD: 0,93 ± 0,24 vs. 2,95 ± 0,33 ; REV : 1,28 ± 0,47 vs 3,48 ± 0,34), the triceps (CD : 0,28 ± 0,12 vs 1,06 ± 0,13 ; REV : 0,61 ± 0,16 vs 1,46 ± 0,30) and the biceps (CD : 1,22 ± 1,08 vs 2,13 ± 0,54) No other difference was found. The sum of ARV and the ball speeds were then correlated. : (R2=0,996). Discussion and Conclusion. The muscles studied can be said to have different functions and uses. The latissimus dorsi muscle and the deltoid muscle are mainly involved in V1. The great effort involved at this intensity consists of maintaining the arm in an appropriate position. The relative contribution of the biceps and the pectoral muscles is most important at V4, their role is to increase the power of shots played. The biceps seems to play a more significant role in high speed forehands. It is worth remembering that in table tennis no less than 82% of points are scored at the third hit of the ball ; which indicates that power is indeed a key factor when it comes to performance. This in turn demonstrates the interest of power and speed related training in relation to the biceps, triceps and pectoral muscles. This demonstrates that amongst those top players who have developed the qualities of muscle control, a specific physical training aimed at an improvement in strength can indeed lead to greater ball speed.
A process oriented approach for match analysis in table tennis
A. Baca and R. Baron
Department of Sport Science, University of Vienna, Auf der Schmelz 6, A-1150 Wien, Austria
In order to identify strengths and weaknesses in the technical and tactical behaviour of racket sports players and to find out possible reasons, structure and process oriented models of the match are constructed. If process oriented models are used, the temporal evolution of the match may be described. This approach has successfully been applied to table tennis (e. g. Boguschewski et al., 1994, Tischtennis Lehre, 8 (1), 5-8). It has therefore been selected to analyse and improve the behaviour of players of the Austrian national and youth national team. In addition, methods from exercise physiology (acquisition of physiological parameters during training and competition) and sports psychology are applied. In cooperation with trainers and players of the Austrian national team a model has been developed for a process oriented description of the match. In addition to grip (shakehand / penhold), left/right handed, type of player (offensive/defensive) and rubber sheet, the model comprises information on
Matches are recorded by a video camera and evaluated afterwards. The possibility to record heart rates synchronized to the video has been provided. Heart rates can therefore be analysed in relation to observable actions of the match. Since the times, when the ball is hitting the table are registered by using the time code information from the digitised video, selected scenes (e. g. related actions found out by using filter functions) may be displayed sequentially with digital video. Since only some matches have been evaluated so far (the system will be employed more intensively from January to April, 2003) only partial results are available at the time of writing. From these, it may be concluded that the method is applicable to answer questions from practice, such as
It is expected that unknown, new and potentially useful information will be found, if larger data sets are available. Methods from artificial intelligence and data mining are to be used for this purpose. Based on the results of the analysis feedback has been and will be given to trainers and players or feedback systems will be applied in training. One aim is the quick presentation of selected meaningful video scenes. Another is to give the player immediate acoustic or optical feedback in training on the position and/or quality of the ball just played. Methods for detecting the point, where the ball hits the table automatically in real time are under development. One approach is to fix three accelerometers onto the underside of the table and to determine the hitting point from the vibration signals. From first experiments it is expected that the method will be accurate enough.
Cardiovascular follow up of young elite squash players
J. Bady1, S. Messager2 and P. Signoret3
1A. Brillard Hospital, 94130 Nogent sur Marne, 2Henri Mondor Hospital, Department of Cardiology, 94000 Créteil, 3Fédération Française de Squash, 94100 Saint-Maur, France, messteph@aol.com
Authors assured the cardiovascular follow-up of 12 young athletes (8 to 13 years old) having an intensive practice of squash (French Hopes) on a period of five years. The initial objective was to assure the protection and the adaptation of the cardiac functions of the young, submitting children to a specific squash effort, and to define parameters of survey and security of the child's growth. In our set, neither pathology nor cardiac failure has been discovered, as well as no hindrance to the physiological and morphological development. This work is only a stage of the observation of the characterization of the profile of the squash player. It defines the necessary medical attention of the follow-up of the teenager and prefigure futures studies. A standard examination includes a questioning on medical history, specifying the personal backgrounds (cardiac illness in the family), factors of risk, symptoms appearing during effort, etc.; a clinical examination with an attentive cardiac auscultation, arterial blood pressure and arterial palpation, and an ECG. To the term of this first exam, it is already possible to track down some serious cardiac abnormalities : a valvulopathy, rhythm or conduction abnormalities, a long QT syndrome, an arythmogenic dysplasy of the right ventricle, a WPW syndrome, an hypertrophic cardiomyopathy, obstructive or not. This initial exam permits to orient the complementary exams. To ascertain the integrity of the cardiovascular system, it is necessary to study the adaptation during effort as well as during recovery. In a recent classification made in Bethesda (USA), squash is considered as a sport with a weak isometric and a strong dynamic component, that is to say putting in play large muscular masses. It results that heart rate, cardiac output and VO2max are much more elevated as the effort is becoming more intensive; however blood pressure changes just a little. The other factors to take into consideration are the length of exercise (running time), the environment (hot or cold atmosphere), the state of dehydration (decrease of the physical performance), and the level of physical fitness. With regard to our personal experience, spread out on a period of 5 years, we can mention that : - no child who underwent an intensive practice with competitions at the national level, and who did not present any anomaly at the beginning, didn't develop a cardiac or arterial pathology during the period of survey. - the rare abnormalities of auscultation or on the ECG which progressively appeared during the survey, proved out to be benign, and never required a complementary examination. - the different parameters showed a normal evolution, in line with age and the child's physical development. We can say therefore, contrarily to those that accuse squash to be too much aggressive for child's heart, that with regular controls and a suitable medical follow-up, this sport can perfectly be recommended to children.
3D intra articular kinematics of the human acromioclavicular joint : in vitro study linking kinematic data obtained by electromagnetic trackers to 3D reconstructions of the joint configurations
J.P. Baeyens, P. Van Roy, E. Cattrysse and J.P. Clarijs
Dep. Experimental Anatomy, Vrije Universiteit Brussel, Brussels, Belgium Laarbeeklaan 103 1090 Brussel, j.baeyens@pi.be
In throwing and racket sports the acromioclavicular (AC) joint can cause severe dysfunction and pain in the shoulder. Yet intra articular kinematics of the AC joint is still unclear. This presentation concerns an in vitro study using a new method linking electromagnetic kinematic tracking (Flock of Birds) and 3D reconstruction of the articular surfaces using a 3D digitizer (Microscribe)
Seven acromioclavicular (AC) specimens were taken from freshly embalmed human cadavers. The scapula was vertically fixed to a holder in such a way that the clavicula was fully free to move. 3D electromagnetic tracking sensors were fixed on the clavicula and scapula. Subsequently, each clavicula was moved through a selection of directions: pro/retraction, elevation/depression and anterior/posterior translation. The positions and rotations of each sensor were collected. A typical movement consisted of three cycles in which the joint was moved through its full range of motion. The individual sensor data were used to determine the parameters of the finite helical axes for discrete sampling ranges of AC motion: i.e. orientation, position, shift along and rotation about the estimated helical axis. Subsequently, the positions of local anatomical landmarks and joint surface configurations were digitized with a 3D drawing stylus. These anatomical data were used for the definition of local bone or articular surface embedded co-ordinate axes. To analyze the 3D intra articular kinematics of the AC joint, the finite helical axes were related to a co-ordinate system based on the configuration of the facets of the AC joint. Furthermore, attention will be given to the shift parameter. The clinical impact of the kinematic results will be discussed in context of the mobilization and manipulation techniques as used in manual therapy.
Glenohumeral arthrokinematics of two test-cases with internal impingement at the late preparatory phase
J.P. Baeyens, P. Van Roy, E. Cattrysse, G. Declercq and J.P. Clarys
Dep. Experimental Anatomy, Vrije Universiteit Brussel, Brussels, Belgium Laarbeeklaan 103, 1090 Brussel, j.baeyens@pi.be
IntroductionWithout signs of anterior glenohumeral instability, throwers and racket sportsmen may present posterior shoulder pain at the end of the late preparatory phase, related to articular side rotator cuff injuries and/or posterior-superior glenoid labial injuries. This clinical presentation was labeled ‘internal impingement’.
MethodsThis paper compares the arthrokinematic results obtained from two test-cases suffering from posterior shoulder pain at the end of the late preparatory phase with non-symptomatic subjects. Initially, these two throwers presented instability nor impingement signs. Within two years, these two problematic shoulders had evolved into an articular side rotator cuff lesion (as confirmed by MRI) without instability signs. The experiment comprised an early stage measurement of the relationships of the glenohumeral joint in two poses. Related to the anatomical planes, the shoulder was first set in 90° abduction and 90° external rotation (pose 1). Subsequently, the late cocking position with the arm maximally externally rotated was assessed (pose 2). Helical CT-data of these discrete shoulder positions were three dimensionally reconstructed. Based on humeral and scapular sets of skeletal landmarks, rotation matrices and translation vectors were estimated and processed in a glenohumeral Euler convention and finite helical axes.
ResultsThe arthrokinematic data between pose 1 and pose 2 demonstrated the following differences: For the normal shoulders, the relative and absolute contribution of intra-articular external/internal rotation (nKG (+/-): external/internal rotation component of the direction vector; qKG (+/-): external/internal rotation magnitude) was minimal (nKG 0.05, -0.01 and –0.21 with qKG 0.27°, -0.18° and –1.67°). In contrast, a significantly different large external rotation component (nKG 0.83 and 0.85) together with a significantly different large external rotation magnitude (qKG 28.43° and 27.22°) were found in the symptomatic shoulders with internal impingement. In the late cocking pose, the centre point of the humeral head of both the internal impingers and the normal shoulders translated into a posteriorly localized position on the glenoid cavity (related to the center of the glenoid -7.54 and –7.73 mm, respectively -7.63, -8.51 and –6.42 mm).
DiscussionInternal impingement has been associated in literature with excessive external rotation with or without anterior-inferior glenohumeral instability. The arthrokinematic data in this study support the impact of excessive external rotation without anterior instability in the development of an internal impingement syndrome. Preventive strategies will be discussed.
The perception of factors that contribute to world class table tennis performance : a comparison of the English and Swedish national junior squads
M.A.K Bawden1, J. Waldner2 and I.W. Maynard1
1Centre for Sport & Exercise Science. Sheffield Hallam University, Collegiate Crescent Campus, Sheffield, UK, m.a.bawden@shu.ac.uk , 2Swedish Table Tennis Federation.
This study investigated the perceptions of the factors that underpin world class performance in table tennis in the English and Swedish national junior squads. The initial phase of this study required the coaches of the two nations to establish the factors that they considered to be important for an individual to become world class in table tennis. The players of both nations then ranked these factors from most important to least important. The players were then required to rate themselves on each of the factors. The hierarchy of factors for the Swedish squad (n =14) were : enjoy playing, self-confidence, motivation to reach goals, natural talent, support from parents, understanding the game, ability to practice hard, good coaching, good practice partners, ability to cope with pressure, physical fitness, good technique, tactical awareness. The hierarchy of factors for the English squad (n = 19) were : enjoy playing, motivation to reach goals, self-confidence, ability to practice hard, ability to cope with pressure, physical fitness, support from parents, understanding and reading the game, tactical awareness, natural talent, good technique, good practice partners, good coaching. The two major differences that existed between the two nations were their perceptions of ability to deal with pressure, and natural talent. The English players perceived ability to cope with pressure as being an essential factor whereas the Swedish players did not see this factor as being as important. For the Swedish players natural talent was perceived to be very important in order to become world class, however the English players did not perceive this to be a major factor. The findings are discussed with reference to cultural differences in attitude, and the perceived competencies of the two nations.
The sources of stress for junior table tennis players who attend the English national training centre
M.A.K. Bawden, B.J. Chell and I.W. Maynard
Centre for Sport & Exercise Science. Sheffield Hallam University, Collegiate Crescent Campus, Sheffield, UK. m.a.bawden@shu.ac.uk
The sources of stress in elite athletes has been well documented in the academic literature (Jones, Swain & Cale, 1990). However, a new development in contemporary sport has been the emergence of national training centre's. When attending these centres many young sports performers are required to live and train within this highly intense environment. The young athlete is required to adapt to many life changes in order to reach the top level in their sport. These adaptations often involve many extra life stressors that contribute to the pressure that athletes perceive themselves to be under, in their quest to reach their potential. The present study interviewed players (n = 20) and coaches (n = 4) at the national table tennis academy in England. The players were asked to identify the sources of stress that negatively influence their performance. The coaches were also required to identify the sources of stress that they perceived the players to be under. The interview required the players and coaches to rank the sources of stress from most stressful to least stressful. The most commonly sighted sources were then placed into an overall hierarchy of sources of stress for both players and coaches. The ten sources of stress that were rated highest for players were : the critical eye of coaches, personal pressure, the constant need to win, living at the centre, other players perceptions of their ability, parents, the need to reach goals, playing players worse than themselves, the perception of people outside the centre and lack of freedom to socialise. The ten highest rated sources of stress as perceived by the coaches were : parents, coaches, lack of social activities, the need to win, the need to improve, evaluation from peers, selection, school, living away from home and the demands of training. The findings are discussed with reference to recommendations to help young players cope with stress when living, training and competing, whilst attending a national training centre.
Effect of the Type 3 (oversize) tennis ball on physiological responses and play statistics during tennis play
J. R. Blackwell1, E.M. Heath2 and C. J. Thompson1
1University of San Francisco, 2130 Fulton Street, San Francisco, California 94117-1080 USA 2Utah State University, 7000 Old Main Hill, Logan, Utah 84322-7000 USA, blackwell@usfca.edu
The International Tennis Federation (ITF) has officially amended the Rules of Tennis in order to approve the use of two new types of balls in tournament play. The aim of introducing the new balls is to either speed up the game (fast-speed, Type 1 ball), or slow down the game (slow-speed, Type 3 ball), compared to the game when using the regular (medium-speed, Type 2) ball. The physics associated with the balls is predictable, and has been confirmed using the Type 3 ball (Blackwell, et al., 2002, Sports Biomechanics, 1(2), 187-191; Brody, 1987, Philadelphia: University of Philadelphia Press; Haake, et al., 2000, Sports Engineering, 3, 131-143). The effect of the Type 3 ball on the players' physiological responses, however, is in question. Anecdotal evidence suggests that senior players tend to default (quit) during match play at a higher rate than when playing with the medium-speed ball. The ITF web site, however, states players do not fatigue while using the Type 3 ball (http://www.itftennis.com/html/rule/framesettst.html). The purpose of this study was to investigate differences in physiological responses of tennis players, and confirm play statistics, using the Type 3, slow-speed ball compared to the regular, Type 2 ball. Twenty skilled tennis players, assigned as opponents by skill level, participated in ten matches, each lasting one hour. Half the time was spent using the Type 3 ball and half the time they played with the regular ball. The order of the ball type was randomized. The mean heart rate for a player while playing with a particular ball was obtained from heart rate monitors (Polar Vantage NV) that collected average heart rates over 5 second time periods. Activity monitors (Stay Healthy RT3) measured motion (acceleration) levels every second with an accelerometer, and these values were averaged for the 30 minute play period. Matches were videotaped to allow for play analysis. Heart rates while playing with the Type 3 ball were 156.8 + 17.8 bpm (mean + SD) and significantly (p<0.05) greater than the heart rates of 152.8 + 17.0 bpm, measured while playing with the regular ball. Statistical significance was also demonstrated for the activity levels (arbitrary units), as Type 3 ball play resulted in 2024.8 + 314.7 units, a higher value than the regular ball result of 1919.7 + 267.1 units. Additional to the physiological variables, significant differences were revealed when looking at play statistics. Using the Type 3 ball, the average percentage of good, first serves, was 75.4 + 10.5%. This is higher than the average using the regular ball, which was 65.3 + 18.6%. The average number of good shots during a rally was also significantly higher while using the Type 3 ball (4.3 + 1.1), compared to the average while using the regular ball (3.6 + 1.0). The development of the Type 3 ball is aimed at reducing the speed of the ball and at the same time making tennis easier to play. This ball is slightly (6%) larger than the regular ball, and the larger size causes additional drag and allows for a greater Magnus effect. This translates into more accuracy and a greater number of balls that stay in the court of play compared to the regular ball. It is logical that players' heart rates and activity levels would increase during Type 3 ball play because the rallies last longer. It is also logical that these results support anecdotal reports that players fatigue more while using the Type 3 ball compared to the regular ball. However, these results seem to contradict the ITF statement that players can play 35% longer while using the Type 3 ball.
Equipment and evolutionary pedagogy in tennis
W. Bothorel
French Tennis Federation, 2 avenue Gordon Bennett, 75016 Paris, France, wbothorel@fft.fr
This presentation aims, through an analysis of the fundamentals and main tennis play parameters, at introducing the latest evolution in tennis teaching and practise. "Evolutionary tennis" (le tennis évolutif), a pedagogy adapted to all ages and all levels, from beginners to confirmed players. Today's pedagogy and equipment used allow a teaching far more oriented towards success and "real play" situations. These principles apply in all teaching programmes developed by the French Tennis Federation : mini-tennis, the junior club, the adult tennis programme and school tennis.
Ultrasonography of the foot and ankle in racket sports players
J.L. Brasseur
CHU Pitié-Salpétrière, Service de Radiologie Centrale, 47-83 boulevard de l’Hôpital, 75651 Paris Cedex 13, France, JLB.RX@wanadoo.fr
Recent advances in ultrasound technology and the development of high-resolution ultrasound transducers have enabled detailed depiction of superficial musculoskeletal structures. The advantages of ultrasound includes wide availability and dynamic evaluation. The main disadvantage is the difficulty of ultrasonography, especially for foot and ankle, and diagnostic accuracy requires time, knowledge and meticulous attention to technical parameters. Ultrasound can be used to evaluate joints, ligaments, tendons, plantar fascias, fore-foot diseases and to look for foreign bodies. Power Doppler can be used to evaluate blood flow. The standardisation of the procedure and the production of normal reference images seems to guarantee a global increase in quality of the sonographic examinations. The diagnostic and therapeutic impact is very important regarding the low cost of this technique.
Self-regulated learning of the forehand top spin in table tennis
A. Bund
Technical University of Darmstadt, Magdalenenstr. 27, Darmstadt, Germany, abund@gmx.net
IntroductionThe effectiveness of self-regulation, or self-control, for learning has been demonstrated in the verbal or cognitive learning for a number of years (for an overview see Boekaerts et al., 2000, Handbook of self-regulation, San Diego a.o.: Academic Press). More recently, researchers have also begun to examine the effect of self-regulation on motor skill learning. In general, these studies show that self-regulation during the learning process can lead to better motor performance. However, in previous studies the researchers stated which aspect of the practice situation should be self-regulated by the learner. Individual preferences have not been considered. Thus, the purpose of our study was to examine the effects of self-regulating a preferred versus non-preferred practice condition during learning the forehand top spin in table tennis. It was hypothesized that participants who can self-regulate a preferred practice condition outperform participants who have the control over a non-preferred practice condition. Method First, the participants (N=52) filled out a questionnaire in order to check up which practice conditions during the learning of the top spin-technique they would prefer for self-regulating and which not. The most preferred practice condition was the frequency of movement instruction; the less preferred condition was the choice of tasks during a practice session. Based on this results the subjects were randomly assigned to one of the following experimental groups: (1) Self-regulation of a preferred practice condition; (2) Self-regulation of a non-preferred practice condition; (3) Regulation of a preferred condition by the instructor; (4) Regulation of a non-preferred condition by the instructor. After a baseline test all participants completed two practice sessions, separated by a 2-day interval. Each practice session consisted of 100 trials. On the following days, the participants performed retention and transfer tests. All sessions (baseline, practice, retention, and transfer) were videotaped. The dependent measures included form (rating of experts) and ac-curacy (target area) of the forehand top spin. ResultsMovement accuracy: All groups demonstrated a consistent increase in the accuracy of the movement across the practice trials (F(9,432)=7.42; p<.001). The main effects of self-regulation and preference were not significant. Also on the retention test there were no significant differences between the groups. On the transfer test, groups that had controlled their practice on a preferred condition (independent from self-regulation or not) had clearly higher scores than the groups that had regulated a non-preferred practice condition (F(1,48)=4.98 p=.03). Movement form: In terms of movement quality, we found across the practice phase a tendency for better performance of the self-regulating groups as compared with the groups that were regulated by the instructor (F(1,48)=3.72; p=.08). Again, on the retention and transfer tests the self-regulated groups had higher form scores than the instructor-controlled groups (F(1,48)=3.42; p<.05 and F(1,48)=5.95; p<.01). Discussion Our goal in this study was to examine whether self-regulated movement learning is more effective, when it refers to a practice condition which is preferred by the learner. The results show differential effects of self-regulation and the preference of practice conditions. Altogether, the findings suggest that the benefits of self-regulated learning are not only caused by motivational processes. Rather it seems to be important to consider cognitive processes, e.g. the processing and representation of movement-related information.
The reciprocal method in the teaching of badminton
D. Cabrera Suarez and G. Ruiz Llamas
Departamento de Educación Física, Universidad de Las Palmas de Gran Canaria, Spainmcabrera@def.ulpgc.es / gruiz@def.ulpgc.es
This paper is basically a comparison between the use of a directive way of teaching (softened direct command) and reciprocal teaching for badminton at an elementary level. The main objectives are: a comparison of the results in efficiency at play of students who have been taught only through softened direct command, and others who have received reciprocal teaching when learning badminton ; the suggestion of alternative methods for the teaching of these racket activities ; the use of a methodology which allows more participation in the teaching of badminton ; noticing the effectiveness of observational papers and their use in other sport rackets. The teaching of badminton, and of other racket activities, has traditionally used direct command exclusively, more or less softened, and this has proved efficient and there is no doubt about its quality. But the problem rises with large groups of students, because they cannot receive properly the necessary individualised information, before or after every situation, and this is an important condition for successful teaching, as Adams suggests. This paper is the result of an attempt to find a solution to this problem. We try to get to individualise, as far as conditions allow, the teaching process and, at the same time, to involve the students from three points of view: motor, affective and cognitive. For this we have tried to use a different and complementary way of teaching, i.e. reciprocal teaching. In this way the students were able to individualise, in some of the sessions, the information about its implementation. At the same time, they had an active participation in the process, far from just an obedient attitude. Subjects : two groups of students (102 boys and girls together) of badminton. Materials : one group was given specific observation sheets. A test for measuring the efficiency in the play was also given to both groups. Methodology : One group (A) was taught only through “softened” or “modified” command. The other one (group B) was taught trough a combination of two ways, i.e. softened direct command and reciprocal teaching. First, direct command was used to order the different types of hits and to mention usual exercises or play routines; later on, reciprocal teaching was used after three different hitting techniques during the main part of the session, and the students were given an observation sheet which they had to give back to the teacher at the end of the session. The students received from the teacher all the necessary information about the elements that had to be observed, and activities unknown to the students were never included. They were then grouped in twos on the different playing fields. Two of them performed the hits suggested in the sheet and other two observed. These functions were later alternated. Every student had a sheet and had to fill it in, giving the names of the “performers” and the “observers”. Results : group B had better results. This was the group using the observation sheets, which meant the combination of reciprocal teaching and direct command. Only in one of the items (saque alto) the results were the same for both groups. Conclusion : we think that group B had a better understanding of the orders, which, together with directive practice, certainly made automation much easier. We also observed that the individuals belonging to group B had more resources during the performance, and made things more difficult for their opponents at play. Apart form that, and from a general point of view, we can also assure that particular group proved a better understanding , and thus a better learning, of the subject “Badminton”.
An analysis of the relationship existing between the exit angle of the shuttlecock and the impact´s height of the clear, drop and smash strokes in badminton.
A. Carazo1, D. Cabello1 and F. Rivas2
1Faculty of Education (A/A David Cabello), University of Granada, Campus de Cartuja, s/n. 18071, Granada, Spain, dcabello@ugr.es . 2University of Amsterdam
The analysis of technical execution in badminton from a biomechanic perspective allows us to develop a precise depiction and evaluation of those techniques, which are used in overhead strokes such as the clear, the drop and the smash. The main goals of this study are: a) to design an effective methodological approach to these strokes; b) to develop a series of appropriate instrumental techniques that allows us to carry out a biomechanical analysis of the technical elements of these badminton strokes; and c) to study those biomechanics factors which will determine the efficiency of these strokes under competition conditions (Sprigings, E., et al., 1994, Journal of Biomechanics, 27(3), 245-254).
In order to analyse these strokes, we recorded two strokes of each type performed by four top-flight sportsmen under competition conditions; one of them was performed from the left side of the court while the other one was thrown from its right side. These strokes were analysed through a three-dimensional photogrametric technique at 50 Hz.
Their analysis followed a two-fold division; on the one hand, we analysed product factors (exit angle of the shuttle) as decisive in the performance of the stroke; on the other hand, we considered process factors. By process factors we understand those variables whose modification or alteration generate changes in the product factors. They include the maximum height of the gravity centre in air phase, the vertical displacement of the gravity centre in air phase, and the height of the gravity centre at the moment impact takes place.
According to results, the exit angle of the shuttle has a significant importance in the execution of these strokes since it determines the final trajectory of the stroke and the fall area of the shuttle. The study of the difference existing between the maximum height of the gravity centre and the height of the gravity centre at the moment impact takes place shows the way players hit the shuttle in the descending phase. Therefore, we can state it doesn't exist a true vertical jump but rather a displacement in back jump due to the difference existing among the two heights; such a difference ranges from 0.04 m in the clear and 0.11 m in the smash.
The exit angle of the shuttle can serve the purpose of predicting the characteristics of the stroke the player will hit. Thus, it allows the opponent to anticipate the kind of stroke the player will perform. Finally, it would be also convenient to carry out some future research in which photogrametric techniques and the analysis of the efficiency of strokes regarding the trajectory and the fall area of the shuttle are combined.
The ancestor of racket sports is not yet dead
L. Crognier and F. Riou
UFR STAPS-Paris 5, Laboratory Cognition and Motricity, JE 2378, 1 rue Lacretelle, 75015 Paris, France, crognier@staps.univ-paris5.fr
Le Jeu de Paume, as it is called in France (Real or Royal Tennis in Britain), is usually considered to be the ancestor of racket sports (De Luze, 1933, La magnifique histoire du jeu de paume). The Renaissance was a golden age for Le Jeu de Paume, the favourite game of the king and his courtiers. The two most famous versions were La Courte Paume, which was played in enclosed court, and La Longue Paume, which was played on the paths surrounding castles. In this paper, we first show how its decline was contrasted by its astonishing usage in the French language. We then explain how Le Jeu de Paume can be used to understand and to justify the origins of the current rules of tennis, which remain mysterious.
Like other forms of entertainment, the history of Le Jeu de Paume explains how French society used to be organized. The places where the game was played, the instruments used to play, the rules and the accidents associated this famous game are good indicators of social practices, habits and faults (Mehl, 1990, Les jeux au royaume de France du XIIIe siècle au début du XVIe siècle). Moreover, Le Jeu de Paume was so popular during the Renaissance that the players’ behaviours became incorporated into the French language. Indeed, a lot of metaphorical expressions have become part of everyday vocabulary: "qui va à la chasse perd sa place", "amuser la galerie", "tomber à pic", "rester sur le carreau", "prendre l’avantage", "paumer", "y laisser sa chemise", "prendre la balle au bond", "faire faux bond", "se renvoyer la balle", "un enfant de la balle" (Arramendy, 2000, Le jeu, la balle et nous, 164-169). La Longue Paume is currently only played in some areas (e.g., Picardy) and only three courts remain in activity (Bordeaux, Fontainebleau and Paris). In spite of this, Le Jeu de Paume appears to be well anchored in the memory of French citizens.
The history of Le Jeu de Paume illustrates the life cycle of games and sports. Lawn tennis was invented by Major Wingfield in 1874. This game was derived from Real Tennis and preserved the crucial idea that the playing always has a chance of catching up. However, the complicated system of chases and the asymmetry of the court were abandoned. The history of its ancestor helps to explain the terms used (the service, the game, the set, the match, the court), the rules (the net, the scoring system, two serves), the rituals (drawing lots by spinning the racket, changing ends, the handicaps for players’ classification), the announcements (advantage in and advantage out), the acts of courtesy which make modern tennis what it is (Réunion des musées nationaux, 2001, Jeu des rois roi des jeux le jeu de paume en France). For example, when the referee calls advantage out (avantage dehors) does he know that " in" (le dedans) refers to a large netted area behind the server called the winning gallery and that " out" (le dehors) was the other side of the court ? Consequently, any changes to the rules may disrupt the subtle balance of the famous game. When the tie-break was introduced in 1971, the two point rule was maintained. The recent attempts to suppress the rule of advantage (" no ad") and to shorten the time of the game (" short set") could alter the spirit of Le jeu de Paume. The level of resistance to these innovations proves that this game still influences the representations of tennis players.
Is anticipation in tennis related to specific knowledge ?
L. Crognier1, Y.A. Féry2 and N. Veret1
1UFR STAPS-Paris 5, Laboratory Cognition and Motricity, UPRES JE 2378, 75015 Paris, France, crognier@staps.univ-paris5.fr , 2UFR STAPS, Laboratory Acte UPRES EA 3596, Campus de Fouillole, 97167 Pointe à Pitre, France (French West Indies)
Does knowledge of tennis make it possible to play a more skilled game and to anticipate your competitor’s shots ? McPherson (1999, Research Quarterly for Exercise and Sport, 70(3), 233-251) showed that expert tennis players have a more refined and connected knowledge base than novices. Therefore, this knowledge may be an important component in anticipation, rather than a by-product of experience (Williams, 1995, Journal of Sport and Exercise Psychology, 17, 259-275). To test this hypothesis, we tested the ability of regional level male tennis players to anticipate shots and related their performances with their task-specific knowledge. Two experiments were carried out at a six–month interval on an indoor tennis court with a fast surface. We studied 20 highly skilled players (mean age = 24.3 years), ranked between -30 and +15/3 in the system used by the French Tennis Federation. All participants faced the same experienced tennis player (ranked +5/6). The first experiment consisted of a ball trajectory anticipation task using a temporal occlusion paradigm. Participants wore a pair of liquid-crystal spectacles that could be opened and closed manually by an assistant (Féry, 2001, Research Quarterly for Exercise and Sport, 72(2), 143-149). The participant’s vision was occluded when the opponent launched the passing shot. The participants, in volley position, had to try to intercept a passing shot launched by the opponent in three situations that differed in terms of the participant’s initiative (i.e. the capacity to impose his playing intent and therefore to reduce the opponent’s response possibilities). For the lowest level of tactical initiative, the opponent delivered his passing shot directly, with no previous rally. For the highest level, the participant adopted the volley position after a rally. The appropriate half court location chosen to intercept the volley was the dependent variable (Crognier, 2002, Congress on Movement, Attention and Perception, Poitiers, 121). In the second experiment, the participants were interviewed during friendly matches by manually operated cassette recorders. All participants were asked to answer the following question, originally developed by McPherson and Thomas (1989, Journal of Experimental Child Psychology, 48, 190-211), after each point : “What were you thinking about whilst playing that point”? A total of 16 between-point interviews were randomly selected for each participant. Knowledge was coded into units of information (concepts) and classified according to five major concept categories (goal, action, condition, execution, emotion). For example, the statement “I decided to move towards the net because the shot was short” was scored considered to be an action concept (coming to the net) plus a condition (the opponent’s shot was short) with a link (because). The results suggested that the players that were best able to anticipate were also the best able to generate more total concepts (r = 0.43) and more links between concepts (r = 0.53). It is noteworthy that these correlations between anticipatory performance and knowledge structure only occurred in situations with high levels of tactical initiative (i.e. after a rally).
Basic and special physical preparation of top table tennis players
Z. Djokic
Fruskorgorska 161, 22000 Sremska Mitrovica, Yugoslavia, djokicz@eunet.yu
Physiological parameters during the play of professional table tennis players – by analyses of movements activities of top table tennis players (240 top players, during the period from 1996 – 2003), major characteristic of duration and intensity during the match.
Basic of fitness testing – theoretically basics and specific implementation of battery of tests in table tennis game.
Adequate testing of the table tennis players – the most common test for evaluation of motorical abilities connected for evaluation of basic and specific motorical abilities. Also, the periodization of the testing (prepare period, competing period, rest and recovery period).
Recovery time between trainings – as the one of the most important elements in programming of training activities, after the 8 years of practice work with top athletes from table tennis and sport games, there are results which can prove the right of the adequate planning and programming training.
Basic motoric abilities – characteristics, basic exercises for improvement, importance in table tennis game and training, specific exercises for table tennis players.
Strength (explosive, repetitive, static) – as a base for further development in play. Speed – as one of dominant abilities in modern concept of table tennis game. Endurance (aerobic) – from the aspect of basic motorical abilities. Endurance (anaerobic) – upgrade the motoric abilities of table tennis players. Coordination – in process of learning and automatization of strokes and movements. Precision – specifically connected with coordination. Flexibility – importance for quality of training and play and as a protection of injuries.
Specification of the physical prepare in stead of the age category of players, cadet and junior players, young players and senior competitors. Also, and specification of physical prepare in club conditions and in case of National Team prepare, will be presented.
Differences caused by changing rules during the period 1995 – 2003 (38mm vs. 40mm ball – season 2000/2001, 11-2 system of play – season 2001/2002, new service rule – season 2002/2003)
Z. Djokic
Fruskorgorska 161, 22000 Sremska Mitrovica, Yugoslavia, djokicz@eunet.yu
Subject of this research is the structure of competitors’ activities in sample of 240 top table tennis players (mostly leading World players - rank in the first 100 at ITTF Rank list) in competing seasons from 1994/95 to 2002/2003. Competitors’ activities were analyzed in 61 activities (variables), grouping in 3 systems of activities (variables): 1. System of variables for evaluation of frequency, way of realization and effective of technical and tactical elements (30 variables) frequency of technical and tactical elements effect of these elements stroke placement zone stroke realization zone 2. System of variables for evaluation of realization service stroke (and returning of service) and effective after service stroke (and returning service) (23 variables) realization of service stroke (type of service and service placement zone) effect of service stroke and activity after the service realization (type) of returning service effect of returning stroke 3. System of variables for evaluation of movement activities (8 variables) side and deep movements change of forehand and backhand position stroke in forehand/backhand position and arm swinging for forehand/backhand strokes Research consists of the analysis of competitor’s activities for all players, and from the aspect of: success in play (winners and losers), quality of players (position at ITTF Rank list) (better player, and lower ranked). For every analyzed activity, basic statistical data, frequency data, percentage in complete activity and group of activity, as a characteristic from the aspect of success of play and quality of player, are done. The statistical importance differences between: Winners and losers / better and lower ranked are fortified. The research consists of interpretation 3 part structure of competitors’ activities of top table tennis players (as the results of Cluster analysis) and interpretation of the main factors of modern table tennis. The structure of analyzed players is fortified, also. Basic aim of this research is rationalization and higher effectively of training process in table tennis. Considering this results of research, which are explaining modern concept of table tennis game, and factors which influence success of play and quality of play and players.
Heart rate monitors in table tennis sport : physiological aspects of the heart rate during the match and training
Z. Djokic
Fruskorgorska 161, 22000 Sremska Mitrovica, Yugoslavia, djokicz@eunet.yu
Heart rate during the game and competition, and also during the training can be sign of quality of work - practice, condition of athletes – his physical status, and good sign for further planning of training process.
It is very hard to get a possibility to check this data during the match situation, especially in area of top table tennis. This methods were done on the senior Yugoslav National Team players, during the season 2002/2003, and as the Team which played this season in top form (leading position in European Super Division), this data represent value for table tennis theory which, of course, will improve a table tennis practice.
Control of heart rate during the match – graphically and with the numbers will be shown intensity and heart rate during the match. The |
