O tênis de mesa é um dos esportes de raquete mais rápidos do mundo, exigindo muito pouco tempo para planejar e executar seus movimentos. Neste sentido, detectar a quantidade de rotação da bola, velocidade e direção torna-se fundamental para produzir respostas motoras eficientes. Entretanto, existem algumas questões que ainda não foram exploradas como o quanto a disponibilidade das informações auditiva e visual interfere na acurácia da percepção da rotação da bola e no tempo necessário para perceber estas rotações. O propósito do presente estudo foi analisar a influência da informação auditiva e visual na percepção da rotação da bola e no desempenho no tênis de mesa. Os atletas profissionais foram submetidos a dois estudos: o primeiro destinado a verificar a contribuição da informação auditiva e visual na percepção da rotação da bola e no tempo necessário para essa percepção. O segundo, proposto para avaliar a influência da informação auditiva no desempenho da tarefa de contra-ataque no tênis de mesa. Participaram do estudo 22 mesatenistas de alto rendimento de ambos os sexos (21 homens e 1 mulher) com média de idade de 22,55 ± 6,15. O teste de percepção de rotação (estudo 1) analisou o número de acertos e o tempo de reação por meio de uma rotina desenvolvida no software Matlab (Apêndice D). Os atletas visualizavam a tela de um computador e respondiam em um teclado o mais rápido possível. Os atletas analisaram um movimento de forehand nas intensidades de rotação: muita rotação (bola girando a aproximadamente 140 r/s); média (bola girando a aproximadamente 105 r/s); pouca rotação (bola girando a aproximadamente 84 r/s); batida chapada (bola girando a aproximadamente 70 r/s), nas seguintes condições: a) informação auditiva; b) informação visual; c) informação auditiva e visual. Os atletas analisaram 20 bolas para cada condição sendo cinco de cada tipo de efeito. Para o teste de desempenho (estudo 2) o atleta teve que responder adequadamente com o movimento de contra-ataque de forehand em um alvo previamente marcado na mesa. Foram golpeadas 80 bolas nas mesmas intensidades de rotação mencionadas acima. Os atletas foram avaliados em duas condições: com informação auditiva e sem informação auditiva. Os resultados do estudo 1 revelaram que mesatenistas foram capazes de perceber a magnitude de rotação da bola nas três condições. O percentual de acertos foi de 77,5%, 91,14% e 96,36% para as condições de informação auditiva, visual e combinadas, respectivamente. Quanto ao tempo de reação, os resultados revelaram que na condição somente informação auditiva (2,32 ± 0,41 s) os atletas demoraram mais tempo para responder do que em relação a condição somente informação visual (2,07 ± 0,36 s), já na condição informação auditiva e visual (1,85 ± 0,35 s) os atletas se mostraram mais rápidos ainda concordando com as informações número de acertos obtidas neste estudo. Para o estudo 2 os resultados revelaram que quando os atletas contra-atacaram na condição informação auditiva, o número de acertos foi de 37,69 ± 5,43 enquanto, quando a audição dos atletas foi privada a média de acertos foi 33,15 ± 6,84. Os resultados apontaram que mesatenistas foram capazes de utilizar as informações auditiva e visual para perceber a magnitude da rotação da bola no golpe forehand, porém, no estudo 1 quando as informações foram combinadas o número de acertos aumentou 5,22% e o tempo de reação diminuiu 0,22 s. No estudo 2 Quando a informação auditiva foi privada houve uma diminuição na média do número de acertos de 4,54. / Table tennis is one of the fastest racket sports in the world, requiring very little time to plan and execute your moves. In this sense, detecting a quantity of ball spin, velocity and direction becomes fundamental to produce efficient motor responses. However, there are some questions that have not yet been explored for example how much the availability of auditory and visual information interferes with the accuracy of the perception of the rotation of the ball and the time needed to perceive these rotations. The purpose of the present study is to analyze the influence of auditory and visual information on the perception of ball rotation and performance in table tennis. The volunteers were submitted to two studies: the first one to verify the contribution of the auditory and visual information in the perception of the rotation of the ball and in the time necessary for this perception. The second, proposed to evaluate the influence of auditory information on the performance of the counter-attack task in table tennis. Twenty-two high-level table tennis players men and women (21 men and 1 woman) with a mean age of 22.55 ± 6.15 participated in the study. The rotation perception test (study 1) analyzed the number of hits and the reaction time through a routine developed in Matlab software. The athletes visualized the screen of a computer and answered in a keyboard as soon as possible. The athletes analyzed a forehand movement in the rotation intensities: fast spin (spinning ball foward at 140 r/s); medium spin (105 r/s); slow spin (84 r/s); flat hit (70 r/s), under the following conditions: a) auditory information; b) visual information; c) auditory and visual information. The athletes analyzed 20 balls for each condition, five of each type of rotation. For the performance test (study 2) the athlete had to respond adequately with the forehand counterattack movement on a previously marked target at the table. 80 balls were struck at the same intensities of rotation mentioned above. The athletes were evaluated in two conditions: with auditory information and without auditory information. The results of the study 1 revealed that table tennis players were able to perceive the magnitude of rotation of the ball in the three conditions. The percentage of correct answers was 77.5%, 91.14% and 96.36% for auditory, visual and combined information conditions, respectively. Regarding the reaction time, the results revealed that in the condition only auditory information (2.32 ± 0.41 s) the athletes took more time to respond, since in the condition only visual information (2.07 ± 0.36 s) delayed a little less and in the condition auditory and visual information (1.85 ± 0.35 s) the athletes showed themselves to be faster still agreeing with the information number of hits obtained in this study. For the study 2 the results revealed that when the athletes counterattacked in the auditory information condition, the number of hits was 37.69 ± 5.43, whereas when the hearing of the athletes was private the average hit was 33.15 ± 6.84. The results indicated that table tennis players were able to use auditory and visual information to realize the magnitude of the ball rotation in the forehand blow, however, in study 1 when the informations were combined the number of right answered increased 5.22% and the reaction time decreased by 0.22 s. In study 2 When the auditory information was depriving, there was a decrease in the average number of hits 4.54.

No description available.

Thesis (M. Sc.)--University of Hong Kong, 2005.

Table tennis playing involves complex spatial movement of the racket and human body. It takes much effort for the novice players to better mimic expert players. The evaluation of motion patterns during table tennis training, which is usually achieved by coaches, is important for novice trainees to improve faster. However, traditional coaching relies heavily on coaches qualitative observation and subjective evaluation. While past literature shows considerable potential in applying biomechanical analysis and classification for motion pattern assessment to improve novice table tennis players, little published work was found on table tennis biomechanics. To attempt to overcome the problems and fill the gaps, this research aims to quantify the movement of table tennis strokes, to identify the motion pattern differences between experts and novices, and to develop a model for automatic evaluation of the motion quality for an individual. Firstly, a novel method for comprehensive quantification and measurement of the kinematic motion of racket and human body is proposed. In addition, a novel method based on racket centre velocity profile is proposed to segment and normalize the motion data. Secondly, a controlled experiment was conducted to collect motion data of expert and novice players during forehand strokes. Statistical analysis was performed to determine the motion differences between the expert and the novice groups. The experts exhibited significantly different motion patterns with faster racket centre velocity and smaller racket plane angle, different standing posture and joint angular velocity, etc. Lastly, a support vector machine (SVM) classification technique was employed to build a model for motion pattern evaluation. The model development was based on experimental data with different feature selection methods and SVM kernels to achieve the best performance (F1 score) through cross-validated and Nelder-Mead method. Results showed that the SVM classification model exhibited good performance with an average model performance above 90% in distinguishing the stroke motion between expert and novice players. This research helps to better understand the biomechanical mechanisms of table tennis strokes, which will ultimately aid the improvement of novice players. The phase segmentation and normalization methods for table tennis strokes are novel, unambiguous and straightforward to apply. The quantitative comparison identified the comprehensive differences in motion between experts and novice players for racket and human body in continuous phase time, which is a novel contribution. The proposed classification model shows potential in the application of SVM to table tennis biomechanics and can be exploited for automatic coaching.

No description available.

The purpose of this study is to describe and analyse how elite sport students who studied at the National Sport Upper Secondary Schools with specialization on table tennis, experienced the aim and content of the subject Physical Education related to the learning of the subject, learning of the Specialized Physical Education, as well as their own elite investment. The theoretical perspective used in the study is Lave and Wengers (1991) theoretical concept the Community of practice. Where the focus is based on how the students like a community fulfills the criteria who used to characterize the Community of practice and also the aspect of "learning as participate" in the Community of practice. The results showed that the students did not experience a specific aim with the subject Physical Education. The biggest difference was in how the students experienced the learning of the subject Specialized Physical Education towards Physical Education. All of the students exemplify the meaning of studying at the National Sport Upper Secondary Schools with the aim of becoming an elite athlete. Therefore the subject Physical Education was seen by the students more as a subject of amusing character than a subject with knowledge, unlike what they experienced with the subject Specialized Physical Education. In relation to their own elite investment it became obvious that the students considered that they could not use the practical skills which were supposed to be developed in the subject of Physical Education. However two of the students emphasized that the theoretical knowledge was important elements in relation to their elite investment.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

published_or_final_version / Sports Science / Master / Master of Science in Sports Science

published_or_final_version / abstract / Linguistics / Doctoral / Doctor of Philosophy

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 159-169).