Made available in DSpace on 2016-12-06T17:07:11Z (GMT). No. of bitstreams: 1 Elementos Pre-textuais.pdf: 21642 bytes, checksum: d29b7adeea945e05f079845fd6a9f07e (MD5) Previous issue date: 2005-02-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This research s main goal was to analyze the arm stroke frequency variation of a swimmer, comparing his/her arm stroke frequency average variation in the 50m freestyle event and his/her arm stroke frequency average variation in the 100m freestyle event. This was based on the Atlanta XXVI Olympic Games Biomechanics report, presented by the Biomechanics and Sports Physiology Subcommission of the International Olympic Committee. This research analyses different items such as speed, arm stroke frequency, arm stroke length, and swimming efficiency of 15 swimmers, males and females, A and B finalists of the 50m freestyle event and of the 100m freestyle event in the Atlanta Olympic Games in 1996, comparing the information about their performances on these 2 events. Eight video cameras placed along the 50m swimming pool plus two control panels to analyze the received data were used in this research. The present research tried to find a supportable relation between the arm stroke frequency variation and the time variation pre-concepted in theory, which could come as one more item to help the athlete understand the concepts of a strategy variation. This is a descriptive interrelation analysis, comparing the relation between those two events. The information collected was analyzed as a whole and compared by the Pearson interrelation. The coefficient R2 = 0,0706 and R2 = 0,0511 indicates there s no relationship between the time and percentile time difference and the arm stroke frequency variation to be used as a guideline for other swimmers. / Este trabalho teve como objetivo geral analisar a variação da freqüência de braçada de um nadador, comparando sua freqüência média de braçadas na prova de 50 metros nado Livre e sua freqüência média na mesma distância de 50 metros durante a parcial da prova de 100 metros nado Livre. O trabalho foi realizado tendo como base o relatório de Biomecânica das competições de Natação dos XXVI Jogos Olímpicos de Atlanta, apresentado pela Subcomissão de Biomecânica e Fisiologia do Esporte do Comitê Olímpico Internacional. O presente estudo analisou os dados de velocidade, freqüência de braçada, comprimento de braçada e eficiência de nado de 15 nadadores de ambos os sexos, que foram finalistas A e B das provas de 50 metros nado Livre e 100 metros nado Livre, da Olimpíada de Atlanta em 1996, comparando as informações relativas aos desempenhos nestas duas provas. Foram utilizados neste estudo 8 câmaras de filmagem distribuídas em uma piscina de 50 metros de comprimento e dois painéis de controle que analisavam os dados recebidos. Esta pesquisa procurou verificar, se há uma relação válida entre a variação de freqüência de braçada com a variação de tempo preconizada em literatura, que pudesse servir como mais um instrumento que auxiliasse o atleta a compreender os conceitos de variação tática. Este estudo é caracterizado como um estudo descritivo de análise de correlação, pois se propõe a investigar as relações entre os eventos.Os dados obtidos foram tratados pela média e comparados através da correlação de Pearson. O R2 = 0,0706 e o R2 = 0,0511 indicam que não há correlação substancial entre a diferença e diferença percentual de tempo e variação percentual de freqüência de braçada que sirva de padrão para os demais nadadores.

Le crawl est actuellement la nage utilisée lors des épreuves de nage libre durant les compétitions de natation aux différentes allures de nage (sprint, demi-fond et fond). Les bras sont les segments corporels qui participent le plus à la propulsion. Les accélérations de ces segments, dans le milieu fluide au repos, génèrent un écoulement complexe qui est à l'origine des forces hydrodynamiques propulsives. L'analyse de cet écoulement est nécessaire pour en comprendre les principaux mécanismes. Dans ce cadre, des « paramètres cinématiques d'écoulement » (vitesse, accélération et orientation de la main, angles d'attaque et de sweepback) ont été définis afin d'analyser et comparer les différentes organisations gestuelles des nageurs et de leurs effets sur la propulsion. Deux des principaux axes d'investigation étaient de vérifier si ces paramètres variaient en fonction de l'allure, et aussi de déterminer quels paramètres cinématiques étaient les plus prépondérants dans la génération des mécanismes propulsifs. Pour cela, un système opto-électronique d'analyse cinématique, a permis de mesurer ces paramètres sur 17 nageurs experts. Par ailleurs, l'écoulement généré par le trajet des bras aux différentes allures a été simulé par résolution numérique instationnaire des équations de Navier-Stokes. Enfin, des mesures expérimentales d'effort ont été faites en nage attachée afin de connaître les forces propulsives.Il apparaît que l'augmentation de l'allure de nage peut davantage s'expliquer par la diminution des durées des phases non propulsives (entrée et allongement) plutôt que par l'augmentation des forces durant les phases les plus propulsives (balayages interne et externe). / Front crawl is a swimming stroke used at swimming competitions at freestyle different paces (sprint, middle distance and long distance). Propulsion in this stroke is achieved primarily by the forearm and hand. Accelerations of these segments, in a fluid at rest, generate complex flow that causes propulsive hydrodynamic forces. Analysis of this flow is necessary to understand the main mechanisms of propulsion. In this context, the "kinematic flow parameters" (velocity, acceleration and orientation of the hand, angles of attack and sweepback) have been defined to analyze and compare the different arm motions and their effects on propulsion. Two of the main axes of this investigation were to determine whether these parameters vary depending on the pace, and also to determine what kinematic parameters were most prominent in the generation of propulsive mechanisms. To this end, an optoelectronic system of motion capture was used to measure these parameters on 17 expert swimmers in free swimming. Furthermore, the flow generated by the experimentally acquired arm trajectory, at different swimming paces, was simulated by an unsteady numerical solution of the Navier-Stokes equations. Finally, tethered swimming experiments were carried out to measure the propulsive forces.The increase in forward velocity by increasing swimming pace can be explained by lower durations of non propulsive phases (entry and stretch) rather than by the generation of higher forces during the most propulsive phases (insweep and upsweep).