Luciana Gassenferth Araujo

Analysis of the lateral push-off in the freestyle flip turn

Abstract The aim of this study was to examine the contact phase during the lateral push-off in the turn of front crawl swimming to determine which biomechanical variables (maximum normalized peak force, contact time, impulse, angle of knee flexion, and total turn time within 15 m) contribute to the performance of this turn technique. Thirty-four swimmers of state, national, and international competitive standard participated in the study. For data collection, the following equipment was used: an underwater force platform, a 30-Hz VHS video camera, and a MiniDv digital camera within an underwater box. Data are expressed as descriptive statistics. Inferential analyses were performed using Pearsons correlation and multiple linear regressions. All variables studied had a significant relationship with turn performance. We conclude that a turn executed with a knee flexion angle of between 100° and 120° provides optimum peak forces to generate impulses that allow the swimmer to lose less time in the turn without the need for an excessive force application and with less energy lost.

Análise da frequência e do comprimento de braçada em provas de 50, 100 e 200m costas na natação

Introduction: This study aimed to analyze and compare the stroke efficiency indicators: average velocity (Av), stroke rate (SR) and stroke length (SL) on 50m, 100m and 200m backstroke events. Materials and Methods: Fourteen swimmers (seven men and seven women) were intentionally selected, mean age 20±4 years old among the 16 finalists of the 50m, 100m and 200m backstroke in XXXVI Brazilian Absolute Swimming Championship José Finkel Trophy 2007, held in the Greater Florianópolis, SC, Brazil. The variables were described by average, standard deviation and coefficient of variation, as all different distances were compared trough ANOVA oneway (Tukey Post-Hoc) and correlated through Pearson correlation test (p<0.05). Results: The results are in accordance to the literature: the smaller distances have a higher SR and a lesser SL with a higher Av. The values are reversed for larger distances, where it has a lesser SR and a higher SL, but Av decreases. Discussion: For coaches and swimmers, it is suggested to develop the technical aspects for a better combination of SR and SL, aiming at an ideal balance to maintain higher speed independently on the distance.

Determinação do número adequado de repetições para a avaliação da virada no nado livre

The aim of this study was to develop a procedure of data collection on freestyle swimming turn (number of repetition). Eleven swimmers executed 8 turns each one. The measured variables were Normalized Peak Force (PFn), Contact Time (TC), Impulse (Imp) and Turn Time in 10 meters (TV10m). The visual stability as for the number of executions was checked through the calculation of the accumulate coefficient of variation that presents small variations curves. No significant differences were found between the accumulate averages using ANOVA between the different groupings and also for the confirmation of the least number of repetitions, it chose in confronting the data, through the Mann-Whitney U test carried out between the variables. Was found that three valid executions are enough to evaluate the performance in front freestyle turn.O estudo propoe um procedimento para coletas de dados da virada no nado livre (numero de execucoes). Onze nadadores executaram 8 viradas cada um. Analisou-se as variaveis Pico de Forca normalizado (PFn), Tempo de Contato (TC), Impulso (Imp) e Tempo de Virada em 10 metros (TV10m). A estabilidade visual quanto ao numero de execucoes foi verificada pelo calculo do coeficiente de variacao acumulado que apresentou curvas com variacoes discretas. Foi verificado se ocorria diferenca entre as medias acumuladas usando a analise de variância (ANOVA) entre os diferentes agrupamentos. Nao houve diferencas significativas. Para confirmar o numero minimo de repeticoes, confrontou-se os dados pelo teste de U de Mann-Whitney. Nao houve diferencas significativas. Observou-se que tres execucoes validas sao o suficiente para avaliar o desempenho na virada.

Determinación del número adecuado de repeticiones para la evaluación del volteo en el nado libre

The aim of this study was to develop a procedure of data collection on freestyle swimming turn (number of repetition). Eleven swimmers executed 8 turns each one. The measured variables were Normalized Peak Force (PFn), Contact Time (TC), Impulse (Imp) and Turn Time in 10 meters (TV10m). The visual stability as for the number of executions was checked through the calculation of the accumulate coefficient of variation that presents small variations curves. No significant differences were found between the accumulate averages using ANOVA between the different groupings and also for the confirmation of the least number of repetitions, it chose in confronting the data, through the Mann-Whitney U test carried out between the variables. Was found that three valid executions are enough to evaluate the performance in front freestyle turn.O estudo propoe um procedimento para coletas de dados da virada no nado livre (numero de execucoes). Onze nadadores executaram 8 viradas cada um. Analisou-se as variaveis Pico de Forca normalizado (PFn), Tempo de Contato (TC), Impulso (Imp) e Tempo de Virada em 10 metros (TV10m). A estabilidade visual quanto ao numero de execucoes foi verificada pelo calculo do coeficiente de variacao acumulado que apresentou curvas com variacoes discretas. Foi verificado se ocorria diferenca entre as medias acumuladas usando a analise de variância (ANOVA) entre os diferentes agrupamentos. Nao houve diferencas significativas. Para confirmar o numero minimo de repeticoes, confrontou-se os dados pelo teste de U de Mann-Whitney. Nao houve diferencas significativas. Observou-se que tres execucoes validas sao o suficiente para avaliar o desempenho na virada.

Determination of appropriete number of repetition to evaluate the freestyle swimming turn

The aim of this study was to develop a procedure of data collection on freestyle swimming turn (number of repetition). Eleven swimmers executed 8 turns each one. The measured variables were Normalized Peak Force (PFn), Contact Time (TC), Impulse (Imp) and Turn Time in 10 meters (TV10m). The visual stability as for the number of executions was checked through the calculation of the accumulate coefficient of variation that presents small variations curves. No significant differences were found between the accumulate averages using ANOVA between the different groupings and also for the confirmation of the least number of repetitions, it chose in confronting the data, through the Mann-Whitney U test carried out between the variables. Was found that three valid executions are enough to evaluate the performance in front freestyle turn.O estudo propoe um procedimento para coletas de dados da virada no nado livre (numero de execucoes). Onze nadadores executaram 8 viradas cada um. Analisou-se as variaveis Pico de Forca normalizado (PFn), Tempo de Contato (TC), Impulso (Imp) e Tempo de Virada em 10 metros (TV10m). A estabilidade visual quanto ao numero de execucoes foi verificada pelo calculo do coeficiente de variacao acumulado que apresentou curvas com variacoes discretas. Foi verificado se ocorria diferenca entre as medias acumuladas usando a analise de variância (ANOVA) entre os diferentes agrupamentos. Nao houve diferencas significativas. Para confirmar o numero minimo de repeticoes, confrontou-se os dados pelo teste de U de Mann-Whitney. Nao houve diferencas significativas. Observou-se que tres execucoes validas sao o suficiente para avaliar o desempenho na virada.