Propose a procedure for swimming turns analysis

This study aimed to propose, through biomechanical methods, a procedure for swimming turns analysis, regarding the distance of performance measurement and the number of executions. The study was characterized as descriptive. Data collection was carried out at the swimming pool of CEFID/UDESC and in Aquatic Biomechanics Research Laboratory. The sample was composed by 11 subjects of Limit Swimming Team, from Florianópolis, SC, all of them associated to the Aquatic Federation of Santa Catarina (FASC). Six video cameras (f = 30Hz) and an underwater force plate were used. Because of its thickness, the force plate was placed in a frame in order to simulate the real conditions of the swimming pool wall. Each swimmer performed 8 turns. Dynamic data were analyzed in SAD 32 System and kinematic data were analyzed through image edition software. Analyzed variables: normalized force peak (PMn), contact time (TC), impulse (Imp), total turn time in 10 meters (TV10m) and total turn time in 15 meters (TV15m). Descriptive statistics was used to present data and the relationship between the variables was verified through Spearman s test (p<0,05). In order to determine the number of executions, Mann-Whitney U test and Kruskal-Wallis test were used, and also values of accumulated average and accumulated coefficient of variation. The results showed that for athletes with the same characteristics of the analyzed swimmers, the turn performance should be measured in 10 meters, because when analyzing turn performance in 15 meters, 67% of total time corresponds to stroke time, while in the 10 meters analysis, stroke time represents 48% of total turn time. Besides, the relationship between the PMn, TC and Imp with turn performance is very similar when comparing TV10m and TV15m. On this way, considering turn performance in 10 meters, one could collect data with fewer cameras and still the evaluation would be focused on turn actions and not on the stroke phase. Regarding the number of executions, all of the tests comparing groups of executions showed no difference. Otherwise, the values of accumulated coefficient of variation graphically showed stabilization starting on the third execution. The values of accumulated average showed that increasing the number of executions, the turn performance decreases, which could be related to swimmer s fatigue. So, one suggest that for turn performance analysis, as a safety procedure, four executions should be performed (one more than results observed) in order to be able to ignore a non-valid one.Este estudo teve como objetivo propor uma metodologia para realização de coletas de dados na virada no nado Crawl, através de métodos de medições biomecânicas levando em consideração a distância para analise da performance e o número de execuções. É caracterizado como um estudo descritivo. Os dados foram coletados nas dependências da piscina do CEFID/UDESC e tratados no Laboratório de Pesquisas em Biomecânica aquática da mesma instituição. Os sujeitos da pesquisa foram 11 nadadores da Equipe da Academia Limit, Florianópolis, SC, federados junto a Federação Aquática de Santa Catarina (FASC). Para coleta de dados foram utilizadas seis câmeras filmadoras (f=30Hz) e uma plataforma de força subaquática, acoplada a um suporte para fixação na parede da piscina e embutida em uma moldura com a finalidade de fornecer aos atletas a sensação de estarem tocando na parede da piscina. Cada nadador realizou 8 execuções. Os dados dinamométricos foram processados pelo sistema SAD 32 e os cinemático por softwares de edição de imagem. Variáveis analisadas: pico de força (PMn), tempo de contato (TC), impulso (Imp), tempo de virada em 10 metros (TV10M) e tempo de virada em 15 metros (TV15m). Foi utilizada estatística descritiva e para relacionar as variáveis foi utilizado o teste de Spearman (p