Three-dimensional analysis of intracycle velocity fluctuations in frontcrawl swimming

The purpose of this study was to determine accurately the magnitude and changes of intra-cycle velocity fluctuation (V-fluc), maximum (V-max) and minimum velocity (V-min) of the center of mass during a maximum 200 m frontcrawl swim, and to examine whether they are associated with performance. Performance was indicated by the mean velocity (V-mean) of the stroke cycle (SC) in the swimming direction. The relative V-fluc, V-max and V-min were also calculated as a percentage of V-mean, while V-fluc was calculated for all three directions. Eleven male swimmers of national/international level participated in this study and their performance was recorded with four below- and two above-water-synchronized cameras. Four SCs were analyzed for the 200 m swim (one for each 50 m). Anthropometric data were calculated by the elliptical zone method. V-mean generally decreased throughout the test. V-max and V-min were positively correlated to performance and were significantly higher in SC1 than in the other SCs. However, the relative V-max and V-min values were remarkably consistent during the 200 m and not associated with performance. Despite the noteworthy magnitude of V-fluc in all directions, they were in general not correlated with performance and there were no significant changes during the test.