de Jesus, K., de Jesus, K., Figueiredo, P. A., Gonçalves, P., Vilas-Boas, J. P., & Fernandes, R. J. (2010). Kinematical analysis of butterfly stroke: Comparison of three velocity variants. A paper presented at the XIth International Symposium for Biomechanics and Medicine in Swimming, Oslo, June 16–19, 2010.

This study compared butterfly kinematical changes during 100 m (the first and fourth laps) at three swimming velocities and in-between those intensities. It was hypothesized that higher intracyclic velocity variation would be observed at the fourth lap of each 100 m, and, when comparing the 100 m performed at different intensities, lower intracyclic velocity variation would occur at higher velocities. Female swimmers (N = 7) performed a protocol of 3 x 100 m butterfly at sub-maximal (60 and 80%, v60 and v80, respectively) and at maximal velocities (v100), on 30-minute intervals. Two above and below water cameras, positioned in the sagittal plane, were used for movement analysis. Kinematic analyses were conducted on the first and fourth lap of each 100 m test.

Velocities for the first and fourth lap of each 100 m were only different in the v100 (higher v values in the first 50 m split). When comparing the v60, v80, and v100 swims, velocity differences were found in the first lap between all the trials. Considering stroke rate, higher values were observed for the first lap compared to the fourth lap in v60 and v100. When swimming intensities were compared, stroke rates in the first and fourth steps were always lower in the v60 swim when compared to the v100 swim. Stroke length tended to be inversely related to stroke rate, without statistical significance. Regarding intracyclic velocity variation, no statistical differences were observed. There was a tendency for higher values at v60 when compared to v100 in the first lap and in the total 100 m effort.

Implication. The velocity and stroking parameters observed followed those usually described when comparing different front crawl intensities. The stroke rate differed between the slow and fast efforts. Intracyclic velocity variation occurred at all effort levels with a tendency for greater variations at the lower/slower intensities. Slow butterfly swimming does not replicate fast butterfly swimming.

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