A kinematic analysis of the "break-out" phase of the freestyle, backstroke, and butterfly swimming strokes

Abstract

This study examined the effect of different time intervals between when a swimmer begins their initial stroke until their head breaks the surface on three variables: horizontal hip velocity when their pull begins, velocity when their head breaks the surface, and peak velocity during the first stroke. Twelve university (Division 1) swimmers performed their breakout-stroke and were analyzed using motion analysis software. Paired-samples t-tests were used to compare self-selected breakout time, elongated breakout time, and shortened breakout time. The mean breakout time was 0.40 ± 0.22 (n=5) for Freestyle, 0.82±0.11 (n=5) for Backstroke, and 0.25±0.17 (n=3) for Butterfly during normal breakout trials. When all strokes were combined, significant differences were found in head break velocity during self-selected trials (1.60±0.20 m/s) when compared to elongated (1.43±0.22 m/s, p≤0.01), and shortened (1.39±0.19 m/s, p≤0.01). Regression analysis showed a significant positive correlation between head break velocity and maximal velocity during the first pull.