ABSTRACT
The purpose of this study was to quantitatively analyze the techniques of New Zealand’s most elite butterfly swimmers. Four male and three female New Zealand Pan Pacific Squad members who race in butterfly and/or individual medley were requested to swim butterfly at race pace. Two PAL video cameras simultaneously recorded the above and below water views perpendicular to the line of travel of each swimmer. Paths of the vertex of the head, shoulders, hips, knees, ankles, and feet were obtained by digitizing the video records. Center of mass, stroke length and stroke frequency, and trunk and thigh angles were computed. Center of mass velocity and acceleration were derived from the Center of mass record. Unlike the findings for a similar study of breaststroke technique, stroke lengths and stroke frequencies varied within a relatively small range. Differences among the subjects were most apparent in the center of mass velocity and acceleration profiles. In particular, swimmers varied in the relative magnitudes of propulsive accelerations associated with the phases of the pull and kick. There was a considerable vertical undulation of the CM for both males (approx 18 cm) and females (approx 14 cm). This finding, together with the shoulder and hip path data, is contrary the belief held by many coaches that center of mass undulations are minimized by out of phase undulations of the hips and shoulders.
