INTRODUCTION: There are three general patterns of co-ordination used in breaststroke swimming known as continuous, glide and overlap. Investigation of co-ordination changes during a race could provide a better understanding of the swimmer`s personal co-ordination and how changes in that co-ordination relate to stroke rate, stroke length and swimming speed (Pelayo et al., 2007) The aims of this study were to: (1) investigate co-ordination changes during a 100 m short course breaststroke swim and (2) compare kinematic variables between each of the four laps as the swimmers progresses through the100 m swim. METHOD: With institutional ethical approval trained breaststroke swimmers (females n=8; males n=18) performed a maximal effort 100 m swim from a water start, in a 25 m pool. Each lap was recorded underwater using three 50Hz video cameras (1 at each end of the pool and a 3rd mounted to a trolley [sagittal plane]). The last three strokes of each length prior to the turn were analysed to determine the duration of arm recovery, arm propulsion, leg recovery, leg recovery and transition phases. Stroke rate, stroke length and clean swim speed were analysed within a 10 m section of the pool that was not affected by starting, turning or finishing. RESULTS: Twenty four of the swimmers showed a decrease in clean swim speed from the 1st to the 4th lap with an overall significant mean decrease in clean swim speed of 8.3% (P=0.002). There was no significant (P>0.05) change in either mean stroke rate or mean stroke length from the 1st to the 4th lap. Changes in transition time from the 1st to 4th lap approached statistical significance (p=0.06) DISCUSSION: As swimmers became fatigued they decreased the transition time between the end of the leg kick and the start of arm pull phases in an attempt to maintain clean swim speed. A better understanding of the changes in co-ordination could assist coaches in the design of training interventions to delay the effects of fatigue.
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