The aim of this study was to analyse the variations of the metabolic and technical parameters during a maximal 400-m freestyle event. Seven trained male swimmers swam a maximal 400-m freestyle as if in competition (255.8 +/- 6.9 s). Intermediate time and stroke rate (SR) were recorded at each length (25 m). To estimate the changes in metabolic parameters during the 400-m event, they swam a 300-, 200-, and 100-m test set from each length of the 400-m event results, resting 90 min between each test. The exact speed at each length was given with a visual light pacer. Oxygen uptake (VO(2)) and blood lactate concentration ( [Lac]) were measured before and immediately after each test. VO(2) and [Lac] were stable during the 100-, 200-, and 300-m test but significantly higher (p < 0.05) during 400-m test. The estimated contribution of anaerobic metabolism (EsCANA ) during the first 100-m and the 400-m represented 45 % and 20 % of total energy output, respectively. Speed decreased significantly (p < 0.05) after the first 100-m and remained stable until the end. SR decreased significantly after the first 100-m, then increased until the end, while stroke length (SL) decreased linearly throughout the 400-m. During the first or the last 100-m, EsCANA was not correlated with the changes in V, SR, or SL between the second and the first 100-m, and between the fourth and the third 100-m, respectively. To conclude, this study showed that the swimmers were not able to maintain stable SL during the 400-m event. Thus, to sustain stable velocity and to compensate for the decrease in SL, swimmers increased SR throughout the last 300-m.

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Abstract:The aim of this study was to analyse the differences between preferential and non preferential start technique, and the inter-trial variability. Seven elite swimmers, who used track start as preferential technique, realised three trials in track and grab start. The kinematical analysis assessed the durations of the block, flight, entry, glide, leg kicking and full swimming phases to the 15-m mark. Aerial (sum of block and flight phase with head mark) and underwater (from entry to the head reach the water surface) phases, number of underwater leg undulations and arm stroke to 15m were also measured. The kinetic analysis assessed reaction and impulse time and total impulses in vertical and horizontal axis. Track start, as preferential technique, had shorter block and entry phases but similar flight phase. In grab start, swimmers spend more time in the impulse and obtained higher vertical impulse values; moreover higher inter-trial variability was found for non-preferential technique suggesting lower efficiency. Differences of kinematics and kinetics observed tended to explain that the preferential technique is highly stabilised and reproducible by the swimmers. However, no differences on the 15m start time performance are observed between the two techniques, confirming the high skill level of the swimmers, and notably their capability to compensate lower block efficiency by effective underwater phases. Indeed, the relative duration of the underwater phases, the number of leg undulations and arm strokes are very similar in both techniques.

The aim of this study was to analyse the differences between preferential and non preferential start technique, and the inter-trial variability. Seven elite swimmers, who used track start as preferential technique, realised three trials in track and grab start. The kinematical analysis assessed the durations of the block, flight, entry, glide, leg kicking and full swimming phases to the 15-m mark. Aerial (sum of block and flight phase with head mark) and underwater (from entry to the head reach the water surface) phases, number of underwater leg undulations and arm stroke to 15m were also measured. The kinetic analysis assessed reaction and impulse time and total impulses in vertical and horizontal axis. Track start, as preferential technique, had shorter block and entry phases but similar flight phase. In grab start, swimmers spend more time in the impulse and obtained higher vertical impulse values; moreover higher inter-trial variability was found for non-preferential technique suggesting lower efficiency. Differences of kinematics and kinetics observed tended to explain that the preferential technique is highly stabilised and reproducible by the swimmers. However, no differences on the 15m start time performance are observed between the two techniques, confirming the high skill level of the swimmers, and notably their capability to compensate lower block efficiency by effective underwater phases. Indeed, the relative duration of the underwater phases, the number of leg undulations and arm strokes are very similar in both techniques.

No abstract