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Abstract
The dive start is an important component of competitive swimming, especially at shorter race distances. Previous research has suggested that start performance depends on kinematic variables pertaining to the swimmer at water entry, notably the distance from the block, the horizontal velocity of the centre of mass and the angle between body and water surface. However, the combined and relative contributions of these variables to start performance remain to be determined. The aim of the present study was therefore to develop a model to predict start performance (time from take-off to reaching the 15-m line) from a set of kinematic variables that collectively define the swimmer’s entry state. To obtain an appropriate database for this purpose, fifteen well-trained, (sub-)elite swimmers performed dive starts under different instructions intended to induce substantial variation in entry state. Kinematic data were extracted from video recordings of these starts, optimised and analysed statistically. A mixed effects analysis of the relation between entry state and start performance was conducted, which revealed a significant and robust dependence of start performance on entry state (χ2(3) = 88, p < .001), explaining 86.1% of the variance. Start time was reduced by 0.6 s (p < .001) when the horizontal displacement at water entry was 1 m further, by 0.3 s (p < .001) when the horizontal velocity of the centre of mass was 1 m/s higher, and by 0.5 s (p < .01) when the entry angle was 1 radian flatter. The robustness of the analysis was confirmed by a similar mixed effects analysis of the relation between entry state and time to the 5-m line. In conclusion, dive start performance can be predicted to a considerable extent from the swimmer’s state at water entry. The implications of those findings for studying and improving block phase kinetics are discussed.
Highlights
ObjectivesThe aim of the present study was to develop a model to predict start performance from a set of kinematic variables that collectively define the swimmer’s entry state
Most competitive swimming events, with the exception of backstroke and medley relay races, begin with a dive start
We developed a model for predicting this performance measure based on data derived from an intentionally broad variation of front crawl dive starts performed by well-trained,elite swimmers
Summary
The aim of the present study was to develop a model to predict start performance from a set of kinematic variables that collectively define the swimmer’s entry state. We aimed to test three hypotheses that were based on a combination of the previous findings and theoretical considerations highlighted in the preceding: 1. Entry state is a strong predictor of start performance and accounts for a considerable amount of variance in overall start time; 2 We aimed to test three hypotheses that were based on a combination of the previous findings and theoretical considerations highlighted in the preceding: 1. Entry state is a strong predictor of start performance and accounts for a considerable amount of variance in overall start time; 2
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