This study analysed the start phases of 15 elite front crawl swimmers, all specialists of sprint events. The first aim was to determine which phases were correlated with the 15-m start time. The features common to the sample of swimmers were then established and individual profiles were clustered. The subjects performed two 25-m trials at the 50-m race-pace using their preferential start technique (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. Stroking parameters and the index of arm coordination (IdC) were analysed for the swimming part (10-20 m) of the 25-m. Through the swimming part IdC increased while stroke length and velocity decreased (p<0.05). The relative durations of the aerial (block, flight), entry and underwater phases were correlated with start time. Inter-subject variability was observed, which suggests that various motor solutions were used for the start. Notably, four clusters led to a short 15-m start time: the leg kicking style, mixed "leg kicking/swimming" style, long glide style and short glide style.

This study analysed motor control during front crawl swimming starts by elite and trained swimmers, based on comparisons of: 1) kinematic and kinetic parameters of the start and 2) variability of these parameters across 3 trials per swimmer. Given that the start time to the 15-m mark is greatly influenced by the swimming phase, the study also compared the stroking and coordinative parameters from water entry to 25-m in the 2 skill groups. The swimmers performed 3 x 25-m at the 50-m race-pace and used their preferential start technique (grab start). The elite swimmers showed better start organization as reflected by higher impulse values in the direction of intended displacement despite similar block phase durations. They then spent more time in the water entry, gliding and leg kicking phases, with shorter swimming phase duration and 15-m start time than the trained swimmers (p<0.05). The trained swimmers showed significantly lower values for stroke length and velocity (p<0.05) during the swimming phase. Analysis revealed low intra-subject variability (across the 3 trials) but high inter-subject variability, indicating that both elite and trained swimmers had mastered distinct, though different, motor patterns.

Seifert, L, Vantorre, J, Lemaitre, F, Chollet, D, Toussaint, HM, and Vilas-Boas, JP. Different profiles of the aerial start phase in front crawl. J Strength Cond Res 24(2): 507-516, 2010-This study analyzed the kinematics and kinetics (jumping ability) of the aerial start phase in 11 elite front crawl sprinters. The aim was to determine whether a particular start technique leads to a short 15 m start time or whether several start profiles contribute equally well. All swimmers performed 3 starts using their preferential style, which was the grab start for all, followed by a 25-m swim at maximal velocity. Countermovement jump enabled to determine vertical jumping ability. Using a video device, phase durations, angles at takeoff and entry, and hip velocity were assessed. Correlation between all variables and the 15 m start time established the common features of an effective start but also revealed great intersubject variability. Cluster analysis enabled to distinguish 4 start profiles (flat, pike, flight, and Volkov), indicating that several individual profiles lead to short 15 m start times. It could be advised to consider the intersubject variability in relation to start time before favoring unique strategy.

The aim of this study was to analyse the kinematics and coordination of the breaststroke start as regards to skill level using a video device. Ten national swimmers were compared with an international swimmer. All swimmers simulated the 100-m pace for 25 m after a grab start. The kinematical analysis assessed the durations of leave block, flight, entry and glide, pull-out, and the swim up to the 15-m mark phases. The coordination analysis assessed the durations of the time spent with the arms close to the thighs after a complete arm pull-push, the time gap between the end of the arm recovery and the beginning of the leg propulsion during the pull-out phase and at the first swim stroke, and the time gap between the end of leg propulsion and the beginning of arm propulsion. The international swimmer had a shorter 15-m start time than the national swimmers due to shorter times in the swim phase, longer times in the underwater phase, longer times spent with the arms close to the thighs and in glide with the body in extension. The whole population showed a negative superposition of leg propulsion with arm recovery at the pull-out phase, which disappeared at the first swim stroke.

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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.