Most of the biomechanical studies of start time have used kinetic and kinematical analyses to compare the two main start techniques used in competition: the grab and the track starts. Using a track start, swimmers tend to leave the block quicker (Ayalon, Van Gheluwe & Kanitz 1975) and to make a flatter flight trajectory due to higher horizontal velocity (Costill, Maglischo & Richardson 1992). With the grab start, swimmers spend more time on the block (lssurin & Verbitsky 2003). The above-referred studies, as many other studies, tried to observe which is the best starting technique to increase performance. Indeed, studies that compared the two start techniques showed the comparison between grab starters and track starters, each swimmer in his preferential technique. These studies were particularly interested in the starting technique effect. However, studies that analyzed differences between start techniques and that take in consideration the swimmers start preference are scarce as Vilas-Boas et al. showed us (2003) or more recently with Vantorre et al. (2011) on angular momentum. Knowing that the use of preferential technique may induce better performance to 1Sm, as well as other differences like a higher variability in some parts of the movement. Indeed, some studies showed that expert swimmers were able to exploit movement variability to achieve the dual-task goal of the swimming start: dive as far as possible to minimise resistances and to make a forward rotation to enter into the water properly (Seifert et al. 2010; Vantorre, Seifert, Fernandes, Vilas Boas & Chollet 2010; Vantorre, Seifert, Fernandes, Vilas-Boas & Chollet 2010). Consequently, it is challenging to investigate the impact of the non-preferential technique in comparison to the preference one. The aim of this study was to analyse inter-individual variability on body angles and velocity between preferential and non-preferential start techniques during aerial phase of swim start.
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