Starting technique is one of the most important factors for race performance in competitive swimming. Start phase (0-15m) is divided into five sub phases, namely, block, flight, entry, glide and stroke phases. There are many studies about both the kinematic and kinetic analyses in the block and the flight phases on competitive swimming start. However, there have been very few studies for entry phase. Therefore, the purpose of this study was to examine the relationship between techniques in entry phase and the performance of the swimming start. Sixteen collegiate elite male swimmers performed maximal efforts competitive swimming start followed by 25m freestyle swim. The mean value of the swimmer’s elapsed time at 15m on 25m maximum effort freestyle swimming trial was 6.86±0.24 sec. A correlation analysis was conducted to examine relationships between performance of start phase (0-15m time) and kinematic variables. There was a significant negative correlation between entry speed and the performance of 15m swim (r=-0.573 p<0.05). Also, there was a significant positive correlation between angle of attack for entry and the performance of 15m swim (r=0.641 p<0.01). There was a significant positive correlation between attitude angle of for entry and the performance of 15m swim (r=0.605 p<0.05). Also, there was a significant positive correlation between glide speed and the performance of 15m swim (r=0.543 p<0.05).
These results suggest that the start performance is influenced by speed, angle of attack (the angle between velocity vector of center of mass and the line from center of mass to hand at entry) and attitude angle (the angle between line from great trochanter to hand at entry and the water surface) for entry. There was a positive correlation between horizontal take off velocity and performance of start phase. These results indicated that a swimmer needs to accelerate the center of mass on the starting block to produce a fast entry speed.
In addition, the results of this study show that the attitude angle and the angle of attack affect the performance of start phase. Therefore, the good performance is attained with high entry speed, small attitude angle and the small angle of attack.
