[[alternative]]Kinematics Analysis of the Swimming Grab and Track Start above and under Water

[[abstract]]The purpose of this study was to kinematics analyze the swimmers performing the grab and track start above and under water. Twelve male elite competitive swimmers were participated in this study. The grab start subjects data were: age 23 ± 1.9 yrs, heights 174 ± 3.5 cm, weights 75 ± 4 kg and 50m freestyle 25.1 ± 0.6 s; the track start subjects data were: age 21 ± 1.3 yrs, heights 177 ± 4.9 cm, weights 73 ± 3 kg and 50m freestyle 24.6 ± 0.4 s. Data were collected from three video recordings (60Hz) above and under water. The video data were digitized and calculated with Kwon3D Motion Analysis System. The results of the grab start showed that: start time were 1.2s, glide velocity were 2.16 ± 0.14 m/s, dolphin kick opportunity under water were 0.79 ± 0.2 s, time to 12m were 5.53 ± 0.19 s. The results of the track start showed that: start time were 1.1 ± 0.1 s, glide velocity were 2.23 ± 0.18 m/s, dolphin kick opportunity under water were 0.73 ± 0.2 s, time to 12m were 5.45 ± 0.17 s. The conclusions of this study were: significant differences between the two techniques were the center of mass at the set position, reaction time, movement time, and start time; no significant differences between dive groups were flight time and distance, takeoff and entry velocity, entry angle above and under water, glide time and distance, and time to 12m. It was suggested that athletes should consider including changed entry angle above and under water, used dolphin kick before the center of mass at the lowest position under water, decided the glide time and distance according to underwater motion analysis.