Author(s): UMEMOTO, M., YASUNORI, F., HIROKI, H., NATSUMI, F., TADASHI, W., KAZUO, F., Institution: PHYSICAL EDUCATION, Country: JAPAN, Abstract-ID: 1573

INTRODUCTION:
Recent studies of the swimming kick start have examined the differences in backplate position and reported on the relationship between the back plate position and the horizontal velocity at the start and the subsequent transit time. However, there are no studies that have reported on the details of the movement on the platform, so there is no established index to indicate the optimal back plate position for on-site instruction. The purpose of this study was to clarify the effects in the lower front leg joint angle in different back plate positions.
METHODS:
Six male swimmers who were senior swimmer (including national level swimmier) and university swimming clubs. Ten motion capture systems (PrimeX13 OptiTrack, Acuity Inc., Japan) were used to acquire kinematic data from the start signal to the entry into the water. Motion data was sampled at 180 Hz, and three-dimensional coordinate data were obtained from the subjects markers. Each swimmer participated using two back plate positions; each dive using a different back plate position and recordings of time were made from the start to 5-10m. The back plate position was varied in two levels: Front (the position closest to the tip of the starting platform) and Back (the position farthest from the tip of the starting platform).
RESULTS:
Lower front leg ankle, knee and hip joint angles at the starting position (0 sec) were no different. There was no difference in maximum flexion angle at each joint angle on the platform. Regarding the beginning of extension, ankle and knee joint angles of the lower front leg were no different, and hip joint angle showed that Back had faster and significantly smaller than Front (p<0.05).
CONCLUSION:
The results showed that the timing of extension for hip joint angle was faster and significantly smaller than Front at the Back plate position. As a result, the swimmer had enough time to raise the upper body, and the take-off angle was close to being horizontal. For further expectation, the effect in the lower rear leg joint angles and the relationship with the start performance in swimming race should be examined.