No abstract

The purpose of this study was to clarify the effect of the presence or absence of upper limb movement on the propulsion direction body velocity (TPV) leaving the platform at kick start. The first trial (Standard trial) is a normal kick start, and the second trial (Lower trial) is the same as a normal kick start. The force from the upper limb movement at the time was set so that the start table was not applied, and the start movement calculated the 3D coordinates of the marker attached to the body by 3D movement analysis. As a result, in the movement speed at the time of leaving the platform, the standard trial had a significantly higher value in the propulsion direction and a significantly lower value in the vertical movement speed than the lower trial. In addition, since the standard trial had a significantly lower value in the jumping angle when leaving the platform, the role of the upper limb movement in kick start is to promote by making the jumping angle closer to the horizontal when leaving the platform. It was suggested that it may affect the directional velocity.

This study aimed to estimate the trunk twist angle from the shoulder and hip rotation angles in short-distance crawl swimming and to elucidate the twist motion of the relationship between the trunk and the rotation angular velocity in response to changes in swimming speed. Swimming speed during the experimental trials was computed from the subject’s best times in the 50 and 100 m crawl swims. Wireless self-luminous LED markers were attached to seven locations on the body. The actual coordinate values of the LED markers were obtained using 18 cameras for underwater movements and 4 on the water for above-water movements. A comparison of the rate of change between trials revealed a high correlation (r = 0.722, p < 0.01) between the twist angle and shoulder rotation angular velocity in the Push phase. In the same phase, a high correlation (r = 0.748, p < 0.01) was also found between the twist angle and the angular velocity of hip rotation. These results suggest that swimmers increase the twist angle of their trunks to obtain a higher swimming speed.