Investigating the mechanisms of body rotation during the standing discus throw using an inclined board: An intraindividual comparative study

In the discus throw, the release velocity is crucial for determining optimal performance, with the angular momentum about the vertical axis playing a significant role. Nonetheless, the underlying mechanism remains unclear. The purpose of the present study was to investigate the rotational mechanics of standing discus throw using an inclined board placed under the right foot. Fifteen male discus throwers performed standing throws under four different inclination angles 0°, 4°, 8°, and 12°. No significant differences in the angular momentum about the vertical axis were observed across various inclined conditions; however, the angular impulse generated by the ground reaction force of the right foot was significantly greater at inclinations of 12° and 8° than at 0°. Conversely, the foot impulse was significantly smaller at 12°, 8°, and 4° than at 0°. The impulse of the throwing direction component was significantly greater at 12° than at 4° or 0°. Our findings suggest that a smaller ground reaction force may generate an equivalent angular momentum under inclined conditions compared with level conditions, indicating an optimal position for facilitating body rotation.