2023 年 30 巻 p. 13-24
This study evaluated the displacement of the body’s center of gravity during running jumps by categorizing it into elements,namely: “hinge moment” and “telescoping of the lower limbs” using a polar coordinate system. We examined whether hinge moment and telescoping of the lower limbs contribute to the jump height in the running jump of basketball players and whether the jump motions are related to these elements. A total of 21 college basketball players were recruited. Running jumps were measured using a high-speed camera. The three-dimensional coordinates of the body’s center of gravity were obtained, and its upward displacement due to the hinge moment and the telescoping of the lower limbs was determined. The results revealed the following:
（１） The factors contributing to the jumping height during the running jump were the maximum upward acceleration, owing to the hinge moment immediately after ground contact, and the maximum upward velocity, because of the telescoping of the lower limbs in the second half of the take-off.
（２） Jumping motions related to hinge moment included more plantar flexion of the ankle joint at heel contact and quicker plantar flexion after heel contact. Moreover，there should be no sudden extension of the hip joint immediately after heel contact. The body tilt at heel contact should be approximately 45 degrees.
（３） Jumping motions associated with telescoping of the lower limbs comprised the horizontal velocity of the body’s center of gravity at heel contact and the maximum dorsiflexion angle of the ankle joint during the latter half of the take-off.