Biomechanical Differences between Successful and Unsuccessful Kicking Pullovers by 10-year-old Children

抄録

The purpose of this study was to clarify the differences between successful and unsuccessful kicking pullovers in elementary school children. Successful (n = 12) and unsuccessful (n = 13) kicking pullovers by elementary school children having an approximate age of 10 years using 1 m high horizontal bars were captured, and sagittal plane analyses at 60 Hz were performed using a rigid body link model. The shoulder joint angles were kept constant in the successful movements, whereas those were steadily flexed in the unsuccessful movements after the take-off. The successful movements had smaller forward velocity of the center of mass (CoM) at takeoff, because of the larger decrease in the forward velocity during the takeoff phase. The angle of the swing leg thigh during the takeoff phase was highly correlated with this change in velocity. In successful movements, the thigh was more downward at touchdown, with the trunk upright and the hip joint of the swing leg largely extended. These results suggest that the downward swing leg in the successful movements allowed for larger and faster swinging during the takeoff phase, resulting in a larger backward reaction force impulse from the ground and decrease in the forward velocity of the CoM. This decreased velocity helps to pull the body towards the bar with upper limb joint torques after the takeoff. Therefore, guiding children to touch down in a posture with the trunk upright and the hip joint of the swing leg fully extended would be effective.