Relationship between Ground Reaction Force and Kinetics of Both Legs in Kicking Pullovers: Kinetics of Single-leg Takeoff for Backward Rotation

Abstract

In this study, we analyzed the relationship between the ground reaction force (GRF) and both leg kinetics in kicking pullovers, with the aim of clarifying the mechanics and techniques for acquiring vertical GRF and moment in single-leg takeoffs for aerial rotation. GRF applied to the support leg foot and kinematics were recorded for the takeoff phase of successful kicking pullovers by 11 adult males. Using a 12-segment, sagittal-plane rigid body link model, the relationship between GRF and kinetics of both legs were analyzed. Although the GRF had its peak in the middle of the takeoff phase, it also contributed to the generation of the moment around the center of mass (CoM) by being tilted forward than to the CoM immediately after touchdown and before takeoff. The support leg was struck against the ground with angular velocities and torques of the hip extension and knee flexion at touchdown. The swing leg accelerated forward in the first half of the takeoff phase. These movements probably contributed to tilt the GRF forward immediately after the touchdown. The torque waveforms of the support leg joints were, on the whole, similar to those in the high jumps. It is suggested that in single-leg takeoffs for aerial rotation, controlling GRF direction with both leg movements while increasing the peak GRF with the takeoff techniques common to running jumps is an efficient strategy to acquire vertical GRF and moment with limited leg strengths.