Control of 3D Limb Dynamics in Unconstrained Overarm Throws of Different Speeds Performed by Skilled Baseball Players

Abstract

This study investigated how the human CNS organizes complex three-dimensional (3D) ball-throwing movements that require both speed and accuracy. Skilled baseball players threw a baseball to a target at three different speeds. Kinematic analysis revealed that the fingertip speed at ball release was mainly produced by trunk leftward rotation, shoulder internal rotation, elbow extension, and wrist flexion in all speed conditions. The study participants adjusted the angular velocities of these four motions to throw the balls at three different speeds. We also analyzed the dynamics of the 3D multijoint movements using a recently developed method called "nonorthogonal torque decomposition" that can clarify how angular acceleration about a joint coordinate axis (e.g., shoulder internal rotation) is generated by the muscle, gravity, and interaction torques. We found that the study participants utilized the interaction torque to generate larger angular velocities of the shoulder internal rotation, elbow extension, and wrist flexion. To increase the interaction torque acting at these joints, the ball throwers increased muscle torque at the shoulder and trunk but not at the elbow and wrist. These results indicates that skilled ball throwers adopted a hierarchical control in which the proximal muscle torques created a dynamic foundation for the entire limb motion and beneficial interaction torques for distal joint rotations.

Upper body contributions to power generation during rapid, overhand throwing in humans

“…Previous research has suggested that the work and power necessary to achieve rapid angular movements in the elbow and wrist are derived from the kinetic transfer of power generated at more proximal joints (Feltner, 1989;Hirashima et al, 2007;Hirashima et al, 2003;Hirashima et al, 2008;Putnam, 1993). We therefore predict that braces restricting more active proximal joints (torso and shoulder) will cause significant decreases in angular velocity in more passive distal joints (elbow and wrist).…”

“…These interaction torques can result directly from muscular actions at other joints or from velocitydependent, centrifugal or Coriolis forces (Hirashima et al, 2008). Mathematical decomposition of throwing kinematics using equations of motion has shown that high angular velocities observed at the elbow and wrist joints at release are largely due to these interaction torques (Feltner, 1989;Hirashima et al, 2007;Hirashima et al, 2003;Hong et al, 2001;Putnam, 1993). Induced acceleration analyses of these interaction torques further show that elbow extension during throwing is driven primarily by velocity-dependent forces generated by torso rotation and shoulder internal rotation (Hirashima et al, 2008).…”

“…Previous work has shown that large angular velocities of torso rotation, shoulder internal rotation, elbow extension and wrist flexion all occur at the moment of release and significantly contribute to projectile speed ( Fig. 1) (Fleisig et al, 1995;Fleisig et al, 1996;Hirashima et al, 2007;Pappas et al, 1985). This study focuses on how these large angular velocities are produced in the upper body.…”

“…There has been considerable inquiry into how this complex motion generates high projectile velocities, and which joints and joint-specific angular motions are primarily responsible Fleisig et al, 1995;Hirashima et al, 2007;Hirashima et al, 2008;Hong et al, , 1985;Putnam, 1993). Previous work has shown that large angular velocities of torso rotation, shoulder internal rotation, elbow extension and wrist flexion all occur at the moment of release and significantly contribute to projectile speed ( Fig.…”

Induced Acceleration Analysis of Three-Dimensional Multi-Joint Movements and Its Application to Sports Movements

“…Figure 9c shows the contributions of the 13 DOF velocities to the fingertip velocity at the time of ball release in skilled baseball players (Hirashima et al, 2007b). This analysis reveals that it is mainly produced by the leftward rotation of the trunk, internal rotation of the shoulder, elbow extension, and wrist flexion.…”