CONTRIBUTION OF TRUNK SEGMENT AND UPPER EXTREMITY TO BALL SPEED AT RELEASE OF OVERARM THROWING
Institute of Engineering Mathematics, Universiti Malaysia Perlis, Malaysia
Introduction: The overarm throw is a sequential body movement where the proximal joints increase their speed first followed by the more distal segments. During pitching, the angular momentum generated in the proximal segments is transferred to the distal segments resulting in a high ball speed at release.
Purpose: The purpose of this study was to investigate contribution of trunk segment and upper extremity to ball speed at release.
Method: An eight-segment three-dimensional simulation model was developed with a view to modelling overarm throwing. The accuracy of the model is evaluated by comparing the simulation values of the ball speed at release with the corresponding values obtained from performance data of fifteen trials of fastball pitching. Vicon Motion Analysis System was used to collect the kinematic data of an elite fastball pitcher.
Results: Reasonable agreement was found between the simulation model and the performance with rootmean-square (RMS) differences of 0.7% for the ball speed at release. Subsequently, the simulation model was used to investigate contribution of trunk rotation and throwing arm to the ball speed at release. Allowing one segment to be constant for every simulation denoted decreased of 23%, 30%, 47% and 7% for the ball speed at release for trunk, shoulder, elbow and wrist, respectively.
Conclusion: During pitching, the angular momentum of the trunk is transferred to the ball through the kinetic chain. At maximum shoulder external rotation, the angular velocity of the shoulder increased first followed by angular velocity of the elbow extension, completed by wrist flexion to neutral position resulted in high velocity of the ball at release. Results indicated that elbow joint has a strong influence on the ball speed at release. This study provide information which is useful for performance enhancement, rehabilitation, and injury prevention.