Relationship Between Kinematics, Strength, And Throwing Velocity Of Adolescent Softball Players During Overhand Throwing

Abstract

The kinematics of overhand throws by adolescent softball players is currently under-reported. Identifying the relationship between kinematics, strength and velocity can help guide further research and promote better understanding of the sport. Current research has investigated the differences between softball and baseball but has not looked at how kinematics and strength correlate with throwing velocity in softball. PURPOSE: To identify the relationship between kinematics, strength, and velocity of an overhand throw in adolescent softball players. METHODS: 25 adolescent softball players performed 3 maximum effort overhand throws. The throws were filmed using a 2-D video analysis system consisting of 3 cameras set up in the frontal and sagittal planes. The velocity of the throws were recorded using a speed gun. Key positions were identified in six throwing phases and angles were measured using software on a tablet. Bilateral hip and shoulder strength of each player were measured using standardized methods via handheld dynamometer. Correlation coefficients were determined. RESULTS: A moderate and significant correlation was found between the velocity of overhand throw and the stride knee flexion angle during the arm cocking phase (r= .55, p=.004), the stance knee flexion angle during stride phase (r= .49, p= .015), and the elbow flexion angle during arm acceleration phase (r= -.45, p=.024). A moderate and significant correlation was found between trunk flexion angle during follow through phase and hip internal rotation (r= -.45, p=.04) as well as hip external rotation (r= -.53, p=.013) strength. CONCLUSION: Increases in velocity were influenced by lower extremity variables including increases in stride knee flexion angle during the arm cocking phase and increased stance knee flexion during stride phase. Upper extremity variables that related to higher velocity included decreased elbow flexion at the end of acceleration phase. Strength parameters including hip internal and external rotation strength were found to be related to higher velocities. These findings highlight the potential influence of lower extremity kinematic variables and strength on performance as measured by velocity. These results can benefit players or coaches who are teaching or learning how to do the overhand throw.