Biomechanical comparison of different types of pitches in high school softball pitchers.

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The sport of softball has gained increasing popularity over the last few decades with young girls competing at many levels in hopes of advancing to collegiate or Olympic competition. The Amateur Softball Association currently has 83,000 teams comprising 1.2 million participants. While many comparisons between baseball and softball have been made, pitch delivery stands out as an obvious difference. Softball pitchers deliver the ball in an underhand motion from a flat mound at a distance of 43 feet. Currently, there are no rules governing the number of pitches a pitcher can throw or the practice of pitching in consecutive games. Current research on the windmill softball pitching motion provides information on only one type of pitch; the fastball. The objectives of this study were to provide kinematic descriptions and kinetic comparisons of the upper extremity for three different types of softball pitches . It was hypothesized that there would be no differences in the kinetic values between pitches. Eleven high school aged softball pitchers were recruited for this study and had to be able to throw fastball, changeup, and drop pitches with proficiency. Motion analysis was used to collect five trials of each type of pitch. Kinematic description included a 4-curve approach for the shoulder motion, while the elbow and wrist motions involved standard Euler calculations. Statistical analysis of the kinetic variables included a one-way analysis of variance and Tukey post-hoc techniques in order to compare peak moment, peak joint reaction force, and peak joint power values between the pitches. Descriptive kinematics established normative data for each of the three pitches using a unique shoulder model. Shoulder, elbow, and wrist compression joint reaction forces were significantly different between pitches with the fastball/changeup and drop/changeup combinations. No significant differences were found for joint moments. Joint powers were significantly different for shoulder horizontal flexion/extension powers. Data from this study can be used to establish normative kinetic and kinematic information for different types of softball pitches in high school softball pitchers. Although the arm is not placed in an abducted position as with baseball pitching, dynamic and static restraint structures are still responsible during the delivery phase for stabilizing against distraction loads at all three joints. These structures include the long head of the biceps tendon and the rotator cuff musculature ; the ulnar and radial collateral ligaments and the distal tendon of the biceps brachii ; and the ulnar and radial collateral ligaments . Future study will involve a lower extremity biomechanical analysis and injury prevention interventions.