Relationship of pelvis and upper torso kinematics to pitched baseball velocity

Generating consistent maximum ball velocity is an important factor for a ba seball pitcher's success. While previous investigations have focused on the role of the upper and lower extremities, little attention has been given t o the trunk. In this study it was hypothesized that variations in pelvis an d upper torso kinematics within individual pitchers would be significantly associated with variations in pitched ball velocity. Nineteen elite basebal l pitchers were analyzed using 3-D high-speed motion analysis. For inclusio n in this study, each Ditcher demonstrated a variation in ball velocity of at least 1.8 m/s (range: 1.8-3.5 m/s) during his 10 fastball pitch trials. A mixed-model analysis was used to determine the relationship between 12 pe lvis and upper torso kinematic variables and pitched ball velocity. Results indicated that five variables were associated with variations in ball velo city within individual pitchers: pelvis orientation at maximum external rot ation of the throwing shoulder (p = .026), pelvis orientation at ball relea se (p = .044), upper torso orientation at maximum external rotation of the throwing shoulder (p = .007), average pelvis velocity during arm cocking (p = .024), and average upper torso velocity during ann acceleration (p = .03 5). As ball velocity increased, pitchers showed an increase in pelvis orien tation and upper torso orientation at the instant of maximal external rotat ion of the throwing shoulder. In addition, average pelvis velocity during a n cocking and average upper torso velocity during arm acceleration increase d as ball velocity increased. From a practical perspective, the athlete sho uld be coached to strive for proper trunk rotation during arm cocking as we ll as strength and flexibility in order to generate angular velocity within the trunk for maximum ball velocity.