The goal of this dissertation was to provide quantitative information about pitching mechanics that could help in the prevention and management of overuse pitching injuries. The first of the four studies within this dissertation was the development of a biomechanical system capable of measuring pitching kinematics. This system consisted of four high-speed cameras and a three-dimensional automatic digitization computer program. Software was written by the author of this dissertation to calculate pitching kinematics from the digitized data.

In the second study, this system was used to characterize the kinematics of six phases of pitching:​ windup, stride, arm cocking, arm acceleration, arm deceleration, and follow-through. During the arm cocking phase, the arm reached an externally rotated position of 175°. During the arm acceleration phase, internal rotation angular velocity reached 7000 °/s.

In the third study, the kinetics of pitching were quantified. To terminate arm cocking and initiate arm acceleration, 67 Nm of shoulder internal rotation torque and 64 Nm of elbow varus torque were generated. During arm deceleration, a 1090 N compressive force was generated to prevent shoulder subluxation.

In the fourth study, eight mechanisms of improper kinematics that lead to increased loads were proposed. To investigate these hypotheses, 72 pitchers were studied and deviations from the kinematic database established in the second study were correlated with increased kinetics. Four kinematic parameters correlated with increased shoulder force:​ placement of the lead foot toward the open side, pointing of the lead toe toward the open side, and increased or decreased shoulder rotation at the instant of front foot contact. Two kinematic parameters correlated with increased elbow force:​ increased shoulder rotation at the instant of front foot contact, and increased shoulder horizontal adduction. Although these correlations were statistically significant, the loading increase from any individual mechanism was minimal. The presence of multiple improper mechanisms may increase loading further. Cumulative effect of increased loads from repetitive pitching may result in increased injury risk.

Kinematic patterns of proper pitching provide practical objectives for pitchers and coaches. Kinetic results may help physicians, therapists, and trainers understand the demands placed upon the elbow and shoulder, improving their ability to design and select optimal injury prevention and management approaches. Kinematic changes correlating with increased kinetics provide the first scientific data of overuse injury factors.