Biomechanics of the Elbow in the Throwing Athlete

The biomechanics of the elbow have been examined during the baseball pitch, the football pass, the tennis serve, the javelin throw, and the underhand softball pitch. Primary emphasis has been placed on the baseball pitch, because most throwing injuries occur during this motion. The baseball pitch is divided into six phases. They are wind-up, stride, arm cocking, arm acceleration, arm deceleration, and follow-through. Low muscle activity and low elbow joint forces and torques occur during the wind-up and stride phases. The wind-up and stride position the body in preparation for the highly dynamic movements that follow. High muscle activity and high elbow joint forces and torques are generated during the arm cocking, arm acceleration, and arm deceleration phases. Consequently, hard and soft tissue injuries about the elbow occur during these highly dynamic phases of the pitch. Overall, elbow joint forces and torques are greatest during the arm cocking and arm deceleration phases of the pitch. The follow-through phase consummates the pitching motion and positions the athlete in a good, balanced position ready to resume play. Similarly to the wind-up and stride, low muscle activity and low elbow joint forces and torques occur during the follow-through phase.