The windup phase begins when the pitcher stepped back with his front foot and positions his back foot against the rubber. The windup phase ends when the front leg is at its maximum height and the two hands begin to separate.
During the stride phase, a pitcher moves his front foot toward home plate as the two arms swing down and apart from each other. The stride phase ends when the front foot touches the mound.
During the arm cocking phase, the pelvis and then upper trunk rotate to face home plate as the throwing arm externally rotates at the shoulder. The arm cocking phase ends when the shoulder reaches its maximum external rotation.
The arm acceleration phase was from the instant of maximum shoulder external rotation until ball release.
From ball release until the arm stops internally rotating is defined as the arm deceleration.
Follow-through begins with maximum shoulder internal rotation and ends when the pitcher regains a balanced position.
The greatest kinetic and kinematic values occurred during the arm cocking, acceleration, and deceleration phases, implying that these are the phases where overuse injuries are likely to happen.
