DESCRIPTION OF PITCHING PHASES
David Phelps, RHP for the New York Yankees
Although the baseball pitch is one continuous motion, it is helpful to divide the motion into phases: windup, stride, arm cocking, arm acceleration, arm deceleration, and follow-through. This will make the biomechanics of baseball pitching easier to understand.
WINDUP: The objective of the windup phase is to put the pitcher in a good starting position. The wind up starts when the pitcher initiates movement and is completed when the front knee reaches its maximum height.
STRIDE: The stride phase begins at the end of the wind-up when the lead leg begins to fall and move toward the target and the two arms separate from each other. This phase ends when the lead foot contacts the mound.
ARM COCKING: The arm cocking phase begins at lead foot contact and ends at maximum shoulder external rotation. Shortly after this phase begins, the pelvis and upper torso rotate to face the batter.
ARM ACCELERATION: The arm acceleration phase is the short time from the instant of maximum shoulder external rotation until the ball is released. The entire phase lasts only a few hundredths of a second.
ARM DECELERATION: This phase begins at ball release and ends when the shoulder has reached its maximum internal rotation. It only lasts a few hundredths of a second.
FOLLOW-THROUGH: The follow-through phase begins at maximum shoulder internal rotation and ends when the pitcher regains a balanced position.
WINDUP: The objective of the windup phase is to put the pitcher in a good starting position. The wind up starts when the pitcher initiates movement and is completed when the front knee reaches its maximum height.
STRIDE: The stride phase begins at the end of the wind-up when the lead leg begins to fall and move toward the target and the two arms separate from each other. This phase ends when the lead foot contacts the mound.
ARM COCKING: The arm cocking phase begins at lead foot contact and ends at maximum shoulder external rotation. Shortly after this phase begins, the pelvis and upper torso rotate to face the batter.
ARM ACCELERATION: The arm acceleration phase is the short time from the instant of maximum shoulder external rotation until the ball is released. The entire phase lasts only a few hundredths of a second.
ARM DECELERATION: This phase begins at ball release and ends when the shoulder has reached its maximum internal rotation. It only lasts a few hundredths of a second.
FOLLOW-THROUGH: The follow-through phase begins at maximum shoulder internal rotation and ends when the pitcher regains a balanced position.