Kinematic Motion of the Windmill Softball Pitch in Prebuscent and Pubescent Girls

Oliver, G.D., Dwelly, P.M., K, Y.H. (2010). Kinematic Motion of the Windmill Softball Pitch in Prebuscent and Pubescent Girls. Journal of Strength and Conditioning Research, 24 (9), 2400-2407.

In this study, 17 pitchers participated and separated into 3 groups: novice, intermediate and advanced. Each threw 5 pitches, one of which was selected for analysis.

Results showed group differences in ball velocity and wrist speed, with the advanced and intermediate groups being higher in both. They also determined a proximal to distal sequence of acceleration and deceleration to generate higher velocities in both the arm. This means that the upper arm accelerated first, then decelerated as the lower arm accelerated. The lower arm decelerated as the hand accelerated, and so on. In the trunk, however, angular velocities were greatest at release. The novice group did not show this same process. Also, all of this sequence happens in the last hundredths of seconds prior to ball release. Other noteworthy items included the shoulder losing angular velocity just prior to ball release and that the peak velocity is in the hand.

Each segment on the proximal side initiates its distal component. The distal component will lag behind and acquires its speed to get to a greater velocity as the proximal segment is decelerated. That’s a fancy way of saying that the part of the body closest to the center accelerates the next part of the body that’s further from the center, which lags behind and accelerates as the part closest to the center of the body slows down. The sequence is followed until the hand and fingers are in full motion. This action is generally referred to as the “whip” action of the arm.

This dialog means that the emphasis to improve the mechanics of the arm should be placed upon the stability of the core, making it rigid through much of the motion but particularly at release. Also, the generation of the “snap” should be talked about and practiced as an entire kinetic chain. This means that you can stop doing static snaps, t-drills, and k-drills, and start adding movement components, such as a back swing, a small step, etc. to allow the chain to happen. If the novice group has such a rigid arm, or a moving trunk, we can assume that drills that mimic such movements are not in the pitcher’s best interest.