I contacted Dr. Glenn Fleisig today at the American Sports Medicine Institute in Alabama. Thought you'd appreciate his words on "pushing off the rubber," "proper stride length," and "proper foot landing."
Should you push off the rubber? Fall? Glide?
ASMI's pitching research is based on:
* principles of biomechanics
* data from many elite pitchers
* a focus on shoulder and elbow motions and loads
Because of this basis, the push or fall issue is not a big focus of ours since injuries do not occur during the stride phase.
What's important in our analysis is that the arm and body are in the proper position and coordination at the time of front foot contact, when significant loading of the elbow and shoulder really start. We have quantified the position used by healthy, elite pitchers at the time of foot contact. We don't care too much how a pitcher gets to this position, and only worry about leg and arm motions in the stride if there is a problem at the time of foot contact or after.
On proper stride length:
The proper position at foot contact is for the arm to be on the way up. For a righty, the ball should be showing to the shortstop at the time of pitcher's foot contact. For a lefty, the ball should be showing to the second baseman. The shoulders should still be closed, while the pelvis should be beginning to open up.
On proper foot landing:
At foot contact, the stride length should be between 78% and 88% of the pitcher's height. Here, stride length is measured as the distance from the front of the rubber to the ankle of the front foot. Just as important, the front foot should land in front of the back foot or slightly to the closed side, with the front foot rotated slightly inward.