Davis JT, Limpisvasti O, Fluhme D, Mohr K, Yocum LA, El Attrache NS, Jobe FS. The Effect of Pitching Biomechanics on the Upper Extremity in Youth and Adolescent Baseball Pitchers. American Journal of Sports Medicine 2009, 37: 1484-1491.
The purpose of this research was to identify specific biomechanical positions in the throwing motion that are associated with different levels of rotational torque at the shoulder and valgus stress at the elbow. They studied the throwing motions of 169 pitchers between the age of 9 and 18. Motion capture and video analysis were used to determine whether the pitchers met 5 specific parameters considered to represent good pitching mechanics. They found that, especially in the younger throwers (9-13) that the humeral internal rotation torque and the elbow valgus torque was reduced if pitchers met 3 or more of the 5 criteria.
A deeper look at the 5 criteria is warranted because of some “unexpected” results. The 5 criteria did not result from the study, but were chosen based on previous literature, as well as consensus of experts in the field. This blog will discuss 2 of the parameters related to the results of the study. The first is “leading with the hips / pelvis.” The proper technique was to have the pelvis driving towards home plate in the early cocking phase. In the adolescent group, 77 out of 83 pitchers met the “correct” criteria. However, in the pitchers demonstrating correct technique, the humeral and elbow torques were higher. This result runs counter to the expectation of the authors.
At Gray Institute®, the pelvis would be expected to lead towards the target compared to the trunk and arm. This pelvis explode out of the loading movement is part of many activities that we describe as “proximal acceleration.” So why did the study find increased torques? It could be that the pelvis should lead, but that the early cocking phase is too soon for this movement. It may be the timing of the movement rather than the movement itself that creates the increased stress on the bones and joints. The proper movement at the wrong time alters the kinematic and kinetic sequence, and could lead to “opening up too soon.”
The potential of the pelvis driving “too soon” links to one of the other markers of good technique: keeping the shoulder closed to the target. A closed position is defined as the glove side shoulder still pointing at home plate at the time the lead foot hits the ground. If the trunk has already rotated towards the target at the time of foot contact, the shoulders are considered open. This leads to increased stress on the shoulder and elbow as the arm comes forward.
At Gray Institute®, the “explode” (opening) happens too soon when the “load” has been unsuccessful. What does unsuccessful mean? It could be either insufficient motion or inability to maintain the loaded position long enough. So could the pelvis lead, that was perceived to be good, be occurring too soon and leading to opening of the shoulders? From the article, it is hard to break out the numbers, but of the entire group of 169 pitchers, 160 led with the hips / pelvis, but 118 opened their shoulders too soon. There is no way from the article to match these 2 criteria for each subject, but could the poor timing of the pelvis lead actually be part of improper sequencing and produce the opening up too soon?
It is impossible to answer the above question. However movement specialists, armed with the knowledge of the Chain Reaction® Biomechanics of throwing combined with the Principle of Load to Explode, can train the body to have the physical resources needed to pitch. Motion (mobility) and control of that motion (stability) are the signature components of the 3D Movement Analysis and Performance System (3DMAPS®). Analyzing motion at specific joints during global movements and then determining the ability to control the available motion through 3DMAPS® empowers the practitioner to identify the impairments and build the body resources for an efficient throwing motion sequence.