The Relationship Between Arm Pain and Pitching Mechanics

There is no question that throwing an excessive number of pitches beyond one's comfort zone can lead to problems.

Even more impressive is the relationship between the way one throws and the chances of developing shoulder and/or elbow injuries.

A baseball playing making a pitch

This relationship became clear to author Robert Shaw. Shaw observed throwing mechanics of different positions and defined the classic outfielder's pattern and the classic infielder's pattern. He noted that among pitchers who had long careers in Major League Baseball, all threw with a similar fluid motion of the classic outfielder's pattern.

The classic outfielder's pattern maximizes speed and distance in a seemingly effortless long arm delivery with the ball delivered high above the head and the elbow extended and traveling in a "downward plane" in reference to the ground. Pitchers with this delivery mechanism developed good speed on the ball because of the long lever arm. They were also accurate because, with an arc that was vertical to the ground, they did not miss inside-outside and their curve balls were more effective because they dropped. Throwing was smooth with little torque evident on the shoulder or elbow.

The classic infielder's throwing pattern maximizes the quick release of the ball and improves accuracy. It involves a "short arm delivery" where the elbow is flexed and the arm is abducted to 90 degrees. During the acceleration phase, the shoulders "open up" creating a "whiplash" effect in order to generate speed. The potential for injury in this pattern occurs when the scapula (shoulder blade) can go back no farther and the soft tissues of the scapula, elbow, and shoulder are whipped forward under a great deal of stress.

Shaw observed a jerking movement that was inconsistent and could not generate great speed without supreme effort—the "whiplash" puts maximum stress on the elbow and the shoulder.

These throwing patterns make it clear that the mechanism of delivery is important. In fact, the incidence of arm and shoulder pain in pitchers with the short arm, infielder pattern was nearly 70 percent while those with the smooth, outfielder pattern was associated with only 20 percent. Robert Shaw's Book: Pitching: Basic Fundamentals, is published by Viking Press and is available through the Library of Congress. It is recommended for relevant exercises that help develop an understanding of the basics in proper throwing. It also will be of interest to serious pitchers as it discusses a successful approach to getting batters out.

John Albright, MD