I have written a few articles pertaining to the increase in pitching related injuries. When it comes to pitching, there are a variety of reasons for the boom in injuries. These include increased throwing volume, suspect training methods and what I will discuss today, problematic mechanics.
At the end of the day, throwing a baseball is one of the most stressful things we can do to our bodies. The pitching motion is the fastest motion in all of sports with the humerus internally rotating at over 6,000 degrees/second. So, even with perfect mechanics, injuries are certainly still possible. However, there are certainly mechanics that can help keep pitchers healthy and those that predispose them to injury.
One such mechanical issue is the position of the arm at foot plant in the pitching motion. Take a look at the pictures below of Mariano Rivera and Roy Halladay. Both pictures were relatively jury free throughout very successful Major League careers.
Notice how at foot plant, their elbows are slightly below their shoulders and the forearm is almost completely vertical. The shoulder is externally rotated 90 degrees.
Now, take a look at the pictures below of Kerry Wood and Josh Johnson. Both very good Major League pitchers, Wood had Tommy John Surgery in 1999 and Josh Johnson has undergone the procedure 3 times.
Notice how at foot plant the ball is even with the elbow and the shoulder has not started to externally rotate yet. This leads to the arm being late to externally rotate as the shoulders begin to rotate towards home plate. This leads to increased vagus stress placed on the elbow, which places more stress on the Ulnar Collateral Ligamnet or Tommy John Ligament.
Here are a few more pitchers that have been among the best in the game and major arm surgery free with their arm in he proper position at foot plant.
Here are a few more who have undergone Tommy John Surgery.