Why do pitchers get hurt? And why are they getting hurt at increasingly alarming rates? It's been a question that is asked around every baseball circle from the major leagues to youth organizations. As athletic trainers specializing in baseball, much of our careers have been dedicated to finding that answer. We have spent countless hours spent addressing posture, shoulder and scapula strength/ flexibility, and kinetic chain issues. Yet we find that pitching mechanics play the most important role when examining upper extremity injury and re-injury rates. Those with poor mechanics are more likely to become injured and are less likely to recover following an injury.
The throwing motion is the fastest motion in all of sports with speeds recorded as high as 8000 deg/sec 2 (that's like spinning your arm in a circle 20 times in 1 second). With speeds and forces so high, any altered mechanics will increase the stress placed on the elbow and shoulder and potentially lead to injury.
There are five phases to throwing: wind-up, stride, acceleration, deceleration, and follow-through. We will highlight important features of each phase, correct mechanics, and common pitfalls. Remember, each pitcher is different and thus mechanics will vary from pitcher to pitcher, however, significant variations will increase stress over time which are more likely to lead to injuries.
During the windup phase, pitchers prepare their body for the throwing motion. Pitchers should keep their wind-up short and simple, as a complex wind-up can negatively affect the remaining motion. In young pitchers and pitchers returning from injury, throwing from the stretch minimizes unnecessary movements.
The stride phase begins as the front foot moves and ends when the front foot hits the ground. Problems in the stride phase are the most likely to lead to injury. Cesar Mejia (former Minor League Pitching Coach with The Phillies) teaches that "the most important part of the throwing motion occurs as the arm reaches maximum height behind the head and the front foot simultaneously contacts the ground."
Issue 1: The stride is often too short, research shows that it should be about 85 percent of your height1, most pitchers end at about 50 to 66 percent. A short stride decreases the amount of time in this phase and the shoulder and elbow will not reach the correct position; this forces the arm to play catch up for the remainder of the throwing motion and increases injury risk. When the front foot hits the ground, the throwing arm MUST be back with the shoulder and elbow essentially making a right angle, and the elbow should be level or slightly lower than the shoulder. This is called early cocking. Be careful not to drop the elbow too low as that can contribute to an elbow injury.
Issue 2: Improper arc taken to get to the early cocking position. Major league pitchers often have a very low arc and allow the ball to drop past their hip and thigh before quickly bringing the ball up to the early cocking position. Most MLB pitchers are fast enough to do this, most young pitchers are not. Some simple corrections to fix this timing issue: increase your stride length; keep the ball above your hips; begin with your hands lower.
Issue 3: The arc taken brings your hand and the ball towards the first base side (for a righty) when reaching back. An arc to the side your body places unnecessary forces on your shoulder and elbow. The ball should be hidden behind your body so the hitter cannot see it. One method to correct this is to stand with your back against a wall and simulate the throwing motion without hitting the wall.
Issue 4: The "Inverted W." It is a result of leading with your elbows instead of the ball as your hands break (from the glove). Your shoulders shrug and the ball hangs below looking like an inverted W. A few MLB players with an inverted W are: Strasburg, Prior, Reyes. In our opinion, the "Inverted W" should NOT be taught! The mechanics are incorrect, lead to injury, and have no place in youth throwing. Using this technique, you may throw harder for a short period of time, but you are much more likely to become injured. Throwing with an inverted W places the elbow in a poor position almost always above the shoulder and disrupts the normal timing of pitching. The scapula (shoulder blade) muscles do not stabilize the shoulder optimally and as a result there is often an increase in force on the elbow and shoulder. To fix this, seek an instructor who truly understands throwing and injuries.
Issue 5: Weight must stay on your back leg throughout the stride phase, which allows your hip/glutes to produce the power needed to throw. Getting power from your hips saves your arm and may increase velocity3.
The acceleration phase begins just as the shoulder begins to move forward from the early cocking position and ends at ball release. Common pitfalls during this phase include moving the head towards the first base side (for a righty) instead of moving it directly towards home plate, which leads to poor control. Secondly, your glove hand should be under control and should end up at your chest or your hip; it should not be flung wildly behind your body. Lastly, your knee should remain bent throughout this phase.
Deceleration and follow through are both very important and occur once the ball is released. These phases are responsible for gradually slowing the body and arm down. A proper follow through has the throwing arm finishing outside of the front foot with a back leg kick that comes off of the ground. This dissipates the forces by using the entire body. A poor follow through is one that occurs too fast or one that moves to the side instead of towards home plate. At no time should the back leg be anchored or dragging behind your body.
Having perfect mechanics is nearly impossible; however using the best possible mechanics will decrease your risk of injury and allow you to utilize your whole body optimally when pitching.
Mark Miller, ATC is a partner with Symetrix Sports Performance specializing in mechanics, injury prevention, and sports performance for baseball players. He has also worked as a clinical athletic trainer for 10 years rehabilitating athletes of all ages and has worked as a Division 1 football athletic trainer with NC State.
1) Flesig G, Barrentine S, Zheng N, et al. Kinematic and kinetic comparison of baseball pitching among various levels of development. J of Biomech. 1999:32,1371-1375.
2) Pappas A, Zawacki R, Sullivan T. Biomechanics of baseball pitching. A preliminary report. Amer J of Spts Med. 1985:13,216-222.
3) Werner S, Suri M, Guido J. Relationships between ball velocity and throwing mechanics in collegiate baseball pitchers. J Shoulder Elbow Surg. 2008:17,905-908.
Read more Sports Doc for Sports Medicine and Fitness.