The importance of external rotation
External rotation is a main component in the throwing motion for creating velocity. External rotation is when your throwing hand lays back behind your throwing elbow. This happens right after arm cocking and right before ball release. The man pictured at the bottom is one of the fastest throwers in MLB history and look how much external rotation he gets. This is why for throwers of any kind having good range of motion in your shoulder is essential for creating maximum velocity. If your ROM in your shoulder is limited and your arm will not lay back much, it shortens the amount of time force can be put into the ball. An example would be if your arm was a plane and you wanted to take off as fast as possible with the most velocity would you want to take off on a 50 yard runway or a 200 yard runway? You would want the 200 yards because it obviously gives the plane more time to gain velocity. It is the same concept with the range of motion in your shoulder. If your arm can not lay back much it will be hard to reach your maximum velocity.
The best way to tell if you are getting enough external rotation (lay back) is to film yourself with a slow motion camera. It is very tough to tell how much external rotation you are getting with the naked eye. The app that many use is called Hudl Technique. It is a free app that will break your motion down frame by frame. As a thrower it is very important to always monitor your mechanics by watching them on film, because it is very easy to fall into bad habits if you do not visually see yourself throwing much.
External Rotation is extremely important obviously, however when you are throwing it should not be something you are thinking about while throwing the ball. The only coaching cue that we use is to relax your shoulders when throwing and your arm should be loose and whippy. When people are trying to muscle the ball to the target your muscles contract and it can limit your ER (lay back). For the most part you will create greater ER by exercises you perform before you throw or exercises that are apart of your daily warm up routine. Another great way to increase ER (lay back) is by long tossing.
