Lack of external rotation appears related to shoulder injuries in professional pitchers

by Brett Holland, PT, DPT, CSCS

A recent study has been published in the American Journal of Sports Medicine regarding shoulder range of motion and its relationship to shoulder injuries.  The study was done in professional pitchers during spring training [1].

Here is the breakdown:

External rotation is the motion that allows a pitcher to take his arm back way behind his body when he throws.

The study examined 296 professional pitchers and measured their preseason range of motion.

Pitchers whom did not have >5 degrees difference between their throwing arm and non-throwing arm were 2.2 times more likely to have a shoulder injury. 

There were 51 pitchers whom injured their shoulders out of 296 (17.2% ouch!).  Even worse was the fact there were 75 total shoulder injuries meaning pitchers whom were injured often re-injured (47%).  20 pitchers had to get shoulder surgery (7% of all pitchers, 40% of the injured pitchers).

Be careful extrapolating this information to other populations.

• Remember this data was collected in professional pitchers meaning we need to be careful applying this information to other populations (high school, college, etc).
• Often times we do not see the same results in amateur athletes that we do in professional athletes.

Why might a pitcher lose external rotation?

• To start, it is normal for a pitcher or baseball player in general to have more external rotation on his throwing arm than his non-throwing arm.  This has to do with throwing a baseball when we are younger.  The throwing arm begins to adapt at an early age when the bones are soft resulting in more external rotation and less internal rotation.  This is called retroversion.
• A loss or a lack thereof external rotation means one of two things:
  • 1. the bones failed to adapt to a certain extent when we were younger
  • 2. soft-tissues developed tightness or stiffness

How can we correct a lack of external rotation?

• Stretching and shoulder mobilization can improve external rotation of the throwing arm.
• Again I would like to throw out a word of caution.  We do not know if improving external rotation has an effect on injury rates or know if this data applies to anyone other then professional pitchers.

What does this mean?

• We should monitor pitchers pre and in-season external rotation.
• Individualized decisions should be made whether an athlete will benefit from increasing external rotation

References:

1.  Wilk, K. E., L. C. Macrina, G. S. Fleisig, K. T. Aune, R. A. Porterfield, P. Harker, T. J. Evans, and J. R. Andrews. “Deficits in Glenohumeral Passive Range of Motion Increase Risk of Shoulder Injury in Professional Baseball Pitchers: A Prospective Study.” The American Journal of Sports Medicine 43.10 (2015): 2379-385 http://www.ncbi.nlm.nih.gov/pubmed/26272516