I recently evaluated yet another Major League baseball player with the “yips,” or what I like to call thoracic outlet syndrome. I really don’t believe in the yips at all and feel that thoracic outlet syndrome is almost always to blame. Telling a professional athlete it’s all in their head or some mysterious mechanical flaw is just insulting.
One of the major reasons that thoracic outlet syndrome occurs in baseball pitchers is from hypertrophy of the scalene muscles (and sternocleidomastoid). Throwing a baseball causes many adaptations to the body, including this increase in scalene size.
Here is a video of the athlete inhaling with his head turned to each side. Notice the significantly larger scalene and sternocleidomastoid on his right side.
I wish I had a magic trick to help in this situation. I will perform manual therapy on the scalene muscles, surround musculature, 1st rib, and thoracic cage, however, it’s hard to combat the hypertrophy associated with throwing.
Understanding what to look for is the first step, though. Scalene hypertrophy is a subtle finding to detect on examination.