I recently had a conversation with one of our players about manually stretching the external rotation (ER) of the throwing shoulder, and why we don't do it in our program. Per
Eric Cressey and CSP, "Want to irritate a labrum, biceps tendon, or the undersurface of the rotator cuff? Stretch a thrower in extreme external rotation and stimulate the peel-back (forearm lay-back) mechanism." He also goes on to outline some alternative ways and drills to increase ER like
improving scapular retraction as well as
thoracic spine mobility, and last but not least...throw more! Says Cressey, "Pitchers gain a considerable amount of glenohumeral external rotation over the course of a competitive season simply from throwing."
I like this quote from Phil Rosengren of
BetterPitching.com on manually stretching into ER, "So when you think about it, actively stretching your arm where it's already getting loose on its own doesn't make much sense. You're just creating more instability in the joint, putting you at greater risk of injury." See the full article
here.