The Limits Of Pronating

6/25/2007

As you may know, I am a big fan of pronating. I believe that, if done early enough, pronating can protect the elbows of many pitchers.
     However, there are limits to the effectiveness of pronating as an injury-prevention measure when it comes to younger kids. This is why Dr. Mike Marshall believes kids younger than 13 should not pitch much if at all.
     For adults (generally people older than 16 or 17), pronating early is an effective way of taking some of the load off of the UCL and putting it on the Pronator Teres muscle.
     The problem is that both the UCL and Pronator Teres muscle attach to the Medial Epicondyle. As a result, if a younger kid pronates while accelerating the arm, they will shift some of the load off of the UCL and onto the Pronator Teres. However, since both the UCL and the Pronator Teres attach to the same point on the bone (the Medial Epicondyle), and that bone is attached to the rest of the Humerus via soft growth cartilage, then you really haven't accomplished anything.
     Regardless of whether the load is carried by just the UCL, or by both the UCL and the Pronator Teres, you face the same risk that the Medial Epicondyle will be irritated at its growth plate or even pulled off the Humerus bone entirely (aka an avulsion fracture).
     Until the growth plate of the Medial Epicondyle closes (at 16 or 17 biological years of age), there isn't much of anything that you can do to reduce the likelihood of this happening other than keeping kids from throwing too much and/or too hard.