The Limits Of
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
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
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
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.