Pitcher Injury Mechanisms
In Pitching MRSA
and Killer Cues, I
identify some of the movement patterns that I believe are
contributing to the pitcher injury epidemic. However, the
question is what exactly is causing the injuries.
Timing Problems
As I mention in
It's the
Timing, Stupid, a 2012 study entitled
Early Cocking Phase Mechanics by Dr. Weimi Douoguih, Medical
Director for MedStar Sports Medicine and Medical Director for
the Washington Nationals, suggests that the problem with the
Inverted W isn't the position itself as much as the timing
problem that the Inverted W tends to create.
The logic is that, by having the pitching arm side forearm at or even below
the horizontal (low to negative degrees of external rotation) at the moment the front foot plants and the
shoulders start to rotate, the greater the amount and force with
which the pitching arm will externally rotate. That will
increase the load on the muscles, enabling the pitcher
to throw harder but placing more stress on the shoulder and
the elbow.
Anthony Reyes
The farther the pitching arm is from 90 degrees of external
rotation at the moment that the front foot plants and the
shoulders start to rotate, the greater the load and the stress
on the arm.
Bob Gibson
In contrast, the closer that pitchers' arms are to 90 degrees of external rotation
— vertical forearm, as when giving a high five — at the moment
that their front foot plants, the less likely it is that their
pitching arm will be overloaded.
Premature Pronation
If you study the anatomy of the elbow, you will find that the
load that is placed on the elbow during a 85+ MPH pitch exceeds the strength of the
Ulnar Collateral Ligament (UCL). That means that some of the
load is being carried by some other structure in the elbow.
Dr. Mike Marshall theorized that the load above the UCL
failure point is carried by the Pronator Teres muscle. The
Pronator Teres also inserts into the Medial Epicondyle and
passes over the UCL. However, recent research suggests that the
load is more likely borne by a different set of muscles that
arise from the Medial Epicondyle.Park 2004,
Udall 2009
Regardless of exactly what muscles are involved, the idea is
that, for the load to not be focused on the UCL, pitchers need
to be activating those critical muscles during the moment that
the UCL is under maximum stress.
The theory is that the problem with cues like
Show the Ball to Center Field,
Keep Your Fingers on Top of the Ball, and many of the other
cues that are used to teach throwing is that they put
the forearm in a position of
premature
pronation and activate the muscles that
arise from the Medial Epicondyle too early. At the
moment when these muscles are needed to help carry some of the
load, these muscles are relaxing. That forces the UCL to carry
more of the load and causes it to degrade more quickly.
This theory is backed up by findings of scientific studies,
including Udall's comments on Ahmad 2003
in which he states, "Electromyographic studies of the
flexor-pronator muscles have shown that these muscles may
actually fire less in pitchers with MUCL deficiency."Udall
2007 Udall also states elsewhere, "Although the arm and
forearm musculature are not large contributors to force
generation during throwing motion, they play important roles in
the accuracy and control in overhead throwing athletes. The
flexor-pronator muscles also play a role in the stability of the
elbow joint to valgus stress..."Udall 2009
Notes
Ahmad 2003. Ahmad, Christopher S.,
Lee, TQ, ElAttrache, N.S. "Biomechanical Evaluation of a New
Ulnar Collateral Ligament Reconstruction Technique with
Interference Screw Fixation." American Journal of Sports
Medicine 31:332-227, 2003.
Park 2004. Park, Maxwell C. and Ahmad,
Christopher S. "Dynamic Contributions of the Flexor-Pronator
Mass to Elbow Valgus Stability." Journal of Bone and Joint
Surgery 86:2268-2274, 2004.
Udall 2007. Udall, John H.,
Fitzpatrick, Michael J., McGarry, Michelle H., Leba, Thu-Ba, and
Lee, Thay Q. EFFECTS OF FLEXOR-PRONATOR MUSCLES ON VALGUS
STABILITY OF THE ELBOW. 53rd Annual Meeting of the Orthopaedic
Research Society, 2007. Poster Number 1154.
Udall 2009. Udall, John H.,
Fitzpatrick, Michael J., McGarry, Michelle H., Leba, Thu-Ba, and
Lee, Thay Q. "Effects of flexor-pronator muscle loading on
valgus stability of the elbow with an intact, stretched, and
resected medial ulnar collateral ligament" Journal of Shoulder
Elbow Surgery 18:773-778, 2009.
|