Discussion: Internally Rotating the Shoulder

by Kyle Boddy on Jan 4, 2009 2:02 AM PST in Pitching Mechanics Comment 6 comments

SB Nation poster NoNameOnCard is a frequent contributor to this site and has published his own blog about biomechanical research as it pertains to baseball - TexasLeaguers.com. For those who think that I go on at length about biomechanical and anatomical concepts, you should check out his stuff!

He has an excellent article up right now that discusses the internal rotation of the shoulder and how it contributes to valgus stress on the elbow (the primary cause of UCL rupture). Dr. Marshall believes that UCL rupture occurs due to "forearm bounce," or when the pitching arm goes from zero acceleration to maximum acceleration with the forearm being "laid back" in a position of shoulder external rotation. An example of external shoulder rotation can be seen below:

Wagner_medium

As a slight digression, Paul Nyman (SETPRO) believes that shoulder external rotation is the cause of high pitched ball velocities. I disagree. It is the effect of high pitched ball velocities.

NoNameOnCard believes that by extending the pitching arm before internal rotation takes place that the triceps can maximally project the baseball towards home plate with higher velocities and reduce the risk of UCL-related injuries.

I'm not sure I agree. I emailed NoNameOnCard this blurb in hopes of stirring up some discussion:

I love the blog so far. However, I don't think that I draw the same conclusions that you do about internal rotation. Dr. Marshall's students experience significantly higher degrees of internal rotation about the shoulder than "elite" pitchers from ASMI, as documented in this study. This would indicate that Dr. Marshall's pitchers should be at much higher risk for UCL injuries than traditional pitchers. Do you think that Dr. Marshall's pitchers use of their triceps via pronation helps to protect against valgus stress?

As for your comments about the anterior deltoid needing to flex to maintain the full length of the forearm behind the shoulder to avoid "forearm bounce" (vertical pitching forearm laying back in external rotation), you are correct - their pitchers do not do this. However, Dr. Marshall does want them to do so. Bill Peterson of RPM Pitching has indicated that his son Patrick had serious injuries in the anterior portion of his shoulder - particularly the deltoid area - after years of training with Dr. Marshall. To me, using the anterior deltoid in this manner causes a position of hyperabduction and poses a serious risk of injury. It takes a genetically gifted individual to accelerate a baseball at meaningful velocities using this technique, and Patrick was one of the few that could. It directly contributed to anterior shoulder injury.

The flaw of "looping" that Dr. Marshall talks about (the bending of the pitching elbow) is not a flaw at all, IMO.

I need to review the videos of Dr. Marshall's students, because while it is true that the internal rotation of their shoulders is significantly higher than ASMI's "elite" group of pitchers, the lack of UCL-related injuries to pitchers in his group could be related to an extended pitching arm before internal rotation, if NoNameOnCard's theories are correct.

I've emailed Dr. Marshall about this issue as well, and I'll start pulling video to see what I can conclude.

I promise that less verbose articles will be published in the future and more pitcher analyses will go up. I'm just knee-deep in tons of research that I want to understand a bit better before I continue. Thanks for your understanding.

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Timing.

According to valgus stress and torque studies (some of which have been performed by the folks at ASMI), traditional pitching deliveries achieve maximum internal rotation velocities during early arm action (elbow flexed, right after foot plant), as you describe above. The thing is, most pitchers turn their forearms over “late” and the acceleration isn’t from zero, it’s from negative. This is essentially true for all pitchers who pick the ball up with their elbows.

Dr. Marshall’s pitchers achieve maximum internal rotation velocities right around pitch release (extended arm, way after foot plant). I truly believe this is the primary reason that his pitchers tend to avoid elbow injuries.

Dr. Marshall’s pitchers clearly extend their arms (and even pronate in some cases) before internal rotation takes place. His pitchers apply the same muscle-contracting force (if not more thanks to their training and strengthening programs) during internal rotation, but the mass being rotated is much closer to the axis of rotation (r is smaller). This means (1) that there is less inertia to overcome, and (2) less torque is required to apply the same force (t = F x r).

Any time a pitcher’s medial epicondyle faces the target, he is experiencing valgus stress in some fashion because the inertia experienced by his forearm directly opposes medial stability. If a pitcher leads with the olecranon instead, the forearm trails peacefully (though this requires external rotation of the shoulder, which i haven’t fully read up on yet). Arm extension can take place from this laid back forearm position, continuing the kinetic chain through the arm and avoiding valgus extension overload syndrome.

At about 30 degrees of elbow flexion, the bones in the elbow start to take over elbow stabilization, and at 20 degrees and lower, they are the primary stabilizer against valgus stress. Even if the same valgus torque values are approached using this arm action (and I don’t believe they are), the load on the UCL itself is dramatically reduced.

Kyle, where can I get more info on Patrick Peterson and his injury?

Neftali Feliz is not a swimmer.

by NoNameOnCard on Jan 4, 2009 1:11 PM PST reply actions 0 recs

From looking at Dr Marshall’s video and the one of Nolan Ryan on TexasLeaguers, I have some opinions on what has been said.

My opinion on a couple of things: I believe Kyle asked if Dr. Marshall’s pitchers protect their UCL by pronating. I absolutely believe so! The pronator teres muscle can help protect against valgus stress in the elbow with throwing. I know that Dr Andrews was (probably still is) against young pitchers throwing curve balls because of the stress on the elbow. I think a young pitcher’s inability to throw a curveball and pronate properly or the inability of his coach to teach him this process puts undue stress on the elbow joint. So, if Dr Marshall’s pitchers are pronating, that helps protect against valgus stress.
Another issue I see is arm slot (delivery angle). With Dr. Marshall’s pitchers the arm slot is in a lot more shoulder flexion or overhead delivery which reduces the amount of external rotation needed. In the Nolan Ryan video (on TexasLeaguers) the arm slot seems to be more 3/4. With the 3/4 arm slot, a pitcher has to severly externally rotate the arm in order to get the olecranon to face the target. When the olecranon faces the target, I agree with NoNameOnCard the joint articulations take over the valgus stress instead of the UCL. I believe the margin of error with a 3/4 arm slot is much smaller. It takes repeated perfect timing to get the olecranon to face the target. Any timing mistakes and the UCL takes the brunt of the valgus stress. So, the margin of error with elite pitchers vs. Dr Marshall’s pitchers is much smaller.
It would be interesting to see when pitchers are more likely to rupture the UCL? Without seeing any research or opinions, I wonder if it is more towards the end of games. Just thinking out loud, if a pitcher gets fatigued and their delivery gets a little lazy, are they unable to get the olecranon to face the target thus stressing the UCL? Does anyone know if there is any research on this?

by seattle_pt1 on Jan 10, 2009 8:13 AM PST reply actions 0 recs

You raise an excellent point about external rotation.

I actually wrote a very poorly explained article despite all the technical language. The degree of external rotation, I believe is directly related to UCL health but not really in the way it came across in my article.

The problem is when external rotation leads to direct opposition of acceleration and internal rotation. I really didn’t address this much, choosing to focus solely on the internal rotation aspect. It left too much out and left me looking sort of stupid in the process.

The re-writes I’m working on will cover these ideas with better explanations.

The pronator teres, I believe, is overrated as a UCL support and underrated as a performance enhancer. It also helps prevent hyper-extension (olecranon fossa and hyaline cartilege isses). The other muscles in the flexor-pronator mass have greater potential for valgus stabilization.

Here’s the biggest thing, though, when it comes to Dr. Marshall’s motion. When performed properly, valgus force is virtually eliminated.

Neftali Feliz is not a swimmer.

by NoNameOnCard on Jan 11, 2009 4:58 PM PST reply actions 0 recs

Good input. Just found an article about the effect of flexor group and its effect on pronation. I totally agree about the pronator teres helping prevent hyper-extension. Here is an interesting point from a joint perspective. When you extend the elbow, you need a conjunct pronatory rotation to achieve full extension of the elbow.

I agree also with Dr. Marshall’s motion, but is the shoulder, T-spine and L-spine being put at risk. I should probably look at more of his pitchers, but that delivery gives me some concern.

by seattle_pt1 on Jan 14, 2009 8:22 AM PST up reply actions 0 recs

When you do that...

I recommend being studying his description of what he believes the ideal delivery to be, particularly in regards to arm action. Most of his pitchers do not achieve it.

His two (relatively?) new 2008 videos have some voice over commentary on them that help point out where his pitchers break from the ideal motion.

Neftali Feliz is not a swimmer.
TexasLeaguers.com

by NoNameOnCard on Jan 14, 2009 10:08 AM PST up reply actions 0 recs