Stephen Strasburg's Injury / Elbow Injuries in General


#1

I wrote a little piece about Strasburg’s injury and UCL ruptures in general. I talk about “scapular loading” and why it’s probably harmful for the elbow. Did you know “scapular loading” was one of four variables (out of 37!) that make up 97% of the variance of elbow valgus stress? (Relationship between throwing mechanics and elbow valgus in professional baseball pitchers - Werner et al.)

If you’re interested, you can read about it here:

And no, I’m not saying that Strasburg’s high values of horizontal shoulder abduction (and the resultant high peak shoulder horizontal adduction angular velocities) are the sole cause of his UCL rupture. It’s a multivariate equation and my article doesn’t make any solid conclusions.


#2

Who doesn’t scap load in the big leagues?


#3

Probably a few guys, I’m sure.

But it’s not binary. It’s a question of degrees.


#4

Probably a few guys, I’m sure.

But it’s not binary. It’s a question of degrees.[/quote]

So a guy like Matt Lindstrom who has an uber scap load is more at risk? Or CC Sabbathia?


#5

Probably a few guys, I’m sure.

But it’s not binary. It’s a question of degrees.[/quote]

So a guy like Matt Lindstrom who has an uber scap load is more at risk? Or CC Sabbathia?[/quote]

In a vaccuum, yeah. If everything’s the same (and it’s not), they may theoretically experience more elbow valgus stress than a pitcher who has lower values of peak shoulder horizontal adduction angular velocity. Obviously there are many other biomechanical factors involved.


#6

There is the nut, the variables. Mechanics, techniques (3/4 side-arm etc), conditioning, HISTORY!!! Heck throw in velocity too (As in Maddux’s avg 86 vs say Pedro’s 93) all of that and video games and moving friends furnature and the myriad of other quirky serendipitous happenings. I suggest that the human body will find it’s individual limits and the human mind will drive that body past those limits, this, along with “freak accidents” and we will always have injury in the top teir of atheltics, it is unescapable. I think mitigating with reasonability will tempor the carnage in the vast herd running for the prize but again injury is largely unavoidable. Not because we don’t have the science but we have this thing called desire…fed by media. I personally believe that Greg Maddux had singular grasp of this and studying his approach would seem enlightened thought…except he was very secretive about what he did. What you see of him though appears a bastion of “reasonable”, very directed thought. Watching him throw a bullpen wouldn’t necessarily help someone understand what he knew though…it was an entire approach to the game.


#7

Kyle
Good post and reference material. jd, another good post by da man.

Well, although good to show here, this material doesn’t really state anything new. I recall a presentation several years ago (I still might have it somewhere) that discussed just what’s being said here. It mentioned the same idea, that testing on cadavers indicated that the stress on the UCL during pitching exceeds its ability to withstand but other tissues serve to mitigate, thus avoiding UCL failure on every pitch.

My amateur reading of what causes velocity is similar to jd’s comment about variables but a large part of it appears to be that tissues get pushed to the limits of what they can withstand. Do high velocities actually cause injury? One could be academic about it and say no, it’s the mechanical elements (and all of the other variables) that stress the tissues in ways that result in velo. Po-tay-to or po-tah-to.

What the articles point to is that rapid, excessive stretching of the UCL with the subsequent recoil causes UCL injury. What is also being said is that certain mechanical elements exacerbate the problem, in this case horizontal abduction with accompanying high angular velocity of adduction. Sure, I buy that. Again, though, this is a nasty motion.

So, Kyle, my question for you is what’s to be done about it? If we reduce that stress by changing the mechanic, are we correspondingly reducing the opportunity to produce velo? If so, what do you propose we replace it with? You mentioned playing with the variables involved in torque, such as changing the elbow angle from the worst case at 90 degrees to something lesser. All sounds wonderful but is velo possibility now dramatically reduced? Mike Marshall had all kinds of mechanical theories about this. He may have been successful in reducing injury risk but he also removed velo production potential. I read one facetious suggestion on this which said the you could remove pretty much all injury risk if you simply walked the ball to the plate. As you know, Bill Peterson was going down an interesting path with this but I haven’t heard anything from him in more than a year, so I’m assuming he’s moved on.

So, what do you propose that doesn’t drop velo production potential to unacceptable levels?


#8

There is the nut, the variables. Mechanics, techniques (3/4 side-arm etc), conditioning, HISTORY!!! Heck throw in velocity too (As in Maddux’s avg 86 vs say Pedro’s 93) all of that and video games and moving friends furnature and the myriad of other quirky serendipitous happenings. I suggest that the human body will find it’s individual limits and the human mind will drive that body past those limits, this, along with “freak accidents” and we will always have injury in the top teir of atheltics, it is unescapable. I think mitigating with reasonability will tempor the carnage in the vast herd running for the prize but again injury is largely unavoidable. Not because we don’t have the science but we have this thing called desire…fed by media. I personally believe that Greg Maddux had singular grasp of this and studying his approach would seem enlightened thought…except he was very secretive about what he did. What you see of him though appears a bastion of “reasonable”, very directed thought. Watching him throw a bullpen wouldn’t necessarily help someone understand what he knew though…it was an entire approach to the game.[/quote]

Good post jd (as always), but that paper that I referenced indicated that ball velocity is not significantly correlated with levels of elbow valgus stress! It might be more stressful on the shoulder or other body parts (and I’m sure it is), but at least in that paper, it didn’t seem to be the case for the elbow.


#9

dm,

Let’s back up just a second before I address your very thorough (and good) post.

You said that the mechanical elements that produce velocity may cause the injuries in pitchers today. Is there significant evidence that shows that higher levels of peak shoulder horizontal adduction angular velocities also contribute positively to ball release velocity? I have not (as of yet) seen a paper that shows any correlation.

EDIT: BTW, I spoke to Bill not long ago. He is well and still working on his book/program. Things didn’t go as planned with Pat, as you may have surmised.


#10

I know…which is how veritably impossible it is to devise a “real world” set of controls for any meaningful study involving the art. Logic and ones own eyes can see that a guy who controls velocity and operates obviously below max has other issues to deal with than ballistic injury issues. I discussed this today with my son and likened it to a vector sum equation. On one quadrant you have velocity and the other you have…say control, with different variables effecting the balance between hi level effectiveness with low level injury potential and something like say “wild” effectiveness with hi injury potential (Think Mitch Williams type hi velo mechs).


#11

I think there are definitely some unmeasurable variables that figured into this. When you take a 100mph guy who is pushing his body to the limits and you add in gametime adrenaline and having to live up to huge expectations then bad things happen.


#12

[quote=“kyleb”]You said that the mechanical elements that produce velocity may cause the injuries in pitchers today. Is there significant evidence that shows that higher levels of peak shoulder horizontal adduction angular velocities also contribute positively to ball release velocity? I have not (as of yet) seen a paper that shows any correlation.[/quote]I haven’t seen actual research to that effect either, Kyle, although the existence of the scap loading process in high level pitchers is ubiquitous. As you know, Paul Nyman has long been of the opinion that it is an essential component of a delivery intended to produce velo.

So, if one is proposing the removal of something as prevalent as this, suspicion is raised as to whether or not the replacement can achieve the same results, in this case regarding velocity production. Mike Marshal removed many things and could never achieve high velos with his proposed replacement. Bill Peterson looked like he was onto something. It sounds like you may have your own take on it. I’m wondering what that might be.


#13

dm,

I agree that some horizontal shoulder abduction is probably required (and is indeed safe) for elite MLB-like velocities (90+, let’s say). But ball velocity wasn’t correlated with elbow valgus while excessive “scapular loading” was. This is a fairly telltale sign, IMO.

If I knew the answer to what created elite levels of release velocity and kept pitchers’ arms safe, I’d be the first to do it. First and foremost, I think that a good strength and conditioning routine can prevent injuries and increase release velocity simultaneously, and I think that most MLB teams do not have a good system set up for this (many independent sources confirm this). Minor league players often get by on little money and very little coaching; their facilities are also usually quite under-equipped for this type of training.

We live in an age where we baby the pitchers, tell them to run a bunch of long distances (poles), pull some bands, stretch out, and this should make them injury-free and ready for professional levels of competition. This simply isn’t true, and exercise scientists know this.

Mechanically, I think that many of the answers are coming out of research papers (some that I’ve quoted). IMO the “answer” (if there is one) is likely to focus on the physical quality of the pitcher (strength, conditioning, flexibility, mobility, stability, etc) with mechanical changes being a secondary focus.

Hope some of that makes sense. We should talk soon via phone so I can explain the backstory with Bill and catch you up to speed on what’s new here. Speaking of, if you know any kinesiology/biomechanics majors, I’m hiring - need some help with building my motion capture laboratory here in the PacNW!


#14

Kyle,

Got a few questions for you.

(1) Does the term “peak shoulder horizontal adduction angular velocity” refer to movement of the humerus relative to the scapula or to the humerus AND scapula together relative to the spine? In other words, what parts are adducting?

(2) If pitchers did not “scap load”, would they still horizontally abduct their humerus and, if so, would that be better or worse than if they did scap load?

(3) In your article, you say…

“When the arm is taken behind the body in this position, it must return to the neutral/anterior portion of the trunk to deliver the ball to the plate. As a result, this will cause peak shoulder horizontal adduction angular velocity to increase, which causes elbow valgus to increase.”

This would seem to imply that pitchers who scap load to a greater degree are at more risk. But my thinking is that the degree of scap load is dictated by each pitchers’ flexibility and what really matters is the “stretch” they achieve (as in stretch-shortening cycle) such that maximizing the stretch is what maximizes peak shoulder horizontal adduction angular velocity. The consequence of this is that a pitcher who doesn’t scap load as much due to limited flexibility but who maximizes the stretch could create a higher peak shoulder horizontal adduction angular velocity and put himself at greater risk than a pitcher who scap loads to a greater degree but who doesn’t maximize the stretch. I think this demonstrates why there are no absolutes in baseball as well as the difficulty in trying to predict injuries. Comments?


#15

You bring up some good points, Roger, which lead me to add that the angle of the humerus relative to the acromial line has another variable at play. That is, the humerus is connected to the trunk via the scapula. Scapular loading isn’t simply moving the elbows behind the acromial line. It involves adducting the scapulae (scapulas, scapuli, :reallyconfused: ) toward the spine, or toward each other. This serves to reduce the angle of the humerus in the glenoid. This probably doesn’t mitigate the elbow valgus stress issue but I thought it would be important for the readership to understand that the angle looks worse than it really is with respect to the humerus in the glenoid.


#16

DM, you’re right on the money. I’m getting ahead of myself since Kyle hasn’t responded yet but what the heck.

The NPA (and the Titleist Performance Institute) came up with a stability/mobility model that identifies joints (word used loosely) as either providing stability or mobility. Basically, going from one end of the body to the other, joints are alternately stable or mobile:

ankle - mobile
knee - stable
hip - mobile
low back - stable (extension/flexion only)
upper back - mobile
scapula - stable
shoulder - mobile
elbow stable
wrist - mobile

Stable joints on either side of mobile joints help protect the mobile joints. Scap movement, as you said, does help to keep the humerus from operating at the extremes one’s range of motion and that certainly does help protect the shoulder.


#17

…in the eye of the beholder.

When I was very young and naïve I believed that “science” could answer all questions. Specifically when it came to understanding movement and motion physics could answer all questions. As time went on I began to understand that what we call science is nothing more than a temporary state of attempting to explain cause-and-effect. Temporary in that science (physics) changes as new cause-and-effect relationships are discovered. In recent years I’ve “discovered” a fascinating new field of study dealing with the behavior of nonlinear dynamic systems also known as chaos theory. One of the most fascinating aspects of chaos theory is the concept of initial conditions and self organization. From Wikipedia:

[quote]Chaos theory is a field of study in mathematics, physics, economics and philosophy studying the behavior of dynamical systems that are highly sensitive to initial conditions. This sensitivity is popularly referred to as the butterfly effect. Small differences in initial conditions (such as those due to rounding errors in numerical computation) yield widely diverging outcomes for chaotic systems, rendering long-term prediction impossible in general.[1] This happens even though these systems are deterministic, meaning that their future behavior is fully determined by their initial conditions, with no random elements involved.[2] In other words, the deterministic nature of these systems does not make them predictable.[3] This behavior is known as deterministic chaos, or simply chaos.

Chaotic behavior can be observed in many natural systems, such as the weather.[4] Explanation of such behavior may be sought through analysis of a chaotic mathematical model, or through analytical techniques such as recurrence plots and Poincaré maps.[/quote]

Having spent the better part of 15 years trying to understand how the body optimally throws a ball and swings a bat which includes working with over 20 players have been drafted, being invited to major-league spring training to work with minor-league pitchers, written numerous articles on how the body swings and throws optimally and developed numerous devices to measure what happens when you swing or throw I can say that based upon my own personal experience and training in physics and engineering that any attempts to categorically attribute injury by observing on videotape how a player throws a baseball has about the same probability of success as picking the right number on one spin of a roulette wheel.

Specific to Kyle’s article regarding Strasburg’s injury. I have copies of the same study(s) Kyle quotes from along with others from biomechanics and medical journals. The common denominator is that maximum UCL stress (stress most likely contributing to UCL injury) occurs during maximum external rotation (MER) and in most instances at the point just prior to MER as illustrated by the following:

One of the great problems is that those who do the studies really don’t understand what it takes to maximally throw baseball. For example in order to maximally transfer momentum to the baseball i.e. kinetic chain or as I would like to term it kinetic whip, momentum is transferred segmentally from larger mass slow moving to smaller mass faster moving i.e. conservation of momentum principle. This can be seen in pitchers as momentum from the larger body parts lower trunk moves its way up through the smaller body parts upper body shoulders and finally through the arm. In our to maximize the with the fact and momentum transfer their something called degrees of freedom i.e. number of segments that are allowed to participate in the momentum transfer process. This is where flexibility i.e. the ability to involve greater number of joints and muscles in the transfer process becomes vitally important in maximizing throwing velocity and as important if not more importantly maximizing throwing efficiency i.e. minimizing the amount of stress on the body and connective tissue.

Maximum throwing velocity will occur if momentum for rotation of the upper torso is maximally coupled to the throwing arm. This occurs if I’m segments are brought into the plane of rotation of the shoulders i.e. through external rotation of the upper arm. There is a study that shows the correlation between external rotation velocity and that young players who have thrown a lot develop what’s called humerral retroversion, i.e. a twist in the upper arm bone favoring external rotation which actually puts less stress on the shoulder when throwing a baseball.

Based on these principles no matter what one does there is a minimal valgus stress for a given body type, physical condition and throwing mechanics and desired throwing velocity. And as stated previously this about the stress occurs just prior to maximum extra rotation regardless of how the arm got to maximum external rotation.

There are also two points that I wish to clarify with respect to the “inverted W” and scapula loading.

Kyles articles states the following:

[quote]When the arm is taken behind the body in this position, it must return to the neutral/anterior portion of the trunk to deliver the ball to the plate. As a result, this will cause peak shoulder horizontal adduction angular velocity to increase, which causes elbow valgus to increase.

“Scapular loading” is a popular term first posited as a mechanical cue that would help improve fastball velocity by Paul Nyman of SETPRO. While he has since taken down his website, you can find this quote on it using The Wayback Machine (all typos his):

Fact: SETPRO was the first to sunderstand and show the difference between HORIZONTAL ADDUCTION or what SETPRO call “SCAPULA LOADING” and HYPEFLEXING. Almost all power pitchers SCAPULA LOAD. SCAPULA LOADING is vital to developing stretch reflex, storage of elastic energy and increasing the Range Of Motion (ROM) of the delivery.

Paul Nyman himself says that scapular loading is horizontal adduction (technically it’s horizontal abduction followed by fast horizontal adduction during the acceleration phase) and that he teaches it to all of his clients as it is vital to “developing stretch reflex.” That’s a story for another blog post, but the end result is absolutely clear: Scapular loading causes higher rates of peak shoulder horizontal adduction angular velocity and therefore causes greater elbow valgus, which we know is positively correlated with UCL rupture.[/quote]

The concept of the inverted W. was developed long before Internet gurus such as Chris O’Leary came on the scene. For the record the inverted W concept was perpetuated as a way to maximize throwing velocity per se.

The inverted W. concept came about in response to Dick Mills advocating that all pitchers should go to what he termed as the “high cock” (Statue of Liberty) position to throw baseball.

My response/reply was to this was/is that advocating going to the high cock position promoted stalling/break in the throwing sequence and that if if you look at pitchers such as John Smoltz (one of the best examples of the inverted W) there is no such thing as “going to the high cock position” The throwing processes one continual action of the arm. And that the inverted W was one of the best examples of this i.e. not going to the high cock position per se.

So the inverted W was/is not a de facto way of throwing the baseball optimally. It was simply a way of advancing the idea that throwing is a continuous process and that advocating a position (teaching dictum) such of the high cock interrupted a more optimal throwing process.

What became known as scapula loading started off as a rebuttal to both Dick Mills definition of hyper flexing of the shoulder and Mike Marshall’s a achromial line mandate, i.e. that there is a static line drawn through both shoulders which creates a plane which the elbow should never pass beyond.

This is similar to what Tom House called the goalpost position. My rebuttal was simply an anatomical observation that the shoulder complex was a dynamic entity i.e. had a number of degrees of freedom (adduction, abduction, rotation). It was a further observation that most pitchers who threw with high velocity had significant degrees of horizontal abduction of the shoulder i.e. pinching of the shoulder blades.

And yes there is a consequence of horizontal abduction or should I say the sequence of abduction to adduction, the consequence has to do with the transfer of momentum that the greater degree of involvement of the shoulder complex as part of the momentum transfer and development mechanism will create greater elbow stress simply by the fact that there is greater energy/momentum to deliver to the baseball. Or simply stated one rule of life that I’ve come to fully understand is that when it comes to energy and momentum you can’t get something for nothing.

What Chaos theory has to do with all of this simply that every human is unique there are an infinite number of ways to throw a baseball attempting to stereotype offer simple solutions when it comes to how the body swings or throws is in most cases an exercise in futility.[/quote]


#18

Paul I’d like to say that this community is honored that you would choose to serve it with such an important statement.
Thank You
jd


#19

What does Chaos theory have to do with all of this is that any attempt to offer offer simple solutions based on video observations as to the cause of throwing injuries is at best and exercise in futility and at worst deceptive and fraudulent.


#20

Well said Paul. But you have to understand that charlatans (like the aforementioned internet guru) can’t dupe people and take their money without these simple scare tactic theories.

It goes against their agenda and ego. :lol: