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The Inverted W

The Inverted W, which I originally called The M, is a term that is used to refer to one of a family of problematic pitching arm actions that include the...

Recent studies have found that pitchers who make the Inverted W and who have a Timing problem as a result, are at a significantly higher risk of experiencing shoulder and elbow problems.


In the Inverted W the pitcher...

  1. Lifts their elbows to the point where they are at, or even above, the level of their shoulders.
  2. While, and more importantly, their forearms are flat or, worse yet, pointing downwards.

Biomechanically speaking, that means bilateral hyperabduction and minimal external external, or worse prolonged internal rotation, of both arms into Foot Plant.

Anthony Reyes and the Inverted W

The Inverted W

That can be problematic and increase the pitcher's risk of elbow and shoulder problems if it hurts their Timing; if their pitching arm isn't up and in the Ready Position when their front foot plants and their shoulders start to rotate.

Anthony Reyes and the Inverted W

Anthony Reyes

In the pictures above of Anthony Reyes, the primary problem isn't the height of his elbows. Rather, that primary problem is that, because his elbows are still high, his forearms are at best flat, and actually slightly internally rotated, when he's at Foot Plant.

ASMI and the Inverted W

Despite the studies of the Inverted W and Timing that are starting to come out, I still get considerable pushback on the idea that the Inverted W is problematic. That is why I was interested by what an ASMI epidemiologist recently said about the Inverted W...

The Inverted W is something that we look for during our biomechanical evaluations here at ASMI. It's essentially a combination of late external rotation and high shoulder abduction at the moment of foot contact during a pitcher's delivery. Both of these issues have been demonstrated to lead to problems that can result in injuries requiring surgery. Low external rotation at foot contact (what we call a "late arm") results in higher stress on the elbow. The ideal angle of shoulder abduction is 90, because the bones and the soft tissues supporting the joint are able to move the most freely and most efficiently. When the arm is raised higher, the soft tissues in the shoulder joint become inpinged, or pinched against the shoulder socket, and can cause injury. So when you add these two things together in the Inverted W, a pitcher can really get into trouble.

I view the fact that ASMI incorporates the Inverted W into their evaluative criteria to be a huge advance and validation for the idea that the Inverted W and the other arm actions are problematic because they often cause Timing problems.

Timing: The Core Problem

The Inverted W, and many other problematic pitching arm actions, often leads to a problem called Flat Arm Syndrome, which is another, easier-to-visualize way of describing the Timing problem that is the root cause of the injury problems of a number of pitchers, including...

As I explained in late 2007 in my analysis of Mark Prior's pitching mechanics, and more recently in my analysis of Stephen Strasburg's pitching mechanics...

The Inverted W isn't (necessarily) a problem in and of itself.
Rather, the Inverted W contributes to injuries in pitchers by creating a timing problem, and timing problems are what tend to hurt pitchers' arms.

The Inverted W increases the likelihood that a pitcher's arm will not be in the proper position when their front foot plants and their shoulders start to rotate. That will increase the load on the elbow and the shoulder, providing a short-term velocity boost but, in the long run, significantly increasing the risk of injury to the pitching arm.

Anthony Reyes

Anthony Reyes

In the picture above of Anthony Reyes, the primary problem isn't the height of his elbows. Rather, the problem is that Anthony Reyes' forearms are pointing downward at the moment his front foot plants and his shoulders start rotating. That will cause his pitching arm to externally rotate (flip over backwards) with much more force than his body can handle.

Comparison of Justin Verlander and Anthony Reyes

Justin Verlander and Anthony Reyes c. 2006

If you compare the arm actions of Justin Verlander and Anthony Reyes, it's obvious why Justin Verlander is still pitching and Anthony Reyes isn't. As I discuss at length in my piece on Flat Arm Syndrome, at foot plant Justin Verlander's pitching arm is UP while Anthony Reyes' pitching arm is at best FLAT.

Anthony Reyes' pitching mechanics -- his Inverted W and resulting Timing problem -- are why he only pitched in the major leagues for a few years before breaking down for good.

The Epidemic
The EpidemicAs a result of the recent discussion about the baseball pitcher injury epidemic, I have put together a webbook called The Epidemic that gives my view of what is happening, why, and what coaches, parents, and physicians can do about it.


The idea that the Inverted W is problematic is controversial, and I have addressed some of the objections to the theory...

Recently, a number of studies have been completed that are relevant to the Inverted W in particular and Timing problems in general. I discuss them on my piece on The Science Behind The Epidemic.

If you are interested in helping to fund this project, I have put together a page for crowdfunding partners.

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