Posts Tagged dr. glenn fleisig

Reviewing ASMI’s Biomechanical Analysis of Dr. Marshall’s Pitchers (Focus: Performance/Velocity)

Posted by Kyle in Articles on October 10, 2011

I’ve been meaning to write on this subject for quite some time, and if it’s received well, I’ll write more about ASMI’s report. A fair warning: This post will be very long and will likely contain a lot of scientific jargon that might be tough to understand. Feel free to contact me with questions or comments at any time.

Understanding ASMI’s Biomechanical Analysis

First and foremost, we need to understand what the biomechanical report actually means. The American Sports Medicine Institute (ASMI) offers high-speed video biomechanical analysis of pitchers. (Driveline Baseball offers a comparable product using similar technology.) Using this technology, ASMI analyzed four of Dr. Marshall’s pitchers, settling on three of them for a grouped analysis report (the fourth was not similar enough to the other three and had significantly lower ball velocity). If you are unaware of who Dr. Marshall is and what his theories are, you have a long road of reading ahead – and if you’re really interested in it, I recommend you read all thirty-seven chapters of his freely available book on his theories before continuing with this article. (I realize that means this article will reach an audience of about 7 people, but whatever.)

Here’s a video of Mike Farrenkopf (a pitcher employing Dr. Marshall’s mechanics) throwing at ASMI’s labs in high-speed:

Getting back on track… ASMI ran their analysis on Dr. Marshall’s pitchers and sent it to Dr. Marshall. Dr. Fleisig (who runs ASMI) and he had some disagreements, Dr. Marshall attempted to discredit ASMI’s techniques, and Dr. Flesig responded with a public in-depth look at Dr. Marshall’s pitchers. ASMI’s published report compares Dr. Marshall’s pitchers with both an “elite” group of pitchers and a “mediocre” group of pitchers – the difference being the ball velocity of the groups (the higher the better).

Reading ASMI’s published report isn’t easy, but I’ll try to simplify it. The categories of Maximum Knee Height and Foot Contact can largely be ignored; they’re just discussing static kinematic measurements during phases of throwing a pitch. What we care about starts in the Arm Cocking phase of the delivery, but before we go into that…

A Simplified Understanding of Where Velocity Comes From

Writing where fastball velocity comes from would take me years and it would hardly be a complete dissertation, so we’re going to go with a basic understanding of the mechanism of action while skipping how we get to that mechanism.

Rotational velocities are generated from various segments of the body from proximal to distal, largest to smallest body part – this is known as the kinetic chain. The legs generate force through ground reaction force (GRF), the pelvis rotates around the front leg, the trunk flexes laterally with some velocity, the upper trunk rotates around the spine, and the pitching arm humerus outwardly rotates (externally rotates). How those forces are achieved and passed from segment to segment is a coaching/training concern and not an analysis concern, so we’re skipping it.

Late Cocking Phase

Maximum External Rotation

Now the forearm is laid back in Maximum External Rotation (MER) – which should really be Maximum Forearm Layback, because the forearm in this position is aided not only by humeral external rotation but scapular tilt – and it’s ready to internally rotate to deliver the ball to the target.

As we understand it, velocity comes from just two factors under a very simple physics-based approach, which should be easy to grasp for most readers.

The final velocity of the ball will be directly related to the distance over which the ball is accelerated and how quickly the ball is accelerated. Seems simple enough, right?

Think of it this way: If you can cover 10 meters of ground at 10 meters/sec^2 but want to have a higher end velocity, you could either increase the distance you accelerate or increase the rate at which the object moves.

And so, with this partial lesson out of the way…

Why Don’t Dr. Marshall’s Pitchers Throw 90 MPH?

It’s commonly said that if Dr. Marshall’s pitching motion was so good, it would produce pitchers capable of 90+ mph velocities (the standard for elite baseball pitchers these days). Dr. Marshall rebuts this by saying that his athletes are not genetically gifted like most professional pitchers are. The truth is somewhere in the middle.

Back to looking at ASMI’s report, I want to point out a few factors that are at play:

  • Maximum Throwing Shoulder External Rotation (MER)
  • Maximum Throwing Shoulder Internal Rotation Angular Velocity (IR Velocity)
  • Maximum Throwing Elbow Extension Angular Velocity (Elbow Extension Velocity)
  • The various forces/torques on the shoulder and elbow

The “elite” group (ball velocity 85+ mph in lab testing) had a +/- 1 standard deviation range of 173 to 191 degrees of MER. Dr. Marshall’s pitchers had an average of 162 degrees of MER, which is substantially less than the “elite” group’s. In fact, Dr. Marshall’s pitchers showed more than 2 standard deviations less than the lower bound of the elite group’s MER! This would mean there is significantly less distance for the forearm to travel before the ball must be released.

What’s really interesting is that Dr. Marshall’s pitchers generated an IR Velocity (7899 deg/sec) well within the +/- 1 SD of the “elite” group’s mean IR Velocity, and the same was true for Elbow Extension Velocity. This would seem to indicate that Dr. Marshall’s pitchers had plenty of “fast-twitch” fibers and adequate sequencing of the body (albeit using a vastly different lower body action) to get the job done.

But… something doesn’t make sense: Why are Dr. Marshall’s pitchers’ ball velocities so much lower than the “elite” group’s despite having comparable kinematics of the body parts that matter? The elbow extends and the humerus inwardly rotates as rapidly as the “elite” pitchers in both categories. This is the only thing that should matter, right?

I racked my brain forever after reading this report three years ago and never really grasped the issue above until a few months ago, when I thought it through and talked to numerous kinesiologists and biomechanists. Here’s my theory.

The Broken Kinetic Chain Theory

Dr. Marshall’s pitchers are instructed to powerfully pronate their pitching forearm (source: Chapter Sixteen, Dr. Marshall’s Pitching Book) to prevent the ulna from colliding into the olecranon fossa. In doing so, pitchers theoretically avoid bone chips caused by valgus extension overload. However, the mechanism of action in doing so contracts the both the pronator teres and the pronator quadratus.

Anyone familiar with cracking a whip can tell you that the “looseness” of the whip is what creates the miniature sonic boom at the end of the whip. Paul Nyman showed through simulations of a mechanical arm that very small differences in the mechanics of throwing an object can create major differences in the final velocity of the object. (Source: The Hardball Times) If you were to make a segment of the whip stiff, it would break the smoothly flowing energy of the kinetic chain down the whip, causing the final velocity of the tip to be much lower than it normally would.

This is what is happening when you powerfully contract the pronator muscles in the forearm: You are very likely protecting the ligaments in the ulnar collateral ligament (UCL) while simultaneously generating equivalent IR Velocity, Elbow Extension Velocity, and related torques (which are just derivatives of acceleration of body parts; this is typically done using inverse dynamics as outlined by Zatsiorsky) – but you’re getting much lower final velocities of the baseball due to this “stiff” portion violating the kinetic chain. Additionally, due to the rotating forearm as the arm is accelerated forward, the wrist is not laid back for the final acceleration into ball release.

Wagner's Layback

Wagner's Laid Back Wrist

This can be seen by evaluating Mike Farrenkopf’s high-speed video above and comparing it to high-speed video of traditional professional pitchers. These factors can help explain why change-ups are slower than fastballs, as traditional change-ups are thrown with active pronation of the forearm. (It does not explain it all, however – in Kinetic Comparison Among the Fastball, Curveball, Change-up, and Slider in Collegiate Baseball Pitchers by Fleisig et al, you can see that rotational velocities and related torques are slower for the change-up as well; this shows that most change-ups are not thrown with the same “arm speed” as fastballs, despite what you hear from coaches.)

Additional Thoughts

It’s often said that the faster the arm externally rotates (rMER) during Arm Cocking that the stretch-shortening cycle (SSC) will cause humeral IR velocity to increase dramatically as a result, but this theory is not supported by ASMI’s research. Why were Dr. Marshall’s pitchers able to generate such amazing IR Velocities and Elbow Extension Velocities with rMER of just 405 deg/sec when the range of rMER for “elite” pitchers is 1291-1866 deg/sec?

I have more thoughts on this subject for future publication if this article is well-received and there is sufficient interest.

Please feel free to contact me with any questions or comments on this blog post.

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Stephen Strasburg, Mechanics, and his “Timing Flaw”

Posted by Kyle in Mechanics, Motion Analysis on March 8, 2011

Tom Verducci has a very interesting article about Stephen Strasburg: Mechanical flaw will be red flag for Strasburg even after return. In it, he says:

The answer to why Strasburg blew out — and why his future is a risky one — may lie in his mechanics. Several pitching coaches quietly predicted Strasburg was at risk before he broke down. He will continue to bear risky loads on his elbow and shoulder unless he changes the way he throws.

To understand the danger of the glitch, first you must understand the most critical point of a pitcher’s delivery. The pitching motion is a kinetic chain of events, carefully calibrated and timed, like a Formula One car’s engine, for maximum efficiency. But above all others one link of the chain is most important: the “late cocking phase,” or the phase during which the shoulder reaches its maximum external rotation with the baseball raised in the “loaded” position (typically, above the shoulder) and ready to come forward.

His description is not exactly correct. The late cocking phase is when the arm is laying back in maximum external rotation (MER) as he points out, but it has nothing to do with where the baseball is raised in the “loaded” position. The “loaded” position he describes is the “high cock position” before the arms lays back and precedes the late cocking phase.

Late Cocking Phase

Late Cocking Phase

It’s not all that important, but it’s worth pointing out.

He goes on to say:

Here is the key to managing the torque levels in the late cocking phase: timing. The ball should be loaded in the late cocking phase precisely when the pitcher’s stride foot lands on the ground.

Interesting. His source?

“If he’s too early or too late he winds up with more force on the shoulder and elbow,” said Glenn Fleisig, Ph.D., research director for the American Sports Medicine Institute in Birmingham, Ala. “The energy gets passed to the arm before it was ready, or after.”

Now this is very interesting. Neither Dr. Fleisig nor ASMI has ever said that this was a specific mechanical flaw that can cause injury. Dr. Fleisig even went on to say:

“It’s not a case of too much armpit angle,” Fleisig said, referring to the moment when the elbows are raised. “It’s that the arm hasn’t rotated yet.”

Fleisig spoke in general about the glitch some pitchers have with the raised elbow, not Strasburg in particular. When I asked him if this glitch puts pitchers at greater risk of injury, he said, “Totally. It is risky and dangerous. That’s a red flag. Definitely.”

This makes sense for a lot of reasons. In Humeral Torque in Professional Baseball Pitchers, Sabick et al. demonstrated that loading rate is an important factor when considering bone stress. The absolute value of MER may not be as important as the rate at which MER is achieved when it comes to evaluating stressors on the arm. If two pitchers have an MER measurement of 170 degrees but Pitcher A’s Shoulder External Rotation Angular Velocity is twice as fast as Pitcher B, then it makes sense that Pitcher A would be more likely to injure connective tissue around his shoulder and/or elbow.

We’ve been doing these types of measurements for more than a year here at Driveline Baseball in our biomechanics lab, as pointed out in January 2010 in the article Kinematic Analysis: Wrist to Elbow Relationship.

Maximum Shoulder External Rotation (MER)

What actually blows my mind is this quote:

How important is this specific timing? I spoke with a key decision maker for one club last week who, speaking on the condition of anonymity, said his club will not consider any pitcher — by draft, trade or free agency — who does not have the baseball in the loaded position at the time of foot strike.

Wow! If true, this is a pretty amazing statement to make! Simply eyeballing these types of metrics from 30 FPS broadcast-quality video is dangerous stuff. High-speed video should be taken of any and all pitchers you are interested in evaluating (if possible) and ideally a planar biomechanical analysis can be done without too much hassle.

However, it’s good to see that these issues are being talked about in the major media outlets. It helps reinforce the need for biomechanical analyses of pitchers to gather a large amount of data and to make inroads on mitigating throwing-related injuries while maximizing performance at the same time.

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My Recent Reading List

Posted by Kyle in Notes on February 1, 2010

Over the past four years I’ve probably spent hundreds of hours reading research papers (full ones, not just abstracts), medical journals, and derivative materials to gain a better understanding of biomechanics, applied anatomy, and kinesiology as it relates to baseball and exercise science in general.

I’m currently doing a lot of research on how to convert 3d biomechanical models of pitchers (which we will be able to construct soon using software and four high-speed cameras that are being ordered for delivery in March) into usable data that includes things like joint loads and torques. This is a rather difficult task given the estimates that go into the methods, but what’s even more difficult to figure out are the methods themselves! Stuff like this isn’t exactly published for the layman and is typically only read by other professionals in academia, not coaches like myself.

Regardless, I continue on, seeking help on the ASMI message boards and asking multiple people in the industry and academia who are very gracious with their time.

Right now I’m focused on the following two papers and their derivative works (both are freely available):

Some of the research papers that I’ve loved in the past and continue to read over and over again are:

  • Humeral Torque in Professional Baseball Pitchers (Sabick et. al.)
  • Kinetic Comparison Among the Fastball, Curveball, Change-up, and Slider in Collegiate Baseball Pitchers (Fleisig et. al.)
  • Biomechanics of the Shoulder in Youth Baseball Pitchers (Sabick et. al.)
  • Correlation of Range of Motion and Glenohumeral Translation in Professional Baseball Pitchers (Borsa et. al.)

And one of the best papers that shapes the most of my training:

There are many others that I enjoy, but those are my favorite. Give them a shot if you’re got some time and inclination to read source material. A warning, though – it gets addicting to those with inquisitive minds!

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