This video is possibly the best example I've found of what Dr. Mike Marshall's arm action is supposed to look like. The catch is that the pitchers in the video aren't throwing baseballs. The pitchers are performing exercises from Dr. Marshall's wrist weights program.
4 of Dr. Marshall's students are shown here doing different things that include his wrong foot slingshot, wrong foot loaded slingshot, and pendulum swing wind-up drills.
One thing I've noticed repeatedly is that despite the straight-line acceleration of the heavy weights during these exercises, Dr. Marshall's students routinely demonstrate a dramatically different arm action when they throw baseballs.
The main difference is where the arm drives the baseball. In the weighted exercises (iron balls and wrist weights), his pitchers unquestionably apply force in a nearly straight line that results in extension that is simultaneously away from the pitcher's body and toward the target. When throwing a baseball, however, his pitchers apply a lot of upward force that results in extension that is away from the pitcher's body but toward the sky instead of the target.
[Added at 12:30 PM, Monday, April 27, 2009]
One of Dr. Marshall's pitchers from the video has emailed me and asked that I clarify the difference that I see. In short, Dr. Marshall writes that the driveline height of the baseball should be just above the ear. This description perfectly fits with the driveline height for the weighted exercises. In the high-speed video I've seen of Dr. Marshall's pitchers, the driveline height for their baseball pitches results in a release point that is almost a full arm's length above the ear.
Some exercise specialists believe that the extremely heavy weights train the muscles to fight gravity. As the pitchers step up the weight increments, their muscles learn more and more to oppose gravity. Holding up a 20-pound wrist weight requires more than 60 times the force that is required to hold up a 5-ounce baseball, so when one of Dr. Marshall's pitchers performs his arm action with a baseball, his body and arm are accustomed to applying much greater upward force than is necessary.
This is one explanation for the upward extension. It makes perfect sense even to a layman, but I don't believe it accounts for all of the differences.
Dr. Marshall himself focuses on the principle of specificity of training - that a pitcher should learn/train to pitch baseballs by pitching baseballs - so his interval-training programs make baseball pitching a part of the daily routine.
So why then do his pitchers have a distinctly different arm action when throwing baseballs compared to when they "throw" heavy weights? Truthfully, I don't have that answer. It could be related to old muscle memory, or I may have misinterpreted Dr. Marshall's ideal arm action.
This aired back on March 25, 2009. The link below will take you to a 7-minute segment from MLB Tonight which airs on MLB Network. In this clip, Harold Reynolds is joined by Dr. Mike Marshall and his left-handed student Joe Williams.
With only 7 minutes in which to work, Dr. Marshall has to skim over a lot of things, but he sums up his arm action very succinctly. He briefly explains the muscles that are involved in his arm action and mentions how pronation helps protect the elbow.
Dr. Marshall also has Joe demonstrate a couple of drills. Pay special attention to the second base pick-off drill. It's a drill he has mentioned in the past when talking about re-training traditional pitchers to correct the flaw of horizontal shoulder flexion.
With the football drill, Dr. Marshall and Joe show Harold how to throw a pronated curveball. The video isn't the best, but if you look closely and use some imagination, you can see the ball spinning forward instead of backward.
When a ball spins, it creates an envelope of air around it called the boundary layer. This boundary layer moves with the ball whether it spins forward or backward or sideways. The interaction of this boundary layer with the surrounding air results in an outside force that changes the path of the baseball. This is the Magnus effect.
Named for German scientist Heinrich Magnus, this effect is a principle of fluid dynamics that describes the lift created by the spin of an object that is moving through a fluid (gas or liquid).
To better understand lift, here is a brief look at how airplane wings create lift. The shape of airplane wings causes air to move faster over the top of the wings than it moves beneath the wings. The faster moving air results in lower air pressure above the wing and greater air pressure beneath the wing. The greater air pressure pushes the wing up; this is lift.
HOW SPIN CREATES LIFT
The spin of the ball dictates the rotation of the boundary layer. When the ball has back-spin, like a fastball, the boundary layer under the baseball shoots air forward into the air that is trying to move around the baseball. The opposing air flows result in slower air movement and higher air pressure underneath the baseball.
On top of the ball, the boundary layer shoots air backward in the same direction as the air that is trying to move around the baseball. These air flows compliment each other and combine to create faster air movement and lower air pressure on top of the baseball.
The combination of slower air movement under the ball and faster air movement over the ball creates lift that opposes gravity - a "rise". The Magnus effect, in this case, acts just like an airplane wing.
For a curveball, the top-spin is like turning that wing upside-down. The opposing air flows are now on top of the baseball, and the complimentary air flows are on bottom. Here, the Magnus effect creates lift that compliments gravity - a drop.
With a tilted spin axis, the Magnus effect creates a tilted lift. A left tilt adds right-to-left movement when the pitch has back-spin and left-to-right movement when the pitch has top-spin. A right tilt has the opposite effects.
When a pitch spins perfectly sideways, like a screwball or a sweeping curveball, the Magnus effect does not create a "rise" or drop. Instead, it creates sideways lift. Viewed from the top, clockwise spin results in left-to-right lift, and counter-clockwise spin results in right-to-left lift.
MAGNUS EFFECT ON OTHER PITCHES
The Magnus effect is greatest when the ball's spin axis is perfectly perpendicular to the velocity of the baseball. As the spin axis turns (or yaws, if you're into that sort of thing) from perpendicular to parallel to the baseball's velocity, the Magnus effect decreases accordingly. Likewise, the magnitude of the Magnus effect increases as the spin axis moves from parallel to perpendicular to the baseball's velocity.
When the ball's spin axis is perfectly parallel to its velocity, the Magnus effect is null, barring crosswinds. In this case, the ball spins like a bullet - clockwise for righties and counter-clockwise for lefties when viewed from the pitcher's perspective - and no part of the boundary layer opposes or compliments the surrounding air flow.
A pitch with this spin is called a gyroball, and despite what was widely reported when Daisuke Matsuzaka came to the states, the null Magnus effect makes this the straightest pitch that can be thrown.
Wind tunnel studies have shown that this type of spin results in a smaller wake behind the ball. A smaller wake means less wind resistance which means a gyroball does not slow down as much as a fastball does on its way to the plate.
A slider is intended to have glove-side lift, but Pitch-f/x data suggests that sliders move less than any other commonly thrown pitch. On Pitch-f/x charts, sliders are usually grouped around or very near to the chart's origin where zero horizontal movement meets zero vertical movement. This suggests that most sliders spin like gyroballs. I tend to agree.
Good sliders, though, will have a spin that is somewhere between that of a curveball and that of a gyroball. Such spin will create the sliding movement and, depending on the degree of tilt, a varied amount of additional drop for the pitch.
If a slider's spin is between that of a curveball and that of a gyroball, the spin of a cut fastball should be between that of a fastball and that of a gyroball. Where a slider ideally has some top-spin, a cut fastball has a large amount of back-spin.
The combination creates lift nearly identical to a fastball, but because the spin axis is turned slightly to the pitcher's glove-side, it also has glove-side run.
Split-finger fastballs can be thrown with one of two different spins. The first spin is simply a slower back-spin than a normal fastball that creates less lift than a normal fastball would. When thrown at nearly the same speed as a normal fastball, the split-finger fastball appears to drop due to the smaller lift.
The second spin is actually top-spin. This is the ideal spin for an effective split-finger fastball because the forward tumble creates a drop like a curveball. The velocity of the pitch is similar to a fastball, but the spin is like a curveball albeit with a much slower rotation.
When top-spin is present in this pitch, it is sometimes called a forkball. A forkball is usually held with a deeper grip than a split-finger fastball, but the two pitches are practically identical give or take a couple of ticks on the radar gun.
Some sinkers spin like reverse-cut fastballs, and some sinkers spin like reverse-sliders. Most are somewhere in between. A power sinker, like the one thrown by Brandon Webb, spins almost like a screwball but with fastball velocity.
The same rules that apply to cut fastballs and sliders also apply to sinkers. The difference is that cut fastballs and sliders have glove-side lift while sinkers have arm-side lift.
THE ROLE OF SEAMS
The 108 stitches on a baseball grab the air around the ball and create a larger boundary layer than a ball with no seams would create. The horseshoe shape all around the baseball allows a pitcher to throw just about any pitch as a two-seam pitch, a four-seam pitch, or something that isn't quite either of those (a three seamer?). Most sliders fall into the third category.
A four-seam pitch spins on an axis that allows four seams to influence the boundary layer. The four seams are evenly spaced (balanced) around the baseball. This symmetry creates a stable and relatively predictable Magnus effect.
A two-seam pitch, though, spins on an axis that unbalances the seams even though all four seams still influence the boundary layer. This axis puts a seam loop on either side of the ball, leaving the two connecting seams close together on one side of the ball.
With the axis turned slightly to the left or the right, one of the seam loops moves toward the point of pressure (where the ball breaks through the surrounding air and experiences the greatest wind resistance), and the other seam loop moves away from it. This axis exaggerates the Magnus effect of the seam that moves toward the point of pressure, and reduces the Magnus effect of the seam that moves away.
The dominant seam, because of its almost circular shape, creates a point of nearly constant friction as it pushes boundary layer air almost directly into the air breaking across the point of pressure. When the seam catches that angle just right, the baseball will dart left or right depending on which seam is dominant.
CLOSING THOUGHTS AND OTHER NOTES
I've talked a lot about how a pitch spins and why it moves the way it does, but I haven't yet touched on the magnitude of the Magnus effect. The obvious part is that greater movement is due to a greater Magnus effect. The not so obvious part is how to increase the Magnus effect to create even more movement. The simple answer is to give the ball more spin.
The faster a ball spins, the greater the resulting Magnus effect will be. Squeezing just one extra rotation out of a pitch can have dramatic results on the pitch's movement.
You may have noticed that I didn't talk about the knuckle ball at all. Well, the knuckle ball doesn't spin, so it has no Magnus effect. A knuckle ball's movement is strictly an aerodynamics issue where the seams cause immediate disruption in the surrounding air flow rather than through a boundary layer. On the pitch's way to the plate, chaos theory takes over and the knuckle ball waivers as the seams catch air and unpredictably change the path of the ball.
Finally, release angles play a sizable role in creating "hidden" movement. For example, if a pitcher releases the ball two feet outside of the rubber, it has to move roughly 3 1/2 feet to reach the opposite corner of the plate. Sliders and curveballs with glove-side lift will look like they are moving nearly 4 feet as they cross that corner, even though they only break about 3 to 5 inches.
Several days ago, it was reported by several local media outlets that Brandon McCarthy choked down 7,000 calories a day this off-season to add about 25 pounds to his slender frame. This weight gain has a lot of fans excited about the positive impact it could have on his 2009 season.
The expectation is that McCarthy will be stronger and more durable going into 2009 than he has ever been before, but while he may be stronger, he may not necessarily be any more durable.
At 7,000 calories a day, there is virtually no chance that all 25 pounds are added muscle, and even if it is all muscle, that isn't necessarily a good thing.
Since coming to the Rangers before the 2007 season, McCarthy has battled a stress fracture in his right scapula, a strained flexor tendon in his flexor-pronator mass, and a strained flexor tendon in his right middle finger.
McCarthy's injury trouble started with a stress fracture in his right scapula in July 2007. A stress fracture occurs when a bone "flexes" repeatedly - an action obviously not meant for bones. The injury indicates that the bone is being bent, stretched, or pulled by some unnatural movement, but it is not out of the question that natural movement can cause it as well.
Following his 2007 shoulder injury, McCarthy spent the off-season working hard to get stronger for 2008. Word had it that he was up about 15 to 20 pounds. Without a doubt, his focus was on staving off another shoulder injury.
The nature of a stress fracture indicates (but does not guarantee) that a mechanical flaw is responsible. The other two injuries are indicative of a lack of physical fitness.
When throwing a pitch, the arm and hand have to be strong enough to overcome the inertia created by the rest of the body. If the inertia is stronger than the bones and soft tissue, the unfit tissues tend to break down.
THE WEAK LINKS
Strains occur when muscles attempt to handle larger loads than what they are capable of handling.
McCarthy's body got stronger, and thanks to both his increased mass and increased strength, he was creating more intense loads for his elbow, wrist, hand, and fingers. His forearm was not ready for the increased load, and his forearm flexor tendon suffered a very serious strain.
Pitching with a compromised flexor tendon puts the ulnar collateral ligament at serious risk for strains and ruptures, and it's usually pretty painful.
After spending several months strengthening and conditioning his forearm, McCarthy finally returned to the mound. With a stronger forearm, the next injury occurred at the next weak link in the kinetic chain, the flexor tendon of his right middle finger.
DOING THE MATH
If you've followed what I've said so far, you can see how it's important for a pitcher to be strong from his toes to his finger tips.
A pitcher's arm must be strong enough and conditioned to handle the loads generated by the rest of his body, otherwise, even someone with anatomically perfect mechanics can suffer muscle strains, fatigue, tendinitis, or worse.
Richard Durrett of the Dallas Morning News wrote the following on January 20, 2008 during the Rangers pitching mini-camp:
McCarthy said he's worked hard to strengthen not only the area that has proved bothersome, but also the areas around that.
To me, this is far more encouraging than reading that he gained 25 pounds. Perhaps now, his arm is ready to take advantage of the leverage his 6' 7" frame is capable of generating. If it is, McCarthy is primed for a break out season.
"Delayed internal rotation" is the term I use to describe the arm action in which internal rotation does not occur until after the elbow is mostly extended. In some instances, depending on the path of the elbow in space, this delay allows the triceps brachii to actively contribute to the throw. It remains to be seen whether this is beneficial to velocity or health when compared to intertial forearm acceleration which is believed to be more common.
In either case, given sufficient external rotation, delaying internal rotation allows elbow extension to occur in the plane established by the path of the humerus -- a sign of system efficiency, two segments working together -- and in the direction of the throw -- a sign of segment efficiency.
ARM ACTION - EFFICIENT SEQUENCING
As the humerus is accelerated, it generally moves in an arc. This arc establishes a plane of motion along with momentum (and therefore intertia) of the forearm and ball.
The distal end of the humerus (near the elbow) reaches peak forward velocity shortly after the humerus is perpendicular to the line between second base and home plate. At this point, from a laid back forearm position, two actions continue the acceleration of the forearm: elbow extension and internal rotation. Sequencing matters.
When internal rotation occurs prior to elbow extension, whether intentional or not, the forearm moves from the laid back position into a more upright position, changing the plane in which elbow extension occurs.
As internal rotation pulls the forearm further out of a laid back position, the further toward the target the humerus must be for elbow extension to be efficient. While that increases segment efficiency, it decreases system efficiency as the forward velocity of the humerus is sacrificed to achieve this.
When the elbow extends prior to internal rotation, the extension accelerates the forearm more directly toward the target and in concert with the forearm's momentum established by the path of the humerus. In this sequence, elbow extension can maximally contribute to pitch velocity and is a strong link in the kinetic chain.
As elbow extension decelerates, pronation, wrist flexion, and internal rotation work together to powerfully finish the pitch directly toward home plate.
A HALL OF FAME EXAMPLE
Take a look at Nolan Ryan's arm action in the following 4-frame image.
In the first frame, you can clearly see that external rotation has taken place with the forearm trailing the elbow.
In the second frame, Ryan has finished accelerating his elbow, and elbow extension has begun. His forearm is still trailing his elbow in a laid back position.
In the last two frames frames, Ryan's elbow extension is decelerating and nearly complete, internal rotation has begun, rotating his forearm toward the plate. As the pitch is released, pronation occurs, and internal rotation continues through the deceleration phase.
DR. MIKE MARSHALL AND ELBOW PATH
Dr. Marshall has something to say about elbow paths that have a large lateral component. From an email he sent me:
When, after 'traditional' baseball pitchers take the baseball laterally behind their body, they drive their pitching arm back to the pitching arm side of their body, they generate forces toward the pitching arm side of their body that 'slings' their pitching forearm laterally away from their body.
This can be fairly easy to see with the naked eye by looking for a lateral component to the elbow's path. For example, if a left-handed pitcher brings his arm toward third base (or a right-handed pitcher brings his arm toward first base), he must drive his elbow laterally to the other side of his body before he can accelerate toward the plate.
Much of this article assumes a traditional delivery in which the humerus moves in an arc as the shoulders rotate. Depending on exactly how the pitcher moves, this arc can be pronounced or nearly non-existent. A pronounced arc is the result of a greater lateral component in the arm path and creates more centripetal force on the forearm.
Dr. Marshall believes those two effects to be inefficient and injurious because he believes:
the triceps can generate elbow extension force that exceeds the centripetal force of a traditional delivery, and
the lack of an effectual triceps contraction prevents the brachialis from properly decelerating elbow extension.
Frankly, I'm not sure either belief stands up to scrutiny, but I'm also far less qualified than Dr. Marshall in such matters. (It's also entirely possible that I've misunderstood or misstated his beliefs. You can investigate this for yourself at his website.)
IN A FEW PARAGRAPHS
A cursory analysis of primary arm action movements suggests that arm actions are generally more efficient when internal rotation is delayed until after arm extension. This means that less energy is wasted on movement that doesn't directly contribute to pitch velocity.
My conclusion: delayed internal rotation has positive performance implications.
This information, coupled with my previous conclusions regarding UCL health, leads me to believe that there are both performance and health benefits to delayed internal rotation.