The Fundamentals of Elite Arm Action

The most important part of a pitcher's mechanics is his arm action. It's the final link in the kinetic chain connecting the ground to the ball. From a seated position, without turning or twisting, someone with good arm action can throw 60 mph - that's 60% of a 100 mph fastball from the arm alone. Hand a baseball to most NFL quarterbacks or Olympic javelin throwers, put them on a mound with a full windup, and they'll throw about the same. Not because they lack athleticism, but because they lack proper baseball arm action. It's a hyper-specific skill, and in this video we're going to break down exactly what that entails.

What Makes Up Elite Arm Action

In short, elite arm action means getting the arm into the right positions, using the right muscles, at the right time. There are successful major leaguers who don't fall under these classifications, but the older a pitcher gets, and the more elite company he wants to keep, the more prevalent that "elite arm action" becomes. These positions can be simplified into two key checkpoints.

A Note on Measurement: Before we start, we need to discuss an important caveat when it comes to analyzing 2D video of 3D space. Angle measurements lie. The camera placement, the specific location you choose to mark the body, the exact frame in question...they're all subjective and drastically skew the measurement. We can't rely on the exact angles taken from video. Instead we need to rely on our eyes, because our goal in analyzing video is to not only describe what happens, but to translate that into words an athlete can feel and understand. Focusing on the minutia of imprecise angle measurements is a waste of time, and for that reason this video won't show them. Instead, we'll discuss angles in general terms that are more easily applied.

Checkpoint 1: Stay Inside 90 Degrees at Footplant

When viewed from the "open" side, the arm needs to stay inside 90 degrees at footplant. This accomplishes three things:

First, staying inside 90 degrees keeps the moment arm shorter, allowing the pitcher to rotate faster and more efficiently. When the arm extends outside 90, the moment arm lengthens, which slows the pitcher's rotation. This overhead angle illustrates the ball's trajectory when the pitcher loads outside 90 degrees. This more gradual path requires greater force - and therefore places more stress on the arm - to achieve the same velocity.

Second, an angle inside 90 degrees enables greater triceps extension, by creating a longer runway to accelerate. Like a racecar reaching top speed, it's a lot easier with a longer track.

And third, a 90 degree angle or less shifts the workload into the larger muscles surrounding the humerus instead of the smaller muscles around the ulna and radius. One of the most fundamental rules of power and health in sports is to use bigger, more proximal muscles whenever possible, allowing smaller, distal muscles to focus on control and stabilization rather than power generation. Staying inside 90 degrees achieves exactly that. To feel the difference yourself, tie a rope to a baseball and throw so the rope gets taut right as your elbow comes forward. Outside 90 degrees, you'll feel immense pressure in your elbow and forearm. Inside 90 degrees, that pressure spreads to your upper arm, shoulder, and torso.

Checkpoint 2: Get the Arm Up on Time

The second fundamental of elite arm action is to achieve arm layback that parallels the spine at footplant. By using the pitcher's spine as a reference point, we account for pitchers of all arm slots. While some big leaguers don't quite reach parallel, most do - and many layback even further. This arm position at footplant provides five key benefits.

First, the arm at parallel allows footplant to layback the arm even more than voluntarily possible. Compare a pitcher's maximum layback during their delivery to what they can achieve standing still - the difference is dramatic. Harnessing footplant to layback allows the muscles of the arm to simply absorb force instead of create it.

Second, parallel layback shortens the amortization phase of the throw. Like a plyometric exercise, the time from footplant to release is critical - the longer it takes the more energy leaks from the system. This 60 FPS video of Payton Tolle shows the consequence of a late arm: it takes 7 frames from footplant to release instead of the typical 5. Which means 1/3rd of the amortization phase is spent getting the ball up and parallel with the spine. Something that the very best pitchers do before footplant. Payton is young, 6'6 and 250 lbs so he leverages his incredible strength and youth to overcome a loss in efficiency. He also reached the major leagues in his very first season of professional baseball, which is a testimony to the fact these arm action fundamentals can be overcome by exceptional physicality.

Third, the benefit of earlier, deeper layback is that it creates a longer acceleration path. A pitcher can't change how long his limbs are, so creating more distance to accelerate the ball requires mechanical adjustments. To accurately compare video, we standardize the angles by using clips from the same game. And we see that an earlier layback means the pitcher gains more distance in the horizontal plane than his counterpart. Like our racecar analogy from earlier, this longer track translates into greater efficiency and is fundamental to arm health.

The fourth benefit of a parallel layback, is it reduces the arm's range of motion during the riskiest part of the throw. Arm stress is minimal before footplant but surges dramatically once the front foot lands. Ask a pitcher at what point in their delivery they are experiencing discomfort, and 99% of the time it will be after footplant. By achieving layback earlier, the pitcher shorten the arm's range of motion during this dangerous window, and therefore reduces the forces absorbed by the shoulder and elbow.

And finally, early layback keeps the ball path tighter to the pitcher's center. Both pitchers and position players alike understand that its better to keep the ball closer to the head during the throw. When the ball transitions from its rotational path to a straight line toward the target, a tighter path means that line points more directly at home plate. Since arm length is fixed, pitchers narrow the path by bending at the elbow to keep the ball closer to their head. This animation depicts an ellipse with a constant circumference, but a changing width. The same principal applies to arm action. Narrowing the width of rotation creates a more direct path to the target.

It's no accident that the game's best pitchers consistently get their arms into these two checkpoints at footplant - the arm inside 90 degrees and laid back to parallel with the spine. By doing so, they gain durability, command, and velocity. Look at the video of any Hall of Fame starting pitcher, and don't be surprised to see they all throw using the fundamentals of elite arm action.

Why Don't All Pitchers Get Their Arms Into These Positions?

Several reasons prevent pitchers from achieving proper arm action, and they're all rooted in skill level.

First, larger movements are harder to control. In every sport, the further you load from the release point, the more challenging it becomes to aim and time correctly. A slap shot, a free kick, a swing, a throw - the bigger the load, the more opportunity for error. And for unskilled athletes, errors are more likely than not.

Activities requiring minimal power and maximum precision - like darts, shooting, and free throws - share a common strategy: move as little as possible to maximize control. But activities demanding both power and control require a large load, which is inherently more difficult to execute. The unskilled athlete will choose the smaller, more controllable load - which in pitching means not laying back as far.

Second, achieving deep layback requires exceptional physical ability. Static flexibility is a poor indicator of a pitcher's ability to get into these positions appropriately. The right muscles have to lengthen while others contract in a very short amount of time, and tendons and ligaments need sufficient load tolerance to withstand the immense forces. It's a physically demanding position only attainable by the game's most capable pitchers.

Finally, the brain finds it easier to track the ball when it's held further from the body. Keeping the ball further away either slows down rotation or increases stress on the arm. Both help the brain have a better sense of where the ball is in space. This same phenomenon appears in hitting, where young hitters hold the bat away from their body instead of wrapping it tightly behind their head. It likely occurs across all sports, but I can only speak confidently about baseball.

Being the best in the world requires a pitcher to achieve things that contradict each other. Velocity, command, and durability don't typically improve together. But the game's most elite pitchers have found a common strategy that delivers all three - via the fundamentals of elite arm action.