# A Technical Discussion on Developing Pitching Velocity

#### prokebyt

##### Newbie
Hey all,

I found this fascinating post on reddit about pitching velocity I thought you'd enjoy. I'll transcribe it below and here's the link:

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Hey all, former player and current sports scientist/data analyst here. I've recently began work digging deeper into what truly helps to develop pitching velocity and what is wasting your time. This will be some what technical so I'll do my best to explain everything in-depth and make it as clear as possible.

There are two important (and obvious) areas that influence velocity; strength and mechanics. Both are equally important in developing sustainable velocity. Today I'd like to share some information about mechanics, specifically pertaining to the lower body.

Mechanics:

Mechanics encompasses the way the body moves through the pitching motion and the forces associated with the motion. While we can cue certain movements to achieve better and more powerful positions, understanding how it affects force provides a more holistic view. In order to demonstrate this idea, pictured below is a force/time diagram of a pitching motion.

• Green line - This represents the force produced in the Z direction (straight down into the mound). When the drive phase is over (~1.3 sec) it dips then reads the Z force of the front leg.

• Red line - This represents the force in the Y direction (2nd base to home). Positive numbers indicate force applied towards 2nd base (during drive phase), while negative number are force toward home plate (during landing phase/lead leg block). As with Z force, when the Y force crosses 0, this indicates that the force has shifted from the back leg to the front leg.

• Blue line - This line represents the force in the X direction (1st base to 3rd). Positive values indicate force toward 3rd base while negative values indicate force toward 1st base.

I have marked the 4 most important metrics as it relates to velocity in chronological order during the motion:

• Impulse - The integral under the Y (red) curve during the back leg drive phase between the zeros. In simpler terms, the area under this shaded curve shows the amount of force being produced toward second base over the back leg drive phase.

• Nz Transfer - Shows the time taken between max Z force into the mound produced by the back leg to max Z force into the mound produced by the front leg.

• Peak Front Leg Y Force - Represents the amount of force the lead leg is applying toward the plate.

• Clawback - The time between lead leg max Y force to 0 Y force.

Why are these important? These 4 metrics have the highest correlation with fastball velocity - this was discovered by The Florida Baseball Armory using machine learning and has been reproduced and confirmed by my own research. Let's break down each and understand why they relate to velocity.

• Impulse - The hardest throwing pitchers are able to utilize their kinetic chain to an elite level. This starts with their legs, specifically their back leg. The ability to plant the back leg and drive without disconnecting from the rubber will allow you to impart more force into the mound for a longer time = a higher impulse = more velocity. A good example of this is Chapman (drive phase pictured below). His whole foot is planted during the drive phase. This allows him to utilize all of the energy produced by his leg and send it up the kinetic chain and into the ball. When the foot becomes disconnected or the back knee collapses in, that power is lost and velocity decreases. The ability to create high force over more time not only increases velo, but also helps to sync the pitching motion. This isn't to say that we should be sitting in or back leg for days or only focusing on producing force in the Y direction. The force production during the drive phase should be proportional and synced up. A good rule of thumb is that you should be producing about 50% of the force in the Y direction that you do in the Z, and that this production should occur at the same time. This single movement sets the stage for the entire motion and is the most important for velocity, so it should be an area that is constantly checked and worked on.

• Nz Transfer - When the drive phase is over you body must switch from producing force from your back leg to stabilizing in on your front leg. The transfer time from peak Z in your back leg to peak Z in your front leg is Nz transfer. The ability to efficiently transfer this force is instrumental in producing velocity. The hardest throwers produce a Nz transfer time around 0.35 seconds. Why that number? It has to do with the timing of the delivery. If this time is significantly quicker or longer than 0.35, this indicates your back leg drive phase is out of wack and needs to be checked on. Whether the deliver is rushed or too slow, a bad Nz transfer time means you're leaking power from your lower body and decreasing velocity.

• Peak Lead Leg Y Force - The amount of force produce by the lead leg in the Y direction is a direct result of the explosiveness of the back leg drive phase (impulse) and the efficiency of the Nz transfer. Naturally, the lead leg has to push into the ground and produce force to decelerate the body. This process happens naturally due to your innate reflexes (think of tripping and your body stumbling to catch your forward moving center of mass). High Y force shows that the pitcher is producing a lot of force during the drive phase, is efficiently transferring it, and has the capacity bear that force and push against it instead of the front leg crumbling. Never try to intentionally produce this force, it will disrupt the flow of your delivery and produce poor results.

• Clawback - The hardest throwers are able to quickly block their front leg, allowing for the back hip to rotate through and for all of the energy that's been built up during motion to unwind, make its way to the arm where it enters the ball. It's important to reiterate that this blocking motion shouldn't be done intentionally. This can ruin the stability of your back and abdominal muscles leading to lower velocity. Pictured below is Scherzer. You can see that his lead leg blocks back straight producing huge amounts of force that transfer to the ball.

As you can see this completely neglects the upper body. The way the arm works through the motion is just as important as well. However, some of this is variable; not everyone takes the ball out of their glove the same or throws from the same slot. However, for the sake of injury prevention two things should be noted:

• When the arm comes overhead, the elbow should be positioned in-line with or slightly higher than the shoulder as the elbow climbs during the throwing motion. Additionally, the angle made by the humerus and the forearm should be 90 degrees or less. It should look something similar to Clase here.

While strength is the other important tenant to developing velocity, I'll save it for another post.

Thanks for reading. I hope you've learned something through this post that you can apply to your motion. I'm happy to answer questions or discuss any disagreements. Also apologies if there any typos, I'll try and fix them if they're pointed out. Cheers!

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• pitching graph.jpg
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• chapman.jpg
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• Peak Lead Leg Y Force - The amount of force produce by the lead leg in the Y direction is a direct result of the explosiveness of the back leg drive phase (impulse) and the efficiency of the Nz transfer. Naturally, the lead leg has to push into the ground and produce force to decelerate the body. This process happens naturally due to your innate reflexes (think of tripping and your body stumbling to catch your forward moving center of mass). High Y force shows that the pitcher is producing a lot of force during the drive phase, is efficiently transferring it, and has the capacity bear that force and push against it instead of the front leg crumbling. Never try to intentionally produce this force, it will disrupt the flow of your delivery and produce poor results.
...
Stomping and Crushing are two different things[IMO]. Gravity is what should be crushing the can, your heel dropping or falling to the ground after the toes plant.

A Stomp is flat footed jerk that accelerates your leg faster than gravity and separates your leg/weight from the rest of you body/weight and gravity. It might produce a peak instantaneous force, but that is not what you want. It causes a jerk reaction/recoil where the foot pops off the ground and everything is not working together anymore and not crushing the can all the way through the finish.

A Crush is smooth and athletic landing on toes first, then dropping the heel with gravity and all your weight. Like a skater dropping down a half-pipe and pumping up the other side. You want to keep gravity and your weight/foot pinning or crushing the can all the way through the finish position with those G-forces, standing in complete balance on the front leg and still crushing it. You don't want to extend too fast and jump off the can or half pipe, but you extend your posture in rhythm to maintain a stable foot/crush start of the swing to finish - one leg drill. You need to pump your leg in tune/rhythm to gravity to pump the swing. You also need to abandon the arm/disc away to gravity in the backswing.

I just try not to be the can.

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