Post-Activation Potentiation with Weighted Baseballs

Post-Activation Potentiation (PAP) is a controversial topic in exercise science, with research pointing in favor and against it working. PAP is not easy to describe, but the simplest way to put it is to think about testing your 60-yd dash time shortly after squatting 3-5 reps of heavy weight. The idea is that by “potentiating” the central nervous system (CNS) using heavy movements, performance increases in subsequent lighter and explosive movements.

Does it Work in Baseball?

First and foremost, it’s important to note that the most popular method of PAP in baseball does NOT work – using a donut or weighted bat sleeve in the on-deck circle before going up to hit.

Baseball - Donut

Dr. Coop DeRenne, a legend in the world of baseball performance science, studied this very phenomenon years ago. Donuts used prior to swinging a real bat show a marked decrease in bat speed, yet hitters use them all the time. The reason for this isn’t because athletes are smarter or more experienced than sports scientists running controlled experiments, of course, it’s just a mix of inertia, superstition, and fear.

Or you could ask the scholarly people in the comments of major news sites, who have stunning results to share with us all:

Average Internet Commenter

Thanks, Doctor.

The reason that PAP doesn’t work in the on-deck circle is because the use of the donut in an attempt to increase the bat weight makes no effort to grasp the significantly changed biomechanics of the swing by adding 200% or more of the weight to the bat in an uneven distribution. This makes the loaded donut swing a completely different motor pattern by drastically changing not only the mass of the bat, but the moment of inertia (MOI) of the bat as well.

In short, it doesn’t work. So if you use donuts in the on-deck circle (or at all, really), you should stop.

But What About Weighted Baseballs Prior to Pitching?

Ah, this is the million dollar question, isn’t it? What about throwing weighted baseballs prior to pitching to potentiate the CNS to increase output?

I think this is a rather fascinating concept, and as it so happens, we’ve studied this effect as best we can in the Driveline Sports Science lab. There are three generally-accepted methods of how PAP works, and the primary one we focused on was the idea that increased recruitment of higher order motor units would activate other motor units to allow for greater than average neuromuscular performance.


Have athletes test run-and-gun velocities with a standard (5 oz) ball after a dynamic warm-up, then throw 6 oz and 7 oz overload balls for 3-5 reps each. After that, test run-and-gun velocities with the standard (5 oz) ball again and see if there are significant changes.

We also tested the OPPOSITE effect – we had athletes throw underload baseballs instead of overload to see if activation might work in a different manner.


We split the athletes into two even groups as randomly as possible while controlling for age and skill level.

First we’ll discuss the underload group: It was a disaster. Subjectively the athletes overwhelmingly hated it when feedback was solicited, and objectively the data was clear as day – velocities went directly into the tank by 2+ standard deviations.

Some things said:

  • “It feels like I’m throwing a brick”
  • “I feel like I’m going to blow my elbow out”
  • “I don’t want to throw 5 oz balls as hard as possible after that”

Pretty clear loser there. We moved underload balls back to where they’ve always been – at the end of the velocity run-and-gun tests.

The overload group, on the other hand, had mixed but statistically insignificant results. No athletes complained about the grouping of the weighted ball throws (5-6-7-5-4-3 oz) and while the average of the group saw higher velocities, it wasn’t statistically significant – and some lost velocity after throwing the overload baseballs. Some statistically insignificant trends that seemed worthy of future study were found, however:

  • Professional pitchers are more likely to see the benefit of PAP with overload instruments
  • Pitchers with certain types of arm action flaws were predisposed to realizing better velocities post-potentiation (and kinematics of the throw did change significantly)
  • Amateur athletes who had trained under the Driveline system for some time saw little to no effect

So, What’s it All Mean?

Overall, I think the idea of PAP is very interesting and perhaps useful when it comes to weighted baseballs, but perhaps not prior to a game. Our study was a very limited trial that did not test one of the most important variables in a game – endurance.

It’s very possible that a comprehensive dynamic warm-up using proper tools captures enough of the “PAP” benefits, and athletes who do not warm-up and potentiate the CNS correctly prior to training or competing may see phantom benefits from what they think is truly PAP.

PlyoCare Balls

In that vein, however, we recommend all athletes use PlyoCare balls to warm-up alongside their dynamic warm-up that should feature resistance bands, foam rollers, and other techniques to properly prepare the body and mind for competing on the diamond.

By |September 28th, 2014|Research, Training|9 Comments

The Mechanics of Throwing Strikes

In my previous article on control problems, I talked about the kinesiological factors that can go into wildness and command issues. In this post, we’ll talk about the specific mechanical factors that go into throwing strikes – with a heavy emphasis on the actual component of physics and mechanics, rather than standard coach-speak of acquiring a target and other mental factors which have been repeated ad nauseam on the Internet in an effort to gain easy pageviews.

“Just stare at the target intently!”

Jon Lester

Not exactly. Let’s get into the particulars.

Actual Margin of Error

At the risk of stating information that everyone knows, here’s a nice layout of a baseball field with all the relevant dimensions:

Baseball Field

We will also assume the pitcher will release the ball 55 feet away from home plate. This number was chosen because Dan Brooks and Harry Pavlidis use it on their great PITCHf/x tool, and insist it carries greater realism than using the Gameday/MLBAM standard of 50 feet. Good enough for me.

A lot goes into throwing a baseball at a specific target, of course. Here are some of the factors that we won’t focus on:

  • Spin rate
  • Release velocity
  • Angle of spin
  • Barometric pressure and relative humidity
  • etc, etc

You get the idea. However, what I don’t think is appreciated enough is the fact that huge misses at home plate can happen on very small adjustments at release.

Let’s assume your release point only varies in initial trajectory by 1° (approximately 0.01745 radians) in all directions. Therefore, assuming a 55 foot radius, the length of 1 arc is angle * radians, or in this case ~0.96 feet in each direction.

(We’ll use a circle here for simplification, but the number is actually larger since we are throwing a projectile against a “flat” surface of the front edge of the strike zone and therefore has greater depth as you move away from the origin point – but we’ll keep it as basic as possible.)

The size of the strike zone varies based on the hitter’s height, umpire in question, and even the count! However, in a general sense, the strike zone is about 1.8 feet tall and 1.5 feet wide giving the pitcher the slight benefit of the doubt. That means if you have a perfect 1° tolerance in any direction, a ball meant to be thrown middle-middle that splits the strike zone in perfect quadrants misses the target slightly high/low at the ends of the margins (0.96 feet * 2 directions = 1.92 feet tolerance high/low vs. 1.8 foot zone) and wide at the ends of the margins by quite a bit (1.92 feet tolerance left/right vs. 1.5 foot zone).

Strike Zone

However, consider that the strike zone expands diagonally (Pythagorean Theorem and all) and you have additional tolerance for missing to the corners – certainly a relief there!

And that’s assuming you can control the tolerance of your release point by a measly 1° in each direction! How little is 1°? Try this right now – hold your pitching hand up with your palm facing the floor. Rotate your hand so the thumb is pointing in the opposite direction (to the right for a RHP, to the left for an LHP). OK. That’s 180° of motion. Do you think you can consciously move your hand by 1/180 of that distance some 100+ times per game?

How Does ANYONE Throw Strikes?

Actually, this is a good question, since if you did the exercise above, it should throw doubt in your mind on how you can even control your release point within 5° of tolerance – much less 1° of tolerance!

The answer is definitely NOT coaches yelling at you to change your mechanics on the mound during a game – or for you to even think that way yourself. You have already demonstrated to yourself that you cannot adequately isolate 1° of forearm rotation, to say nothing of controlling the angles of your spine, torso rotation, internal rotation, and so many other kinematic variables that go into throwing a ball! So don’t think about your “mechanics” when you’re wild.

Proprioception is the correct answer. It is often called “feel” or “sense” by coaches and analysts, but it’s far more complex than that. Proprioception is not a conscious act – it is a map of your muscles, tendons, ligaments, bones, and nerves that has been built up over hundreds of thousands of reps of throwing objects or similar patterns that integrate themselves into this neural net of human action. Ever wonder why a 9 year old can’t hit the broad side of a barn? Yes, the young athlete is skeletally immature, but he is also lacking the proprioception that unconsciously guides his arm into the proper places to throw a strike to the target.

This phenomenon is also responsible for relatively inefficient pitching mechanics that all humans display. In Feltner and Dapena’s groundbreaking work on the biomechanics of throwing a baseball, they proposed a more effective model of throwing a baseball at higher velocities:

Feltner Model

However, as Feltner and Dapena also theorized:

After stopping the external rotation, the pitcher could conceivably keep the arm in its position of maximum external rotation and simply increase the speed of elbow extension to give the ball a large velocity at release. However, the actual pattern of motion is somewhat different from this (Figures 12 and 13): the arm undergoes a rapid motion of internal rotation immediately after reaching its position of maximum external rotation (Figure 9) , and the elbow stops short of full extension (Figure 10a). The motion of internal rotation may be unavoidable, due to the stretch of the internal rotation musculature and the inability of the abduction and horizontal adduction torques to elicit much external rotation when the arm is nearly straight. Still, regardless of whether the motion of internal rotation is voluntary or involuntary, the combination of this motion with a slowing down of the elbow extension may protect the elbow against injury.

If the elbow joint reached a maximum speed of extension just prior to the instant of full extension, this would lead to a large ball speed, but it would also risk injury to the posterior part of the elbow joint when the elbow locked straight immediately afterward (Figure 19a). The risk of injury would force the pitcher to limit the speed of the ball prior to release. The pattern actually used by the pitchers may be a good solution to this problem: by stopping the extension of the elbow before the attainment of full extension, and combining this with a rapid internal rotation at the shoulder joint (Figures 12 and 19b) , injury of the posterior part of the elbow joint can be avoided while permitting the hand to move forward beyond the position of the elbow without slowing down.

They were ahead of their time – later studies showed that premature elbow extension and the “locking” of the elbow were indeed correlated with increased rate of elbow injuries. The human body (usually) knows this is the case, so this theoretical model is never seen in the wild – though some pitchers occasionally display flaws that come close to this model, no doubt. (JJ Putz is a good recent example.)

Plotting the Map to Improve Control

The above information is interesting, but not necessarily immediately useful. Our theories at Driveline Baseball are to reject the idea of conscious mechanical reformation (except in cases of severe injury to the pitching arm and on a post-throwing program), and to use ballistic tools to help create a better and more detailed “map” for the nervous system to use. Our three-step plan is as follows:

  • Getting and keeping pitchers healthy as best as possible so there are few, if any, misfirings due to pain/discomfort
  • Developing a more specific and clearer proprioceptive map through weighted implement training (wrist weights, weighted balls, PlyoCare balls, etc)
  • Cataloging and reinforcing mechanical changes through the use of high-speed video from multiple angles

Mello Compare

This is our plan of attack in our Elite Pitchers Program – and one that we’re fairly sure isn’t duplicated anywhere else!

Control Problems on the Mound? It’s Not Always “Mental.”

How many times have you heard these lines?

  • “It’s a mental issue.”
  • “He has the yips.”
  • “He lost the ability to throw strikes.”
  • “It’s all in his head.”
  • “He’s mentally weak.”

They’re catch-all phrases that hope to capture the essence of why a pitcher like Daniel Bard can put up these kinds of insane runs:

It’s generally assumed that pitchers like Bard simply lose it mentally and can’t throw strikes because of some ephemeral issue that no one can pinpoint. Let me state for the record that this kind of thing DOES happen, but very often it’s actually an underlying physiological issue, not a mental/psychological one (or at least one rooted in those areas). Daniel Bard can still throw 95+ MPH – just like a handful of my pro clients who were throwing at their top velocities despite spraying the ball all over the place. None of them reported pain, soreness, or weakness – so it couldn’t be physical, right?

Unfortunately, that’s not how it always works.

First, let’s take a closer look at just how hard it is to throw strikes.

A Matter of Timing

Throwing a five ounce baseball with raised seams to a catcher at a target of your choosing is not exactly the easiest thing to do, yet the actual physics-to-performance marriage goes largely unexamined. Here’s two slow-motion videos shot from the side and overhead to capture the two main planes that the arm’s trajectory is on (capturing internal rotation, elbow extension, and trunk rotation). Aaron West is on the left, Taiki Green is on the right.

Aaron West vs. Taiki Green

The distal wrist of the pitching arm (and therefore, the ball) is on a weird curvilinear path around the body that is very individual to the pitcher in question. However, for simplicity’s sake to understand the basic geometry behind throwing strikes, we’ll make the arm path a simple circle below:

Tangent Arc

Imagine the black circle is the arm path and the blue line with points A and B is the ball’s trajectory. This is a line drawn tangent to the arc, and this is how a ball is thrown from the arm path. A line drawn tangent to a circle has only one point of intersection (inflection point).

So, now that the basic geometry lesson is over, here’s how it relates to throwing a baseball at a target – a baseball is ejected from the hand at a “release point” that has just one point of intersection with the hand (the moment of separation between the baseball and the hand, usually the middle finger). Now imagine that the circle above is rotating at something like 4500 degrees per second (internal rotation) but is also being deformed at up to 2500 degrees per second by increasing the radius of the circle (elbow extension), and you have a good idea of just how difficult it is to “repeat” your mechanics. (Take a look at an interactive display – change the point on the circle just slightly, and see how much the tangent line deviates.)

Actually, when you think of it that way, how is it even possible to repeat your mechanics? How is it possible that professional pitchers can hit their target on a somewhat regular basis? Mathematically, it seems to require superhuman reaction speeds and timing ability.

Physiologically, the body is one hell of a weapon.

Proprioception is Everything

Your body has the ability to automatically and unconsciously sense and control motor units in a complex way to perform incredibly difficult tasks – like ballistically ejecting an object at 90+ MPH towards a target with some degree of precision. Your body uses a set of levers (bones), pulleys (muscles, tendons, ligaments), and a central processing unit (brain, nerves installed in the muscles) to coordinate everything together to make minute changes that are impossible to consciously repeat. This is the genesis of the so-called “10,000 hour rule” as made popular by Outliers, and the MUCH better book by Geoff Colvin, Talent is Overrated.

Proprioception is the sense of the relative position of various body parts in relation to one another, usually while they are being moved. This is a generally automatic function of the body – you don’t think about firing the muscles of the upper leg in relation to the lower leg while you’re walking, nor do you think about expanding your chest manually when you breathe. When the body is damaged, there may be a temporary loss of proprioception, but the feedback given to the nervous system generally makes quick adaptations and allows for quick recovery.

For healthy pitchers, this is why we do a lot of overload/underload training using wrist weights, PlyoCare balls, and Driveline Elite Weighted Baseballs. By forcing the body to adapt to new stimuli through similar ranges of motion (and with vastly different ballistic profiles), the motor units of the pitching arm become more efficient.

However, for injured pitchers, it’s a completely different story – and that includes both pitchers who were previously injured and are now healthy in addition to pitchers who are injured but display no symptoms of injury.

Rebuilding Proprioception Through Rehabilitation – Early Intervention is Key

Rehabilitation of previously injured pitchers is far more complex than sending them to physical therapy after surgery and “returning to function” based on strength and skill tests. A pitcher who has had UCL graft/replacement (Tommy John surgery) will now have holes drilled in his arm plus a brand new tendon in place of the original ligament, not to mention severe cuts to the pronator/flexor mass that were required to get to the connective tissue in the first place.

Tommy John

Retraining the pitcher’s proprioceptive ability is similar to what we do with our healthy pitchers, though the focus is generally more on partial and constraint movements that get backchained into the full throwing motion. By using overloaded drills to help force the body to feel the proper movement patterns to more safely generate velocity, we can start the primary programming of the interval throwing program off with an accelerated pace. It is critical that when the athlete starts interval throwing that he immediately starts these simple and safe drills, because the minute a pitcher picks up a baseball, he will revert to primary programming – even if that programming is detrimental to his arm’s health. Furthermore, primary programming is not always applicable, because leftover proprioceptive sense believes the ligament is in one place, the forearm flexors have sufficient strength, the biceps work in a certain way…

Get where I’m going with this? Is it any wonder that a pitcher who seems “healthy” after surgery has ridiculous control problems? It may partially be due to psychological fear of getting on a mound and “cutting loose,” but often it is due to proprioceptive failure. Remapping the proprioceptive senses is incredibly important, and one that is often lost in the physical therapy world. Even if the PT uses Bosu Balls or other unstable surfaces to work on proprioceptive sense, these are not sport-specific and have little to no carryover to ballistic training.

Rebuilding and Regaining Control

For athletes who have microtears in their ligaments or otherwise damaged tissues that they cannot feel – ligaments have poor blood supply and innervation – this can have a serious negative impact on their ability to throw strikes. The proprioceptive mapping of how to throw strikes may be on one setting but cannot adequately adjust to the new situation of slightly damaged tissue that presents no symptoms to the central nervous system. This is why pitchers who have destabilization of the elbow tend to display control/command issues well before their UCL ruptures, even if their velocity does not significantly drop in the process.

Close monitoring of these markers should be done by all professional teams, and athletes themselves should integrate proprioceptive remapping exercises into their training.

The next time you think your favorite pitcher has simply “lost his marbles” and has developed “Steve Blass disease,” consider that maybe he has a serious injury that is simply asymptomatic. Just because he doesn’t feel pain doesn’t mean he’s not hurt – and that’s one of the most frustrating things any athlete can go through.

College Training Sessions – Spots Open

This summer’s been an absolute blast so far – with Trevor Bauer doing well in the big leagues (throwing strikes, velocity staying up), two of our HS kids being drafted (Drew Rasmussen and Gage Burland), three of our Oregon State guys being drafted (Jace Fry, Ben Wetzler, and Scott Schultz), and our facility expansion adding 5,000+ square feet, it’s been awesome.

College summer training sessions are well underway, with many college arms currently in the facility with others planning on attending after summer ball wraps up. Here’s a quick video I shot from a recent workout that shows off the serious and the lighter side of our training:

You’ll note the guy in yellow hitting 99 MPH on a pulldown – I’m afraid to say that’s underselling it, since Joe Mello of Lewis-Clark State actually hit 100.6 MPH after that!

Joe Mello - 100 MPH

If you’re interested in joining our Elite Pitcher Program for a week or two in the summer, don’t hesitate to contact us for more information. We’d love to have you out here.

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