I believe that elbow valgus torque is an overrated metric to determine stress on the medial elbow. I think you should warm up with grey plyo balls first. I think you should not throw overloads before bullpens or game days. These two big claims are the result of a recent deep dive into energy flow in the arm.
In a velocity focused phase, structural adaptations to absorb more energy will occur by progressing the weight of the ball, as opposed to increasing the velocity of a certain ball. With the influence of mass in the energy equation, to maximize the energy flowing into the arm, high intent throws with very heavy balls are the driving force. This strategy should better prepare the arm to both absorb and transform greater sums of energy.
The body is so well adapted to handle peak torques. If prepared, it can safely handle the valgus torque of nearly any pitch.
Driveline had the correct inherent realization well over a decade ago as many pitchers saw massive velocity jumps while pulling down 1 and 2lb balls routinely. Although the initial results caught the immediate attention of the baseball world, the focus on arm energies was years away, and preceded by a rise in injury rates.
I first dove into this topic at an entry level in late 2021 while in high school, and today, we will dive deeper with a revamped understanding of the topic, which is ulnohumeral gapping.
Ulnohumeral Gapping: The Core Concept
Ulnohumeral gapping (UHG) is a straightforward topic: as you throw, the gap between the ulna and humerus increases, and the gap between the radius and ulna decreases. This is done to offset the forces pulling the arm away from the body over time.
Kinetic Energy is our guiding metric for this thesis, where KE = (1/2)(m)(v²)
I initially believed velocity squared should dominate this equation, and to exploit this, pitchers should significantly bias underloads such as 3oz, grey balls, golf balls, lacrosse balls, etc. However, once I calculate the kinetic energies of different pitches, the relative delta in implement mass is the driving variable.
Analyzing energy flow to the arm using KE = 1/2mv², here's the velocities required to match the same energy flow as a 90mph pitch (where the standard velocity spread is roughly 3mph per ounce):
- From 5 to 4oz, this is 10.6mph higher; 100.6mph 4oz and 90mph 5oz have the same kinetic energy
- From a 5 to 6oz, this is a 7.8mph drop to 82.2mph
- The standard spreads of 87mph 6oz, and 90mph 5oz show a significant loss in energy when dropping to a baseball
Arm Stress Strategies
With this higher total energy flow to the arm, there are 4 primary methods to absorb this stress:
- Heat. Let's forget it, this can't change
- Forearm muscle strength and tendon stiffness. This is going to be the primary variable, and is, rightfully so, the most talked about
- Ulnohumeral gapping and relative skeletal motion
- UCL
The primary thesis behind this argument is diving deeper into UHG. This is a useful adaptation to throwing, but only when used correctly. The standard view on this, and what I first discussed in high school, was that as the gap between joints is stretched, the UCL has to take on more stress and is more prone to injuries. Yeah, of course.
But now, diving deeper, let's discuss the use for this. As you send more amounts of energy into the arm, these 4 strategies are used to absorb the stress. As the energy flows into the arm and the distraction forces add up, the arm uses UHG as a strategy to withstand these higher energies and distraction forces. The joint has given, which softens the impact of slamming into elbow extension and shoulder adduction at release.
So, 2 pitchers throwing the same velocity and one has a 4mm UHG, and the other has a 7mm gap, the pitcher with the smaller gap is obviously better suited to handle the stress of the throw, with all else being equal.
There are alternative benefits from compressing the joint beyond the scope of this article: The forearm tendons and muscles are stronger in a mid length than 3mm more extended. This is the same as doing a bicep curl with a 3" higher starting point. If 2 people of the same bicep strength do a curl and one begins fully extended while the other starts from 3" higher, taking out the most distal portion of the rep, the second person will always win. Same principle here.
So applying the same amount of torque, let's say 75nm to 2 elbows, the one that has relative range to create additional gapping while the tendons pull from a more mid range position, results in a significantly stronger elbow.
The Energy Math: Overloads Create Massive Stress
Now taking this into application, if we begin our throwing for the day tossing the green, 2kg plyo ball 30, 35, and 40mph, these throws send the same amount of energy into the arm as 5oz ball thrown at 113, 131 and 150mph; similarly throwing the blue plyo ball at 70mph sends the same amount of energy into the arm as throwing a pitch 125mph.
A 90mph pitch on mocap for me is 266lbs of distraction forces at the elbow and 297lbs at the shoulder, which is the limiting factor.
Using a scaling law of F(v) = F(90mph) (v/90)². Taking these same stresses to these overload energy flows, time throwing a ball 113 would be 419.8 and 468.5lb of distraction forces, and at 150mph, this would be 739.7 and 825.5lbs of distraction forces.
As Brice Crider mentioned in a recent video discussing Adam Bloebaum's energy flow article, the limiting factor in throwing 150mph is that if you do this, your arm is also ending up in the catcher's glove. In the hierarchy of needs for survival, throwing a baseball is nowhere to be seen; however, keeping your arm attached is a foundational element.
This highlights how the brain needs to understand, experience, and feel safe with these distraction forces to continue sending higher amounts of energy through the arm.
Ulnohumeral gapping is a useful tool to help a pitcher offset these distraction forces, which are a primary limiting factor of throwing a ball 150+mph.
Mass and Body Weight
This is corroborated by my recent analysis of body mass in pitchers and its influence on arm stresses. The heavier the individual, the heavier the arm. This includes bodybuilders. Strength is king, and tissue that does not aid in producing significantly more force is a net negative. All mass should have value to directly aid with strength gains.
Using maximal strength testing for strength to bodyweight ratios gives insight into the efficiency of one's mass. So the heavier pitcher (with the heavier arm) throwing at the same velocity, will place significantly higher torque, but primarily for this argument, distraction forces on the elbow and shoulder.
The Torque Analysis
Now we will begin the torque analysis. Valgus torque is calculated by:
Torque (Nm) = Force (F) × Distance (r) × sin(θ)
This utilizes how much force is applied over what distance and what angle. So valgus stress is not determined by ball weight, as mass is irrelevant in this formula. If I haven't distraction-force-pilled you yet, let's continue.
Throwing a 2kg and a 100g ball at the same arm speed (throughout the entire throw) can produce the same Nm of valgus torque on the elbow, but throwing the 2kg ball is significantly more stressful in terms of the distraction forces.
First, the measure of valgus torque estimates the peak amount of torque on the elbow using the rotational velocity of the forearm in revolutions per minute. When comparing a 2kg ball to a 100g ball, the 2kg ball will require a flatter impulse curve to overcome the inertia of its zero velocity position in layback during the amortization phase, while the 100g ball has a much lower moment of inertia and much steeper impulse curve.
Although these 2 throws might read similar or the same in terms of peak valgus torque in Nm, the accumulated stress on the UCL and forearm tendons is significantly greater, since they are exposed to a higher amount of torque for a longer duration.
When measuring peak valgus torque, the peak forearm rotational velocity in RPM is a factor, along with the derivative of angular velocity for rate of change metrics and timing of the peak angular velocity. So these factors help account for the inherent differences between ball weights. However, this solely accounts for the calculation for peak torque on the elbow, not the structural impact of the throw, where duration of strain adds up for each the UCL and forearm tendons.
The Rebuttal: UHG and Velocity
The opposition argument to compressing the UHG as much as possible is that the longer distance between the 2 will increase the range of motion. This would theoretically increase lever length and ball velocity.
For a significant increase in gapping of 5mm for a pitcher at 1000rpm arm speed, using 104.7 (rad/s) × 0.005m (increased lever), this would increase pitch velocity by 1.1mph, and for a pitcher with 1400 this would be 1.6mph.
So yes, UHG does allow for the pitcher to apply more force to the baseball and increase velocity.
However, should a pitcher rely on this, in my opinion, ABSOLUTELY NOT. This is, again in my opinion, asking for a greater portion of the stress to be absorbed by the UCL, opposed to the UHG, and stronger leverage for the forearm muscles and tendons.
With this increased velocity, I believe this could help to explain why pitchers are often throwing their hardest just before an elbow injury. They have been throwing hard for a long duration of time and built up significant chronic adaptations to throwing, which likely include fatigued forearm muscles, increased compliance of the forearm tendons, and thickening of the UCL with excessive UHG.
So they begin throwing harder and have exhausted their ability to rely on UHG as a strategy for absorbing the stress of throwing, and now are tasking compromised forearm muscles and tendons with an already lengthened UCL to lengthen even further with layback.
This combination is now insufficient to absorb the stress of the throw and leads to an acute injury of the UCL or forearm tendons.
Valgus v Distraction: The Real Thesis
After all this, we finally arrive back at the thesis of my argument.
Valgus torque is the scapegoat, not the villain; UHG is the enemy sitting inside the Trojan Horse.
As the season approaches and many pitchers look to bolster their pre-throwing routines and coaches write programs, I am arguing to leave the overload balls behind on game days. The increased energy flow, distraction forces, and forearm fatigue from the heavy balls can aid in the added UHG (while compromising other structures at the elbow) that should be reserved for the stress of game intensity.
You are going to the well of UHG utilization before stepping on the mound, while increasing time under tension and potential fatigue induced by heavier balls.
By warming up with underweight balls, at a very low velocity to begin, of course, you are reducing the demands of the forearm muscles and tendons, with lower distraction forces and energy sent through the arm. This allows the arm to be fresher for the game, when output matters, and to throw hard, longer, and safer.
And the added benefit of this strategy is that I now would cite the benefits of underload balls to come, not from sending more energy into the arm or cleaning up the throw, but solely from the neurological exposure. Sprinters use downhill sprints and band assisted work not to create specific structural adaptations to running faster, but to unlock the neurological and coordination benefits of higher peak velocities.
This will help to remove the "governor" of neurological inhibition and golgi tendon organ response, which caps an athlete's output.
While valgus torque plays the role of taking the killshot of the elbow and offloading stresses that cannot be otherwise handled, I believe it is only an issue in the presence of significant ulnohumeral gapping and/or structural incapacity.
Historical Context: Players Have Always Known
Players have inherently known for decades that a heavy ball feels more stressful on their arm, and they are often hesitant to unleash high velocities with overload implements. Hindsight is 20/20, but solely analyzing the peak valgus torque being higher in a 3oz throw than a 9oz throw and claiming that lighter balls are more stressful on the arm is not only incorrect, but significantly shortsighted.
Players have thrown baseballs for over a century and a half, yet we believe as coaches/data scientists/biomechanists that 1 decade of (incredibly useful and groundbreaking data) can entirely invalidate the experiences of the players throwing the ball.
Young kids have no issues ripping hundreds of max effort whiffle ball throws in a day, but have the same kid rip max effort pitches with a 1lb ball, and he will likely be hanging the next day. Coaches working with younger athletes realize this to the extent they will never have a 10 year old rip the green ball… but if a heavier ball is entirely less stressful, this should be the standard for all young baseball players. However, the opposite exists, and these children safely throw "dangerous" underloads at max intent with tremendous volume, and their only thoughts are which video games they are playing that night when they get home.
Cross-Sport Comparison
A simple counter would be comparing injury rates at the elbow in quarterbacks, javelin throwers, tennis players, and volleyball players:
- QBs throw with much slower arm speeds, reduced ROM, which would result in low distraction forces
- Javelin throwers do see high injury rates, but it is likely a result of such extreme valgus torque that I don't think can accurately be compared to pitchers, yet their distraction forces are most similar to a pitch, as they do have the second highest rate of elbow injuries
- Tennis serves can have similar or higher peak valgus torque, with significantly lower distraction forces, and only a handful of tennis players have ever undergone Tommy John surgery
- Volleyball players have higher shoulder than elbow stresses and do not compare well
If tennis serves can average over 70nM of elbow valgus torque with significantly lower elbow distraction forces, and only a handful of tennis players have ever received Tommy John surgery, it is not feasible for this blame to fall primarily on valgus torque.
While throwing a javelin, or more extreme, a 25lb dumbbell, this is by all accounts exponentially more stressful than a 3oz baseball. But if a 3 oz baseball is more stressful than a 5oz baseball because of peak valgus, yet a 25lb dumbbell is more stressful than a 5oz baseball, this would create an inverse bell curve for stress where there would be a "least stressful" possible weight to throw at max intent, which I believe does not exist.
This leads to a criticism of dry reps and towel drills (I have different criticisms for these), which would say that throwing the arm itself is most stressful. But for pitchers who complete high intensity dry reps and towel drill throws, are they more likely to get hurt from throwing a 5oz ball, or their dry reps/towel drills? I have yet to hear of a TJ epidemic caused by towel drills with extraordinary amounts of peak valgus torque. Or a TJ epidemic in professional whiffle ball leagues (which I admittedly do not follow).
Recovery Day Recommendations
On a recovery throwing day, at least in season and other times of high chronic throwing workload and potential UHG, I would now advocate for throwing a whiffle ball, tennis ball, or lacrosse ball.
The lower distraction forces are obviously not a green light to rip anything post outings or in season recovery days as there is:
- Substantial localized fatigue
- The need to calm the CNS with low output movements
However, using a baseball or underload opposed to a 1lb plyo ball, for lower distraction forces, lower muscular fatigue of the forearms, reduced time under tension, and lower tendon compliance.
I believe there should be reconsideration of the value placed on valgus torque as the primary metric to determine arm stresses, with far more emphasis placed on the limiting factor of the throw, distraction forces. These are both 2 important metrics, but the unequivalent discussion biasing torque over distraction force I entirely disagree with.
The Ideal Performance Outcome
The typical goal of player development as a whole is to identify the players' lowest hanging fruit and improve them. But when we look at arm energies, we isolate elbow valgus torque as the only metric and look to get that as low as possible at the same velo, which is definitely a great idea, reducing valgus torque and throwing the ball the same velocity is a good thing.
However, as shoulder and elbow distraction forces are the lowest hanging fruit in the arm energy equation and directly inhibit pitchers from throwing 150mph, this is probably wicked important.
So the ideal "win" for reducing stress on the arm should be throwing the same velocity with a lower distraction force at the same body weight.
A recent analysis I conducted showed shoulder ER velo at max external rotation, pelvis max velocity in the Y plane, trunk angle in the Z plane at foot plant, bodyweight, and elbow flexion at maximum shoulder external rotation had the 5 highest r² correlations to increasing elbow distraction forces.
My Personal Solution
As I have been dealing with extensive elbow issues, my current solutions to offset the stresses of throwing is excessive ulnohumeral compression and radioulnar gapping (antagonistic to UHG).
Coincidentally, maybe, this arm pain was at the conclusion of my efforts to jump from 190–192lbs bodyweight to 200lbs bodyweight…. Which was solely a hyper fixation of chasing faux peak power output on my countermovement and squat jumps (lol). Me adding just 10lbs (at the most extreme was 185 to 201lbs) could add ~10% in both torque and distraction forces at both the elbow and shoulder. And again, I was throwing harder at a significantly higher bodyweight leading into this…
My primary solution strategy has been bench press liftoff ISOs for 8–10 seconds with as much as 455lbs after hitting them now 4 days in a row. This might seem like a lot or even excessive, but it only comes out to 227.5lbs of peak compression per arm compared to a more significant 266lbs of distraction force in the opposite direction each throw I make.
Other exercises I believe are useful:
- Top of dip pogos
- Heavy top of dip ISOs
- Heavy planks
- Pushup drop catch (landing with extended elbows)
- OHP liftoff ISO or even boxing
I have also hung a weight from my wrist while in supination to create radioulnar gapping and restore pronation, while also adding in some more dynamic exercises like standing falls and catching myself with extended elbows.
While there is a similar (more extreme) distraction force pulling at the shoulder, the posterior shoulder capsule has an anterior resting posture that decreases the runway for deceleration of the shoulder and can put the labrum at greater risk of injury.
While in an overload phase, the arm is experiencing significantly higher distraction forces, and without sufficient compression in the joint, chronic lengthening will remove the force dispersion strategy using UHG.
The primary reason I have focused heavily on the high impact skeletal forces is that I believe this is the starting point. Skipping this step and having players address tendon stiffness immediately requires the tendons to actively pull the joint closed, opposed to maintaining the smaller gap created by dedicated compression work.
TLDR
- More energy sent to the arm with a heavier ball, or a heavier arm throwing the same velocity, will significantly increase distraction forces on the elbow. Stress dissipates to: heat, forearms, ulnohumeral gapping, and UCL.
- Ulnohumeral gapping is my primary concern with higher energy and distraction forces that result from more distraction forces.
- Elbow valgus torque measures peak torque, but I believe the structural demands are higher for a heavier implement with a flatter impulse curve than a lighter implement with a steeper impulse curve.
- The driver of elbow injuries is the UCL being the last layer to absorb stress once there is no more room for ulnohumeral gapping to occur and forearm tendons pulling from a mechanically disadvantageous position, not the peak valgus torque itself.
- Gapping has a small performance value at the major expense of drastically increased injury risk.
- Underweight ball = lower distraction force + higher neurological adaptation.
- Players are inherently scared to rip heavy balls; intuition doesn't lie.
- Javelin is the second highest distraction force and second highest elbow injury rate.
- I used ulnohumeral compression to throw 90 with less pain than I had throwing 80 a week before.
Thesis Defense
Valgus torque applied to an elbow that has run out of room to utilize ulnohumeral gapping, paired with mechanically disadvantaged forearm tendons and weaker muscles allows the same valgus to bypass prior security measures and target the UCL.
At Magna, we go deeper than surface-level metrics. Understanding the real mechanisms behind arm stress, not just the numbers that are easy to measure, is what separates intelligent development from guesswork. If you're ready to train with coaches who actually understand arm biomechanics, let's talk.
