Don’t Stress The Stress
I am a minor league baseball player.
Everything I do is in an effort to make the Major Leagues.
In order to optimize my performance, I have immersed myself into the cutting edge world of baseball research. I want to throw harder, I want to throw more strikes, and I want to stay healthy while doing so.
The advancements that the baseball industry has made, even over just the last five years, are astonishing. But with how fast the game is evolving, it’s easy to leave fans behind. Not nearly enough current players talk about the how and why behind their training, myself included.
Unfortunately, many aspects of the modern game are presented to fans through buzzwords and soundbites. This often leads to an incomplete and often confusing picture of what players are doing and why.
Adding to the confusion, many well-meaning broadcasters and former big leaguers share negative opinions about things that have changed over the years without fully understanding why those changes have occurred.
These developments are certainly complex, even for somebody as entrenched as me. But I wanted to lend my perspective on what works and what doesn’t, while also eliminating some of the hyperbole. Along the way, I hope I can help narrow the player-fan gap as much as possible.
Today, I want to talk about a common concern in modern baseball: pitching injuries. In particular, I’m going to explain how modern research has put an old-school understanding of the arm into a new context, and what concepts I use in my own training to not only get better but to also lower my chance of getting hurt.
The rise of ailing arms
Why have people been so concerned about injuries recently? Well, the short answer is that pitcher injuries seem to be higher than ever before.
Injury data compiled by Jon Roegele shows a scary trend: the number of Tommy John surgeries, done to repair the ulnar collateral ligament (UCL) in the elbow, has skyrocketed over the last two decades.
Tommy John surgeries per year among professional pitchers. Data from Jon Roegele.
Even though the 2020 season was shortened, arm injuries were still happening at an alarming rate. Analysis by Ben Lindbergh found that arm-related injuries through the first 10 days of the season tripled from 2019 to 2020.
Injuries through the first 10 days of the season. Data from The Ringer.
It’s important to keep in mind that elbow injuries didn’t suddenly start happening in the 1980s. Before Tommy John surgery existed, an injury usually meant your career was over rather than having a second chance due to modern medicine. Part of the rise of Tommy John rates can be explained by the fact that the surgery is safer and more effective than ever.
Still, it’s unlikely that pitchers were ever getting hurt as often as they are now. What could be contributing to this massive rise in arm injuries?
The status quo
In the mid-1990s, MLB salaries began exploding to unprecedented levels. The highest paid player in 1985 was Mike Schmidt, making slightly over $2 million. Ten years later, Cecil Fielder was making over four times that much.
Similar inflation was seen in the MLB Draft. In 1985, the highest signing bonus was given to the Rangers 3rd overall pick, Bobby Witt, at $179,000. By 1995, 8 first rounders received over $1 million, with Angels 1st overall pick Darin Erstad leading the way at a whopping $1.575 million. These numbers have done nothing but continue to rise in the years since.
MLB organizations, with more money invested in their pitchers than ever, naturally wanted to prevent those assets from getting hurt.
Teams began imposing restrictive throwing programs based around those given by doctors to rehabbing pitchers; they started out with a dozen or so throws from very short distances and slowly built in intensity over 6-8 weeks to around 100 throws from 120 feet. These programs were fine for their intended rehab purposes, but they were never meant to be the norm for healthy pitchers.
Still, as time went on, more and more organizations began implementing similar throwing programs for their whole rotations. Cones were placed on the ground at 120 feet. Throwing long distances or with high intensity was highly discouraged or even forbidden, and innings and pitch count limits soon followed.
The conventional thought became that throwing a lot was dangerous and that “your arm only has so many bullets — you don’t want to waste them”.
Legendary coach Tom House, who’s worked with Nolan Ryan, Randy Johnson, and Tom Brady, among countless others, was around before this level of control.
“In the 60’s and 70’s, there wasn’t a throwing program — the closest thing to it was long toss,” said House. “The more you threw, the better your arm got.”
This seemed to be the consensus before teams started imposing more restrictions in the 90s and beyond. Alan Jaeger, long toss advocate and baseball thought leader, concurs with House.
“Throwing was purely an instinctive act — it was something you just did according to how your arm felt,” he said. “And not so ironically, the more I threw the better my arm felt.”
(If you’re interested in learning more about the history of the throwing program, please check out Alan’s article “The Origin of Throwing Programs“.)
“These aren’t just abstract concepts; these are what I’m applying in my own training so that I can be a Major League Baseball player.”
Stress builds adaptations
So what caused this to change? Why did organizations begin to think, after decades of pitchers throwing how they pleased, that more throwing would lead to more injuries?
In one word, they were afraid of “stress”. They feared that long toss and high-effort throwing in general would cause large amounts of stress on the arms of their throwers.
In a way, they were correct. A study on elbow torque showed that throwing long distances was similar to in-game levels of stress and more stressful than throwing short distances.
Elbow valgus torque by distance. Data from Motus.
But this fear of stress is based on a misconception that has dominated the last few decades: that stress is always a bad thing and must be avoided.
The reality of pitching is that stress is unavoidable. Pitching in a game will always lead to massive amounts of stress on the shoulder and elbow of a pitcher; nothing is ever going to change that.
Different studies have found that throwing a pitch can cause anywhere from 60 to 100 Newton-meters (Nm) of valgus torque on the elbows of professional pitchers.
Valgus torque happens when the elbow moves like this. This happens in the throw leading up to release. Image from IEEE Spectrum.
Now consider research by the American Sports Medicine Institute (ASMI), founded by famed Tommy John surgeon Dr. James Andrews. Their study found that the UCL can only handle around 35 Nm of valgus torque before failing.
This means that throwing a pitch will almost always put more stress on the elbow than the UCL would be able to handle alone. The only way this would be possible is if the surrounding muscles of the elbow help to handle some of that torque.
The anatomy of the elbow. Image from IEEE Spectrum.
It is much easier to strengthen muscles than ligaments like the UCL. With this in mind, we want to make the surrounding muscles of the elbow stronger so they can help disperse the stress of throwing. To do so, we can take advantage of the fact that when we put stress on the body, it adapts into something stronger than before.
If you’ve ever began running after a long period of time without exercising, you’ll know what I mean. The first few times are extremely difficult, but if you keep at it for a week or two, it becomes much easier. The stress of running actually helps you get better at running. You can run further distances with less effort. Your body adapts.
But adaptations aren’t just about improving performance. They help prevent injury as well.
Take, for example, bench pressing 225 pounds. If an untrained person tried to lift that much, they would fail and most likely get injured trying. For a professional powerlifter, though, 225 pounds is a warm-up.
The stress to the body of each person is the same. But the powerlifter’s body has handled much more than 225 pounds, so it has adapted to be strong and stable when handling that load. They can lift it safely while someone not as strong cannot.
Now think about how this applies to pitchers. We know that pitchers experience enormous amounts of stress in competition. If the only time our bodies feel that stress is in a game setting, we’re like the untrained lifter; we will not perform as well and be at a higher risk for injury.
On the other hand, if we have trained our body to handle that level of stress consistently, our performance will improve and we will have a lower chance of injury, just like the powerlifter.
This is precisely the benefit of throwing long distances and with high intent.
As Tom House and Alan Jaeger noted, pitchers have always known this instinctively. Preventing pitchers from doing these things doesn’t actually stop us from experiencing stress — we still get that during games. But it does prevent us from being able to adequately prepare ourselves.
“Arms were being “trained” in 2nd gear (120 feet), and then asked to perform in 5th gear in game situations,” said Jaeger. “It should be the other way around — arms should be trained in 7th gear, per se, to perform in 5th gear. This is the basis for training in any sport.”
Managing your workload
Okay, so now we know that stress isn’t the bogeyman. It can actually be very helpful at preparing us for a game if applied smartly in training. How do we take advantage of this knowledge to safely get our arms into shape?
Just because stress can be useful doesn’t mean we can put large stresses onto our arm every day and expect to stay healthy; there is a reason that starting pitchers can’t throw every day.
A crucial part of the adaptation process is that our bodies need time to recover and rebuild. We also can’t take a large amount of time off and then pick up where we left off because our muscles will have gotten weaker over that time.
The stress, recovery, adaptation cycle. Putting a stress on your body causes a homeostatic disruption, decreasing performance. As your body recovers, it develops an adaptation so that it can more easily handle that stress, increasing performance. If you don't continue to reinforce the adaptation, it will dissipate. Image from JPS Health & Fitness.
This is where the concept of “workload” comes in. Throwing workload, in the simplest terms, is the average amount of stress put onto the arm over a certain period of time.
On any given day, your “one-day workload” is what you get if you add up the stress of every throw you made. High-effort throws are weighted more than low-effort throws; in other words, 10 hard throws puts more total stress on your arm than 20 throws at half the intensity.
If you take your average one-day workload over the course of a week, you get your “acute workload”. This number gives you a good idea of how much you’ve thrown recently.
If you take your average one-day workload over the course of a month or longer, you get your “chronic workload”. This number gives you a good idea of how much you’ve thrown over the medium- to long-term.
A higher chronic workload signals that the arm is more built up, and we can use that info to figure out how much we can throw on a given day without getting fatigued or injured.
Research by Dr. Tim Gabbett, originally into rugby players and later into cricket bowlers, found that athletes with higher chronic workloads can handle higher acute and one-day workloads without getting injured.
As chronic workload increases, likelihood of injury decreases, especially at high chronic workloads. Image from Dr. Tim Gabbett.
Increasing your chronic workload can be done incrementally by first increasing your acute workload. This means that you need to throw more (on average) over the last week than you did over the last month.
However, it’s crucial that your acute workload doesn’t get too much higher than your chronic workload. Further research by Dr. Gabbett found that if the acute to chronic workload ratio was too high, injury risk increased greatly.
When acute workload greatly exceeds chronic workload, injury risk increases. Injury risk is lowest when acute workload is in a range slightly lower to slightly higher than chronic workload. Image from Dr. Tim Gabbett.
Dr. Sameer Mehta led a study testing this concept with pitchers. He found that if your acute workload was more than 30% greater than your chronic workload, you were FIFTEEN TIMES more likely to get injured.
To give some perspective, imagine a pitcher who has taken some time off from throwing and wants to build back up to their in-season workload without ever exceeding that 30% number.
I’ll spare the dirty math details, but this would take at least 9 weeks of throwing. If they want to play it safe and keep their growth to 20% a week instead, it would take at least 12 weeks.
Now think about what many pitchers have been told over the last few decades: that we shouldn’t throw too much, that we shouldn’t throw hard unless we’re in a game, and that we should take large amounts of time off every offseason so that we don’t overwork our arms.
Once Spring Training rolls around, many pitchers haven’t thrown with high intent in months. They throw a couple bullpens and have a few short appearances in Spring Training games. When the regular season starts, they don’t have nearly enough chronic workload on their arms to handle throwing 100 pitches every 5 days. This is a recipe for disaster.
If the traditional mindset that injuries are caused by throwing too much was true, we would expect to see most pitcher injuries happen towards the end of the season.
Instead, a study of MLB injuries found that injury rates are the highest in the first month of the season and go down throughout the year. A similar conclusion was drawn by a Ben Lindbergh analysis. Yet another study found similar results in high school baseball and softball.
Percentage of TJ-inducing injuries in MLB pitchers by month. If a player had TJ in June but first missed games due to elbow injury in May, he would appear in the data for May. Image from Grantland.
This could explain the spike of injuries we saw in 2020. Pitchers who normally build up during Spring Training in March saw a three and a half month pause due to the pandemic. In July, the season resumed with only a 3 week “summer camp” to prepare.
If a pitcher didn’t throw over the quarantine period, they would need much longer than 3 weeks to build back up. Remember, you need at least 9 weeks or so to build up safely from a period of time off.
Many of the injuries we saw in 2020 may have been caused by pitchers who didn’t have enough of a chronic workload to handle an in-season pitching schedule, or who built up their chronic workload too quickly after an extended period of time off.
Why guess what we can measure?
Now all of this sounds nice in theory, but how practical is it to actually apply this knowledge? We can use number of innings or number of pitches as a crude estimate of workload, as many teams do. But those metrics don’t consider warm-up throws or throws made on non-pitching days. Is there a better way?
This is where modern technology comes in. A wearable sensor such as the Motus pitching sleeve tracks arm speed and elbow stress on a pitch-by-pitch basis. Motus also tracks one-day, acute, and chronic workloads, and suggests a maximum number of safe throws every day.
The Motus app suggests a readiness score and a safe number of throws every day (left), has a live mode to analyze the valgus torque, arm slot, arm speed, and shoulder rotation of each throw as it happens (center), and calculates one-day, acute, and chronic workload levels (right). Images from Motus.
Motus sleeves have begun making their way onto the arms of MLB pitchers. Garrett Crochet of the White Sox was seen throwing a bullpen with one in January:
And Shohei Ohtani was seen wearing a Motus sleeve at Spring Training last month:
I started using one myself this offseason and have found it to be an irreplaceable tool for managing my workload.
Motus sleeves have another benefit that may not be as obvious: helping gauge intent on lower intensity days. If you’re supposed to throw a bullpen at 80% intensity, is there any way to know if you’re actually doing that besides by feel?
Well, if you know what your arm speed is at full intensity, you can scale that down to your desired percentage and use Motus to make sure all your throws are near that number.
Using a tool such as Motus is a much better way of managing fatigue and injury risk, and it is likely that properly built-up pitchers can throw much more than traditional wisdom suggests. Trevor Bauer believes that he can pitch every four days due to his high chronic workload and recovery routines.
This is my arm at close to maximum external rotation. Who knew arms could move that way?
When we start looking through the lens that stress isn’t always bad, but can help us drive adaptations when applied strategically, other training methods begin to make more sense.
Take, for example, weighted balls. Studies have shown that a well-monitored weighted ball program can increase throwing velocity. But some remain wary of weighted balls, as other studies have shown that they may slightly increase arm stress.
But remember, stress isn’t something to be afraid of! If a pitcher has a high enough chronic workload, and they implement the weighted ball program in a smart way, they can see the benefits of increased velocity without putting their arms at risk.
Weighted balls have been used effectively and safely for decades, from Tom House in the 1980s to organizations such as Driveline today. Not to mention the fact that kids throw everything from wiffle balls (1 oz) to baseballs (5 oz) to footballs (16 oz) without getting hurt.
Another staple of modern training is heavy lifting in the weight room. There was an article here in BallNine a couple months ago blaming heavy lifting for the increase in arm injuries. Is this the case?
Even outside of its performance-enhancing potential, lifting is actually one of the best things a pitcher can do to prevent injury, for many of the same reasons mentioned above. Since the body is going to experience a ton of stress during throwing, it needs to be strong enough to handle those loads safely.
Take, for example, maximum external rotation of the shoulder during throwing, also called “layback”.
The shoulder is similar to the elbow in that it experiences forces during throwing that are much higher than it could theoretically handle alone. At this point in the throw, the pec and the lat assist the shoulder in dispersing stress.
By training our pecs and lats, we can gain strength and elasticity that help the shoulder handle that load. But if we refuse to train those muscles, our shoulder is going to receive the brunt of the stress, making a rotator cuff or labrum injury much more likely. This same logic applies to other parts of the body as well, even those not in the arm.
(Both of these topics deserve their own article, but I wanted to touch on them briefly here due to how often I hear them blamed for increasing injuries.)
The path forward
With all of this being said, nothing is perfect. Injuries are incredibly complex, and somebody could do everything right and still get hurt; that is an unfortunate reality of playing sports.
Still, many organizations are finally turning the corner from the dark ages of the last couple decades. In 2019, there were only 5 or so organizations that discouraged long toss, though there were still around a dozen that discouraged weighted ball training.
More and more organizations are hiring both front office personnel and coaches with a deeper understanding of these concepts, and others are leading the way with research into workload management and other injury prevention methods. We are getting better at understanding why injuries happen and, hopefully, closer to preventing them.
We are far from knowing everything about the topics I mentioned, and they are more complex than I may have made them seem. I ultimately wanted to give a good overview without getting too far into the weeds, but if you want to learn more, there are rabbit holes waiting for you.
As a brief aside, there are unfortunately a lot of times that I see a pitcher post a video using certain training techniques or throwing with high velocity only to be met with replies of “Tommy John waiting to happen!” Even experts using biomechanical data can’t reliably predict injuries, so an out-of-context Twitter video is definitely not enough to draw that conclusion. I think we could all do better to make a more supportive and understanding environment for players trying to improve, and appreciate amazing athletic feats when they happen.
Like I said before, my goal moving forward is to be as transparent as possible. If you have any questions or topics you’d like to see covered in the future, please feel free to leave a comment below, DM me on Twitter @joshhejka, or email me at firstname.lastname@example.org.
At the end of the day, these aren’t just abstract concepts; these are what I’m applying in my own training so that I can be a Major League Baseball player. Even if you don’t fully buy some of these ideas, I hope you can at least respect that I am putting my money where my mouth is.