CS #1: The Effects of 100 Pitches at Max Effort on the Throwing Shoulder

In the last several years, we have seen the number of throwing related injuries in professional baseball steadily rise.  A standardization of pitch counts and guidelines among age groups have been introduced to combat the ongoing epidemic of throwing related injuries.  If you are affiliated with the game of baseball in any manner, have you ever asked yourself the question as to why injuries are on the rise?  With all of the advancement in medical technology, nutrition, and strength programs, why are pitchers getting injured more often?

Just 50 years ago, it was common for major league teams to adhere to a four-man rotation, have pitchers throw far more than 100 pitches in an outing, and then pitch again on short rest.  So what happened?  In general, throwers today are stronger, but are limited to throwing far fewer pitches on average than their predecessors. Not only that, but they have a much lower ability to recover between starts as well. 

Our team at DVS has spent the time finding answers to this current dilemma. We want to enhance the game of baseball and empower pitchers with the ability to throw more often without the risk of injury. Many leading doctors, including Dr. James Andrews, advocates youth players to take time off from throwing and stay within the constraints of recommended pitch counts. USA Baseball and Major League Baseball have partnered to promote safer pitching practices. Pitch Smart was created to provide “a series of practical, age-appropriate guidelines to help parents, players and coaches avoid overuse injuries and foster long, healthy careers for youth pitchers.” The table indicates the amount of pitches recommended for each age group.

 PITCH SMART GUIDELINES

PITCH SMART GUIDELINES

According to the Pitch Smart guidelines given through mlb.com, it is suggested that individual’s between the ages of 13 and 18 should not exceed a maximum of 95-105 pitches within a given throwing bout. However, the amount of stress that accumulates through a specific number of pitches within a given throwing bout is relative to an individual’s mechanics and training. Through our research, we have found as a player’s DVS score increases, the amount of time needed to fully recover from high intensity throwing decreases. This relationship derives from an ongoing in-house study that we started back in January 2013.

The alterations in a player's ROM after high-intensity throwing frequently go untracked and unnoticed. Serially tracking ROM, although should be a norm, are foreign to many high school, college, and even some professional programs. Determining health and function solely based on "feeling" can prove to be costly, as many ROM Risk Factors that precede a throwing-related injury are asymptomatic. This means that even though you may feel fine, your body might not be efficiently handling the demands of throwing, which could lead to decreased performance and potential injury in the future. For this reason, a program should routinely track their players' ROM as it can help spot fluctuations and more adequately prescribe throwing regimens/rest throughout the course of the year.

The Pitch Smart guidelines serve as a safety net for a large population of youth players, however, they provide only an initial layer of protection. For example, if a player’s throwing mechanics place increased stress on the arm when throwing , the current set of guidelines may not serve much good. On the flip side, a player with more efficient throwing mechanics may not fit into the guidelines at all. Rather, they could throw more pitches, more often, and require less time off during the year. Other factors may influence this as well, including arm care routines, recovery protocols, and training regimens. 


cs #1: the effects of 100 pitches at max effort on the throwing shoulder

 

INtroduction

It is widely accepted within the baseball and medical community that the throwing shoulder of a baseball player can undergo specific range-of-motion (ROM) alterations in response to a high-intensity throwing bout. These alterations have been shown to occur acutely (immediately post throwing), and can stay present for several days. As certain ROM adaptations have proven to be injurious to the overhead athlete, a player could significantly reduce their chance of injury and improve recovery time with the right information. An individual’s throwing mechanics has been speculated to play a role in the amount of stress transferred to the elbow and shoulder. However, there are no studies to date that have objectively linked a mechanical pattern to injury risk through ROM testing. The DVS Scoring System will be utilized to assess and quantify the quality of the thrower’s mechanical pattern exhibited in this study.

HYPOTHESIS

As the subject being used in this study has a DVS Score of 20, which signifies efficient throwing mechanics, his arm will undergo less relative stress. As such, there will be little to no reduction in passive ROM within the throwing arm immediately post, and up to 5 days following a high-intensity, 100 pitch throwing bout. Additionally, specific injurious risk factors such as Dominant Total Arm Motion Deficit (DTAMD), Glenohumeral Internal Rotation Deficit (GIRD), and Glenohumeral External Rotation Deficit (GERD) will not be negatively influenced based on pre and post ROM measures. 

methods

  • Setting: Controlled High-Intensity Bullpen
  • Number of Subjects: 1
  • Age of Subject: 30
  • # of High-Intensity Throws: 55
  • Average Ball Velocity: 88 mph
  • Max Ball Velocity: 91
  • Subject DVS Score: 20

One asymptomatic male baseball pitcher with a DVS Score of 20 participated in the study. Passive ROM measurements were recorded using a digital inclinometer for shoulder total arc motion, shoulder internal rotation, and shoulder external rotation on both the throwing and non-throwing arm. For each shoulder, the limb was moved passively in each direction until maximal motion occurred. In order to ensure each shoulder achieved its full range of motion, the examiner used a combination of capsular end-feel and visualization of compensatory movement. The humeral head was not stabilized in order to allow for natural shoulder motion to occur. For each measurement of internal rotation and external rotation, the scapula was securely stabilized on the table. Measurements were taken at rest prior to throwing, and then post measurements taken at five minutes and 120 minutes after throwing was complete. Five additional resting measurements were also taken each morning at 24, 48, 72, 96, and 120 hours post throwing to track the effects on a full recovery cycle. The subject threw a total of 170 throws, which included a sub-maximal warm up and 100 max-effort pitches off the mound. All 100 pitches are captured in a time-lapse format in Video 1. In order to ensure that the subject was throwing at max-effort for all 100 pitches, a radar gun was used to measure velocity. The subject maintained an average velocity of 88 mph and reached a maximum velocity of 91 mph, shown in Video 2. The table below further outlines the throwing protocol used, as well as the intensities of each throw.

100 PITCHES IN 30 SECONDS

VIDEO 1

AVERAGE VELOCITY 88MPH

VIDEO 2

RESULTS

In comparison to pre-throwing resting measures, there was a minimal decrease in Dominant Total Arc Motion (DTAM) and Dominant Internal Rotation (DIR) immediately after throwing. This pattern stayed consistent up to 24 hours after throwing with the greatest deficit in DTAM and DIR occurring at 48 hours post. However, by 72, DTAM had fully returned to resting levels. Throughout the entire duration of the study, the subject failed to exemplify any injurious risk factors (DTAMD, GIRD, GERD) as outlined in the current literature. The table below represents all ROM measurements taken throughout the study’s entire 5-day window along with bilateral measures of DTAMD, GIRD, GERD.

BREAKDOWN

For the non-medical and non-research community, we don't expect the majority of readers to grasp the significance of the data listed in the table above. However, as we begin to break this down, just remember that a loss in motion typically accompanies excess stress, trauma, and overuse. When the body gets beat-up, particularly muscle, the neuromuscular system restricts motion to protect against vulnerability and potential injury. As a DVS Score is a reflection of stress and efficiency, individual's with higher DVS Scores will theoretically endure less relative stress when throwing a baseball, and thus get beat-up less. On the contrary, someone with a lower DVS Score will endure higher amounts of relative stress, and get beat-up more. 

With that said, let’s look at the table above and dig a little deeper. As you can see in the first and third columns, DIR and DTAM didn't really change too much from resting to immediately after throwing. Furthermore, DTAMD, which is the difference in total motion between the throwing and non-throwing arm, was never less than -1. And if you've read Range-of-Motion: A Pitcher's Best Friend...or Not, you know that DTAMD of less than -5 significantly increases the likelihood of sustaining a throwing-related injury. So what's the overall take-a-way here? Greater efficiency, higher DVS Score, less stress, less damage, and better ROM.

DISCUSSION

From this study, it’s safe to infer the subject effectively supported the demands of throwing 100 pitches at a maximal intensity. This is evident by his ROM measurements, and the fact that he returned to resting levels by 72 hours. Not only that, but there was no soreness present at any time during those three days, which is another indicator that he handled the demands of throwing extremely well. 

In the days following the 100 pitch bullpen, the subject adhered to the soreness and throwing guidelines found within the USPBL Throwing Program. Because no soreness was present at any point, the guidelines allowed him to throw at specific, sub-maximal intensities every day. Additionally, the subject never passively stretched the arm during the entire five-day recovery window; instead, he followed the guidelines and exercises set forth by The DVS Arm Care System to expedite the recovery process and restore ROM.

So what allowed him to effectively handle that amount of stress? The answer can't be narrowed down to just one variable, as there are a number of factors that play a role in this process. Genetics. Strength. Recovery Cycle. Training. These a just a few of the pieces that are going to dictate muscle and tissue tolerability. However, based on his DVS Score of 20, mechanical efficiency had an undeniable impact by reducing the amount of stress transferred into the shoulder and arm upon each throw. To further substantiate this claim, let's compare the results of this study with those of similar studies found within the literature.

The first study we're going to reference was conducted by Reinold et al., and the highlights of the study are listed in the table below. They used 67 professional baseball pitchers, and incorporated a similar design to the one used above. However, the main difference is that their group stopped ROM measurements at 24 hours post throwing, as we tracked measurements up to 120 hours after. Furthermore, they didn't obtain measurements on the non-throwing arm at 24 hours post, so we can't calculate measures of DTAMD, GIRD, and GERD. Regardless, it's enough time and data to see how the subjects responded to the stresses associated with throwing. 

As you can see, within 24 hours of throwing, subjects lost an average of 8-10º of internal rotation within their throwing shoulder. This was accompanied by an average decrease of roughly 8-10º DTAM in the same time frame. However, the most significant column relates to DTAMD, as the subjects experienced an average decrease from 3.3º to -8.9º. This is alarming because this measurement becomes more injurious the closer it gets to -5; and not only did it drop down to nearly -9º, which is in the "risk" range, but if you do the math, these individuals exhibited roughly a 12º swing in the wrong direction. 

The second study we're going to use was conducted by Kibler et al., and the results are portrayed in the table below. This team utilized 45 professional pitchers and a similar study-design to the Reinold study. However, the main differences were that they calculated measurements up to 72 hours post throwing, and those measurements were only conducted on the throwing arm. This means that we can't calculate DTAMD, GIRD, and GERD, but we can see the effects that stress had on the throwing arm. 

Once again, notice that DIR exhibited an average decrease of approximately 7º immediately after throwing, which held true throughout the entire 72 hours.  Also, you can see that even though DTAM only decreased by 2º immediately after throwing, it dropped nearly 8º by the 72-hour mark. 

Regardless of the subtle differences that these studies have with CS #1, they are important to recognize as these are two of the few studies in existence that look at the acute effects that throwing has on the body. As we covered in Range-of-Motion: The Fundamental Truth (Part 2), the injurious changes that take place within the throwing arms of baseball pitchers potentially occur immediately after each throw, and it all boils down to stress. If the stress on the outside exceeds what the body, particularly muscle, can tolerate on the inside, the body loses stability (i.e. joint control) and tightens as a result. It's this phenomenon that the baseball research community has come to recognize as injurious ROM patterns. However, there a numerous ways to influence this balance, and tilt the scale so a pitcher can handle greater amounts of stress. Just take our subject from CS #1. He was able to throw 100 pitches, which is nearly 40-50 more pitches than subjects threw in the Reinold and Kibler studies, while not exhibiting any significant limitations or injurious symptoms. How can this be? Well, as we said earlier, a number of factors are likely at play, but mechanical efficiency certainly had a large role. As the subject in CS #1 had a DVS Score of 20, and the current DVS Score average in Major League Baseball is close to 13, there is no doubt that these pitchers experienced different amounts of relative stress. 

CONCLUSION

The stressful effects that high-intensity throwing have on the injurious ROM patterns found in baseball players has been previously documented. However, as these ROM adaptations are related to excess stress, overuse, or trauma, the quality of a thrower’s mechanical pattern has a large impact on shoulder and elbow health. The results of this study suggest a newly defined mechanism for evaluating injury risk within the throwing athlete. By objectively quantifying the efficiency of a thrower’s mechanical pattern and prehab/rehab/training routines, we can start to create correlations with research-established ROM Risk Factors.


The results and concepts introduced by this study should have the baseball world at least second guessing the modern day throwing culture. As it stands now, a starting pitcher will make their start, maybe throw a fairly high number of pitches, and then spend the next 4-6 days trying to recover from a sore arm. Even if they do throw in the days following the start, they are more than likely trying to keep the volume fairly low. Imagine how much better a delivery could be if it was repeated 300 times per day? 300 throws at max intensity is a different story, but actively throwing through your delivery at lighter intensities is beneficial to the overall skill development necessary for a pitcher. It's definitely possible, as seen here with this study, but not with the current throwing culture. 

As we performed this study, we couldn't help but think about two recent scenarios in Major League Baseball. First, the 2014 World Series and Madison Bumgarner. Bumgarner pitched on three separate occasions during the World Series. He threw 106 pitches in Game 1, and after four days rest, he threw another 117 pitches in Game 5. Once again, three days later, he threw a final 68 pitches in Game 7. Throughout the World Series, especially leading up to Game 7, talks abounded about the use of Madison Bumgarner. Was it healthy to pitch him on short days rest? What are the potential repercussions of pitching on short rest? It's tough to know without factoring in his DVS Score, in addition to many other variables, but it seems like he handled it pretty well. 

The larger issue at play in this particular case is how much information did the Giants have at their disposal. Did they test Bumgarner’s ROM after each outing? Was the decision to pitch him in Game 7 a slam dunk because they truly knew he was healthy? I don’t think we will ever know, but these are great questions for organizations moving forward.

On the flip side, anybody remember the 2012 Postseason when Stephen Strasburg was shut down? He wasn't allowed to pitch any more innings because he supposedly reached his "innings limit" for the calendar year. How did the Nationals and their team of doctors even come up with that arbitrary number of innings? Maybe it was a good call, but maybe not. We would definitely argue that Strasburg endured far more stress per outing than Bumgarner did based on their DVS Scores, but nobody really knows how much without some type of objectifiable measure. Did the Nationals have something like this in place? We doubt it, as most teams don't. Besides, if the Nationals were smart, they would be trying to figure out ways to make Strasburg less of an injury risk instead of just delaying the inevitable.

-Will

Case StudiesWill FoxComment