This post was written by Dr. James Buffi.
‘Overuse’ is being blamed for the eruption of Tommy John surgeries among baseball pitchers. Consequently, people in baseball have become hyper-focused on preventing overuse of the pitching arm. This has led to pitch counts, inning limits, and training guidelines that are more restrictive than ever before.
And yet ulnar collateral ligament (UCL) injuries continue to mount.
Usage restrictions are not helping because no one really knows where the line is between ‘acceptable use’ and ‘overuse.’ And the line will be very different for every pitcher. It will depend on many physiological factors, including physical fitness, that are constantly adapting and unique to each individual. A recent study attempted to find a general relationship between previous innings pitched and future injury in professional pitchers , but no significant correlations were found. Despite the lack of justification, organizations continue to excessively restrict throwing because they don’t know what else to do.
These excessive restrictions are a bad idea.
While rest is obviously necessary, it is too easy for a pitcher to go too far in this direction and severely undertrain. Without adequate training, the body is unprepared for the rigorous demands of pitching. A pitcher should not be so afraid of overuse that he or she never pushes the body’s limits. Responsible overloading is necessary for tissue adaptation. Muscles, in particular, get stronger and more capable from increased use and exposure to progressively increasing loads .
Therefore, it is essential for a pitcher to expose his or her muscles to controlled demanding situations where they can adapt. As I’ve said before, stronger muscles can generate and absorb more power. At joints like the elbow, stronger and more capable muscles can also likely absorb the damaging forces that would otherwise harm more vulnerable tissues, like the UCL.
Thankfully, muscle tissue is one of the most adaptable tissue types in the body. Muscles have the ability to quickly (relative to other tissues types) adapt to situations of increased use and loading. A single muscle is made up of many muscle fibers, and almost everything about each individual fiber can adapt, including its size, strength, speed, and endurance .
In a muscle fiber, speed and endurance are intimately related . The faster muscle fibers, often referred to as fast twitch fibers, have the worst endurance. They contract more quickly and fatigue quickly. The slower fibers, often referred to as slow twitch fibers, have the best endurance. They contract more slowly and fatigue slowly. Additionally, the faster fibers are generally stronger than the slower fibers.
What is incredible about a muscle fiber is that it can actually transform from a faster fiber to a slower fiber, or vice versa, in accordance with external demands . When it is exposed to increased use, in other words when it is used more frequently or for longer durations, a fiber will eventually transform from fast to slow. Thus, after transformation, the fiber has more endurance to handle the increased use, but it is also likely weaker.
It is important to note that even though a muscle fiber that adapts to increased use may contract more slowly, the change in speed is likely insignificant relative to other muscle properties in most relevant situations.
Now what about muscle fiber size?
The size of a fiber (and more specifically the cross sectional area) is a primary indicator of its strength. As is well known in popular culture, bigger fibers are stronger, and they get bigger and stronger when they are exposed to larger loads . Both fast and slow fibers can grow in size (i.e. experience hypertrophy) after exposure to increased loading.
A classic example of muscle adaptation can be seen in marathon runners versus sprinters. The muscles of marathon runners are much smaller and weaker than the muscles of sprinters, but they can last much longer. This is primarily because marathon runners train their muscles almost exclusively for increased duration of use while sprinters train their muscles to generate greater forces.
So what does this mean for a pitcher?
It means that a pitcher should expose his or her muscles to both increased use and increased loading to increase both the endurance and strength of muscle fibers. Pitching requires both adaptations. However, a pitcher should not expose his or her muscles to both demands at once. When a muscle receives two adaptation messages at one time, it does not fully respond to either . Moreover, a pitcher should not go overboard with the aforementioned adaptation principles. Living tissue needs both rest and proper nutrition to recover from demanding work.
From what I’ve seen, most training regimens for pitchers do include exposure to increased duration of use. A typical training regimen will have a pitcher slowly increase the amount of pitches in a session and/or the frequency of sessions. This type of training should increase muscle endurance… but it may not adequately increase muscle strength. And this is especially true if muscle fibers transition from fast to slow without substantial hypertrophy.
In general, the body adapts to most efficiently accomplish what is demanded of it. So if extra strength is not needed to accomplish the task at hand, the body may lose the extra strength capacity because it is not needed and therefore it is not efficient to maintain it.
I’m afraid this phenomenon could be manifesting itself in pitchers who follow a typical training plan with a regulation baseball.
For example, a typical training regimen for a pitcher could involve going out every five days and throwing up to 100 pitches, with a few shorter side sessions mixed in. If exposed to this usage pattern, it is likely that the pitcher’s body would adapt to most efficiently throw the 100 pitches every five days. So then what would happen during a critical game when adrenaline is pumping and the pitcher needs to throw 115 pitches at game-level intensity? What would happen when there are no outs and a guy on third so the pitcher needs to reach back for a little extra to get a key strikeout?
In these situations, the pitcher’s body would likely not have the maximum strength capacity to effectively handle the extra effort, and therefore more vulnerable tissues would be at increased risk.
The crucial component that seems to be missing from many training regimens is the exposure to increased loading that substantially increases muscle strength. This is especially true for the muscles crossing the elbow, which are imperative for protecting the UCL. Many pitchers never expose these muscles to increased loading. They limit the training of the elbow muscles to what they can do with a regulation baseball. Even if a pitcher is slowly ramping up from minimal effort to maximal effort, he or she is still limited by the regulation baseball’s weight. And maximal effort in practice is likely much different than maximal effort in a game.
Studies have shown that shoulder resistance training likely decreases shoulder injury risk . Accordingly, it seems that more pitchers are incorporating shoulder resistance training into their training regimens. This could help explain the leveling off of shoulder injury rates in the past few years. However, elbow injury rates keep going up, leading to the hypothesis that pitchers are still not doing a good job of conditioning elbow muscles.
There are a myriad of methods available for conditioning elbow muscles. These include typical resistance training, wrist weights, weighted balls, long toss and many other advanced protocols. In addition, research has revealed that exercise specificity is important . So if a pitcher wants to exercise the pitching muscles, he or she needs to include the pitching motion in any training regimen. This is the reason why I am a proponent of long toss and weighted baseball throwing. I’ve read several studies touting the benefits of over and under weighted baseballs [4, 5], and I have not yet come across a study showing increased injury risk using these implements.
With all that being said, I want to reiterate that pushing the elbow beyond its structural capacity is a serious concern. We still do not know how much the UCL is stressed by each pitch, and there is evidence of a ligament stress/strain threshold that should not be exceeded . Furthermore, an injured ligament may never return to its pre-injury strength , which is why even partial UCL tears often require Tommy John surgery.
Therefore, it is absolutely critical for a pitcher to enlist the help of an intelligent and reputable expert (who is not just a former player) when designing a personalized training program. It may be challenging to walk the line between overuse and increased use, but I believe it is necessary. A pitcher must be prepared for game-level pitching durations and intensities. Proper exposure to increased use, increased loading, and adequate rest are all indispensable components of an effective program. I firmly believe that with appropriate training, a pitcher can confidently confront the specter of elbow overuse that is paralyzing the pitching population of today.
Dr. James H. Buffi has a degree in mechanical engineering from the University of Notre Dame and a PhD in biomedical engineering from Northwestern University. His doctoral dissertation was called, “Using Biomechanical Modeling and Simulation to Calculate Potential Muscle Contributions to the Elbow Varus Moment during Baseball Pitching.” He has also been a visiting scholar in the National Center for Simulation in Rehabilitation Research at Stanford University as well as a visiting researcher at Massachusetts General Hospital. You can follow @jameshbuffi on twitter.
- Karakolis, T., S. Bhan, and R.L. Crotin, Injuries to young professional baseball pitchers cannot be prevented solely by restricting number of innings pitched. J Sports Med Phys Fitness, 2015.
- Lieber, R.L., Skeletal muscle structure, function & plasticity : the physiological basis of rehabilitation. 3rd ed. 2009, Philadelphia: Lippincott Williams & Wilkins.
- Tyler, T.F., et al., Risk Factors for Shoulder and Elbow Injuries in High School Baseball Pitchers The Role of Preseason Strength and Range of Motion. American Journal of Sports Medicine, 2014. 42(8): p. 1993-1999.
- Escamilla, R.F., et al., Effects of throwing overweight and underweight baseballs on throwing velocity and accuracy. Sports Med, 2000. 29(4): p. 259-72.
- van den Tillaar, R., Effect of different training programs on the velocity of overarm throwing: a brief review. J Strength Cond Res, 2004. 18(2): p. 388-96.
- Provenzano, P.P., et al., Subfailure damage in ligament: a structural and cellular evaluation. J Appl Physiol (1985), 2002. 92(1): p. 362-71.
- Woo, S.L., et al., Tissue engineering of ligament and tendon healing. Clin Orthop Relat Res, 1999(367 Suppl): p. S312-23.