Range-of-Motion: The Fundamental Truth (Part 2)

As a follow up to Part 1 of this series, in which we conceptually outlined movement, and tagged muscle as the primary culprit responsible for the injurious ROM patterns that occur in baseball players, I wanted to present some hard evidence to support our claims here in Part 2. In doing so, I’ll document some compelling information found within the research, while referencing a few reputable studies that validate my points. 

However, before we dive in, let’s start things off with a little refresher. In Part 1, we discussed how health, specifically as it relates to the joint system (i.e. Joint Integrity), is towards the top of the body’s priority list. Therefore, when this becomes compromised, or the body senses a vulnerability within movement, it’s only natural that the body will restrict ROM and protect itself. We went on to establish how joint stability is created and maintained within the body; and based on the muscular system's role in this process, any instability, in addition to the ROM restrictions related to that instability, are simply the resultants of muscle dysfunction. As the functional purpose of any muscle is to generate tension via the strength of each individual muscle fiber, any dysfunction within this tension-generation process can therefore be classified as muscle weakness.  

With that said, this theory suggesting muscle weakness as the culprit behind these ROM limitations assumes a relatively healthy, structurally normal joint. There are a lot of good researchers out there that have proposed numerous theories as to why the throwing shoulder in baseball players sometimes exhibits limited mobility (i.e. injurious ROM patterns). Some of these theories include, but aren't limited to, calcifications, osteophytes (bone spurs), impingement issues, rotator cuff problems, inflammation, tendinitis, joint instability/dysfunction, labrum problems, and ligament/capsular contracture (tightening). And I'm not saying that one, if not multiple of these couldn't be the cause of some type of movement restriction, because they absolutely could be.

But any idea what all of those fancy terms above have in common? They are all symptoms of either excess stress, irregular wear-and-tear, altered joint kinematics (movement), or lack of joint control (i.e. stability). And can you guess what has the largest influence over all of these? Muscle. If you remember from Part 1, it's your active system (muscles) that serves as your steering wheel, and acts as your first line of defense. If there are problems with movement quality, or your passive system is getting beat up, it's likely because your muscular system is dysfunctional, and not effectively generating tension in a timely and efficient manner. In other words, the symptoms listed previously are the result of a longer, more chronic problem that occurs slowly over time, through hundreds and thousands of repetitions, with each one taking it's toll. Therefore, in order to solve the chronic problem, you first have to solve the acute problem, which potentially occurs each and every time you throw a baseball at a high intensity. And it centers around muscle.

How do I know this? Well, in 2008, a guy named Mike Reinold, a former PT for the Boston Red Sox, put out a study that changed the game in a sense. Up to this point, researchers pretty much looked at these ROM alterations from a passive standpoint. They were perceived to occur slowly, over a longer period of time, as the ligaments and other passive structures began to scar and shorten. Because of this, nobody really ever thought to observe the acute, short-term changes that could be happening after each throwing bout. Well, maybe they did, but nothing was published on the topic until this study in 2008. In order to do this, Reinold and his team set up a study using 67 professional baseball players designed to observe any changes that might occur immediately after, and 24 hours after throwing. The main highlights from the study are shown in the graph below (click here to read the full article).

Now, before we even start breaking down the table above, we have to acknowledge a very important point. All of the changes that occurred in ROM were within a 24-hour time block, with the earliest changes coming immediately after throwing. Any idea why this is significant? It's because acute, short-term changes like this are essentially too fast for any other tissue in the body to adapt besides muscle. And if you look closer, you’ll see that the changes were fairly significant. In the first row, notice that on average, players lost somewhere between 8-10º of internal rotation within 24 hours after throwing. These changes were reflected again in the last row, as players lost between 8-11º of total motion within their throwing shoulder. 

Another study conducted by Dr. Ben Kibler in 2011 yielded similar results (click here to read the full article). However, unlike Reinold’s study, this group tracked changes up to 72 hours after throwing. The results are shown below, and notice once again that on average, players lost ROM immediately after, and up to three days post throwing. This is reflected in the first data row, as players lost between 5-7º of internal rotation in their throwing arm as soon as throwing was complete. And once again, the main theme is still the same; these changes are simply too fast for anything else but muscle.

So why is this relevant again? Well, lets connect a few dots. In Part 1, we established that ROM is a product of health and Joint Integrity. Furthermore, Joint Integrity is created and maintained by both the active and passive systems of the body, but it's muscle that arguably has the greatest influence on this process. This is especially true as it relates to joint control (i.e. “stability) and movement. The muscular system’s ability to facilitate this depends on the function of each muscle, and their ability to effectively generate tension. Therefore, dysfunction within muscle would lead to a vulnerability in Joint Integrity, which would ultimately cause the body to restrict ROM as a protective mechanism. 

This is why these ROM limitations are so powerful (and alarming) to you as an athlete. Honestly, who really cares about a few extra degrees of motion? However, if that limit in motion relates to a deficiency in your muscular system's ability to produce force in an effective and timely manner, which is an essential piece to performance and health, then...well, you get the picture. And as we just proved, the injurious ROM Patterns that exist in baseball players, and other overhead athletes alike, originate in muscle.

Therefore, the validity of any arm care routine, modality, or therapy as it relates to not only ROM, but heath and performance as well, centers around how well it improves the muscular system’s ability to function and generate tension. As such, in Part 3, we’ll expand on this concept, and outline a great solution that is research-proven, and was designed to eliminate these injurious ROM patterns by targeting their root…Muscle. 

- Will

 

References

Reinold, M. (2008). Changes in Shoulder and Elbow Passive Range of Motion After Pitching in Professional Baseball Players. The American Journal of Sports Medicine, 36, 523-527.

Kibler, B. (2012). An Acute Throwing Episode Decreases Shoulder Internal Rotation. Clinical Orthopaedics and Related Research, 470, 1545-1551.

 

 

 

Arm HealthWill FoxComment