"It hurts when I throw hard, especially when I haven't warmed up properly. I can't remember doing anything specific to cause it, but I often have this problem at the beginning and the end of the season, and it normally goes away. But this year, it won't go away."
This is a common story for players with deceleration-related shoulder pain. Whether it's at the start of the season, after returning from an in-season break, skipping proper warm-ups, or jumping straight into a boot camp or tournament, the underlying issue is often the same: a rapid increase in throwing load. And remember, returning from a break (from throwing) to "normal" throwing load often involves a relatively rapid increase in activity.
Mechanisms
As the name suggests, players often describe pain during or after the ball release, with the pain typically located in the anterior-superior part of the shoulder. Throwing velocity is often not affected, at least not in the early stages, though throwing accuracy may be impacted. During the deceleration phase and follow-through (after ball release), the posterior and superior parts of the rotator cuff work eccentrically to decelerate the motion, acting like a brake. The rotator cuff tendons, which are wrapped around the humeral head, also experience compression loads during this process. This combination puts significant stress on the rotator cuff, particularly the tendon. Normally, the tendon can adapt to these loads, but rapid overloading (too many throws, too soon) can result in reactive tendinopathy.
Initially, this problem is often manageable for the player. However, as time goes on, it can become increasingly difficult to warm up, and the pain after throwing may last longer. This often leads to a cycle where the player alternates between playing and reducing the number of hard throws for a few days, only to return to the same cycle until they can no longer throw without significant pain. At that point, they typically seek medical attention.
Assessment
The physical examination rarely reveals any major injuries. Instead, it often shows painful isometric and eccentric contractions, especially during external rotation (ER) and abduction in an overhead position (<90°). Occasionally, underlying instability may be found, which could contribute to the problem and should be addressed. We'll explore instability in more detail in an upcoming blog post. Depending on the severity of the pain, assessing strength can be challenging. However, in a neutral position (elbow at the side of the body), ER strength is often assessable. In many players with this condition, a deficit in ER strength is found compared to the non-throwing side. Bear in mind that in uninjured players, the dominant arm is (or at least should be) normally 20-30% stronger, so this is the benchmark we aim for. Another rule of thumb is that we don't want the ratio of ER to internal rotation (IR) strength to be less than 75%, with an ideal ratio above 80%. This means that if IR strength is 100N, ER strength should be at least 75N (ratio 0.75). However, it's important to note that the ratio is just a guideline.
In younger players, particularly female players, we sometimes find a "perfect" or acceptable ratio, but this is often due to low IR strength. On the other hand, for professional players, especially males, achieving a ratio above 0.8 can be difficult due to their high IR strength. If you want to learn more about how to measure strength (or force output, to be more accurate), there is blog post on that on the way. Stay tuned!
In most throwers, we normally find less internal rotation range of motion (ROM) on the dominant side, and contrary an increased external rotation ROM on the dominant side. This is a normal adaptation to throwing when growing up which will keep the dominant arm in a more retrotorsed position. This has been named Glenohumeral Internal Rotation Deficite or GIRD and has in the past (and sometimes still do) been unjustifed blamed to cause everyting from shoulder pain to the lack of Stanley Cup wins for the beloved Toronto Maple Leafs. If you want to know more about assessing ROM, GIRD, humeral torsion and how to interpret the findings, there a blog coming soon on that as well. In short terms, what we expect to see is a difference in IR and ER ROM respectively between the dominant and the non-domianant arm, however the total ROM (total IR + total ER) or TROM should be the same for both arms. So the TROM is a better measure to identify any deficit that need to be adressed. Throwers with TROM defict of 5 or more degrees in the diominant arm has been reported to have a higher risk of shoulder injuries, so this could be a role of thumb as of when to adress ROM deficits in throwers.
More rarely, tissue injury is seen at the muscle-tendon junction. This is often associated with a specific onset, more significant strength loss, and persistent problems even after unloading the shoulder. Diagnostic ultrasound or MRI usually does not add much to the picture, except for excluding severe tissue damage and serving as a good educational tool to show the player that nothing is "broken" in the shoulder. However, most players will have asymptomatic "abnormalities" in the shoulder, so when referring for ultrasound or MRI, there should be a clear indication and suspicion—not a "fishing expedition" approach, beacuse you are more or less guaranteed a catch.
Management
If the player presents with a more acute reactive tendinopathy, initial adaptation to loading (e.g., throwing and overhead exercises) is necessary, and a short course of anti-inflammatory medication could be indicated. If there is no improvement within a week despite unloading, a reevaluation should be made, especially in youth athletes. Crucial to management is the progressive loading and strengthening of the shoulder, with a focus on ER, abduction, and horizontal abduction. Since these tendon problems often take time to fully resolve—especially in older athletes or players with long-standing issues—it is essential that the player engages in the loading program.
Educating and explaining the problem to the player is often crucial for successful rehabilitation. I often explain it like this:
"There is very unlikely any tissue damage. Your shoulder has been temporarily overloaded and has reacted to that. With appropriate care, your problems should resolve, but it is necessary that you follow the plan to build up the capacity of your shoulder and continue to do so to prevent further problems."
When isometric and eccentric loading is manageable within the inner range of motion, progress toward loading in the full range of motion and throwing position, and finally interval throwing. Once the shoulder is torable for outer range of motion loading, heavy loads can be applied as this will also increase ROM. As mentioned, the prognosis for this condition is good, but it mainly depends on how long it's been going on and how much of a problem it has become. A first-time acute reactive tendinopathy is often fully resolved in 2-6 weeks, while recurrent problems that have been neglected for longer and tendon-muscle junction injuries, or decceleration related problems with an underlying instability, often ´ take more time to resolve. I recommend at least 12 weeks of progressive rehabilitation before considering alternatives.
Moreover, it is important to address the rapid increase in throwing load that often triggered the problem and adjust what can be adjusted in terms of load progression. For instance, during the summer break, it is important to keep throwing to maintain shoulder function and gradually increase throwing volume as the season approaches, ensuring a smooth transition from off-season to in-season.
Summary
Deceleration-related shoulder pain is a common issue among throwers, often linked to rapid increases in throwing load or inadequate warm-up routines and pre-reason preparation. Understanding the mechanics behind this pain and implementing proper assessment and management strategies is crucial for a successful rehabilitation and return to sport and to prevent recurrent problems.
In the next part of this series, we'll shift our focus to acceleration-related shoulder problems, which often occur during high-velocity throws and can significantly impact a player's performance. We'll explore the underlying causes, assessment techniques, and rehabilitation strategies to address these issues effectively.
