Okay. So today’s post is on the shoulder and range of motion needed for the overhead athlete. Things may get a little hairy, as I’m about to nerd out like a 90’s kid on some old Pokemon cards; the path ahead may become science-y and there may be instances where you say, “I think he just made that joint up…” but trust me, it’s there and it’s important! The shoulder girdle is a very complicated series of joints fixed upon the thoracic spine. Many factors actually play into shoulder health that are often overlooked and unaddressed within traditional "injury prevention" routines. I will go over those factors to help promote a more thorough and global understanding on how the shoulder is affected by specific movements and adaptations of overhead sports.
Most people view the shoulder as just the glenohumeral joint, this is where your humerus (upper arm bone) sits inside the glenoid (socket, on the side of the scapula). But many times they forget that the scapula glides around the ribs and is suspended by several muscles to the thoracic spine. It is also attached to the clavicle at the Acromioclavicular joint; the clavicle is attached to the sternum by the Sternoclavicular joint. Of course the sternum is attached to the ribcage which is also suspended by the, drum roll please, thoracic spine. The thoracic spine is comprised of 12 vertebrae and is supposed to be the more mobile part of the spine. All of this comes into play when assessing shoulder issues and creating preventative maintenance.
First let’s start with the obvious, the glenouhumeral joint. This is an important area because it is where most of the mobility of the shoulder is orchestrated. The scapula changes its angle to help add mobility, but the glenohumeral joint, the actual ball and socket of the shoulder, is the most mobile joint in the entire body. This mobility can be altered, especially in overhead sports. The shoulder girdle will undergo soft tissue and bony adaptations due to the high velocity, extreme movements imposed on it; we generally see the result as having more external rotation and less internal rotation in the throwing shoulder. This phenomenon is known as Retroversion. This is a somewhat needed adaptation in overhead athletes. But if there is an asymmetry in total range of rotational motion between shoulders, that is known as Glenohumeral Internal Rotation Defecit(GIRD). This is not a needed adaptation.
It's theorized that a healthy, "perfect" shoulder should have 180 degrees of total rotation (90 degree external rotation + 90 degrees internal rotation). Someone with Retroversion typically loses some internal rotation on the dominant arm and gain extra external rotation. However, they will not always have the total 180 degrees of rotation due to the tightening of the tissues or bony adaptations. This is not a huge issue, unless Retroversion on the dominant arm becomes so bad it causes GIRD. GIRD early in an athlete’s career has been associated with Impingement Syndrome and Labral issues.
Traditional prehab approaches for overhead athletes seem to focus on the internal and external rotation of the humerus in the glenohumeral joint. It's pretty well known that the muscles of the rotator cuff undergo the most stress in the deceleration phase of the pitch. These muscles are forced to slow that arm down over and over again and tighten as up as a result. This is an important aspect to address, but when a pitcher throws a pitch, or a volleyball player spikes a ball, is it only that joint that comes into play? No! It’s a series of joint movements that ride and feed off of each other to translate into the action that the athlete needs to accomplish. So for that reason, we should not assume that when we find a case of GIRD, that it’s only an issue of the rotator cuff needing the proper stretching/strengthening. The rotator cuff does need extra treatment, but we can't pretend that that is the only factor needing to be addressed.
Having excessive external rotation has always been a usual thing among most overhead athletes. In fact, it's needed to add speed to a pitch or spike. However, we really can't say how much external rotation is needed for performance versus how much is too much and will increase the likelihood of injury. Even researchers haven’t been able to truly establish an, “acceptable” range of motion for glenohumeral rotation in baseball players or any other overhead athlete. I hypothesize this is because you can't try to quantify the effects of a total body movement on a single joint. When you watch a pitcher throw, you see some borderline exorcism-like external rotation occur in that shoulder. Immediately you can see that that repeated movement is going to cause an adaptation in the shoulder girdle to allow a crap ton of external rotation. But, is all external rotation created equal? What if the pitcher has poor thoracic extension, giving him a hunched posture? Or sub-par upward scapular rotation? Would it not then cause a compensation further down the chain of movement? That arm would need to cock back for the throw, but the thoracic spine wouldn't extend and the scapula wouldn't upwardly rotate properly. It would require even more movement out of the glenohumeral joint through external rotation, causing the glenohumeral joint to lose congruency between the ball and socket. This would mean that his shoulder or even elbow, would burn out much faster than the other team’s pitcher who has been training as SAPT.
Our first job as Strength and Conditioning Professionals is to create a program that will essentially "bullet proof" the athlete from the demands of their sport and give them the strength and power to excel. That pitcher with the exorcism arm isn’t going to stop playing baseball, and continuing to throw through an entire season has shown to increase external rotation. It’s hard to say at what point it will become an issue since, again, there is no established norm. But from common sense we know that too much of anything can be a bad thing. So giving him drills to increase his internal rotation should help. Yet, I think addressing his global movement restrictions to ensure he is not compensating through even more external rotation in his throw will help too. Put them together with some scapular stabilization and eccentric external rotation drills and you’ve got a pretty effective prehab program.
Now I’m sure all the volleyball and tennis players are sitting patiently, waiting for their sport's turn. These concepts apply to all sports. If your thoracic spine is locked up and you slouch in your posture, it’s going to affect your entire, global, shoulder movement when you serve that ball. All overhead sports require thoracic extension, flexion and rotation as well as scapular upward rotation. Without it, the rotator cuff is going to take a larger brunt of the work. So when GIRD shows its ugly face, don't drop all the blame on your rotator cuff, it may not be the only root cause. If you have lost mobility in one area, it will be reciprocated elsewhere. Never look solely at the one joint in question, look at the movement.