It is almost inevitable that if you do CrossFit your shoulders are going to hurt. It seems like every day you’re doing some sort of overhead movement. Whether it’s snatches, jerks, HSPUs, burpees, wall balls, strict press, etc. you use your shoulders A LOT.  

I know, I’ve been there.  

Almost 8 years ago I began my CrossFit journey. I started working at a local gym in O’Fallon, Missouri: CrossFit O’Fallon. I immediately thought that I was going to make it to the games and began training with programs such as: CompTrain & CrossFit Invictus. Then I decided I was better at Olympic lifting than CrossFit, so I took my competitive drive there.  

Unfortunately, on the road to a 300lb snatch I messed up my left shoulder and I didn’t know then what I know now. But I hope to share my faults and knowledge with those of you who decide to read this.  

The shoulder is by far one of the most unstable joints in the entire body. And there are many things about it that intrigued me to dive deeper.  

Let’s first get some basic anatomy out of the way:

-        The glenoid is a part of the scapula (shoulder blade)

-       The humerus (arm bone)

-       The shoulder complex is comprised of 3 joints and one pseudo joint  

The humerus (arm bone) is roughly 3-4x larger than the glenoid (the “shoulder joint”), so right from the beginning we have a very large object trying to stabilize on a smaller object. Some compare it to a seal balancing a ball on their nose. This allows for a significantly large range of motion potential, but also leaves the shoulder vulnerable to injury.  

There are a ton of muscles that attach, move, and stabilize the shoulder. Some attach further away from the center of rotation and some are very close. Muscles that attach further away from the instantaneous center of rotation are most often the prime mover, and muscles closer are stabilizers.  

As the arm moves it wants to stay in what’s called the instantaneous center of rotation (ICR). This is also called functional joint centration. It means that there is good balance of muscular pull and as the arm moves there is no unwanted accessory movements that could damage passive structures. As you lift your arm into flexion or abduction the scapula should upwardly rotate, posteriorly tilt, and abduct. This is an ideal scenario, but in order for this to occur A LOT has to go right in the shoulder. And unfortunately, not very many people are in a position to optimize shoulder function.  

This is due to several factors. One of them being posture. Yes, how you sit can and will have an effect on your shoulder function. If you sit in a slumped position with your shoulder blades rolled forward, you’re going to lengthen your external rotators and adductors. If they are lengthened for too long, they don’t return back to their optimal positioning and their ability to create torque around the shoulder just went way down. This is a DEAL!  

This is the kicker. Every muscle that internally rotates your arm attaches to the skeleton and they are BIG. Pectoralis major and latissimus dorsi specifically. Every muscle that externally rotates your shoulder attaches to the scapula, and not the skeleton. This means that in order for them to create ample amount of torque to offset the strong pull of internal rotation they need a stable base: the scapula.   The scapulothoracic joint is a pseudo joint, meaning that there is not a true articulation between the shoulder blade and the ribcage. However, there are 17 muscles that attach to the shoulder blade and they all come into play when talking about stability and positioning.   Let’s go back to the example of sitting with forwardly rolled shoulders. If the scapula is in a position of downward rotation often times the levator scapula and rhomboids are over-active while the upper trapezius and serratus anterior are in a lengthened position. Both sets of muscles no longer have the ability to create synergistic activity to allow the shoulder blade to move. If you scroll up, you’ll notice that the scapula needs to abduct, and upwardly rotate when the arm goes over head; but if the scapula is in a position of downward rotation is needs to upwardly rotate way more in order to get to the same position. And not to mention the muscles responsible for upper rotation (co-activation of serratus anterior and upper trapezius) are in a lengthened state.  

Starting to get the picture? If one thing goes wrong or is off in the shoulder complex the whole thing can blow up.  

Having a properly functioning shoulder isn’t just about getting weak things strong or sitting with better posture. It’s about getting the right muscles to fire at the right time and having balance. A pectoralis major that pulls more into IR than the subscapularis can create anterior translation of the humeral head and lead to pain in the front of the shoulder.   So, what does all of this mean you ask?   Take your time. Be precise with your shoulder movements. Slow things down. Make sure that everything is moving the way it should be. Get the timing down. Work on stabilizing your shoulder blade, but also getting it to move more efficiently.

Stay tuned for more!     

Ryan Crandall

Ryan Crandall

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