Have you been told about the rotator cuff?
Perhaps it was from a physician who said you tore it.
Maybe it was from a friend at the gym who said you hurt yours.
Possibly you scored Dr. Google and learnt about it.
For most people these are three means of learning about – clinicians, friends, and the internet.
Usually people initially learn about the rotator cuff after experiencing some kind of shoulder injury; possibly being given a diagnosis like rotator cuff tear, shoulder impingement, etc.
In that situation, you are then usually guided to either try rest or surgery.
Interestingly, for most people who have rotator cuff related pain, rest and surgery are not the recommended first treatments.
Actually the first line recommendations for these people is to do rehabilitation – particularly resistance training!
In our introduction article, we want to outline some of the major anatomical factors that contribute to exercise selection.
The rotator cuff is made up of 4 primary muscles – the supraspinatus (on top), the infraspinatus (on the back), the subscapularis (on the front), and the teres minor (on the bottom of the back).
Collectively these four muscles are termed the rotator cuff given their seemingly synchronized movements to help create rotation of the shoulder.
We see that the supraspinatus, infraspinatus and teres minor primarily assist with external rotation (turning your arm outwards) and the subscapularis primarily assist with internal rotation (turning your arm inwards).
Generally when people begin to think of rehab for these muscles, it gets directed to them. This isn’t inherently bad, but it might be worth considering a bit from an anatomical perspective.
What many people don’t realize is that these muscles do not act in isolation.
Various musculature such as the anterior portion of the deltoid, pectoralis major, and latissimus dorsi also internally rotate the shoulder.
As well, other muscles of the shoulder girdle help with external rotation – most notably the posterior portion of the deltoid.
Further, the muscles of the rotator cuff don’t just rotate the humerus. This might blow some people away, but the name is pretty misleading.
The muscles of the cuff also work to perform actions such as shoulder flexion, abduction, adduction, extension, and just about every motion we could do!
In some positions these muscles are actually doing a lot of the work.
Moving past just the rotational thinking of their action, there is one more critical thing the cuff does – suction the humerus into the glenoid fossa.
It is this action that you hear about the rotator cuff being so important for stability. What people mean when they talk about the cuff aiding in stability, they mean that the cuff helps to control the position of the humerus in the socket of the shoulder.
Much like our previous points, the cuff does not do this alone.
Essentially any muscle that crosses the glenohumeral joint (what most people think of as the shoulder) will have some action of this.
Therefore we will see muscles like the long head of the biceps and deltoid.
Now we wouldn’t argue that their impact on this is the same, and there can be a lot of nuance with it – which is something we will get into in further articles – but the point remains the same that they do not function in isolation.
Having the functions of the rotator cuff out of the way, there are still a few other anatomical considerations the would be unfair to ignore and impact rehab/training.
How challenged a muscle is to work is dictated by a few factors:
– It’s length when contracting (muscles contract best at mid ranges)
– It’s level of fatigue (inherently a more fatigued muscle will not be able to produce as much force – this can be local, peripheral, central, or systemic fatigue related)
– It’s level of fuel source available (this is a complex one, but in simple terms if you have less fuel available, contraction will diminish)
– It’s moment arm/torque demands
The first three points rehab will not drastically affect – muscles will move through different lengths during most exercises, fatigue & fuel source are beyond the scope of this article – but the last point is an important one here.
To understand the impact of a moment arm, grab a cup of water and reach out with a straight arm and feel the difficulty.
Then bend your elbow and bring it closer to your body.
You probably noticed it got a lot easier to hold? That’s because your shortened the moment arm.
When a muscle contracts it exerts a certain amount of force. That amount of force that is expressed is heavily dictated by the moment arm it uses.
When we change the position of the scapula, the humerus, etc. we change the demand on the muscles working.
Altering the position of the body during activities can change how much certain muscles work.
This is beneficial across the spectrum of rehab where we may want to alter positioning to make it easier on a muscle in early rehab to reduce the demand on it, but then change it to make it work harder as we get into later rehab.
Progressing off that point, this is a reason many people see a lot of benefit from performing different movements for their thoracic spine when dealing with shoulder pain.
The thoracic spine position affects how the scapula can move, which then dictates the moment arms for many of the muscles of the shoulder.
There are times when we want the thoracic spine to be flexed, extended, or rotated to accommodate scapular positioning in a certain way.
Given all of this information, you can see there is a lot more nuance to a comprehensive program to help rehab the rotator cuff.
If you’d like to see how we utilize these anatomical considerations into shoulder rehab, or you’re looking for a well designed shoulder rehab program – check out our training support program that features a 6 phase program for shoulder rehab. https://members.citizenathletics.com/training-support-programming-1
In coming articles we will expand on this and build out more details around shoulder rehab.
The Citizen Athletics Team,
Sam