Compared to some of the other information on this site, this is going to be a really nerdy post. For anyone reading this who has shoulder pain there are definitely some important pieces of information. However, there is a lot of anatomy talk in this that I realize not everyone is familiar with (or wants to be familiar with). Therefore, you may want to skip around and find what is most pertinent to you.
With that said, reading the entire thing will give some insight as to just how much thought process should go into selecting some of the exercises you do, as well as the exercises I select for my clients.
The basis for this post is a study I found titled, Subscapularis muscle activity during selected rehabilitation exercises.
First off, what is the subscapularis?
The subscapularis is one of the rotator cuff muscles. You know, that thing your doctor told you is messed up? And he/she said just pull on an elastic band to make your shoulder feel better…yet you can still barely move your arm.
There are four muscles that make up the cuff, and the subscapularis is one of them.
Why you care about it:
This muscle internally rotates the humerus (upper arm) and depresses the humeral head. In other words, when you move your arm the subscapularis helps keep the shoulder nice and snug in its socket.
One of the more common causes of shoulder pain that I see with new clients is an overstretched and weak subscapularis. This is often visible to the eye: Ever see people where the front of their shoulders look really boney?
Or feel your own shoulder. There should be a little give when you touch the front portion of the joint. it shouldn’t be protruding, and it shouldn’t be tender. If it is, there is a good chance your subscapularis could use some strengthhening, which will help with your shoulder pain. Or prevent it.
So what exercises best strengthen it? Based on the paper above, for the exercises they looked at, they ranked the exercises they used as follows (for a detailed look at the exercises check out the paper; click for a clearer image):
While the author’s chart makes things seem pretty straight forward, there is more to what exercise one should select. It’s actually not as simple as this exercise has greater activity than that exercise, so pick that one.
As mentioned, often times the subscapularis becomes long and weak. When one muscle becomes long and weak, often times another muscle, or muscles, becomes tight and or overactive.
When it comes to muscular imbalances (and pain) often times we want to strengthen the long and weak muscle(s) and get the tight and or overactive one(s) to calm down. So not only do we want to pick exercises that wake up the long and weak muscle, but we want to pick exercises that, if not simultaneously, calm down the tight/overactive one.
What becomes tight/overactive when the subscapularis is long/weak?
Often times the tight/overactive muscles in this case are pectoralis major and latissimus dorsi. This is because the subscap isn’t internally rotating the humerus like it should be. So, other internal rotators, like pec major and the lat, pick up the slack. Infraspinatus and teres minor pick up the slack as depressors.
Therefore, when strengthening the subscap we want to pick exercises that elicit great activity in the subscap, but don’t elicit much activity in pec major, lat, infraspinatus, and teres minor.
That’s where this chart from the paper comes in (click for a clearer image):
In comparing the activity of the muscles I’m going to only look at the upper subscapularis in relation to the other muscles we’re looking at. This is because I’m really not sure how important the distinction between the two is. The authors go out of their way to talk about the importance of the subscap being separately innervated. However, they mention the upper subscap has been found to be dysfunctional in those with shoulder pain, but make no such mention of the lower subscap. I’ve also seen other authors make no distinction when it comes to the shoulder issues and simply stick with, “strengthen the subscap.”
Furthermore, the upper subscap is the portion of the muscle that consistently had the highest activity, and the exercises were ranked nearly identical in terms of effectiveness between the two sections. So again, while there may be a better approach, I’m just going to look at the upper.
All right, so from looking at the chart we can see that exercises such as the diagonal would be a poor choice due to the fact that pec major is more active than the subscap. This is important as simply taking the authors data at face value could lead one to suggest the diagonal is a great exercise as it was ranked as the second best.
And we can tell an exercise such as IR High is a good exercise due to the fact the subscap is more active than pec major, infraspinatus, and the lat, which are all barely active at all.
So, changing the author’s original order in terms of best exercises for the subscap based strictly on activity to best exercises based on activity in relation to the other muscles, I’d do something more along the lines of:
1) IR High
2) Push-up plus
3) Dynamic Hug
4) IR Mid
5) Forward Punch
6) IR Low
I put the IR High first because it had the biggest difference between subscap activity and other muscles with at least a 38% difference. The push-up plus and dynamic hug are next as there was still a good sized difference between the subscap and other muscles, 16 and 12% respectively. These exercises get the serratus anterior involved too, which is often overstretched and weak also.
IR High is also ranked above these as preventing the head of the humerus from moving is much easier to do than with other exercises such as the push-up plus or dynamic hug. I’ll show an example of this later.
The IR Mid and Forward Punch both favored the subscap as well, but with very small differences. The IR Mid, similar to IR High, is a better choice in my mind though because of the ability to prevent the head of the humerus moving forward.
IR Low and the Diagonal both favored the overactive muscles, thus would be contraindicated for people looking to strengthen their subscapularis.
This means that if you are trying to strengthen your rotator cuff and keep your shoulder healthy , performing internal rotation with your arm by your side (IR Low) could cause you to spin your wheels, if not make things worse. This is because you are strengthening pec major just as much, if not more, than the subscap. In other words, get rid of this exercise:
And switch to this one:
You’ll notice that the opposite hand is pressed down on the shoulder joint. This is to make sure the humerus does not glide anteriorly during the movement. This is crucial because the whole point of doing this exercise to get the shoulder to stop protruding.
Performing IR High already helps a lot to make sure this doesn’t happen since the muscles that cause anterior glide are primarily dormant, however, it can still happen. Therefore, putting the hand on the humerus and pushing it down and back only helps. Also, it gives the client a better understanding of why we are doing this particular exercise, as well as how we are going about ceasing their shoulder pain. This can be hard as hell to do with an exercise where a lot more is going on e.g. push-up plus.
Lastly, the IR High can be performed in the prone position as well. I’m not sure why this wasn’t examined in the study, but people who really know their stuff, such as Shirley Sahrmann and Mike Reinold, are advocates of this.
I’ll say that getting people to perform the exercise prone has proven to be more difficult for me, so I tend to go with the standing version first. If you go with the prone variation make sure 1) You can see your elbow to make sure it’s not moving forward and backward (sign you are using the deltoid/lat instead of the subscap) and 2) That the humerus is not moving anteriorly.
If you look closely at the humerus here you can see how it glides toward the mat:
Again, this is exactly what we want to avoid. Putting something under the humerus can help get rid of this movement:
Just make sure that whatever is put under the shoulder does not block the person’s ability to see their elbow.
Again, I tend to go with the standing variation first. It’s a bit easier to learn and there is a much greater range of motion involved. Both seem to get the job done though.
Check out some information on the law of repetitive motion for a related post.