Healthy & Powerful Shoulder Series Part 2 – The Supraspinatus
This is the first muscle of the four rotator cuff muscles that I will cover in great detail. As a baseball player you have trained this muscle with a very common exercise in the baseball world known as the “empty can” drill which was popularized by Dr. Jobe. I will talk about why this isn’t the best exercise to target the supraspinatus and why we should stop doing it altogether but first let’s get into some of the geeky information about the supraspinatus.
Where is it?
To find your supraspinatus take your left hand and reach over your right shoulder and place it on your shoulder-blade (scapula). Poke around until you find what’s known as the spine of the scapula which runs horizontally across the top of your shoulder-blade, you’re feeling around for a rigid but thin bony part of your shoulder blade. Check out the picture for a visual.
Once you have your fingers on the spine of the scapula push down into it and let you fingers slide off of the spine towards the top of your shoulder-blade – you now have your fingers on your supraspinatus. The name comes from the fact that it is above the spine, supra in medical terms means superior or above. To make sure you have your fingers in the right place move your right arm away from your body just a little bit and you should feel your supraspinatus contract.
The problem with the supraspinatus is that it runs through what’s known as the
subacromial space. There isn’t much room in this subacromial space and when our shoulder doesn’t work properly this space can be further diminished which means the supraspinatus can be pinched which is obviously not a good thing to have happen.
What Does It Do?
The role of the supraspinatus is to compress (pulldown) on the head of the humerus to counteract the forces of the deltoid.
It is also responsible for the first 30 degrees of abduction (moving your arm away from your body) and it peaks in activity between 30 and 60 degrees (90 degrees would have your arm straight out to the side while zero degrees would have it next to your body hanging straight down) of abduction in the scapular plane. Finally it can generate some external rotation torque on the humerus – but not much. (Alpert et al. 2000).
What’s the Best Exercises?
If I can do one thing with this blog post it would be to stop people from doing the empty can drill. Every exercise has a certain amount of risk and certain amount of reward and in the case of the empty can exercise the reward is not worth the risk.
The reason the empty can is a thumbs down exercise, literally and figuratively, is when you internally rotate your arm and then lift it to shoulder height the greater tuberosity of the humerus (outer edge of the humerus) is not able to clear from under the acromion which can lead to that impingement due to a closing of the subacromial space (DeWilde et al. 2003).
The Full Can exercise on the other hand offers the same amount of supraspinatus activation without running the risk of causing an injury (Reinold & Wilk 2007) so in my humble opinion it is no brainer decision. The full can exercise was also shown to have less recruitment from the deltoid muscles (middle and posterior fibers) – I am usually fan of exercises that hit as many muscles as possible but there are occasions when isolation is needed and the supraspinatus is a prime example (Reinold & Wilk 2007)
Dr. Jobe was the first guy to find that doing exercises in the scapular plane did a much better job of recruiting the supraspinatus than those that are done straight out to the side. The scapular plane is pretty much half between lifting your arms straight out in front and straight out to the side.
The supraspinatus has also been shown to be active in exercises that are not classified as rotator cuff exercises like pushups, rows, OH med ball throws which solidify its role as a dynamic shoulder stabilizer (pulling the head of the humerus down).
The Bottom Line
1 – Stick to the full can exercise
2 – Keep the reps high (8-12) & the weight low (5-10lbs)
3 – Stay in the scapular plane
4 – Keep perfect posture – stay tall and don’t sway from your lower back
5 – And for the love of god stay away from the empty can drill!!!!
If you have played baseball I can guarantee that you have done some form of shoulder exercises that are aimed at keeping your throwing arm healthy. These drills are now a staple of any good throwing program and have been integrated into the game of baseball. The problem that I see is that these exercises are so common that very little attention is given to which exercises we should be doing, how we should be doing them and with which tools (bands vs. weights). I see players today performing the same set of arm drills that I did back in the mid 90’s (I’m almost 30, yikes!!) yet there has been plenty of research performed in this area.
This is the first blog in a series that looks into how we can train the shoulder not only for injury prevention but for performance enhancement as well.
The Shoulder – Mobile Yet Hostile
The shoulder is delicate structure that literally hangs off the side of our body being held in place by a series of tendons, ligaments and muscles. Yet it can produce and harness extremely high forces. To give you an idea of the power that can occur at the shoulder you don’t have to look any further than research produced by Dr. Glen Fleisig that states the shoulder reaches rotational velocities of 7200 degrees per second during the acceleration phase. That is the equivalent of your arm doing 20 full revolutions in one second – that’s crazy!!
When you look closely at the shoulder joint, known in the medical community as the glenohumeral joint, you will discover that it is able to perform more movements with a bigger range of motion when compared to any other joints in the body. This is because has what is classified as a ball & socket joint and is relatively unrestricted by bulky muscles (the hip is also a ball and socket joint but doesn’t have the same range of motion)
The ball is the head of the humerus (the upper arm bone) and socket is the glenoid fossa/cavity which is part of the scapula (the shoulder-blade).
This mobility comes with a price and that is that is lacks stability. The shoulder couldn’t do many of its movements if it were bound up by surrounding muscles and bones which stresses the importance of strengthening the muscles that do stabilize the shoulder. This where the rotator cuff comes into play.
SITS down and learn
Anatomy professor’s commonly use the acronym “SITS” to help students memorize the names of the muscles that make up the rotator cuff.
S – Supraspinatus
I – Infraspinatus
T – Teres Minor
S – Subscapularis
Each of theses muscles performs its own role when individually fired however as a group their role is to dynamically stabilize the shoulder – this is the way that we use when we throw a baseball (Lee et al. 2000) When you do an overhead activity, like throwing a baseball, your deltoid muscle (a.k.a shoulder muscle) wants to pull the head of the humerus up and unless there it is counteracted by the muscles of the rotator cuff it will rub up against the top of socket, the acromion process (Brossmann et al. 1996) and potentially cause an impingement type of injury (Sharkey et al. 1995).
The Sweet Spot
Within the glenohumeral joint is an optimal spot where the ball (head of the humerus) rotates inside of the socket (glenoid fossa/cavity). I like to think of it as the “Sweet Spot” since every baseball player knows about this magical spot on a baseball bat where good things happen. The same is true with the shoulder joint – if we can train our rotator cuff to keep the head of the humerus in the “Sweet Spot” good things will happen and the chances of injuring our shoulder due to throwing go way down.
The next blog post will look at the each rotator cuff muscle individually and tell you what are the best exercises and how to do them properly.