Shoulder Impingement

Today and tomorrow I am giving a little tutorial in shoulder impingement and how to go about strengthening your rotator cuff. This is in answer to something that came up on the PN Forums, so for those of you who didn’t come from there, I haven’t gone completely off my rocker.

Just so’s you know, I am actually a qualified personal trainer (you wouldn’t believe it to see the pictures) and sports massage therapist, so those are my credentials.

The majority of the muscular stability in the shoulder comes from the four muscles that make up the rotator cuff group: the subscapularis, supraspinatus, infraspinatus and teres minor. If you click on the picture, it’ll open up the full-size image. These poor under-appreciated muscles all attach onto the head of the humerus, from front to back, in that order, and work together as dynamic stabilisers to hold it in its socket.

Now if you look at the picture of the back of the shoulder, there is a bony prominence running across the scapula (shoulder blade) between the supraspinatus and the infraspinatus. This is called the spine of the scapula, and the big bit that sticks forward on the left is called the acromion process. If you look at the picture again, you will see that there’s a bunch of stuff between the acromion process and the head of the humerus, including the rotator cuff muscles, but also (and not shown in the picture) the tendon of the biceps and the subacromial bursa, a little sac that helps prevent too much friction.

Normally, there is a little bit of space between the tissues and the acromion process, but if something causes this subacromial space to decrease, some of the soft tissue structures can become ‘trapped’ between the two hard structures. This is a sometimes painful condition called ‘impingement’. It will be more or less painful depending on the position of the arm, because some movements will tend to decrease the subacromial space, but others will increase it, easing off or removing the pain. Actions that decrease the space include arm abduction (lifting the arm away from the body to the side), extension (taking the arm behind you), or overhead activities. Overuse in these activities may lead to impingement.

Common causes of impingement

• Things you were born with and cannot change, such as a longer than normal acromion process
• Loose bodies, ie. little bits of things moving around freely on the inside, most likely caused by an injury
• Muscle imbalances causing a narrowing of the subacromial space
• Inflammation of the subacromial tissues, eg. Swimmer’s Shoulder
• Hypertonicity (too big-ness) of the deltoid muscle relative to the rotator cuff. This is a very common cause in body builders who like to train the nice obvious deltoid muscle that sits on top of their shoulders, but don’t pay much attention to what’s underneath.

What you’ll notice

• Pain on overhead function, usually when the arm is lifted between around 70° and 120° to the side, as this is the range of motion (ROM) that tends to decrease the subacromial space. The pain will likely not occur when the arm is lower than this, or higher than this, as the space increases again relieving the pressure.
• You will find it difficult to do overhead tasks, such as reaching up to get things off shelves.
• Also, when lifting your arm past 90° you might find the scapula having to move upwards to facilitate the movement to compensate for the decreased ROM, although a lot of people do this anyway due to tight traps. Try pilates, people. Or at least, stretch!

What to do about it

• If you find the pain causes you to stop using the shoulder much at all, see a professional immediately. It can take less than a week for ‘frozen shoulder’ to develop, and then you are likely to have problems with the shoulder for the rest of your life. Suitable mobility exercises are critical at this time.
• Massage may help, but deep frictions may be necessary for chronic tendinosus (ouch time). Depending on how long the shoulder has been bothering you – for some people it will be years – fixing it will likely take some time.
• Strengthening the rotator cuff muscles.

When to see a specialist

• If you feel pain deep in the joint that doesn’t seem to improve
• If the pain is referred to another location or if you lose sensation along the arm
• If you have no improvement in pain levels or not much improvement in flexibility following remedial massage treatment, eg. sports massage
• If you feel you want to… always trust your own insticts when it comes to your body

Anybody can benefit from doing some rotator cuff strengthening exercises as part of their normal training routine. They’re simple and don’t take much time, but unfortunately, due to the ridiculous length of this post, the exercises will have to wait till tomorrow. ‘night all.

Next: Stabilising the Scapulae & Shoulder Mobility