Shoulder Impingement Syndrome

One of the most common types of pain that prevents us from doing things we love to do is shoulder pain, more specifically shoulder impingement syndrome. There are many reasons that cause shoulder impingement syndrome as you can imagine, and the purpose of this article is to cover some of the main reasons linked to the development shoulder impingement syndrome and how it can be mildly treated and corrected with strength training.

Anatomy of the shoulder

Understanding the anatomy of the shoulder is crucial in understanding how impingement may occur. If you read bodybuilding magazines you already know there are three deltoid heads, and if all you read is bodybuilding magazines, then that’s about all you know about the anatomy of the shoulder.

But, there is a lot more going on there than just the front delt, side delt, and often forgotten and neglected rear delt. The deltoid muscles make up the outer most layer of the shoulder.

The inner most part is the actual shoulder joint itself. The shoulder is comprised of three bones: the humerus (upper arm bone), the scapula (the shoulder blade), and the clavicle (the collar bone). The ball and socket configuration of the shoulder joint is comprised of the head of the humerus as it connects to the glenoid of scapula (socket of shoulder blade).

The next layer is the joint capsule, enveloping the joint, which is comprised of ligaments and rotator cuff tendons. The rotator cuff muscles originate (start) from the scapula and insert (end) around the humeral head (top of upper arm bone).

The primary purpose of the rotator cuff muscles is to hold the shoulder in place, keeping the humeral head centered, and rotate to lift the arm. The biceps muscle has two heads, with the tendon of the long head running over the shoulder joint and attaching to the glenoid fossa (shallow socket of scapula).

To enable the moving parts of a joint to glide smoothly, we have a special fluid filled sac called bursa located between tendon and bone. In the case of the shoulder, the bursa is called the subacromial (below the acromion) bursa. Just above the shoulder joint a bony projection from the top of the scapula sticks out, sort of like a shelf, called the acromion.

There is a small space that enables the humerus to move freely between the acromion and the shoulder joint, and it is known as the subacromial space (space below the acromion).

How shoulder impingement occurs

The term shoulder impingement means certain structures are being pinched in the subacromial space. This defines shoulder impingement syndrome.

Raising the arm overhead causes the head of the humerus to rise, therefore closing the gap between the head of the humerus and the bottom of the acromion (subacromial space). This movement may cause pinching/compression on the shoulder capsule, rotator cuff muscles, long head biceps tendon and bursa.

When these structures become impinged, they become inflamed which leads to shoulder pain. When the rotator cuff and bursa become inflamed due to repetitive stress, the subacromial space is compromised, causing more compression. It may even become a chronic inflammatory condition that may lead to a weakening of rotator cuff tendons, and eventually a rotator cuff tear.

If the impingement is too great, or too repetitive, injury to the bursa, rotator cuff, or long head biceps tendon may result. Injuries in these areas may lead to subacromial bursitis (which means the bursa is inflamed), biceps tendonitis (which means the biceps tendon is inflamed), or damage to the rotator cuff.

All of these injuries can be caused by factors other than shoulder impingement, or a combination of factors including shoulder impingement.

Not everyone who suffers from shoulder impingement presents it in the same manner, as different structures may be injured and varying biomechanics may have been the cause. The three most common structures involved in shoulder impingement are the subacromial bursa, the rotator cuff, and the long head of the biceps tendon.

An impingement can be caused by bone spurs, capsular tightness, and rotator cuff weakness.

A bone spur, in this case, is a hook that forms on the bottom of the acromion which narrows the subacromial space, increasing the likeliness of impingement. These hooks are rated as first degree, second degree or third degree. The larger the hook is the higher probability of an impingement occurring.

When the joint capsule is tight, the shoulder moves in abnormal fashion. Most commonly the bottom of the capsule will tighten up, causing the shoulder to rise up into the subacromial space.

If the rotator cuff is weak, the shoulder is less stable. A lack of stability will allow the head of the humerus to elevate into the subacromial space.

Symptoms of shoulder impingement

If you have shoulder impingement syndrome you’ll know it. The pain is very noticeable and typically starts in the top outer portion of the shoulder. It can vary from mild to severe and even remain constant. You may also notice an increase in pain doing any movement that causes the humerus to press against the bottom of the acromion, such as raising your arm overhead, and even lowering your arm from an overhead position. Weakness when the arm is in various positions is a sign of shoulder impingement syndrome.

Controllable factors/activities that can cause shoulder impingement

The position of the arm, either at rest or during activity, is the main factor in regards to shoulder impingement.

1. Raising the arm above shoulder height to the front or side of the body, much like you would by doing a lateral raise or front raise, leads to a position of impingement

2. Turning the arm inward (internally rotating) also creates a position of shoulder impingement

3. Anything where the arm travels overhead repetitively can cause repeated contact/friction between the rotator cuff and the subacromion (bottom part of the top of shoulder blade)

4. Weight lifting – there are too many exercises to mention, and to do so goes beyond the scope of this article

5. Swimming

6. Tennis amongst other overhead racquet sports

7. Volleyball

8. Painting – like a ceiling or top of a wall

9. Putting on a shirt/sweater/coat

10. Washing your hair

Uncontrollable factors that can cause shoulder impingement

In many cases of shoulder impingement the cause is due to the physical structure of the acromion. Some people’s acromions are angled downwards which decreases the space between the acromion and the humerus. The less subacromial space there is the greater the likeliness of impingement.

How to prevent/rehabilitate

1. The state of the scapulothoracic joint will greatly affect the subacromial space during function which is often the major factor in shoulder impingement and is ultimately the key to effective rehabilitation

2. Focus should be on strengthening the rotator cuff as well as the retractors to prevent the upper arm bone from rising excessively when the arms travel above the head

3. Slouching (poor posture) can narrow the gap between the head of the humerus and subacromion which can lead to and/or worsen shoulder impingement

4. Stiffness of the shoulder is common with impingement syndrome and stretching the muscles in and around the shoulder is helpful

5. Avoid movements that place the arm overhead or internally rotated

6. Ice reduces inflammation

7. Heat will help with warming up the muscles around the shoulder and reduce muscular tension

These tips should help with rehabilitation/prevention of shoulder impingement syndrome. If the pain is simply too severe then worst case scenario would be the have surgery. Surgery is used to make more room for the tendons of the rotator cuff by removing bone spurs that the tendon rubs on, as well as the bursa.

If you have any questions about shoulder impingement syndrome, feel free to contact me at ben@paramounttraining.ca. I'm available for online consulting and personalized program design, as well as one on one training if you are located in the Greater Toronto Area (GTA).