Shoulder pain, Shoulder Impingement Syndrome, Rotator Cuff Tendinitis and Rotator Cuff Tendon tearing are common problems that a large percentage of the population face by the time they reach their 40s or 50s, regardless of what they do for a living. These conditions occur for a variety of reasons but one thing that these
conditions frequently have in common is relative weakness of the rotator cuff muscles. This weakness may develop secondarily to a shoulder injury or condition, or it may be the primary cause of the shoulder problem.
The Rotator Cuff muscles are a group of 4 muscles that attach the shoulder blade to the upper arm. Their main movements are to rotate the arm internally and externally. They also have the important function of stabilizing the shoulder joint by keeping the upper arm bone (called the humerus) in the shoulder joint. Their most important function from a clinical perspective is their action to maintain the space between the top of the arm bone and the bony roof of the shoulder (called the acromion) when the arm is raised. This space is call the subacromial space (space below the acromion). This is where the Rotator Cuff tendons glide back and forth when the arm is moved. There is a fluid filled sack called the Subacromial Bursa, which is there to cushion the tendons from being squeezed between the top of the humerus and the roof of the shoulder.
The Deltoid muscle is the primary mover of the humerus when lifting the arm up at the shoulder joint. Because the deltoid sits above the shoulder joint, when it contracts, it not only rotates the humerus up, it also pulls it up and tends to squeeze the rotator cuff tendon and the bursa within the subacromial space. The main job for rotator cuff muscles and the long head of the biceps muscle is to pull the head of the humerus inward and down when the arm is elevated, so that the subacromial space is maintained, and the Rotator cuff tendons and bursa are not squeezed when the arm is elevated.
When there is actual weakness or relative weakness of the rotator cuff muscles in relation to the strength of the deltoid muscles, the subacromial space is squeezed every time the arm is raised up above shoulder height. When this is done repetitively enough the tendon wears and tears over time, and the bursa can sustain damage. Shoulder pain, rotator cuff tendon inflammation (tendinitis) and microscopic tearing of the tendon can develop over time.
Repeatedly working from these positions will eventually lead to degenerative arthritis of the shoulder as the problem worsens.
Strengthening of the Rotator Cuff Muscles and tendon can help to prevent this shoulder impingement and improve the function of the shoulder joint. This will allow you to perform physical work at chest height or above with less wear and tear of the rotator cuff tendon and bursa, as well as with less shoulder pain or discomfort.