by Jennifer Trizuto, MPT
You probably don’t spend much time thinking about your shoulders. If you did, you might come to realize the important role they play in your everyday life, helping you dress, eat, drive, type, and care for your family. But for the most part, people don’t really notice how much they need their shoulders until something goes wrong. Then it becomes clear how necessary it is to care for them.
The shoulder is truly an amazing joint. It can move your arms in any direction in front of you, to your sides, over your head, and even behind you. When you shake hands, throw a ball, comb your hair, or reach for something on a high shelf, you are making use of your shoulders’ extraordinary range of motion. But with this versatility comes a greater risk of injury and pain. In fact, problems with the shoulders are relatively common. In 2003, 1.37 million Americans sought help for shoulder problems. People can develop shoulder pain from all sorts of activities, including household chores, heavy lifting on the job, and recreational sports.
Why are shoulder problems so common? To answer that question, you first need to understand how the shoulder is designed.
The shoulder is the meeting place of three bones: the arm bone, or humerus, which is shaped like a ball at the top; the collarbone, or clavicle, which is at the front of the shoulder; and the shoulder blade, or scapula, which is in the back of the shoulder. These three bones actually create three different joints, all of which play a role in shoulder movement. The main joint — the one most people are referring to when they talk about the “shoulder joint” — is called the glenohumeral joint. Like many joints in the body, the glenohumeral joint is a ball-and-socket joint. The “ball” at the end of the humerus fits into a concave “socket” in the scapula. As with all mobile joints in the body, the ends of the bones in the shoulder are covered by a layer of slippery cartilage, making the motion of the joint smooth and easy.
When you think of a ball-and-socket joint, you probably imagine a deep socket at one end with a ball that fits snugly inside it on the other. The hip exemplifies this type of ball-and-socket joint. The shoulder, however, is different. It has a shallower socket than the hip and looks more like a golf ball on a tee. The benefit of the shallower socket is mobility. If you compare the mobility of your hip with that of your shoulder, the difference is clear. What the hip lacks in mobility, however, it makes up for in stability.
The shoulder, while very mobile, is much less stable than the hip. Just as it is easy for a golf ball to slip off a tee, it is relatively easy for the ball of the humerus to slip out of its socket — in other words, to dislocate. The reason that your shoulders aren’t “slipping off the tee” every day is that you have many supporting structures in the shoulder. One type of supporting structure is the ligaments in the shoulders, which connect the various bones in the joint. Another supportive soft tissue structure is the joint capsule, which is a kind of envelope around the joint that holds everything inside. Within the capsule is fluid called synovial fluid that helps keep the joint nourished and moving smoothly. The ligaments also help to support the capsule.
Two other contributors to joint stability are tendons and muscles. Tendons are tough cords of tissue at the ends of muscles that attach the muscle to the bone and help the joint move. The most well-known shoulder muscles are those of the rotator cuff. The rotator cuff is a group of four muscles and several tendons that surround the top of the humerus and help keep it in the socket of the scapula. The rotator cuff is among the most commonly injured parts of the shoulder.
Another important component of the shoulder is the bursae — small, fluid-filled sacs that create a cushion for the tendons to glide on, helping to decrease friction in the joint. Bursae are found in most joints and save the tendons a great deal of wear and tear.
It should now be clear how complex the shoulder is. In part because of the shoulder’s wide range of movement, many of the structures described above can run into problems. For example, the ligaments can loosen, decreasing joint stability and increasing the risk that you will dislocate your shoulder. The joint capsule itself can become inflamed and stiffen, a condition called adhesive capsulitis, or “frozen shoulder.” Weakness in the muscles and tendons can cause tendon inflammation, known as tendinitis. The tendons and muscles can also wear out and even tear (rotator cuff tears are especially common). The bursae can become inflamed and swollen, causing pain.
The shoulder may be injured during sports or other recreational activities, or by heavy lifting. But often the cause of shoulder pain is the gradual degeneration of the soft tissues around the joint, including the rotator cuff muscles, that comes with age. According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases, people are much more likely to have rotator cuff problems after age 60. Regularly participating in activities that involve a lot of overhead reaching, including house painting, washing windows, and sports such as tennis, can increase the likelihood of developing shoulder pain at younger ages.
Another potential problem is degeneration of the cartilage that lines the ends of the bones in the joints. When the cartilage wears away, the resulting condition is called osteoarthritis (OA), a common cause of pain in the shoulder. Nobody really knows why people develop shoulder OA, although it is thought that the shoulder’s mobility and the prevalence of activities that put stress on the shoulder are involved.
Rheumatoid arthritis (RA) can also affect the shoulders. Unlike OA, RA is a body-wide condition, causing chronic inflammation that can lead to the destruction of cartilage and other structures in the joint. Both OA and RA can cause debilitating pain.
If you experience shoulder pain, your first inclination will probably be to keep your shoulder still. It is often the case that if you don’t move your shoulder, it won’t hurt. Of course, there are many reasons why your doctor would want you to rest your shoulder, and he or she will tell you when that is appropriate. However, for most causes of shoulder pain, immobility is the enemy because it can begin a vicious cycle. That is to say, the less you move your arm, the harder it becomes to move it.
So what is the best type of movement or exercise for your shoulders? There are three main types of exercise: range-of-motion or stretching exercises, strengthening exercises, and endurance or aerobic exercises. All three should be part of a program to keep shoulders strong and flexible. You can find examples of range-of-motion and strengthening exercises here.
Before you begin an exercise program for your shoulder, it is a good idea to check with your doctor. Your doctor may want to give you tests to make sure you don’t have any serious underlying problems. He or she may also want to refer you to a physical therapist or exercise physiologist, who can help you get started with a program of exercise. Once your doctor has examined your shoulder and told you that there is nothing to prevent you from exercising, it is time to get started.
Range-of-motion (stretching) exercises. Range-of-motion or stretching exercises are designed to take your shoulders through their maximum range of movement. These exercises can help you maintain your shoulders’ current mobility and, when done consistently, increase their mobility over time. Range-of-motion exercises can be done lying down, sitting, or standing. Unlike some strengthening exercises, range-of-motion exercises can and should be done every day. At first you may feel very stiff and sore after doing them. If the feeling doesn’t go beyond soreness, then you may only have to move more slowly or do fewer repetitions until your shoulders get used to the exercises — the soreness should decrease after a while. However, if you feel more pain after exercising than when you started, or if the pain persists for longer than two hours after you are finished exercising, you should see a doctor.
Strengthening exercises. Strengthening exercises can help the muscles in your shoulder better support the joint and decrease the wear that can come from overuse. The stronger your muscles are, the easier it is for them to do their job. As the muscles grow stronger over time, you may notice that you have less pain. These exercises can be done as often as every other day. It’s a good idea to aim for three strengthening sessions a week, with at least one day between each session.
Aerobic exercise. Endurance training, or aerobic conditioning, is important for heart health, and a healthy heart is better able to circulate the blood in the body and get necessary nutrients to your joints. Examples of aerobic exercise include walking, swimming, exercise classes, and bicycling. The American College of Sports Medicine recommends 30 minutes of aerobic exercise on five days a week. The 30 minutes does not have to be done all at once. For example, you can break it down into three separate 10-minute sessions.
No matter what, it is important to remember that your ability to use your arms to do everyday tasks depends on healthy shoulders. It only takes a little shoulder pain to make us realize how much we take these joints for granted. Not moving our shoulders because they hurt will only make them more difficult to use. Exercise can help improve the function of your shoulders and lead to less pain, and even small amounts of pain relief can make a huge difference in your quality of life. Don’t forget your shoulders in your everyday exercise routine.
Last Reviewed March 3, 2015
Jennifer Trizuto is a senior physical therapist at Mills Health Center in San Mateo, California, and has worked with people with arthritis since 1994.
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