The shoulder is a fascinating joint. It allows us to manipulate objects in an infinite number of directions at various speeds. The shoulder is the most mobile joint in the body and provides many degrees of motion. This freedom of motion allows us to reach high and low, far and near for objects in space. The large amount of shoulder mobility does not come without a price. Increase in shoulder or (Glenohumeral Joint) mobility leads to a decrease in the stability of the joint. When a joint is unstable, it is more likely to suffer an injury. The most common injury to the shoulder is from a repetitive movement on an unstable joint. This movement can vary from typing at a computer with poor posture to an unstable tennis or golf swing. Shoulder injuries are not discriminatory to a specific sport or action. They affect both male and females athletes and non-athletes alike.
The following guidelines will help to prevent the possibility of developing a shoulder injury due to overhead sports, poor posture and improper weight training.
Anatomy – The shoulder complex is made up of four joints. The glenohumeral joint, acromioclavicular joint, sternoclavicular joint and the scapulothoracic joint. Aside from these joints, there are other anatomical structures that play a large role in normal shoulder function. These include the cervical spine (neck), thoracic spine (upper back), clavicle and ribs. If any one of these structures is not functioning properly, they will have a direct negative impact on the shoulder complex. Full shoulder flexion in the saggital plane in a normal adult is 180°. This movement is not accomplished by the glenohumeral joint alone. In fact, full arm elevation involves thoracic extension, the 1st & 2nd ribs must depress and move posterior, the scapula (shoulder blade) must rotate upwards, the clavicle needs to elevate and roll back and finally the glenohumeral joint needs to glide downward and roll upward.
Mechanism of Injury – If any one of these movements does not occur, the shoulder joint is susceptible to injury. The most common area of injury to the shoulder occurs in what is known as the sub-acromial space. This space is located just under the acromioclavicular joint. There are many structures passing through this space leading to a very tight passage. Included in this space is rotator cuff tendons, neurovascular bundles and other connective tissues. If any one of these structures is irritated or injured, inflammation occurs. Inflammation will take up valuable real estate in the sub-acromial space leading to possible impingement of the tendons, nerves or vasculature.
The Rotator Cuff Muscles play a vital role in shoulder stability and injury prevention. The job of the four rotator cuff muscles (infraspinatus, supraspinatus, teres minor & subscapularis) is to synergistically contract at the same time to hold the shoulder centrally in the glenoid fossa to maintain an precise axis of rotation. If any one of these muscle is weak or injured, the shoulder will migrate out of position and either elevate or move forward in the joint capsule. This movement reduces space in the sub-acromial region which often leads to rotator cuff impingement. The rotator cuff tendons rub against the acromion causing friction, inflammation and eventually will tear if not resolved.
The 3 Rules of Shoulder Injury Prevention:
1. Proper posture
2. Good body mechanics
3. Well rounded exercise program
We are a product of our environment. A normal day for someone consists of the following: Wake up and head down to the breakfast table. We may sit for 20 minutes eating breakfast. Shower, get in the car or train and sit for a daily commute to work. Many people are sitting at a desk working on a computer for at least 5 hours daily. Then we get back in the car for the commute home. Dinner time arrives and again we sit down at the table for an hour. Following dinner maybe we sit and watch television or sit reading a book. Do you see a common theme here? Most of us are sitting all day long. When positioned in a seated position, gravity works against us to pull our head and shoulders forward. This posture leads to a decrease in sub-acromial space and places us at risk for shoulder impingement. How can this be avoided? Having a good ergonomic chair that places the hips slightly above the knees will orient the back in a good position. Arm rests are important for taking pressure of the shoulder girdle. The neck should be positioned in neutral by tucking the chin back in an attempt to lengthen the neck. The shoulders should be positioned down and back. Try to imagine bringing the shoulder blades toward the opposite back pocket. A stretch should be felt across the chest and shoulders.
Body Mechanics – Lifting, throwing and exercising using proper positioning can make a big difference in preventing injury. When lifting something overhead, the shoulders must stay down. If the shoulder moves upward towards the ears, you are increasing risk for impingement by closing down the sub-acromial space. Repetitive movements using improper body mechanics leads to shoulder injury. If an athletic movement such as the golf swing or tennis serve leads to pain in the shoulder, don’t try to work through the pain. Seek professional advice from a physical therapist or a sports doctor. You may avoid a serious injury by inquiring when the discomfort first begins. Waiting until you can’t bear the pain usually means the injury is serious and may require surgery.
Shoulder Exercises -Exercising the shoulder to prevent injury should be conducted three times per week. There are many variations of exercises that can be used to strengthen the rotator cuff muscles and back musculature. Seated rows and lat pull-downs are great ways to strengthen the muscles around the shoulder blades. Keeping the shoulders down and pinching the blades together is the proper mechanics during this movement. Shoulder external and internal rotation will keep the infraspinatus, teres minor and subscapularis strong. Shoulder elevation to the front and side will strengthen the deltoids & supraspinatus. Make sure the shoulders do not hike up toward the ears with this exercise. Finally, proper stretching to keep the shoulders and pectoral muscles loose is vital to healthy shoulders. A door or corner stretch is great to open up the thoracic spine. This is accomplished by placing both forearms along the frame of the door with the elbows at shoulder height and keeping the abdominals tight. Gently bring the chest forward into the door until a comfortable stretch is felt across the chest and shoulders. Do not bounce or arch low back. This stretch should be held for a minimum of 30 seconds.
In summary, proper posture and body mechanics is vital for preventing shoulder injuries. A well balanced exercise program that promotes flexibility, rotator cuff and back strengthening and precise body mechanics during exercise will allow persons to excel in their respective activities minimizing the risk for shoulder injury.