The Shoulder & Repetitive Strain Injuries

Anatomy

The shoulder is a unique joint in the body. It has a great deal of mobility in order to allow us to reach and perform activities away from our body. The cost of this mobility is a lack of stability. Most of the stabilizing forces at the shoulder are muscular and ligamentous rather than bony. These soft tissues that provide the shoulder motion and stability can be at risk for repetitive strain injuries.

The shoulder is composed of three bones: the clavicle (collar bone), the scapula (shoulder blade), and the humerus (long bone of the upper arm). The rotator cuff surrounds the shoulder and provides muscular stability for the humeral head. The shoulder blade controls shoulder motion. Nine of the fifteen muscles that attach to the scapula provide this motion.

RSI

With computer, desk, assembly or other types of hand intensive work, the neck and shoulders round forward and the upper arm tends to rotate inward. The chest muscles become tight. The muscles of the back weaken and stretch. The upper trapezius (the big, bulky muscles that make up the top of the shoulder) try to compensate by working harder than they should. Muscle knots and tension develop. The arms feel tired and weak. Eventually, this muscular imbalance can cause a tendonitis in the rotator cuff (supraspinatus) or in the biceps where it attaches to the humerus. Or the fluid cushion (bursa) between the rotator cuff and the shoulder bones can become inflamed (bursitis).

Poor posture can be the primary factor in developing shoulder pain. Other activities that tend to cause problems are prolonged or repetitive overhead reaching (such as when lifting binders or books down from shelves above the computer) or holding the arms elevated while typing, using the mouse, or performing other hand work. Tichauer (1978, The Biomechanical Basis of Ergonomics) discovered that a chair height that was 3 inches too low for a worker caused excessive shoulder movements and reduced productivity by as much as 50%.

RSI Prevention for Shoulder Pain

  • Neutral and Relaxed Shoulder Positioning
    • Postural awareness is of major importance in injury prevention.
    • The shoulders (upper trapezius muscle) should be relaxed while working.
    • Arms should be positioned at your side with the ears, shoulders and elbows in line.
    • Avoid rounding the shoulders or hunching forward
    • Maintain a neutral neck posture.
  • Ergonomics
    • Chair height should allow you to reach the work surface/keyboard/mouse with the elbows opened slightly greater than 90 degrees and the shoulders relaxed, not elevated.
    • Use of arm supports has been debated in the therapeutic community. The shoulders should be allowed to move freely to position the hands so that excessive movement is not required at the more vulnerable elbows, wrists and fingers. However, unsupported use of the arms is a contributing factor in shoulder pain.
    • If using arm rests, they should be positioned at a height that allows the shoulders to be relaxed. Do not plant the forearms down on the rests while typing. Allow the forearms to glide over the rests unless taking a break from hand activity.
    • Articulating Arm Rests are a good option for providing support with movement.
    • Position your activity and supplies so that repetitive or sustained lifting or reaching is avoided.
    • If you do need to reach frequently overhead, use a step-stool so that the object you are reaching for is closer to you with less shoulder stretch needed.
    • Keep the keyboard and mouse in close to the body
    • Place frequently needed items in a close work envelope between hip and shoulder height.
  • Tension and Stress
    Many people hold tension in their shoulders. When feeling stressed, try to break the cycle by practicing diaphragmatic breathing techniques or taking a quick break away from the demanding situation. Perform some shoulder rolls emphasizing the backwards and downwards movements.
  • Exercise
    • Stretch frequently throughout the day.
    • Take frequent micro-breaks.
    • Try these exercises to recreate muscular balance in the shoulder complex. Remember, these exercises should not cause pain. Start slowly using a light weight. Add additional weight and repetitions gradually.
      • Strengthen the Rotator Cuff with Side-Lying External Rotation
        • Hold a light weight in your right hand. Lying on your left side, hold your right elbow tucked in at your side. Not moving the elbow away from your side, lift your hand towards the ceiling, then smoothly and slowly move your hand towards your stomach. Repeat 8-12 times. Perform 1-2 sets. Repeat with the other arm.
      • Stretch the Pecs with the Doorway Stretch
        • Stand in a doorway facing the doorway jam. Bend your elbow placing one forearm along the doorway jam with the hand at about head height. Slowly rotate your body away from the doorway jam until you feel a nice stretch in your chest muscle close to your shoulder. Hold for 20-30 seconds. Repeat 2-3 times. Repeat with the other arm.
      • Towel Stretches for Internal and External Rotation
        • Drape a towel over your left shoulder holding to the upper end of the towel with your left hand. Place your right arm behind your back and grab on to the end of the towel. With your left hand, pull your right hand up along the spine as if you are trying to scratch an itch as high up your back as possible. Hold for 20 seconds. Repeat 2-3 times. Then with your right hand, pull the towel down, stretching the left hand along the spine as if you are trying to scratch an itch as low on the back as possible. Hold for 20 seconds. Repeat 2-3 times. Repeat with the other arm.
      • Shoulder Opener
        • Lie on a Foam Roller with the spine and heal supported and the arms relaxed at your sides. Support the arms with pillows if needed. Let the shoulders roll back around the foam roller. Stretch for a minimum of 3 minutes. Perform diaphragmatic breathing while stretching.
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