Gravity comes into play, especially with our inactive lifestyles, which allow the scapulae (shoulder blades) to gradually be pulled down. If you think about it, we rarely have opportunities to raise our arms overhead. Many ergonomic controls in industrial settings are actually designed to eliminate overhead motions -- to the detriment of scapular function. As our arms work below shoulder height for longer and longer periods of time, our shoulder blades lose their fight with gravity and are pulled downward. This lengthens the trapezius, making it weaker as well.
Find out more about this book:Fixing You: Shoulder & Elbow Pain: Self-treatment for rotator cuff strain, shoulder impingement, tennis elbow, golfer's elbow, and other diagnoses.