By Dr. Johanna Lelke, DC, ART, Graston Are you a baseball, football, tennis, volleyball player or swimmer? If so, you all have something in common: you’re more prone to shoulder injuries. A few key elements in your shoulder biomechanics----apart from your technique----can make you more susceptible to conditions like shoulder impingement, SLAP lesions, and rotator cuff tears. On the other hand, the more you know about your shoulder movement, the better able you are to prevent these injuries. Your shoulder is the most complex joint in the body, and the most inherently unstable. For that reason, more than a dozen muscles wrap and stabilize the shoulder girdle. When you serve a tennis ball, for example, a major force on your ball-and-socket joint is pulling apart or distraction. The rotator cuff muscles work the hardest in resisting distraction, thereby keeping your arm bone connected to your scapula. Repetitive throws or serves can put a demand on these small cuff muscles that is disproportionate to their size. Early signs of rotator cuff fatigue and muscle imbalances can be evaluated before symptoms appear. Shoulder impingement and rotator cuff tears are probably the most common shoulder injuries in throwing athletes. USA Baseball has responded to the prevalence of shoulder injuries in youth pitchers by instilling caps on pitches per game and days of rest between games. It’s particularly important for talented kid athletes not to over-train in throwing or serving because they can also get bony changes that affect their shoulder joint throughout life.