Throwing is a complex motion that requires a stable foundation starting with the legs and rotation of the pelvis. The shoulder has to be stable to produce power, and the outer head of the bicep is key in stabilizing the head of your upper arm bone.
Rotating the shoulder away from the midline of the body helps the thrower throw the ball faster. However, doing so moves the top of the arm bone forward, which places stress on the connective tissue in the front of the shoulder. Over time, the connective tissue loosens, which helps the thrower rotate his or her shoulder even farther away from the midline of the body and throw the ball faster — but, as the connective tissue loosens, the thrower has less shoulder stability.
“It’s difficult to predict who will have problems,” says Dr. Mark Fulcher, director of hand and upper extremity surgery at Augusta University Orthopaedics. “Though we do know that kids who throw all year long — summer and school time — will experience more injuries.”
Dr. Lynn Crosby, director of shoulder surgery at Augusta University Orthopaedics, has advice for fending off throwing injuries.
“It’s important to stretch and strengthen under the supervision of an experienced athletic trainer in the preseason to prevent throwing problems,” he said.