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It's a wonder we can throw at all!

Ross Bailey M.Ed., ATC, LAT, Associate Director of Sports Medicine & Athletic Operations at Texas Christian University. Ross is a member of the NATA, SWATA, NTATS, and Texas Society of Sports Medicine and received his M.Ed in 1978. He has given WebBall permission to take excerpts of his report on shoulders. For much more detail, check out his injury articles on the TCU website (tcusportsmedicine.com). (Click to close.)

By Ross Bailey, TCU

The more you read up on shoulder movement and injury risk, the more you realize just how challenging throwing a baseball really is. To come back from a shoulder injury, click here.

The phases of throwing

The pitching motion can produce many and varied injuries to the throwing shoulder. Newer diagnostic techniques, EMG studies, and arthroscopy have helped to increase the knowledge of what happens during each phase of the throwing motion. With more research and information, specialist can help determine where in the throwing phase a particular injury may have occurred and which muscles and joints the injury involves.

Wind up - This is a relatively slow motion phase that prepares the body posture and balance in preparation of the cocking phase. Individual to the person and the specific sport demands. This phase starts when the ball leaves the glove in baseball.
Cocking - Early phase, the scapula is retracted, the elbow is flexed, the humerus abducted, laterally rotated, and horizontally abducted. The trunk begins a very slight forward movement related to movement of the lower extremity. Late phase, the trunk rotates forward on the throwing side and the scapula protracts, the humerus adducts and rotates to a maximum when the humerus is at 90 degrees of abduction. The ball is not moved forward during this phase.
Acceleration - This is a very fast, explosive, short phase. The scapula continues to protract, the humerus is horizontally adducted and medial rotation of the humerus and elbow extension occur. The body is brought forward with the arm following behind. The of movement have been determined in the range of 5000 + degrees per second. [Actual angular movement is in a split second.] The muscles of the posterior cuff start firing eccentrically to check the horizontal adduction movement of the humerus. This action occurs very briefly, but it can produce very strong forces. If the body opens up too soon, the elbow trails behind and is subjected to very high forces.
Release - Deceleration - This phase was initially described as the release phase. New research has expanded this phase which has a strong eccentric component. The deceleration forces are approximately double the acceleration forces. The majority of pain in the back of the throwing shoulder is related to deceleration forces and the fatigue of the eccentric - antagonistic muscles that must fire to slow the accelerating arm. The exact timing of ball release varies from individual to individual and upon the pitch thrown.
Follow through - The body moves forward with the arm which helps to reduce the forces applied to the posterior shoulder complex. The planted opposite leg is the point of fixation to the ground and is responsible for helping maintain the body balance.

If you get all that, you now understand...

Baseball shoulder injuries

Injuries to the shoulder complex occur as the result of varied causes. Previously thought of as acute or chronic, it's now more apparent that some macrotrauma [major injuries] may be the result of microtrauma [gradual weakening]. Acute trauma-related injuries of the shoulder are often easier to assess than chronic cases that result from long term dysfunction - often related to poor mechanics. The loads imposed on the shoulder offer a diverse combination of open and closed chain loads.
[Editor's note: The full article covers injuries in detail - see side note. Basically, they fall under these terms... Contusions, Dislocations, Subluxations, Fractures. Separations, Lesions, Tears. On this page we spare you the gory details. What's important is...]

Preventing shoulder injuries
Proper equipment, protective taping, wrapping
Baseball specific weight training and conditioning
Proper warm up and cool down techniques
Proper techniques during the game
Preventing overuse syndromes
Pitch counts
Post practice or game treatment
In-season training programs
Rest schedules
Observing the concepts of gradualness and intensity (building up to peak performance gradually.)

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