A new 3-D motion detection system could help identify baseball pitchers who are at risk for shoulder injuries, according to a new study by scientists at the Loyola University Medical Center, Maywood, IL. The laptop computer-based system can be used right on the field.

In a well-rested pitcher, the humerus and scapula move together in what is called the scapulo-humeral rhythm. But, after a pitcher has been on the mound for a while, the muscles start to tire, the scapulo-humeral rhythm begins to deteriorate, and the bones stop moving in sync, which can lead to shoulder injuries. To prevent these injuries, identified at-risk pitchers could undergo strengthening exercises and physical therapy.

The subtle changes in the scapulo-humeral rhythm can be detected with a portable tracking system. Researchers positioned sensing units on the pitcher’s scapula, humerus, forearm, and sternum, gathering information from 3D gyroscopes, 3D magnetometers and 3D accelerometers.

They enrolled 13 Chicago-area college pitchers in the study. For each pitcher, the system tracked the scapulo-humeral rhythm three times: Before pitching, after throwing 60 pitches, and 24 hours after a pitching session.

The results showed that only two pitchers showed similar measurement at all three sessions; five showed deterioration after pitching, but the rhythm was completely restored at 24 hours; three showed deterioration after pitching and their rhythm was not completely restored after rest; while the remaining three demonstrated deterioration even after 24 hours of rest signifying that they are the most at risk for injury.