Increasing Shoulder Horizontal Abduction Position Increases the Magnitude of Anterior Force on the Shoulder at Ball Release

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Increasing Shoulder Horizontal Abduction Position Increases the Magnitude of Anterior Force on the Shoulder at Ball Release

Increasing shoulder horizontal abduction position has shown to considerably increase the magnitude of the anterior force on the shoulder at ball release in baseball players confirms a recent study published in "The American Journal of Sports Medicine." In addition, the combination of 80.6° of shoulder abduction and 10.7° of horizontal shoulder adduction reduced the shear forces on the shoulder at this point.

The present descriptive laboratory study included estimation of a relationship between force on the shoulder while releasing the ball and horizontal abduction posture of the shoulder. The analysis also assessed the range of shoulder motion and relative rotational pose of the shoulder at ball release to reduced the force on the shoulder.

A total of 183 young baseball pitchers of 15.5 ± 1.2 years old who had no elbow/shoulder problems were selected. Overall, five fastballs were thrown to a catcher behind the home plate by every pitcher. The 3-dimensional measurements from 36 reflective markers were used to assess kinetics and kinematics of the shoulder which is used to pitch the ball. An association between forces on the shoulder (proximal, superior-inferior and anterior-posterior) and relative rotational postures of the shoulder (horizontal adduction-abduction and abduction) at the time of releasing the ball. After that, which range of motion and particular rotational position reduce the forces on the shoulder was also evaluated.

The magnitude of anterior-posterior and superior-inferior forces on the shoulder showed a statistically significant relationship with horizontal adduction-abduction and abduction position of the shoulder respectively (P< .001). The least superior-inferior and anterior-posterior forces were observed with the combination of 10.7° of horizontal adduction and 80.6° of shoulder abduction. Both superior-inferior and anterior-posterior forces got increased considerably in case of any >5° deviation from above noticed the least value of forces. These results might be helpful to reduce and prevent shoulder pain and injury by screening the pitching technique.


The American Journal of Sports Medicine

Link to the source:

Original title of the article:

Estimation of Shoulder Behavior From the Viewpoint of Minimized Shoulder Joint Load Among Adolescent Baseball Pitchers


Hiroshi Tanaka et al.

Exploratory, Sports Injury, Shoulder, Descriptive Laboratory Study
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