Shoulder Rotational Laxity is Related to Joint Loading During Throwing

Throwing arm injuries are common and often related to shoulder rotational laxity. Both shoulder external and internal rotational laxity are often checked in a physical assessment. The shoulder external rotation of the throwing arm during physical assessment is reported to be about 10 degree greater than the non-throwing arm [1]. Throwing arm injuries often occur during throwing activities. High forces and torques were generated during throwing activity. Extremely high shoulder external rotation (about 180°) and high internal rotation velocity (over 7000°/s) during baseball pitching are reported [2].