Effects of Shoulder Corrective Training Program on Pitching Loads and Sonographic Morphology in Elbow Joint in Youth Baseball Players

We assessed the effects of a 12-week shoulder corrective training program for shoulder flexibility and strengthening on pitching loads and sonographic morphology of the elbow joints in youth baseball players. Seventeen subjects were recruited and underwent evaluations before and after the training program. We found that following training, subjects demonstrated significantly increased ranges of shoulder internal rotation (38.9 +/- 12.9 degrees vs. 69.2 +/- 10.8 degrees, p < 0.001), external rotation (91.2 +/- 14.6 degrees vs. 107.3 +/- 9.5 degrees, p = 0.004), and horizontal adduction (21.5 +/- 8.0 degrees vs. 32.7 +/- 7.3 degrees, p = 0.002); improved strength in the shoulder internal rotators (8.7 +/- 1.6 kg vs. 9.8 +/- 2.1 kg, p = 0.04), external rotators (6.5 +/- 1.9 kg vs. 7.5 +/- 2.8 kg, p = 0.04), middle trapezius (12.7 +/- 2.1 kg vs. 14.3 +/- 2.4 kg, p = 0.04), and middle deltoid muscles (10.8 +/- 3.3 kg vs. 14.8 +/- 3.2 kg, p = 0.001); and decreased thickness of the ulnar collateral ligament (6.1 +/- 0.6 mm vs. 4.8 +/- 0.7 mm, p = 0.002). Although there was no substantial change in elbow torque and arm speed, significantly increased ball speed (51.2 +/- 4.6 mph vs. 54.1 +/- 4.5 mph, p < 0.001) and decreased arm slot (63.8 +/- 11.9 degrees vs. 53.0 +/- 12.7 degrees, p = 0.02) were observed. We suggest that adequate corrective training should be performed regularly to minimize or mitigate adverse soft tissue changes at the elbow in youth baseball players. Balanced shoulder strength and flexibility may decrease medial elbow stress during pitching. Future studies should consider the kinetic and kinematic effects of other corrective training programs on the shoulder or elbow joint during pitching.