Effects of Shoulder Stretching and Strength Training Program on Pitching Biomechanics in Baseball Players with Glenohumeral Internal Rotation Deficit

• Main Authors: Yu-Jen Chiang, 江育任
• Other Authors: Pei-Hsi Chou
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/rwtqt9

碩士 === 高雄醫學大學 === 運動醫學系碩士班 === 104 === Background：Most baseball injuries result from repetitive throwing movement. Because of chronic practicing and participating in games, many overhead athletes developed decreased shoulder rotation angle of the throwing arm during the adolescent years, which is described as Gleno-Humeral Internal Rotation Deficit (GIRD). Epidemiologic studies reported overhead athletes with GIRD have higher risk of Superior Labrum Anterior to Posterior Lesion (SLAP), partial tear of the rotator cuff, and Ulnar Collateral Ligament (UCL) tear. In recent GIRD studies have proved that stretching posterior shoulder capsule can improve the problem of GIRD. To overhead athletes, they should not only possess suitable range of movement, but with dynamic stability. However, there is very little biochemical relative information on the effect of stretch or stretch combing strength training on overhead athletes’ shoulders and elbows. Purpose：The purpose of this study is to investigate the effect of stretch or stretch combing strength training program on ROM of Gleno-Humeral Joint, maximal voluntary isometric contraction and throwing biochemistry. Method：Twenty pitchers with GIRD were recruited in this study. These subjects were randomly divided into two groups, Stretch group: S-group and Stretch & strength group: SS-group. The intervention of everyday stretching program and at least four times a week strength training program were conducted for 12 weeks. ROM of Gleno-Humeral Joint and maximal voluntary isometric contraction were tested before and after the training programs. The pitching motion before and after the 12-week training programs was also analyzed. Independent-samples t-test was used to compare the differences between the basic information of two groups (S-group and SS-group), and was also used to compared the differences before and after the 12-week training programs. Paired t-test was used to analyze the value of Pre-test and Post-test. Assume p-value= 0.05 as significant level. Results：There were significant increase in the ROM of internal rotation and significant decrease in GIRD (NTIR-IR). Regarding to MVIC data, there were significant increase in extensor, supraspinatus, middle trapezius, lower trapezius and rhomboid of S-group; there were significant increase in extensor, supraspinatus, middle trapezius, lower trapezius and rhomboid of SS-group. The increase of lower trapezius MVIC in SS-group is significantly greater than in S-group. The kinematics of pitching motion analysis found that there were significant increase in shoulder horizontal abduction of S-group at FC. Also at FC, the increase of external rotation in SS-group is significantly greater than in S-group. At AC, max horizontal adduction of both groups both reached statistical increase. There were significant increase in max extension angular velocity of SS-group。At MIR, there were significant increase in elbow flexion of S-group. Kinetics of pitching motion analysis showed that there were significant increase in internal rotation torque and anterior force of SS-group at AC, and was increase significantly greater than S-group in internal rotation torque. There were significant decrease in proximal force of S-group at AA and at AD. There were significant decrease in flexion torque of S-group at AD. There were significant increase in shoulder internal rotation, posterior force and inferior force of SS-group, and the increase of shoulder inferior force is significantly greater than S-group. Conclusion：This study is the first example that attempt to carry out a convenient self-conducting stretching program aiming for GIRD population. Not only does it increase the internal rotation in glenohumeral joint to improve GIRD, but it also raise the fluency of shoulder during pitching. The most important of all is that it can decrease the risk of Superior Labrum Anterior Posterior (SLAP). Besides, the effects of stretching do not affect by combining it with strength training program. With the addition of strength training, it can be more beneficial to AA, and increase the strength of posterior shoulder to protect glenohumeral joint during AD. All in all, this study suggests that combining strength training and stretching to increase strength and controllability of posterior shoulder muscle group can balance out the burden during AD, which can cut down the risk of shoulder injuries.