Original Article

Effects of Scapular Kinetic-Chain Exercise on Muscle Activity in Overhead-Pitching Baseball Players


Background: We aimed to demonstrate the effect of 8 wk of scapular kinetic-chain exercise on muscle activity in collegiate baseball players diagnosed with scapular dyskinesis.

Methods: The subjects were career baseball players with at least a 7-year career assigned into either a SICK (S; scapular malposition, I; inferior border prominence, C; coracoid process pain, K; scapular dyskinesis; n=7) group or a normal group (n=16), respectively. The groups were further divided into SICK-Dominant, SICK-Non-Dominant, Normal-Dominant, and Normal-Non-Dominant to examine the dominant and non-dominant deviation of each group. Twenty-three subjects finally recruited through the Sports Science Institute of Korea National Sport University, Seoul, Korea in Sep 2014. Subjects were only allowed drug treatment for acute injuries during matches or training, and matches, training, and diet were controlled by university dormitory life.

Results: There was a significant increase in maximal muscular activation (MA) in elevation motion of Normal-Dominant upper trapezii (UT), mean MA of SICK-Dominant UT, and mean MA of SICK-Dominant lower trapezii (LT) (P<0.05). In depression motion, the mean MAs of SICK-Dominant, Normal-Dominant, and Normal-Non-Dominant UT were significantly increased (P<0.05). The maximal MA of Normal-Dominant LT was significantly increased (P=0.029), and the SICK-Dominant and Normal-Dominant groups showed significantly higher maximal and mean MAs after exercise compared with the Normal-Non-Dominant group (P<0.05). The maximal MA of SICK-Dominant musculi serratus anterior was significantly lower than Normal-Dominant at pre-test (P=0.034), and the mean MA of SICK-Dominant musculi serratus anterior differed from Normal-Dominant and Normal-Non-Dominant (P<0.05) before testing, but only from Normal-Non-Dominant after testing (P=0.031).

Conclusion: Scapular kinetic-chain exercise improved muscle activation in both overhead-pitching players with scapular dyskinesis and normal players.

1. Terry GC, Chopp TM (2000). Functional anatomy of the shoulder. J Athl Train, 35(3):248-255.
2. Spławski R, Lubiatowski P, Manikowski W, et al (2003). The reconstruction of invet-erate rotator cuff lesions and lesions of the glenoid labrum of the shoulder with open and arthroscopic techniques. Ortop Traumatol Rehabil, 5(4):463-468.
3. McCluskey GM, Bruce AG (2000). Patho-physiology of anterior shoulder instabil-ity. J Athl Train, 35(3):268-272.
4. Donatelli R (2000). Assessment of shoulder strength in professional baseball pitchers. J Orthop Sports Phys Ther, 30: 544-551.
5. Kevin GL, Justin MS, Keith M (2007). Dif-ferences in scapular upward rotation be-tween baseball pitchers and position players. Am J Sports Med, 35:2091-2095.
6. Burkhart SS, Morgan CD, Kibler WB (2003). The disabled throwing shoulder: spec-trum of pathology part I: pathoanatomy and biomechanics. Arthroscopy, 19:404-420.
7. Cools AM, Dewitte V, Lanszweer F, et al (2007). Rehabilitation of scapular muscle balance. Am J Sports Med, 35(10): 1774-1751.
8. Meyer KE, Saether EE, Soiney EK, et al (2008). Three-dimensional scapular kine-matics during the throwing motion. J Appl Biomech, 24(1):24-34.
9. Kibler WB (1998). The role of the scapula in athletic shoulder function. Am J Sports Med, 26(2):325-337.
10. Kibler WB, McMullen J, Uhl TL (2000). Shoulder rehabilitation strategies, guide-lines, and practice. Oper Tech Sports Med, 8(4):258-267.
11. McMullen J, Uhl TL (2000). A kinetic chain approach for shoulder rehabilitation. J Athl Train, 35:329-337.
12. Prentice WE (2007). Rehabilitation technique for sports medicine and athletic training. (4th ed). New York, Mcgraw-hill.
13. Porterfield JA, DeRosa C (2004). Mechanical shoulder disorders. Perspective in functional anat-omy. St Louis, Missouri, USA: Elsevier Science.
14. Kibler WB, Press J, Sciascia A (2006). The role of core stability in athletic function. J Sports Med, 36:189-198.
15. Cram JR, Kasman GS, Holtz J (1998). Intro-duction to surface electromyography. Maryland, Aspen.
16. Jobe FW (1995). Operative Techniques in Upper Extremity Sports Injuries. St. Louis: Mosby.
17. Fleisig GS (1994). The biomechanics of baseball pitching [dissertation]. University of Alabama at Birmingham. USA.
18. Speer KP, Hannafin JA, Altchek DW, et al (1994). An evaluation of the shoulder re-location test. Am J Sports Med, 22(2):177-183.
19. Cools AM, Witvrouw EE, Declercq GA, et al (2003). Scapular muscle recruitment patterns: trapezius muscle latency with and without impingement symptoms. Am J Sports Med, 31(4):542-549.
20. Cools AM, Witvrouw EE, Declercq GA, et al (2004). Evaluation of isokinetic force production and associated muscle activity in the scapular rotators during a protrac-tion-retraction movement in overhead athletes with impingement symptoms. Br J Sports Med, 38(1):64-68.
21. Ludewig PM, Cook TM (2000). Alterations in shoulder kinematics and associated muscle activity in people with symptoms of shoulder impingement. Physical Therapy, 80(3):276-291.
22. Wadsworth DJ, Bullock-Saxton JE (1997). Recruitment patterns of the scapular rota-tor muscles in freestyle swimmers with subacromial impingement. Int J Sports Med, 18(8):618-624.
23. Cools AM, Witvrouw EE, Mahieu NN, et al (2005). Isokinetic scapular muscle per-formance in overhead athletes with and without impingement symptoms. J Athl Train, 40(2):104-110.
24. Ruwe PA, Pink M, Jobe FW, et al (1994). The normal and the painful shoulders during the breaststroke. Electromyo-graphic and cinematographic analysis of twelve muscles. Am J Sports Med, 22(6):789-796.
25. Neumann DA (2017). Kinesiology of the musculo-skeletal system: Foundations for rehabilitation, 3rd ed. Mosby/Elsevier.
26. Ishii S, Palmer AK, Werner FW (1998). An anatomic study of liganebtous structure of the triangular fibrocartilage complex. J Hand Surg Am, 23(6):977-985.
27. Sciascia A, Cromwell R (2012). Kinetic chain rehabilitation: a theoretical framework. Rehabil Res Pract, 2012:853037.
IssueVol 49 No 5 (2020) QRcode
SectionOriginal Article(s)
Kinetic-chain Muscle activity Scapular dyskinesis Scapular kinetic-chain exercise

Rights and permissions
Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
How to Cite
SONG K-J, YOON JH, OH J-K. Effects of Scapular Kinetic-Chain Exercise on Muscle Activity in Overhead-Pitching Baseball Players. Iran J Public Health. 49(5):875-885.