Scapular muscle recruitment patterns and isokinetic strength ratios of the shoulder rotator muscles in individuals with and without impingement syndrome (original) (raw)

Abstract

The aim of this study was to compare the recruitment patterns and latencies of the scapular muscles, as well as the isokinetic performance of the shoulder rotators in 10 subjects with unilateral impingement syndrome who comprised the impingement group (IG) with a control group (CG) of 10 asymptomatic subjects. The recruitment patterns and latencies were evaluated by electromyographic activity during arm elevation in the scapular plane. Isokinetic work ratios of the shoulder rotator muscles were used to analyze muscular performance. A 2 x 2 ANOVA detected that muscular performance and recruitment patterns were similar for both groups and sides. However, the ANOVA revealed a significant side and group interaction, indicating that the scapular muscle latencies of the affected shoulder was greater than that of the nonaffected side only for the IG (p < .001). These findings indicated that subjects with light to moderate impingement syndrome showed late recruitment of the scapular muscles during arm elevation. However, muscular performance of the shoulder rotator muscles was not affected. (J Shoulder Elbow Surg 2008;17:48S-53S.) Duetotheassociatedmovementsoftheentireshoulder joint complex, the shoulder girdle has the highest mobility of all joints of the human body. 10,24,9 In normal conditions, each joint acts in a consistent and coordinated way, following a specific movement pattern to allow the upper limb to perform several motor functions, without compromising the integrity of the complex. 13 This kinematic relationship is dependent on muscular coordina-tion, 7 which, at the same time, allows adequate performance of the desired movement and provides dynamic stability of all involved joints. Several studies 2,3,16,28 have demonstrated the importance of a coordinated, synchronized action of the scapular and glenohumeral muscles, as well as a proportional relationship of strength of the rotator cuff muscles during all ranges of motion of the shoulder. Minimal alteration in performance and coordination of these muscles have the potential to lead to dysfunctions and compensations that could compromise normal joint function and lead to disabilities, 13,16 resulting in inactivity 6 and lower quality of life. The impingement syndrome (IS) is the most common diagnosis of shoulder pain. Electromyographic studies of the scapular stabilizing muscles have found changes in patients with IS compared with asymptomatic individuals. In addition, imbalance of the rotator cuff muscles assessed by their isokinetic performance has been well documented. 15,29 Therefore, neuromuscular dynamic control and muscle imbalance have been the focus of investigations related to scapular positioning and function of the shoulder girdle. 16 However, studies evaluating electromyographic activity of the scapular stabilizers and rotator cuff in the same patientss with IS are lacking.

Loading...

Loading Preview

Sorry, preview is currently unavailable. You can download the paper by clicking the button above.

References (29)

  1. Brindle T, Nyland J, Shapiro R, Caborn DNM, Stine R. Shoulder proprioception: Latent muscle reaction times. Med Sci Sports Exerc 1999;31:1394-8.
  2. Cools AM, et al. Scapular muscle recruitment pattern: Electromyo- graphic response of the trapezius muscle to sudden shoulder move- ment before and after a fatiguing exercise. J Orthop and Sports Phys Ther 2002;32:221-9.
  3. Cools AM, Witvrouw EE, Declercq GA, Danneels LA, Cambier DC. Scapular muscle recruitment patterns: Trapezius mus- cle latency with and without impingement symptoms. Am J Sports Med 2003;31:542-9.
  4. Cram JR, Kasman GS, Holtz J. Introduction to surface electromyog- raphy. Maryland: Aspen Publishers; 1998.
  5. David G, Magarey ME, Jones MA, Dvir Z, Tu ¨rker KS, Sharpe M. EMG and strength correlates of selected shoulder muscles during ro- tations of the glenohumeral joint. Clin Biomech 2000;15:95-102.
  6. Doukas WC, Speer KP. Anatomy, pathophysiology, and biome- chanics of shoulder instability. Orthop Clin North Am 2001;32: 381-91.
  7. Ebaugh DD, McClure P, Karduna AR. Three-dimensional scapulo- thoracic motion during active and passive arm elevation. Clin Biomech 2005;20:700-9.
  8. Fonsenca ST, Silva PLP, Ocarino JM, Ursine PGS. Ana ´lise de um me ´todo eletromiogra ´fico para quantificac ¸a ˜o de co-contrac ¸a ˜o muscular. Rev Bras Cienc Mov 2001;9:23-30.
  9. Halder AM, Itoi E, An K. Anatomy and biomechanics of the shoul- der. Orthop Clin North Am 2000;31:159-76.
  10. Hart DL, Carmichael SW. Biomechanics of the shoulder. J Orthop Sports Phys Ther 1985;6:229-34.
  11. Hess SA. Functional stability of the glenohumeral joint. Man Ther 2000;5:542-9.
  12. Janos SC, Boissonnault WG. Dysfunctions, evaluation, and treat- ment of the shoulder. In: Wooden D, editor. Orthopaedic Physical Therapy. Philadelphia: Churchill Livingstone; 2001. p. 144-65.
  13. Kelley MJ, Clark WA. Orthopedic therapy of the shoulder. Phila- delphia: Lippincott Williams and Wilkins; 1995.
  14. Kibler WB. The role of the scapula in athletic shoulder function. Am J Sports Med 1998;26:325-37.
  15. Leroux J, Codine P, Thomas E, Pocholle M, Mailhe D, Blotman F. Isokinetic evaluation of rotational strength in normal shoulders and shoulders with impingement syndrome. Clin Orthop Rel Res 1994; 304:108-15.
  16. Ludewig PM, Cook TM. Alterations in shoulder kinematics and associated muscle activity in people with symptoms of shoulder impingement. Phys Ther 2000;80:276-91.
  17. MacDermid JC, Ramos J, Drosdowech D, Faber K, Patterson S. The impact of rotator cuff pathology on isometric and isokinetic strength, function, and quality of life. J Shoulder Elbow Surg 2004;13:593-8.
  18. Magarey ME, Jones MA. Dynamic evaluation and early manage- ment of altered motor control around the shoulder complex. Man Ther 2003;8:195-206.
  19. Matsui M. The painful shoulder: Is it impingement syndrome? J Am Acad Physician Assistants 2000;13:18-32.
  20. Ng GYF, Lam PCW. A study of antagonist/agonist isokinetic work ratios of shoulder rotators in men who play badminton. J Orthop Sports Phys Ther 2002;32:399-404.
  21. Noffal GJ. Isokinetic eccentric-to-concentric strenght ratios of the shoulder rotator muscles in throwers and non-throwers. Am J Sports Med 2003;31:537-41.
  22. Perrin DH. Isokinetic exercise and assessment. Champaign, IL: Human Kinetics; 1993.
  23. Poppen NK, Walker PS. Normal and abnormal motion of the shoulder. J Bone Joint Surg 1976;58A:195-201.
  24. Rowe CR. The shoulder. New York: Churchill Livingstone; 1988.
  25. Schneider R, Prentice WE. Reabilitac ¸a ˜o das leso ˜es do ombro. In: Prentice WE, editor. Te ´cnicas de reabilitac ¸a ˜o em medicina espor- tiva. Barueri: Manole; 1999. p. 309-57.
  26. Semmler JG. Motor unit synchronization and neuromuscular perfor- mance. Exerc Sport Sci Rev 2002;30:8-14.
  27. Taylor DC, Dalton JD Jr, Seaber AV, Garrett WE Jr. Viscoelastic properties of muscle-tendon units: The biomechanical effects of stretching. Am J Sports Med 1990;18:300-9.
  28. Wadsworth DJ, Bullock-Saxton JE. Recruitment patterns of the scap- ular rotator muscle in freestyle swimmers with subacromial impinge- ment. Int J Sports Med 1997;18:618-24.
  29. Warner JJP, Micheli LJ, Arslanian LE, Kennedy J, Kennedy R. Pat- terns of flexibility, laxity, and strength in normal shoulders and shoulders with instability and impingement. Am J Sports Med 1990;18:366-75.