Shoulder Muscle Activity and Function in Common Shoulder Rehabilitation Exercises

Abstract

The rotator cuff performs multiple functions during shoulder exercises, including glenohumeral abduction, external rotation (ER) and internal rotation (IR). The rotator cuff also stabilizes the glenohumeral joint and controls humeral head translations. The infraspinatus and subscapularis have significant roles in scapular plane abduction (scaption), generating forces that are two to three times greater than supraspinatus force. However, the supraspinatus still remains a more effective shoulder abductor because of its more effective moment arm.

Both the deltoids and rotator cuff provide significant abduction torque, with an estimated contribution up to 35–65% by the middle deltoid, 30% by the subscapularis, 25% by the supraspinatus, 10% by the infraspinatus and 2% by the anterior deltoid. During abduction, middle deltoid force has been estimated to be 434 N, followed by 323N from the anterior deltoid, 283N from the subscapularis, 205N from the infraspinatus, and 117N from the supraspinatus. These forces are generated not only to abduct the shoulder but also to stabilize the joint and neutralize the antagonistic effects of undesirable actions. Relatively high force from the rotator cuff not only helps abduct the shoulder but also neutralizes the superior directed force generated by the deltoids at lower abduction angles. Even though anterior deltoid force is relatively high, its ability to abduct the shoulder is low due to a very small moment arm, especially at low abduction angles. The deltoids are more effective abductors at higher abduction angles while the rotator cuff muscles are more effective abductors at lower abduction angles.

During maximum humeral elevation the scapula normally upwardly rotates 45–55°, posterior tilts 20–40° and externally rotates 15–35°. The scapular muscles are important during humeral elevation because they cause these motions, especially the serratus anterior, which contributes to scapular upward rotation, posterior tilt and ER. The serratus anterior also helps stabilize the medial border and inferior angle of the scapular, preventing scapular IR (winging) and anterior tilt. If normal scapular movements are disrupted by abnormal scapular muscle firing patterns, weakness, fatigue, or injury, the shoulder complex functions less efficiency and injury risk increases.

Scapula position and humeral rotation can affect injury risk during humeral elevation. Compared with scapular protraction, scapular retraction has been shown to both increase subacromial space width and enhance supraspinatus force production during humeral elevation. Moreover, scapular IR and scapular anterior tilt, both of which decrease subacromial space width and increase impingement risk, are greater when performing scaption with IR (‘empty can’) compared with scaption with ER (‘full can’).

There are several exercises in the literature that exhibit high to very high activity from the rotator cuff, deltoids and scapular muscles, such as prone horizontal abduction at 100° abduction with ER, flexion and abduction with ER, ‘full can’ and ‘empty can’, D1 and D2 diagonal pattern flexion and e The serratus anterior also helps stabilize the medial border and inferior angle of the scapular, preventing scapular IR (winging) and anterior tilt. If normal scapular movements are disrupted by abnormal scapular muscle firing patterns, weakness, fatigue, or injury, the shoulder complex functions less efficiency and injury risk increases.

Scapula position and humeral rotation can affect injury risk during humeral elevation. Compared with scapular protraction, scapular retraction has been shown to both increase subacromial space width and enhance supraspinatus force production during humeral elevation. Moreover, scapular IR and scapular anterior tilt, both of which decrease subacromial space width and increase impingement risk, are greater when performing scaption with IR (‘empty can’) compared with scaption with ER (‘full can’).

There are several exercises in the literature that exhibit high to very high activity from the rotator cuff, deltoids and scapular muscles, such as prone horizontal abduction at 100° abduction with ER, flexion and abduction with ER, ‘full can’ and ‘empty can’, D1 and D2 diagonal pattern flexion and extension, ER and IR at 0° and 90° abduction, standing extension from 90–0°, a variety of weight-bearing upper extremity exercises, such as the push-up, standing scapular dynamic hug, forward scapular punch, and rowing type exercises. Supraspinatus activity is similar between ‘empty can’ and ‘full can’ exercises, although the ‘full can’ results in less risk of subacromial impingement. Infraspinatus and subscapularis activity have generally been reported to be higher in the ‘full can’ compared with the ‘empty can’, while posterior deltoid activity has been reported to be higher in the ‘empty can’ than the ‘full can’.

This is a preview of subscription content, access via your institution.

Table I
Table II
Table III
Table IV
Table V
Table VI
Table VII
Table VIII
Table IX
Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig.4
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10

References

  1. 1.

    Uhl TL, Carver TJ, Mattacola CG, et al. Shoulder musculature activation during upper extremity weight-bearing exercise. J Orthop Sports Phys Ther 2003; 33 (3): 109–17

    PubMed  Google Scholar 

  2. 2.

    DiGiovine NM, Jobe FW, Pink M, et al. Electromyography of upper extremity in pitching. J Shoulder Elbow Surg 1992; 1: 15–25

    PubMed  Article  CAS  Google Scholar 

  3. 3.

    Escamilla RF, Fleisig GS, Zheng N, et al. Biomechanics of the knee during closed kinetic chain and open kinetic chain exercises. Med Sci Sports Exerc 1998; 30 (4): 556–69

    PubMed  Article  CAS  Google Scholar 

  4. 4.

    Zheng N, Fleisig GS, Escamilla RF, et al. An analytical model of the knee for estimation of internal forces during exercise. J Biomech 1998; 31 (10): 963–7

    PubMed  Article  CAS  Google Scholar 

  5. 5.

    Lawrence JH, De Luca CJ. Myoelectric signal versus force relationship in different human muscles. J Appl Physiol 1983; 54 (6): 1653–9

    PubMed  CAS  Google Scholar 

  6. 6.

    Solomonow M, Baratta R, Zhou BH, et al. Historical update and new developments on the EMG-force relationships of skeletal muscles. Orthopedics 1986; 9 (11): 1541–3

    PubMed  CAS  Google Scholar 

  7. 7.

    Perry J, Bekey GA. EMG-force relationships in skeletal muscle. Crit Rev Biomed Eng 1981; 7 (1): 1–22

    PubMed  CAS  Google Scholar 

  8. 8.

    Bigland-Ritchie B. EMG/force relations and fatigue of human voluntary contractions. Exerc Sport Sci Rev 1981

    Google Scholar 

  9. 9.

    Thomas CK, Johansson RS, Bigland-Ritchie B. EMG changes in human thenar motor units with force potentiation and fatigue. J Neurophysiol 2006; 95 (3): 1518–26

    PubMed  Article  CAS  Google Scholar 

  10. 10.

    Decker MJ, Tokish JM, Ellis HB, et al. Subscapularis muscle activity during selected rehabilitation exercises. Am J Sports Med 2003; 31 (1): 126–34

    PubMed  Google Scholar 

  11. 11.

    Ekstrom RA, Donatelli RA, Soderberg GL. Surface electromyographic analysis of exercises for the trapezius and serratus anterior muscles. J Orthop Sports Phys Ther 2003; 33 (5): 247–58

    PubMed  Google Scholar 

  12. 12.

    Reinold MM, Wilk KE, Fleisig GS, et al. Electromyographic analysis of the rotator cuff and deltoid musculatureduring common shoulder external rotation exercises. J Orthop Sports Phys Ther 2004; 34 (7): 385–94

    PubMed  Google Scholar 

  13. 13.

    Alpert SW, Pink MM, Jobe FW, et al. Electromyographic analysis of deltoid and rotator cuff function under varying loads and speeds. J Shoulder Elbow Surg 2000; 9 (1): 47–58

    PubMed  Article  CAS  Google Scholar 

  14. 14.

    Meyers JB, Pasquale MR, Laudner KG, et al. On-the-field resistance-tubing exercises for throwers: an electromyographic analysis. J Athletic Training 2005; 40 (1): 15–22

    Google Scholar 

  15. 15.

    Moseley Jr JB, Jobe FW, Pink M, et al. EMG analysis of the scapular muscles during a shoulder rehabilitation program. Am J Sports Med 1992; 20 (2): 128–34

    PubMed  Article  Google Scholar 

  16. 16.

    Townsend H, Jobe FW, Pink M, et al. Electromyographic analysis of the glenohumeral muscles during a baseball rehabilitation program. Am J Sports Med 1991; 19 (3): 264–72

    PubMed  Article  CAS  Google Scholar 

  17. 17.

    Lee SB, Kim KJ, O’Driscoll SW, et al. Dynamic glenohumeral stability provided by the rotator cuff muscles inthe mid-range and end-range of motion: a study in cadavera. J Bone Joint Surg Am 2000; 82 (6): 849–57

    PubMed  CAS  Google Scholar 

  18. 18.

    Hughes RE, An KN. Force analysis of rotator cuff muscles. Clin Orthop Relat Res 1996; (330): 75–83

    PubMed  Article  Google Scholar 

  19. 19.

    Liu J, Hughes RE, Smutz WP, et al. Roles of deltoid and rotator cuff muscles in shoulder elevation. Clin Biomech (Bristol, Avon) 1997; 12 (1): 32–8

    Article  CAS  Google Scholar 

  20. 20.

    Otis JC, Jiang CC, Wickiewicz TL, et al. Changes in the moment arms of the rotator cuff and deltoid muscles withabduction and rotation. J Bone Joint Surg Am 1994; 76 (5): 667–76

    PubMed  CAS  Google Scholar 

  21. 21.

    Burke WS, Vangsness CT, Powers CM. Strengthening the supraspinatus: a clinical and biomechanical review. Clin Orthop Relat Res 2002; (402): 292–8

    PubMed  Article  Google Scholar 

  22. 22.

    Sharkey NA, Marder RA. The rotator cuff opposes superior translation of the humeral head. Am J Sports Med 1995; 23 (3): 270–5

    PubMed  Article  CAS  Google Scholar 

  23. 23.

    Jobe FW, Moynes DR. Delineation of diagnostic criteria and a rehabilitation program for rotator cuff injuries. Am J Sports Med 1982; 10 (6): 336–9

    PubMed  Article  CAS  Google Scholar 

  24. 24.

    Rowlands LK, Wertsch JJ, Primack SJ, et al. Kinesiology of the empty can test. Am J Phys Med Rehabil 1995; 74 (4): 302–4

    PubMed  Article  CAS  Google Scholar 

  25. 25.

    Kelly BT, Kadrmas WR, Speer KP. The manual muscle examination for rotator cuff strength: an electromyographic investigation. Am J Sports Med 1996; 24 (5): 581–8

    PubMed  Article  CAS  Google Scholar 

  26. 26.

    Takeda Y, Kashiwaguchi S, Endo K, et al. The most effective exercise for strengthening the supraspinatus muscle:evaluation by magnetic resonance imaging. Am J Sports Med 2002; 30 (3): 374–81

    PubMed  Google Scholar 

  27. 27.

    De Wilde L, Plasschaert F, Berghs B, et al. Quantified measurement of subacromial impingement. J Shoulder Elbow Surg 2003; 12 (4): 346–9

    PubMed  Article  Google Scholar 

  28. 28.

    Roberts CS, Davila JN, Hushek SG, et al. Magnetic resonance imaging analysis of the subacromial space in the impingement sign positions. J Shoulder Elbow Surg 2002; 11 (6): 595–9

    PubMed  Article  Google Scholar 

  29. 29.

    Thigpen CA, Padua DA, Morgan N, et al. Scapular kinematics during supraspinatus rehabilitation exercise: acomparison of full-can versus empty-can techniques. Am J Sports Med 2006; 34 (4): 644–52

    PubMed  Article  Google Scholar 

  30. 30.

    Smith J, Dietrich CT, Kotajarvi BR, et al. The effect of scapular protraction on isometric shoulder rotation strength in normal subjects. J Shoulder Elbow Surg 2006; 15 (3): 339–43

    PubMed  Article  Google Scholar 

  31. 31.

    Solem-Bertoft E, Thuomas KA, Westerberg CE. The influence of scapular retraction and protraction on the width of the subacromial space: an MRI study. Clin Orthop Relat Res 1993; (296): 99–103

    PubMed  Google Scholar 

  32. 32.

    Kibler WB, Sciascia A, Dome D. Evaluation of apparent and absolute supraspinatus strength in patients with shoulder injury using the scapular retraction test. Am J Sports Med 2006; 34 (10): 1643–7

    PubMed  Article  Google Scholar 

  33. 33.

    Itoi E, Kido T, Sano A, et al. Which is more useful, the “full can test” or the “empty can test,” in detecting thetorn supraspinatus tendon? Am J Sports Med 1999; 27 (1): 65–8

    PubMed  CAS  Google Scholar 

  34. 34.

    Ballantyne BT, O’Hare SJ, Paschall JL, et al. Electromyographic activity of selected shoulder muscles in commonly used therapeutic exercises. Phys Ther 1993; 73 (10): 668–77; discussion 677-82

    PubMed  CAS  Google Scholar 

  35. 35.

    Blackburn TA, McLeod WD, White B, et al. EMG analysis of posterior rotator cuff exercises. Athletic Training 1990; 25 (1): 40–5

    Google Scholar 

  36. 36.

    Horrigan JM, Shellock FG, Mink JH, et al. Magnetic resonance imaging evaluation of muscle usage associatedwith three exercises for rotator cuff rehabilitation. Med Sci Sports Exerc 1999; 31 (10): 1361–6

    PubMed  Article  CAS  Google Scholar 

  37. 37.

    Malanga GA, Jenp YN, Growney ES, et al. EMG analysis of shoulder positioning in testing and strengthening the supraspinatus. Med Sci Sports Exerc 1996; 28 (6): 661–4

    PubMed  Article  CAS  Google Scholar 

  38. 38.

    Worrell TW, Corey BJ, York SL, et al. An analysis of supraspinatus EMG activity and shoulder isometric force development. Med Sci Sports Exerc 1992; 24 (7): 744–8

    PubMed  CAS  Google Scholar 

  39. 39.

    Smith J, Dahm DL, Kaufman KR, et al. Electromyographic activity in the immobilized shoulder girdle musculature during scapulothoracic exercises. Arch Phys Med Rehabil 2006; 87 (7): 923–7

    PubMed  Article  Google Scholar 

  40. 40.

    Cordasco FA, Wolfe IN, Wootten ME, et al. An electromyographic analysis of the shoulder during a medicine ball rehabilitation program. Am J Sports Med 1996; 24 (3): 386–92

    PubMed  Article  CAS  Google Scholar 

  41. 41.

    Hintermeister RA, Lange GW, Schultheis JM, et al. Electromyographic activity and applied load during shoulder rehabilitation exercises using elastic resistance. Am J Sports Med 1998; 26 (2): 210–20

    PubMed  CAS  Google Scholar 

  42. 42.

    Itoi E, Berglund LJ, Grabowski JJ, et al. Tensile properties of the supraspinatus tendon. J Orthop Res 1995; 13 (4): 578–84

    PubMed  Article  CAS  Google Scholar 

  43. 43.

    Kronberg M, Nemeth G, Brostrom LA. Muscle activity and coordination in the normal shoulder: an electromyographic study. Clin Orthop Relat Res 1990; (257): 76–85

    PubMed  Google Scholar 

  44. 44.

    Ekholm J, Arborelius UP, Hillered L, et al. Shoulder muscle EMG and resisting moment during diagonal exercise movements resisted by weight-and-pulley-circuit. Scand J Rehabil Med 1978; 10 (4): 179–85

    PubMed  CAS  Google Scholar 

  45. 45.

    Kadaba MP, Cole A, Wootten ME, et al. Intramuscular wire electromyography of the subscapularis. J Orthop Res 1992; 10 (3): 394–7

    PubMed  Article  CAS  Google Scholar 

  46. 46.

    Greis PE, Kuhn JE, Schultheis J, et al. Validation of the liftoff test and analysis of subscapularis activity during maximal internal rotation. Am J Sports Med 1996; 24 (5): 589–93

    PubMed  Article  CAS  Google Scholar 

  47. 47.

    Suenaga N, Minami A, Fujisawa H. Electromyographic analysis of internal rotational motion of the shoulder in variousarm positions. J Shoulder Elbow Surg 2003; 12 (5): 501–5

    PubMed  Article  Google Scholar 

  48. 48.

    Gerber C, Krushell RJ. Isolated rupture of the tendon of the subscapularis muscle: clinical features in 16 cases. J Bone Joint Surg Br 1991; 73 (3): 389–94

    PubMed  CAS  Google Scholar 

  49. 49.

    Decker MJ, Hintermeister RA, Faber KJ, et al. Serratus anterior muscle activity during selected rehabilitation exercises. Am J Sports Med 1999; 27 (6): 784–91

    PubMed  CAS  Google Scholar 

  50. 50.

    Welsch EA, Bird M, Mayhew JL. Electromyographic activity of the pectoralis major and anterior deltoid muscles during three upper-body lifts. J Strength Cond Res 2005; 19 (2): 449–52

    PubMed  Google Scholar 

  51. 51.

    Barnett C, Kippers V, Turner P. Effects of variations of the bench press exercise on the EMG activity of five shoulder muscles. J Strength Cond Res 1995; 9 (4): 222–7

    Google Scholar 

  52. 52.

    McCaw ST, Friday JJ. A comparison of muscle activity between a free weight and machine bench press. J Strength Cond Res 1994; 8 (4): 259–64

    Google Scholar 

  53. 53.

    Wagner LL, Evans SA, Weir JP, et al. The effect of grip width on bench press performance. Int J Sport Biomech 1992; 8: 1–10

    Google Scholar 

  54. 54.

    Freeman S, Karpowicz A, Gray J, et al. Quantifying muscle patterns and spine load during various forms of the pushup. Med Sci Sports Exerc 2006; 38 (3): 570–7

    PubMed  Article  Google Scholar 

  55. 55.

    McClure PW, Michener LA, Sennett BJ, et al. Direct 3- dimensional measurement of scapular kinematics during dynamic movements in vivo. J Shoulder Elbow Surg 2001; 10 (3): 269–77

    PubMed  Article  CAS  Google Scholar 

  56. 56.

    Ludewig PM, Cook TM, Nawoczenski DA. Three-dimensional scapular orientation and muscle activity at selected positions of humeral elevation. J Orthop Sports Phys Ther 1996; 24 (2): 57–65

    PubMed  CAS  Google Scholar 

  57. 57.

    Sagano M, Magee D, Katayose M. The effect of glenohumeral rotation on scapular upward rotation in different positions of scapular-plane elevation. J Sport Rehab 2006; 15: 144–55

    Google Scholar 

  58. 58.

    Bagg SD, Forrest WJ. Electromyographic study of the scapular rotators during arm abduction in the scapularplane. Am J Phys Med 1986; 65 (3): 111–24

    PubMed  CAS  Google Scholar 

  59. 59.

    Hardwick DH, Beebe JA, McDonnell MK, et al. A comparison of serratus anterior muscle activation during a wallslide exercise and other traditional exercises. J Orthop Sports Phys Ther 2006; 36 (12): 903–10

    PubMed  Article  Google Scholar 

  60. 60.

    Ludewig PM, Hoff MS, Osowski EE, et al. Relative balance of serratus anterior and upper trapezius muscle activity during push-up exercises. Am J Sports Med 2004; 32 (2): 484–93

    PubMed  Article  Google Scholar 

  61. 61.

    Graichen H, Bonel H, Stammberger T, et al. Three-dimensional analysis of the width of the subacromial space inhealthy subjects and patients with impingement syndrome. AJR Am J Roentgenol 1999; 172 (4): 1081–6

    PubMed  CAS  Google Scholar 

  62. 62.

    Ludewig PM, Cook TM. Alterations in shoulder kinematics and associated muscle activity in people with symptoms of shoulder impingement. Phys Ther 2000; 80 (3): 276–91

    PubMed  CAS  Google Scholar 

  63. 63.

    Wiedenbauer MM, Mortensen OA. An electromyographic study of the trapezius muscle. Am J Phys Med 1952; 31 (5): 363–72

    PubMed  CAS  Google Scholar 

Download references

Acknowledgements

No sources of funding were used to assist in the preparation of this review. The authors have no conflicts of interest that are directly relevant to the content of this review.

Author information

Affiliations

Authors

Corresponding author

Correspondence to Dr Rafael F. Escamilla.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Escamilla, R.F., Yamashiro, K., Paulos, L. et al. Shoulder Muscle Activity and Function in Common Shoulder Rehabilitation Exercises. Sports Med 39, 663–685 (2009). https://doi.org/10.2165/00007256-200939080-00004

Download citation

Keywords

  • Rotator Cuff
  • Internal Rotation
  • External Rotation
  • Abduction Angle
  • Anterior Deltoid