HSS Journal

, Volume 7, Issue 1, pp 21–28 | Cite as

A Spectral Analysis of Rotator Cuff Musculature Electromyographic Activity: Surface and Indwelling

  • Sherry I. Backus
  • Daniel P. Tomlinson
  • Bavornrat Vanadurongwan
  • Mark W. Lenhoff
  • Frank A. Cordasco
  • Eric L. Chehab
  • Ronald S. Adler
  • R. Frank HennIII
  • Howard J. Hillstrom
Original Article


Electromyography (EMG) of the shoulder girdle is commonly performed; however, EMG spectral properties of shoulder muscles have not been clearly defined. The purpose of this study was to determine the maximum power frequency, Nyquist rate, and minimum sampling rate for indwelling and surface EMG of the normal shoulder girdle musculature. EMG signals were recorded using indwelling electrodes for the rotator cuff muscles and surface electrodes for ten additional shoulder muscles in ten healthy volunteers. A fast Fourier transform was performed on the raw EMG signal collected during maximal isometric contractions to derive the power spectral density. The 95% power frequency was calculated during the ramp and plateau subphase of each contraction. Data were analyzed with analysis of variance (ANOVA) and paired t tests. Indwelling EMG signals had more than twice the frequency content of surface EMG signals (p < .001). Mean 95% power frequencies ranged from 495 to 560 Hz for indwelling electrodes and from 152 to 260 Hz for surface electrodes. Significant differences in the mean 95% power frequencies existed among muscles monitored with surface electrodes (p = .002), but not among muscles monitored with indwelling electrodes (p = .961). No significant differences in the 95% power frequencies existed among contraction subphases for any of the muscle–electrode combinations. Maximum Nyquist rate was 893 Hz for surface electrodes and 1,764 Hz for indwelling electrodes. Our results suggest that when recording EMG of shoulder muscles, the minimum sampling frequency is 1,340 Hz for surface electrodes and 2,650 Hz for indwelling electrodes. The minimum sampling recommendations are higher than the 1,000 Hz reported in many studies involving EMG of the shoulder.


shoulder rotator cuff electromyography isometric contraction 


  1. 1.
    European Recommendations for Surface Electromyography: results of the SENIAM project. Enschede, the Netherlands: Roessingh Research and Development; 1999.Google Scholar
  2. 2.
    Beck TW, Housh TJ, Johnson GO, et al. The effects of interelectrode distance on electromyographic amplitude and mean power frequency during isokinetic and isometric muscle actions of the biceps brachii. J Electromyogr Kinesiol. 2005;15:482–495.CrossRefPubMedGoogle Scholar
  3. 3.
    Bilodeau M, Arsenault AB, Gravel D, et al. The influence of an increase in the level of force on the EMG power spectrum of elbow extensors. Eur J Appl Physiol Occup Physiol. 1990;61:461–466.CrossRefPubMedGoogle Scholar
  4. 4.
    Bogey R, Cerny K, Mohammed O. Repeatability of wire and surface electrodes in gait. Am J Phys Med Rehabil. 2003;82:338–344.CrossRefPubMedGoogle Scholar
  5. 5.
    Cordasco FA, Chen NC, Backus SI, et al. Subacromial injection improves deltoid firing in subjects with large rotator cuff tears. HSS J. 2010;6:30–36.Google Scholar
  6. 6.
    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;24:386–92.CrossRefPubMedGoogle Scholar
  7. 7.
    Decker MJ, Tokish JM, Ellis HB, et al. Subscapularis muscle activity during selected rehabilitation exercises. Am J Sports Med. 2003;31:126–134.PubMedGoogle Scholar
  8. 8.
    Dimitrova NA, Dimitrov GV. Interpretation of EMG changes with fatigue: facts, pitfalls, and fallacies. J Electromyogr Kinesiol. 2003;13:13–36.CrossRefPubMedGoogle Scholar
  9. 9.
    Duchene J, Goubel F. EMG spectral shift as an indicator of fatigability in an heterogeneous muscle group. Eur J Appl Physiol Occup Physiol. 1990;61:81–87.CrossRefPubMedGoogle Scholar
  10. 10.
    Durkin JL, Callaghan JP. Effects of minimum sampling rate and signal reconstruction on surface electromyographic signals. Journal of Electromyography and Kinesiology, 2005;15:474–481.CrossRefPubMedGoogle Scholar
  11. 11.
    Farina D, Fosci M, Merletti R. Motor unit recruitment strategies investigated by surface EMG variables. J Appl Physiol. 2002;92:235–247.CrossRefPubMedGoogle Scholar
  12. 12.
    Fuglsang-Frederiksen A, Rønager J. The motor unit firing rate and the power spectrum of EMG in humans. Electroencephalogr Clin Neurophysiol. 1988;70:68–72.CrossRefPubMedGoogle Scholar
  13. 13.
    Gerdle B, Larsson B, Karlsson S. Criterion validation of surface EMG variables as fatigue indicators using peak torque: a study of repetitive maximum isokinetic knee extensions. J Electromyogr Kinesiol. 2000;10:225–232.CrossRefPubMedGoogle Scholar
  14. 14.
    Giroux B, Lamontagne M. Comparisons between surface electrodes and intramuscular wire electrodes in isometric and dynamic conditions. Electromyogr Clin Neurophysiol. 1990;30:397–405.PubMedGoogle Scholar
  15. 15.
    Henneman E, Somjen G, Carpenter DO. Functional significance of cell size in spinal motoneurons. J Neurophysiol. 1965;28:560–580.PubMedGoogle Scholar
  16. 16.
    Ives JC, Wigglesworth JK. Sampling rate effects on surface EMG timing and amplitude measures. Clin Biomech. 2003;18:543–552.CrossRefGoogle Scholar
  17. 17.
    Kaplanis PA, Pattichis CS, Hadjileontiadis LJ, et al. Surface EMG analysis on normal subjects based on isometric voluntary contraction. J Electromyogr Kinesiol. 2009;19:157–171.CrossRefPubMedGoogle Scholar
  18. 18.
    Kelly BT, Backus SI, Warren RF, et al. Electromyographic analysis and phase definition of the overhead football throw. Am J Sports Med. 2002;30:837–844.PubMedGoogle Scholar
  19. 19.
    Kelly BT, Cooper LW, Kirkendall DT, et al. Technical considerations for electromyographic research on the shoulder. Clin Orthop Relat Res. 1997;335:140–151.Google Scholar
  20. 20.
    Kelly BT, Williams RJ, 3rd, Cordasco FA, et al. Differential patterns of muscle activation in patients with symptomatic and asymptomatic rotator cuff tears. J Shoulder Elbow Surg. 2005;14:165–171.CrossRefPubMedGoogle Scholar
  21. 21.
    Komi PV, Linnamo V, Silventoinen P, et al. Force and EMG power spectrum during eccentric and concentric actions. Med Sci Sports Exerc. 2000;32:1757–1762.CrossRefPubMedGoogle Scholar
  22. 22.
    Kumar S, Narayan Y, Amell T. EMG power spectra of cervical muscles in lateral flexion and comparison with sagittal and oblique plane activities. Eur J Appl Physiol. 2003;89:367–376.CrossRefPubMedGoogle Scholar
  23. 23.
    Kumar S, Narayan Y, Amell T. Power spectra of sternocleidomastoids, splenius capitis, and upper trapezius in oblique exertions. Spine J. 2003;3:339–350.CrossRefPubMedGoogle Scholar
  24. 24.
    Moritani T, Muramatsu S, Muro M. Activity of motor units during concentric and eccentric contractions. Am J Phys Med. 1987;66:338–350.PubMedGoogle Scholar
  25. 25.
    Moritani T, Muro M. Motor unit activity and surface electromyogram power spectrum during increasing force of contraction. Eur J Appl Physiol Occup Physiol. 1987;56:260–265.CrossRefPubMedGoogle Scholar
  26. 26.
    Oberg T, Sandsjo L, Kadefors R. Arm movement and EMG mean power frequency in the trapezius muscle: a comparison between surface and intramuscular recording techniques. Electromyogr Clin Neurophysiol. 1992;32:87–96.PubMedGoogle Scholar
  27. 27.
    Oppenheim AV, Schafer RW. Digital signal processing. US Ed ed. Englewood Cliffs, NJ: Prentice-Hall, Inc; 1975.Google Scholar
  28. 28.
    Perry J, Easterday CS, Antonelli DJ. Surface versus intramuscular electrodes for electromyography of superficial and deep muscles. Phys Ther. 1981;61:7–15.PubMedGoogle Scholar
  29. 29.
    Pullman SL, Goodin DS, Marquinez AI, et al. Clinical utility of surface EMG: report of the therapeutics and technology assessment subcommittee of the American Academy of Neurology. Neurology. 2000;55:171–177.PubMedGoogle Scholar
  30. 30.
    Riley ZA, Terry ME, Mendez-Villanueva A, et al. Motor unit recruitment and bursts of activity in the surface electromyogram during a sustained contraction. Muscle Nerve. 2008;37:745–753.CrossRefPubMedGoogle Scholar
  31. 31.
    Sadhukhan AK, Goswami A, Kumar A, et al. Effect of sampling frequency on EMG power spectral characteristics. Electromyogr Clin Neurophysiol. 1994;34:159–163.PubMedGoogle Scholar
  32. 32.
    Schweitzer TW, Fitzgerald JW, Bowden JA, et al. Spectral analysis of human inspiratory diaphragmatic electromyograms. J Appl Physiol. 1979;46:152–165.PubMedGoogle Scholar
  33. 33.
    Sleigh JW, Donovan J. Comparison of bispectral index, 95% spectral edge frequency and approximate entropy of the EEG, with changes in heart rate variability during induction of general anaesthesia. Br J Anaesth. 1999;82:666–671.PubMedGoogle Scholar
  34. 34.
    Soames RW, Atha J. The spectral characteristics of postural sway behaviour. Eur J Appl Physiol Occup Physiol. 1982;49:169–177.CrossRefPubMedGoogle Scholar
  35. 35.
    Soderberg GL, Knutson LM. A guide for use and interpretation of kinesiologic electromyographic data. Phys Ther. 2000;80:485–98.PubMedGoogle Scholar
  36. 36.
    Tesch PA, Komi PV, Jacobs I, et al. Influence of lactate accumulation of EMG frequency spectrum during repeated concentric contractions. Acta Physiol Scand. 1983;119:61–67.CrossRefPubMedGoogle Scholar
  37. 37.
    Turker KS. Electromyography: some methodological problems and issues. Phys Ther. 1993;73:698–710.PubMedGoogle Scholar
  38. 38.
    Winter DA, Rau G, Kadefors R, et al. Units, terms and standards in the reporting of EMG research. Report by the As Hoc Committee of ISEK. 1980; Aug.Google Scholar

Copyright information

© Hospital for Special Surgery 2010

Authors and Affiliations

  • Sherry I. Backus
    • 1
  • Daniel P. Tomlinson
    • 2
  • Bavornrat Vanadurongwan
    • 3
  • Mark W. Lenhoff
    • 1
  • Frank A. Cordasco
    • 4
  • Eric L. Chehab
    • 5
  • Ronald S. Adler
    • 6
  • R. Frank HennIII
    • 7
  • Howard J. Hillstrom
    • 1
  1. 1.Department of Rehabilitation, Leon Root MD, Motion Analysis LaboratoryHospital for Special SurgeryNew YorkUSA
  2. 2.Department of Orthopaedic SurgeryCrystal Run HealthcareMiddletownUSA
  3. 3.Department of Orthopaedic Surgery, Faculty of Medicine Siriraj HospitalMahidol UniversityBangkokThailand
  4. 4.Sports Medicine and Shoulder Service, Department of Orthopaedic SurgeryHospital for Special SurgeryNew YorkUSA
  5. 5.Department of Orthopaedic SurgeryIllinois Bone and Joint InstituteGlenviewUSA
  6. 6.Department of Radiology and Imaging, Division of Ultrasound and Body CTHospital for Special SurgeryNew YorkUSA
  7. 7.Hospital for Special SurgeryNew YorkUSA

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