Muscle activity and fatigue in the shoulder muscles during repetitive work

An electromyographic study
  • H. Christensen


The amplitude distribution probability function (ADPF) and the power spectrum of the surface electromyogram from m. deltoideus anterior, m. infraspinatus and m. trapezius pars descendens were analyzed from 7 persons working at a pillar drill. Recordings were performed 6 times during a working day. The ADPF was analyzed from 2–3 work-cycles from each recording. The static contraction level was 11.0% MCV in m. deltoideus anterior, 8.5% MVC in m. infraspinatus, and 20.5% MCV in m. trapezius, without any change occuring throughout the day. When compared to previous suggested upper limits of ADPF levels, both the static and the medium contraction levels were too high in the performance of this particular task. The power spectrum of the EMG was analyzed during isometric contractions of the shoulder muscles. The mean power frequency decreased during the day in m. trapezius only, suggesting muscular fatigue in this area.

Key words

Fatigue Monotonous work EMG Power spectrum Amplitude distribution 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Antti SJ (1977) Relationship between time means of external load and EMG amplitude in long term myoelectric studies. Electromyogr Clin Neurophysiol 17:45–53Google Scholar
  2. Asmussen E, HeebØll-Nielsen K, Molbech S (1959) Methods for evaluation of muscle strength. Communication from the testing and observation. Institute of The Danish National Association for infantile paralysis. Hellerup, Denmark 5:3–13Google Scholar
  3. Bigland B, Lippold OCJ (1954) The relation between force, velocity and integrated electrical activity in human muscles. J Physiol [Lond] 123:214–224Google Scholar
  4. Bjelle A, Hagberg M, Michaelson G (1981) Occupational and individual factors in acute shoulder-neck disorders among industrial workers. Br J Ind Med 38:356–363Google Scholar
  5. Björkstèn M, Jonsson B (1977) Endurance limit of force in long-term intermittent static contractions. Scan J Work Environm Health 3:23–27Google Scholar
  6. Borg GAV (1982) Psychophysical bases of perceived exertion. Med Sci Sport Exerc 14:277–381Google Scholar
  7. Christensen H, LoMonaco M, Dahl K, Fuglsang-Frederiksen A (1984) Processing of electrical activity in human muscle during a gradual increase in force. Electroenceph Clin Neurophysiol 58:230–239Google Scholar
  8. Edwards RG, Lippol OCJ (1956) The relation between force and integrated electrical activity in fatigued muscle. J Physiol [Lond] 132:677–681Google Scholar
  9. Ekholm J, Aborelius UP, Nemeth G, Schüldt K, Harms-Ringdahl K, Nisell R, Svensson O (1983) Effekter på rörelsesorganen av belastnings-reducerede åtgÄrder ved medeltungt stående materialhanteringsarbete och sittande monteringsarbete med små komponenter. Forskningsrapport 30/6 Karolinska Institutet, Stockholm [Swedish]Google Scholar
  10. Herberts P. Kadefors R, Broman H (1980) Arm positioning in manual tasks. An electromyographic study of localized muscle fatigue. Ergonomics 23: 7:655–665Google Scholar
  11. Jonsson B (1978) KINESIOLOGY: With special reference to electromyographic kinesiology. Contemp Clin Neurophysiol [Suppl] 34:417–428Google Scholar
  12. Jonsson B (1982) Measurement and evaluation of local muscular strain in the shoulder during constrained work. J Human Ergol 11:73–88Google Scholar
  13. Jonsson B, Ericson B-E, Hagberg M (1981) Elektromyografiska metoder för analys av belastningen på enskilda muskler och muskulÄre uttröttningseffekter under lÄngre tids arbete. Arbetarskyddsstyrelsen Undersökningsrapport 9:84–95 [Swedish]Google Scholar
  14. Kadefors R, Kaiser E, Petersèn I (1968) Dynamic spectrum analysis of myopotentials and with special reference to muscle fatigue. Electromyography 8:39–74Google Scholar
  15. Kahabka G (1984) Erweiterung arbeitswissenschaftlicher Methodik durch differenzierte Elektromyographie. VDI-Verlag, DüsseldorfGoogle Scholar
  16. Komi PV (1973) Relationship between muscle tension, EMG and velocity of contraction under concentric and eccentric work. In: Desmedt JE (ed) New development in electromyography and clinical neurophysiology. Karger, Basel, pp 596–606Google Scholar
  17. Komi PV, Buskirk ER (1970) reproducibility of electromyographic measurements with inserted wire electrodes and surface electrodes. Electromyography 4:357–367Google Scholar
  18. Kvarnström S (1983) Occurence of musculoskeletal disorders in a manufacturing industry with special attention to occupational shoulder disorder. Scand J Rehab Med [Suppl] 8:1–56Google Scholar
  19. Kwatny E, Thomas DH, Kwatny HG (1970) An application of signal processing techniques to the study of myoelectric signals. IEEE Transactions bio-medical engineering 17: 4:303–313Google Scholar
  20. Lawrence JH, DeLuca CJ (1983) Myoelectric signal versus force relationship in different human muscles. J Appl Physiol: Respirat Environ Exercise Physiol 54: 6:1653–1659Google Scholar
  21. Lindström L, Magnusson R, Petersèn I (1970) Muscular fatigue and action potential conduction velocity changes studies with frequency analysis of EMG Signals. Electromyography 4:341–356Google Scholar
  22. Luopajârvi R, Kuorinka I, Virolainen M, Holmberg M (1979) Prevalence of tenosynovitis and other injuries of the upper extremities in repetitive work. Scand J Work Environ Health [Suppl] 3:48–55Google Scholar
  23. Onishi N, Nomura H, Sakai K, Yamanoto T, Hirayama K, Itani T (1976) Shouldermuscle tenderness and physical features of female industrial workers. J Human Ergol 5:87–102Google Scholar
  24. Onishi N, Sakai K, Kogi K (1982) Arm and shoulder muscle load in various keyboard operation jobs of women. J Human Ergol 11:89–97Google Scholar
  25. Petrofsky JS, Glaser RM, Phillips CA, Lind AR, Williams C (1982) Evaluation of the amplitude and frequency components of the surface EMG as an index of muscle fatigue. Ergonomics 3:213–223Google Scholar

Copyright information

© Springer-Verlag 1986

Authors and Affiliations

  • H. Christensen
    • 1
  1. 1.The Rehabilitation Institute, RigshospitaletUniversity of CopenhagenCopenhagenDenmark

Personalised recommendations