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Effects of Motor Activation Strategies on the Relationship Between EMG and Force

  • S. J. Day
  • M. Hulliger
  • W. M. Morrow
  • B. Kacmar
  • M. Edström

Abstract

It should be possible to predict muscle force from the electromyogram (EMG), but a general EMG-force relationship has not been identified (reviewed by Basmajian & De Luca, 1985). Apart from technical differences, it is conceivable that different motor activation strategies may result in genuinely different EMG-force characteristics (Lawrence & De Luca, 1983; Woods & Bigland-Ritchie, 1983). Motor unit (MU) action potential size may not be linearly related to twitch amplitude (see Milner-Brown & Stein, 1975). Therefore EMG amplitude will depend on whether a given level of force is generated by uniform activation of all MUs (predominant rate modulation) or by more selective activation of smaller MUs (predominant recruitment). To re-assess the role of different MU activation strategies, a preparation has now been used in which activation of MUs could be controlled precisely and in which finer details of MU activation patterns could also be manipulated.

Keywords

Motor Unit Rate Modulation Activation Strategy Motor Unit Firing Motor Unit Synchronisation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. Basmajian, J. V. & De Luca, C. J. (1985) Muscles Alive (5th edition). pp. 187–200. Williams & Wilkins, Baltimore.Google Scholar
  2. Fuglevand, A. J., Winter, D. J. & Patla, A. E. (1993) Models of recruitment and rate coding organization in motor-unit pools. J. Neurophysiol. 70, 2470–2488.PubMedGoogle Scholar
  3. Lawrence, J. H. & De Luca, C. J. (1983) Myoelectric signal versus force relationship in different human muscles. J. App. Physiol. 54, 1653–1659.Google Scholar
  4. Milner-Brown, H. S. & Stein, R. B. (1975) The relation between the surface electromyogram and muscular force. J. Physiol. 246, 549–569.PubMedGoogle Scholar
  5. Woods, J.J. & Bigland-Ritchie, B. (1983) Linear and non-linear surface EMG/force relationships in human muscles. Am. J. Phys. Med. 62, 287–299.PubMedGoogle Scholar

Copyright information

© Springer Science+Business Media New York 1995

Authors and Affiliations

  • S. J. Day
    • 1
  • M. Hulliger
    • 1
  • W. M. Morrow
    • 1
  • B. Kacmar
    • 1
  • M. Edström
    • 1
  1. 1.Department of Clinical NeurosciencesUniversity of CalgaryAlbertaCanada

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