The Origin of Electromyograms — Explanations Based on the Equilibrium Point Hypothesis

  • A. G. Feldman
  • S. V. Adamovich
  • D. J. Ostry
  • J. R. Flanagan


In the present chapter, we review and further develop the equilibrium-point (EP) hypothesis or λ model for single and multi-joint movements (Feldman 1974, 1986; cf. Chapters 11, 13–22). A departure point is the notion of the measure of the central control signals underlying movement production. According to the EP hypothesis, central commands parameterize the threshold of motorneuron (MN) recruitment. The usual assumption that central signals are directly associated with muscle activation, i.e. recruitment of MNs and their firing frequencies, is rejected (see also Bernstein, 1967). This assumption ignores the role of muscle afferents in motor control as well as the non-linear threshold properties of MNs. In this chapter, we discuss electromyographic (EMG) patterns of single- and multi-joint movements in terms of the EP hypothesis.


Joint Angle Muscle Spindle Extensor Muscle Muscle Length Antagonist Muscle 
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.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Abdusamatov R.M., Adamovich S.V., Beikinblit M.B., Chernavsky A.V. and Feldman A.G. (1988) Rapid one-joint movements: a qualitative model and its experimental verification. In Stance and Motion: Facts and Concepts (Eds. Gurfinkel V.S., Ioffe M.E., Massion J. and Roll J.P. ), Plenum Press, New York, pp. 261–270.Google Scholar
  2. Abdusamatov R.M., Adamovich S.V. and Feldman A.G. (1987) A model for one-joint motor control in man. In Motor Control. (Eds. Gantchev, G., Dimitrov, B. and Gatev, P. ), Plenum Press, New York, pp. 183–188.Google Scholar
  3. Abdusamatov R.M. and Feldman A.G. (1986) Description of electromyograms by a mathematical model of single joint movements. Biofizika 31: 503–505.PubMedGoogle Scholar
  4. Adamovich S.V., Burlachkova N.I. and Feldman A.G. (1984) Wave nature of the central process of formation of the trajectories of change in joint angle in man. Biophysics 29: 130–134.Google Scholar
  5. Abend W., Bizzi E. and Morasso P. (1982) Human arm trajectory formation. Brain 105: 331–348.PubMedCrossRefGoogle Scholar
  6. Adamovich S.V. and Feldman A.G. (1984) Model of central regulation of the parameters of motor trajectories. Biophysics 29: 338–342.Google Scholar
  7. Baldissera F., Hultbom H. and Illert M. (1981) Integration in spinal neuronal systems. In Handbook of Physiology, Sec. 1, Vol. II, The Nervous System: Motor Control, Part 1, (Ed. Brooks, V.B. ), Williams and Wilkins, Baltimore, pp. 509–595.Google Scholar
  8. Bernstein N.A. (1967) The Coordination and Regulation of Movements. Pergamon Press, London.Google Scholar
  9. Beikinblit M.B., Gelfand I.M. and Feldman A.G. (1986) A model for the control of multi-joint movements. Bioflzika 31: 483–488.Google Scholar
  10. Bizzi E. (1980) Central and peripheral mechanisms in motor control. In Tutorial in Motor Behavior (Eds. Stelmach G.E and Requin J. ), North-Holland, Amsterdam, pp. 131–144CrossRefGoogle Scholar
  11. Brown S.H. and Cooke J.D. (1981) Amplitude- and instruction-dependent modulation of movement-related electromyogram activity in humans. J. Physiol 316: 97–107.PubMedGoogle Scholar
  12. Burke R.E., Rymer W.Z. and Walsh J.V. (1976) Relative strength of synaptic input from short- latency pathways to motor units of defined type in cat medial gastrocnemius. J. Neurophysiol. 39: 447–458.PubMedGoogle Scholar
  13. Cooke J.D. & Brown S.H. (1990) Movement related phasic muscle activation. II: Generation and functional role of the tri-phasic pattern. J. Neurophysiol. 63: 465–472.PubMedGoogle Scholar
  14. Descherevsky V.I. (1977) Mathematical Models of Muscle Contraction. Nauka, Moscow, pp. 1–160.Google Scholar
  15. Feldman A.G. (1974) Control of the length of a muscle. Biophysics 19: 776–771.Google Scholar
  16. Feldman A.G. (1979) Central and Reflex Mechanisms in Motor Control. Nauka, Moscow, pp. 1–184.Google Scholar
  17. Feldman A.G. (1980) Superposition of motor programs. II. Rapid forearm flexion in man. Neurosci. 5: 91–95.CrossRefGoogle Scholar
  18. Feldman A.G. (1986) Once more on the equilibrium- point hypothesis (> model) for motor control. J. Mot. Behavior 18: 17–54.Google Scholar
  19. Feldman A.G. and Orlovsky G.N. (1972) The influence of different descending systems on the tonic stretch reflex in the cat. Exp. Neurol. 37: 481–494.PubMedCrossRefGoogle Scholar
  20. Feldman A.G. and Orlovsky G.N. (1975) Activity of interneurones mediating reciprocal la inhibition during locomotion in cats. Brain Res. 84: 181–194.PubMedCrossRefGoogle Scholar
  21. Flash T. (1987) The control of hand equilibrium trajectories in multi-joint arm movements. Biol. Cybern. 57: 257–274PubMedCrossRefGoogle Scholar
  22. Gantmaher F.R. (1966) The Theory of Matrices. Nauka, Moscow, pp. 1–576.Google Scholar
  23. Georgopoulos A.P., Kettner R.E. and Schwartz, A.B. (19XX) Primate motor cortex and free arm movements to visual targets in three-dimensional space. II. Coding of the direction of movement by a neuronal population. J. Neurosci. 8: 2928–2937Google Scholar
  24. Gordon, J. and Ghez, C. (1984) EMG patterns in anatagonist muscles during isometric contraction in man: Relations to response dynamics. Exp. Brain Res. 55: 167–171.PubMedCrossRefGoogle Scholar
  25. Grillner, S. (1975) Locomotion in vertebrates: central mechanisms and reflex interactions. Physiol. Rev. 55: 247–304.PubMedGoogle Scholar
  26. Hasan Z. and Karst G.M. (1989) Muscle activity for initiation of planar, two-joint arm movements in different directions, Exp. Brain Res. 16: 651–655.CrossRefGoogle Scholar
  27. Hogan N. (1984) An organizing principle for a class of voluntary movements. J. Neurosci. 4: 2745–2754.PubMedGoogle Scholar
  28. Hollerback, J.M. (1985) Computers, brains and the control of movements. Trends in Neurosci. 5: 189–192.CrossRefGoogle Scholar
  29. Houk J.C. and Rymer Z.W. (1981) Neural control of muscle length and tension. In Handbook of Physiology, Sec. 1, Vol. II, The Nervous System: Motor Control, Part I (Ed. Brooks, V.B. ), Williams and Wilkins, Baltimore, pp. 257–323.Google Scholar
  30. Hollerbach, J.M. and Flash, T. (1982) Dynamic interaction between limb segments during planr arm movement. Biol. Cybern. 44: 67–77.PubMedCrossRefGoogle Scholar
  31. Hultbom H. (1972) Convergence of interneurons in the reciprocal la inhibitory pathway to motoneurones. Acta Physiol. Scand., Suppl. 375: 1–42.CrossRefGoogle Scholar
  32. Lundberg A. (1975) Control of spinal mechanisms from the brain. In The Nervous System, Vol. 2, (Ed. Tower, D.B. ), Raven Press, New York, pp. 253–265.Google Scholar
  33. Mussa-Ivaldi F.A., Morasso P. and Zaccaria, R. (1988) Kinematic networks. A distributed model for representing and regulation of motor redundancy. Biol. Cybern. 60: 1–16.PubMedGoogle Scholar
  34. Nichols T.R. (1989) The organization of heterogenic reflexes among muscles crossing the ankle joint in the decerebrate cat. J. Physiol. 410: 463–477.PubMedGoogle Scholar
  35. Pellison D., Prablanc C., Goodale M.A. and Jeannerod M. (1986) Visual control of reaching movements without vision of the limb. II. Evidence of fast unconscious processes correcting the trajectory of the hand to the final position of a double-step stimulus. Exp. Brain Res. 62: 303–311.Google Scholar
  36. Schmidt R.A. (1982) Motor Control and Learning: A Behavioral Emphasis. Human Kinetic Publishers. Champaign, IL, pp. 303–326.Google Scholar
  37. Soechting J.F. and Lacquaniti F. (1981) Invariant characteristics of a pointing movement in man. J. Neurosci. 1: 710–720.PubMedGoogle Scholar
  38. Viviani P. and Terzuolo C.A. (1982) Trajectory determines movement dynamics. Neurosci. 7: 431–437.CrossRefGoogle Scholar
  39. Wadman W.J., Danier van der Gon J.J., Geuze R.H. and Mol C.R. (1979) Control of fast goal-directed arm movements. J. Hum. Mov. Studies 5: 3–17.Google Scholar

Copyright information

© Springer-Verlag, New York 1990

Authors and Affiliations

  • A. G. Feldman
  • S. V. Adamovich
  • D. J. Ostry
  • J. R. Flanagan

There are no affiliations available

Personalised recommendations