An equilibrium-point model for fast, single-joint movement: II. Similarity of single-joint isometric and isotonic descending commands

Mark Latash, Gerald L. Gottlieb

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

The model for isotonic movements introduced in the preceding article in this issue is used to account for isometric contractions. Isotonic movements and isometric contractions are analyzed as consequences of one motor program acting under different peripheral conditions. Differences in isotonic and isometric EMG patterns are analyzed theoretically. Computer simulation of the EMG patterns was performed both with and without the inclusion of possible effects of reciprocal inhibition. A series of experiments was performed to test the model. The subjects made fast isotonic movements that were unexpectedly blocked at the very beginning in some of the trials. The observed differences in the EMG patterns between blocked and unblocked trials corresponded to the model's predictions. The results suggest that these differences are due to the action of a tonic stretch reflex rather than to preprogrammed reactions. The experimental and simulation findings, and also the data from the literature, are discussed in the framework of the model and the dual-strategy hypothesis. They support the hypothesis that the motor control system uses one of a few standardized subprograms, specifying a small number of parameters to match a specific task.

Original languageEnglish (US)
Pages (from-to)179-191
Number of pages13
JournalJournal of motor behavior
Volume23
Issue number3
DOIs
StatePublished - Jan 1 1991

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Isometric Contraction
Isotonic Contraction
Joints
Stretch Reflex
Computer Simulation

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Orthopedics and Sports Medicine
  • Experimental and Cognitive Psychology
  • Cognitive Neuroscience

Cite this

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An equilibrium-point model for fast, single-joint movement : II. Similarity of single-joint isometric and isotonic descending commands. / Latash, Mark; Gottlieb, Gerald L.

In: Journal of motor behavior, Vol. 23, No. 3, 01.01.1991, p. 179-191.

Research output: Contribution to journalArticle

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