Force and surface mechanomyogram frequency responses in cat gastrocnemius

Claudio Orizio, Richard V. Baratta, Bing He Zhou, Moshe Solomonow, Arsenio Veicsteinas

Research output: Contribution to journalArticlepeer-review


Muscle surface displacement is a mechanical event taking place simultaneously with the tension generation at the tendon. The two phenomena can be studied by the surface mechanomyogram signal (MMG) (produced by a laser distance sensor) and the force signal (from a load cell). The aim of this paper was to provide data on the reliability of the laser detected MMG in muscle mechanics research. To this purpose it was verified if the laser detected MMG was suitable to estimate a frequency response in the cat medial gastrocnemius and its frequency response was compared with the one retrieved by the force signal at the tendon level. The force and MMG from the exposed medial gastrocnemius of four cats were analysed. The frequency response was investigated by sinusoidally changing the number of orderly recruited motor units, in different trials, in the 0.4-6 Hz range. It resulted that it was possible to model the force and MMG frequency response by a critically damped second-order system with two real double poles and a pure time delay. On the average, the poles were at 1.83 Hz (with 22.6 ms delay) and at 2.75 Hz (with 38 ms delay) for force and MMG, respectively. It can be concluded that MMG appears to be a reliable tool to investigate the muscle frequency response during stimulated isometric contraction. Even though not statistically significant, the differences in the second-order system parameters suggest that different components of the muscle mechanical model may specifically affect the force or MMG. (C) 2000 Elsevier Science Ltd.

Original languageEnglish
Pages (from-to)427-433
Number of pages7
JournalJournal of Biomechanics
Issue number4
Publication statusPublished - Apr 2000


  • Frequency response
  • Mechanomyogram
  • Modeling
  • Muscle contraction physiology

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine


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