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Between-muscle differences in coactivation assessed using elastography.

Simon Avrillon1, François Hug2, Gaël Guilhem1

  • 1French Institute of Sport (INSEP), Research Department, Laboratory Sport, Expertise and Performance (EA 7370), Paris, France.

Journal of Electromyography and Kinesiology : Official Journal of the International Society of Electrophysiological Kinesiology
|September 29, 2018
PubMed
Summary
This summary is machine-generated.

Ultrasound shear wave elastography assessed muscle coactivation. While myoelectrical activity was present, elastography indicated negligible coactivation in semitendinosus and semimembranosus muscles.

Keywords:
HamstringsMuscle coactivityQuadricepsShear wave elastographySurface electromyography

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Area of Science:

  • Biomechanics
  • Musculoskeletal research
  • Medical imaging techniques

Background:

  • Muscle coactivation is crucial for joint stability and movement control.
  • Quantifying coactivation, especially in antagonist muscle pairs like quadriceps and hamstrings, is important for understanding neuromuscular function.
  • Traditional methods like electromyography (EMG) primarily measure electrical activity, not the mechanical properties of muscle contraction.

Purpose of the Study:

  • To evaluate the utility of ultrasound shear wave elastography (SWE) for assessing muscle coactivation.
  • To compare SWE-derived coactivation measurements with myoelectrical activity in quadriceps and hamstring muscles during isometric contractions.
  • To investigate differences in coactivation magnitude across individuals and between specific muscles.

Main Methods:

  • Ultrasound shear wave elastography was employed to measure the shear modulus of antagonist muscles during maximal voluntary isometric contractions (MVC).
  • Myoelectrical activity (EMG) of the same muscles was recorded simultaneously.
  • To isolate coactivation, shear modulus during MVC was compared to passive cycling measurements at identical knee angles, accounting for joint rotation effects.

Main Results:

  • Myoelectrical activity was detected in all measured antagonist muscles, averaging 8.0% of maximal EMG RMS.
  • Significant differences in shear modulus between MVC and passive states were found for most muscles (p < 0.011), indicating coactivation.
  • Coactivation assessed by elastography was negligible for semitendinosus and semimembranosus, with no significant differences observed (p > 0.16).

Conclusions:

  • Ultrasound shear wave elastography provides a novel method to assess muscle coactivation by measuring mechanical properties.
  • While myoelectrical activity is present, elastography suggests negligible coactivation in the hamstring muscles (semitendinosus and semimembranosus) during these specific contractions.
  • Significant inter-individual variability in coactivation magnitude highlights the need for further research into factors influencing muscle coordination.