Trunk response analysis under sudden forward perturbations using a kinematics-driven model

B. Bazrgari, A. Shirazi-Adl, C. Larivière

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


Accurate quantification of the trunk transient response to sudden loading is crucial in prevention, evaluation, rehabilitation and training programs. An iterative dynamic kinematics-driven approach was used to evaluate the temporal variation of trunk muscle forces, internal loads and stability under sudden application of an anterior horizontal load. The input kinematics is hypothesized to embed basic dynamic characteristics of the system that can be decoded by our kinematics-driven approach. The model employs temporal variation of applied load, trunk forward displacement and surface EMG of select muscles measured on two healthy and one chronic low-back pain subjects to a sudden load. A finite element model accounting for measured kinematics, nonlinear passive properties of spine, detailed trunk musculature with wrapping of global extensor muscles, gravity load and trunk biodynamic characteristics is used to estimate the response under measured sudden load. Results demonstrate a delay of ∼200 ms in extensor muscle activation in response to sudden loading. Net moment and spinal loads substantially increase as muscles are recruited to control the trunk under sudden load. As a result and due also to the trunk flexion, system stability significantly improves. The reliability of the kinematics-driven approach in estimating the trunk response while decoding measured kinematics is demonstrated. Estimated large spinal loads highlight the risk of injury that likely further increases under larger perturbations, muscle fatigue and longer delays in activation.

Original languageEnglish
Pages (from-to)1193-1200
Number of pages8
JournalJournal of Biomechanics
Issue number9
StatePublished - Jun 19 2009

Bibliographical note

Funding Information:
This work is supported by the NSERC-Canada.


  • Delay
  • Finite elements
  • Muscle force
  • Spinal loads
  • Stability
  • Sudden load
  • Trunk rotation

ASJC Scopus subject areas

  • Biophysics
  • Orthopedics and Sports Medicine
  • Biomedical Engineering
  • Rehabilitation


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