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Related Experiment Video

Updated: Jun 23, 2026

Method to Measure Tone of Axial and Proximal Muscle

Method to Measure Tone of Axial and Proximal Muscle

Published on: December 14, 2011

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

B Bazrgari¹, A Shirazi-Adl, C Larivière

¹Department of Mechanical Engineering, Ecole Polytechnique, Station "centre-ville", Montreal, Quebec, Canada.

Journal of Biomechanics

|April 21, 2009

Summary

Sudden trunk loading reveals a 200ms delay in extensor muscle activation, increasing spinal loads and injury risk. However, muscle recruitment and trunk flexion enhance system stability.

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Area of Science:

Biomechanics
Human Movement Science
Spinal Injury Research

Background:

Accurate quantification of trunk response to sudden loading is vital for injury prevention, rehabilitation, and training.
Understanding trunk muscle forces, internal loads, and stability dynamics is essential for evaluating and managing spinal health.

Purpose of the Study:

To evaluate the temporal variation of trunk muscle forces, internal loads, and stability under sudden anterior horizontal loading.
To assess the reliability of an iterative dynamic kinematics-driven approach in decoding trunk biomechanics.

Main Methods:

An iterative dynamic kinematics-driven approach was employed, integrating measured kinematics, applied load, trunk displacement, and surface electromyography (EMG).
A finite element model incorporated nonlinear spinal properties, detailed trunk musculature, gravity load, and biodynamic characteristics to estimate the trunk's response.

Main Results:

A delay of approximately 200ms in extensor muscle activation was observed in response to sudden loading.
Net moment and spinal loads significantly increased due to muscle recruitment, while trunk flexion improved system stability.
The kinematics-driven approach demonstrated reliability in estimating trunk response and decoding measured kinematics.

Conclusions:

The study highlights the significant increase in spinal loads and potential injury risk associated with sudden loading, especially with delayed muscle activation or fatigue.
The findings underscore the importance of understanding trunk response dynamics for developing effective prevention and rehabilitation strategies.
The validated kinematics-driven approach offers a reliable method for assessing trunk biomechanics under dynamic loading conditions.