Extracting low-velocity concentric and eccentric dynamic muscle properties from isometric contraction experiments

Area of Science:

• Biomechanics
• Muscle Physiology
• Computational Modeling

Background:

• Determining dynamic muscle properties like force-velocity relations is experimentally challenging.
• Isometric contraction experiments (ICEs) are simpler but traditionally not used for dynamic analysis.
• Muscle models require accurate parameterization for predicting muscle behavior.

Purpose of the Study:

• To investigate if ICE data can be used to identify dynamic muscle model parameters.
• To compare different activation dynamics models for physiological relevance.
• To develop methods for estimating dynamic parameters from ICEs.

Main Methods:

• Sensitivity analysis of a muscle model to identify influential parameters.
• Optimization of dynamic parameter subsets using experimental ICE data.
• Comparison of two activation dynamics formulations.
• Development of a method to determine electro-mechanical delay from ICEs.

Main Results:

• One activation dynamics formulation was found to be superior.
• The force-velocity relation's slope at isometric force was the least influential dynamic parameter.
• A novel method was developed to determine electro-mechanical delay from ICEs.
• Model simulations showed contractile element shortening/lengthening peaks during activation/deactivation.

Conclusions:

• ICEs can be utilized to identify crucial dynamic parameters of muscle models.
• The proposed method offers a simpler approach to measure electro-mechanical delay.
• This research advances the understanding and modeling of muscle dynamics using accessible experimental data.