Phenomenological Muscle Constitutive Model With Actin-Titin Binding for Simulating Active Stretching

Area of Science:

• Biomechanics
• Computational Biology
• Muscle Physiology

Background:

• Current muscle models for human movement simulations often lack numerical stability due to simplified force-length relationships.
• These models do not fully capture the complex contractile history-dependent properties of muscle, such as residual force enhancement.

Purpose of the Study:

• To present a novel constitutive model for muscle exhibiting residual force enhancement.
• To implement this model as a hyperelastic material within the FEBio finite element software for accurate biomechanical simulations.
• To demonstrate the numerical stability and utility of the model in simulating active muscle lengthening.

Main Methods:

• Developed a constitutive model incorporating residual force enhancement based on sarcomere length at activation.
• Implemented the model as a hyperelastic material in FEBio.
• Performed eigenvalue analysis and simulations of muscles with varying fiber lengths and a 3D muscle geometry to assess stability and effects.

Main Results:

• The proposed model successfully exhibits residual force enhancement.
• Numerical stability was demonstrated through eigenvalue analysis and simulations.
• The model accurately predicts the effect of force enhancement on stress development and fiber length distribution in a 3D muscle geometry.

Conclusions:

• The developed muscle material model provides a more realistic representation of muscle behavior during active lengthening.
• This model enhances the stability and accuracy of finite element simulations of human movement.
• The implementation in FEBio allows for reproducible research and further investigation into muscle mechanics.