On multiscale tension-compression asymmetry in skeletal muscle

Area of Science:

• Biomechanics
• Tissue Engineering
• Materials Science

Background:

• Skeletal muscle tissue displays tension-compression asymmetry (TCA), a difference in passive stress response to tensile versus compressive deformation.
• Understanding the origin of TCA across different length scales is crucial for accurate biomechanical modeling.

Purpose of the Study:

• To compare TCA at the tissue and individual muscle fiber scales for the first time.
• To investigate volume changes during tensile and compressive loading at both scales.
• To elucidate the role of the extracellular matrix in skeletal muscle's mechanical behavior.

Main Methods:

• Experimental analysis of passive stress-stretch characteristics of skeletal muscle tissue and isolated muscle fibers.
• Measurement of volume changes during axial tension and compression experiments.
• Comparative analysis of TCA and compressibility across length scales.

Main Results:

• TCA differs significantly between tissue and fiber levels, being substantially greater at the tissue scale.
• Tissue-level TCA increases non-linearly with deformation, while fiber-level TCA shows a more complex pattern.
• Muscle tissue exhibits low compressibility, whereas fibers significantly decrease in volume under compression, suggesting ECM influence.

Conclusions:

• The extracellular matrix plays a critical role in amplifying TCA and maintaining tissue incompressibility.
• TCA originates significantly at the tissue level, influenced by the extracellular matrix's interaction with muscle fibers.
• Findings provide essential data for microstructure-based modeling of skeletal muscle.