Viscoplasticity of rabbit skeletal muscle under dynamic cyclic loading

Area of Science:

• Biomechanics
• Skeletal Muscle Physiology
• Materials Science

Background:

• Skeletal muscle mechanical behavior is complex, often modeled as purely elastic and viscous.
• Understanding the dynamic response of muscle-tendon units is vital for injury prevention and rehabilitation.

Purpose of the Study:

• To investigate the strain and strain-rate dependent effects of dynamic cyclic loading on skeletal muscle-tendon units.
• To elucidate the non-linear mechanical characteristics, including viscoelasticity and plasticity, of muscle tissue.

Main Methods:

• Dynamic cyclic loading tests were performed on New Zealand white rabbit muscle-tendon units.
• Varying strain levels and strain rates were applied under ketamine general anesthesia.

Main Results:

• Muscle-tendon unit responses were significantly dependent on both strain and strain rate, exhibiting non-linear characteristics.
• Viscoelastic behavior was observed below 12% strain, transitioning to plastic behavior above 16% strain.
• Loading and unloading energies were more influenced by strain than by strain rate.

Conclusions:

• Plasticity is a significant biomechanical property of skeletal muscle, contributing to its mechanical behavior.
• The concept of viscoplasticity provides a more comprehensive model for skeletal muscle mechanics than purely elastic and viscous models.
• Understanding muscle viscoplasticity is essential for determining the functional capabilities and limitations of muscular tissue.