What is Biomechanics?

biomechanics introduction mechanics biology
Last updated: 2025-01-18

What is Biomechanics?

Biomechanics is the study of the motion of living (biological) material under known or assumed forces. It represents the application of mechanical principles—originally developed for engineered systems—to the complex world of living organisms.

Foundations in Classical Mechanics

Biomechanics is founded on the same basic principles as ordinary mechanics:

  • Newton’s laws of motion
  • Conservation of mass
  • Conservation of momentum
  • Conservation of energy

However, fewer idealizations can be made when analyzing biological systems compared to engineered mechanical systems. The complexity of living tissues, irregular geometries, and variable material properties mean that much of biomechanics remains at a descriptive rather than quantitative level of analysis.

Progress in Quantification

Despite these challenges, considerable progress has been made in quantifying and predicting the material properties of biological tissues on the basis of molecular structure. Researchers have successfully characterized:

  • Muscles: Contractile properties and force generation
  • Tendons: Elastic behavior under tension
  • Bones: Structural strength and stress distribution
  • Other body tissues: Viscoelastic properties and deformation patterns

The Challenge of Accessibility

One major problem in biomechanics is the accessibility of the material under investigation. The desired properties are those found in vivo (in the living organism), but these are often difficult to obtain experimentally.

In Vitro Versus In Vivo

An alternative approach is to measure properties in vitro (from excised tissue in a test tube), keeping the differences between in vitro and in vivo properties as small as possible. Considerations include:

  • Maintaining tissue viability with oxygen and nutrients
  • Preserving physiological temperature
  • Keeping tissue hydrated
  • Minimizing time between excision and measurement

The Need for Invasive Procedures

Because biomechanical measurement generally requires invasive procedures, an in vitro technique is often the only choice, with tissue obtained from:

  • Surgery
  • Autopsy
  • Animal models

The challenge is to ensure that measurements from excised tissue accurately represent the behavior of tissue in the living, functioning organism.

Biomechanics and Voice Science

For voice science, biomechanics provides essential tools for understanding:

Tissue Properties:

  • Stiffness and elasticity of vocal fold layers
  • Viscous properties affecting energy dissipation
  • Stress-strain relationships during vibration

Muscle Function:

  • Force generation in laryngeal muscles
  • Control of vocal fold tension and position
  • Active versus passive tissue properties

Vibratory Behavior:

  • How tissue properties affect oscillation
  • Energy transfer during vibration
  • Collision forces between vocal folds

Clinical Applications:

  • Understanding voice disorders
  • Predicting surgical outcomes
  • Designing therapeutic interventions

The Descriptive-to-Quantitative Continuum

Much of biomechanics remains at a descriptive level because:

  • Biological variability complicates measurement
  • Irregular geometries prevent simple mathematical models
  • Material properties change with physiological state
  • Multiple coupled systems interact

However, progress continues toward more quantitative understanding through:

  • Improved measurement techniques
  • Better mathematical models
  • Computational simulation
  • Integration of multiple scales (molecular to macroscopic)

Summary

Biomechanics applies classical mechanical principles to living biological material, though with greater complexity than traditional engineering applications. While founded on Newton’s laws and conservation principles, biomechanics must account for irregular geometries, variable material properties, and the challenge of measuring properties in living tissue.

For voice science, biomechanics provides the framework for understanding how laryngeal tissues generate sound through mechanical vibration. Despite the challenges of accessibility and measurement, significant progress has been made in characterizing the mechanical properties of vocal fold tissues and their role in phonation.

The field continues to evolve from descriptive to quantitative analysis, enabling more precise understanding of normal voice production and more effective approaches to treating voice disorders.

Key Takeaways

  • ✅ Biomechanics studies motion of living material under known or assumed forces using classical mechanical principles
  • ✅ Fewer idealizations are possible with biological materials compared to engineered systems
  • ✅ In vivo properties are ideal but difficult to measure; in vitro measurements provide practical alternative
  • ✅ Significant progress has been made in predicting material properties based on molecular structure
  • ✅ Biomechanics remains partly descriptive due to biological complexity and measurement challenges
  • ✅ For voice science, biomechanics provides essential framework for understanding tissue behavior during phonation

Further Reading

  1. Fung, Y. C. (1981). Biomechanics: Mechanical properties of living tissues. New York: Springer-Verlag.
  2. Halliday, D., & Resnick, R. (1988). Fundamentals of physics. New York: Wiley.
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