PRA 545

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PRA 545

• Biomechanics

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Basic Terminology

• Qualitative
• Non-numerical
• Based on direct observation
• Equipment not necessary
• Focus on time and space
• Examples
• Rotation of femur during golf swing
• Adduction of humerus during freestyle swim

• Quantitative
• Numerical
• Based on data collected
• Equipment necessary
• Focus on forces
• Examples
• Stress on shoulder during baseball pitch
• Compression force on femur during landing

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Areas of Study

• Biomechanics vs. Kinesiology
• Anatomy vs. Functional Anatomy
• Linear vs. Angular Motion
• Kinematics vs. Kinetics

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Human Movement Analysis
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Biomechanics vs. Kinesiology

• Kinesiology
• Scientific study of human movement
• Anatomical, physiological, psychological,
  biomechanical
• Biomechanics
• Application of mechanics to biological systems
• More specific than kinesiology

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Anatomy vs. Functional Anatomy

• Anatomy
• Structure of the body
• Focus on structure
• Example Study of biceps brachii
• Functional Anatomy
• Body components necessary to achieve goal
• Focus on function
• Example Analysis of bicep curl

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Linear vs. Angular Motion

• Linear Motion
• AKA translation or translational motion
• Movement on straight or curved pathway
• All points move same distance, same time
• Angular Motion
• Motion around some point

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Kinematics vs. Kinetics

• Both are biomechanical analyses
• Kinematics
• Examines space and time
• Kinetics
• Examines forces

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Statics vs. Dynamics

• Statics
• Examines systems not moving or moving at a
  constant speed
• Equilibrium no acceleration
• Example Spaceship gliding through space
• Dynamics
• Examines systems that are being accelerated
• Example Softball pitch

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Stress-Strain Curve

• Stress (s)
• Force applied to deform a structure
• Force per unit area
• Measured in N/m2 or pascals
• sF/A
• Strain (e)
• Deformation caused by applied stress
• e?L/L

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Stress-Strain Curve (cont.)

• Elastic modulus (k)
• Stiffness of a material
• kstress/strains/e
• Residual strain
• Difference between original length and length
  resulting from stress into the plastic region
• Safety factor
• 510x typical stress on structure

Insert figure 1-9.
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Types of Materials

• Elastic
• Linear relationship between stress and strain
• Viscoelastic
• Non-linear relationship between stress and strain
• Hysteresis energy lost in a viscoelastic material

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Degrees of Freedom

• Degree of freedom
• Number of planes in which a joint has the ability
  to move
• 1 degree of freedom
• Uniaxial
• Example Elbow
• 2 degrees of freedom
• Biaxial
• Example Wrist
• 3 degrees of freedom
• Triaxial
• Example Shoulder

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Summary

• Human movement analyzed using
• Qualitative analysis
• Quantitative analysis
• Materials structures analyzed using
• Stress-strain curve
• Movement described
• Using anatomical movement descriptors
• In relation to planes of motion