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Basic Biomechanical Factors and Concepts

Basic Biomechanical Factors and Concepts. Anatomy and Kinesiology 420:024. Outline. Introduction Levers Anatomical Levers Laws of Motion. Biomechanics.

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Basic Biomechanical Factors and Concepts

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  1. Basic Biomechanical Factors and Concepts Anatomy and Kinesiology 420:024

  2. Outline • Introduction • Levers • Anatomical Levers • Laws of Motion

  3. Biomechanics • Biomechanics - study of the mechanics as it relates to the functional and anatomical analysis of biological systems and especially humans

  4. Biomechanics • Mechanics: • Mechanics is divided into: • Statics • Dynamics

  5. Biomechanics • Statics - study of systems that are in a constant state of motion, whether at rest with no motion or moving at a constant velocity without acceleration • Dynamics - study of systems in motion with acceleration

  6. Biomechanics • Kinematics & kinetics • Kinematics - description of motion and includes consideration of time, displacement, velocity, acceleration, and space factors of a system‘s motion • Kinetics - study of forces associated with the motion of a body • Mechanical advantage • Load/effort or load divided by effort • Ideally using a relatively small force, or effort to move a much greater resistance

  7. Outline • Introduction • Levers • Anatomical Levers • Laws of Motion

  8. Introduction to Levers • Lever: Simple machine that operates according to principle of torques • Torque: The turning effect of a force T = Fd

  9. d How can you change torque? F

  10. d F

  11. Function of Levers • Two functions: 1. Force 2. Speed/ROM

  12. Function of Levers • Force • Examples? • Common traits? • Rigid bar • Fixed point • Lever movement vs. resistance movement

  13. R F

  14. Function of Levers • Speed/ROM • Examples? • Common traits? • Rigid bar • Fixed point • Lever movement vs. resistance movement

  15. R F

  16. Components of a Lever System • Lever: Rigid bar • Fulcrum: Axis of rotation/fixed point • Force: • Applied force (F) • Resistance force (R) • Moment arm: d • Applied force • Resistance

  17. More Concepts • Mechanical advantage • Levers designed for force • Mechanical disadvantage • Levers designed for speed/ROM

  18. F R Mechanical advantage or disadvantage? How does mechanical advantage affect movement of the lever?

  19. Human Application? • Lever? Bones (Not always a bar) • Fulcrum? Joints • Applied force? Muscles • Resistance force? Weight of limb, external resistance

  20. Classification of Levers • Lever classification based on the relative location of: 1. Axis of rotation/fulcrum (A) 2. Resistance force (R) 3. Applied force (F) A R F

  21. First Class Lever • Center: (A) – Axis of rotation/fulcrum • Mechanical advantage • Mechanical disadvantage • Examples Crow bar Seesaw

  22. Advantage or disadvantage?

  23. Second Class Lever • Center: (R) – Resistance force • Mechanical advantage • Always • Mechanical disadvantage • Never • Examples Wheelbarrow Nutcracker

  24. Third Class Lever • Center: (F) – Applied force • Mechanical advantage • Never • Mechanical disadvantage • Always • Examples Rowing Shoveling Bat, tennis racket

  25. Baseball, tennis?

  26. Human Application • First class lever • Elbow extension against a resistance

  27. Mechanical advantage or disadvantage (R) – Resistance force (F) – Applied force (A) – Axis of rotation/fulcrum

  28. Human Application • Second class lever • Ankle plantar flexion

  29. Mechanical advantage or disadvantage?

  30. Human Application • Third class lever • Elbow flexion

  31. Mechanical advantage or disadvantage?

  32. In general, is the human body built for force application or speed/ROM?

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