Biomechanics concepts

1. BIOMECHANICS CONCEPTS BIOMECHANICS Study of Biological Systems by Means of Mechanical Principles father of Mechanics Sir Isaac Newton

2. 22-Jun-12 P.Ratan (MPT, Ortho & Sports) 2

3. 22-Jun-12 P.Ratan (MPT, Ortho & Sports) 3 HUMAN MOVEMENT ANALYSIS BIOMECHANICS KINESIOLOGY KINETICS FUNCTIONAL KINEMATICS Linear Position Velocity Acceleration Position Velocity Acceleration Linear Angular Force Torque Angular

4. Basic types of Motion Linear Rectilinear Curvilinear Angular or rotational Combined or general 22-Jun-12 P.Ratan (MPT, Ortho & Sports) 4

5. Human Analysis Internal : mechanical factors creating and controlling movement inside the body External : factors affecting motion from outside the body 22-Jun-12 P.Ratan (MPT, Ortho & Sports) 5

6. Kinematics Describes motion Time Position Displacement Velocity Acceleration Vectors Angular and linear quantities 22-Jun-12 6 P.Ratan (MPT, Ortho & Sports)

7. Kinematics Formulas 22-Jun-12 7 P.Ratan (MPT, Ortho & Sports)

8. Kinetics Explains causes of motion Mass amount of matter (kg) Inertia: resistance to being moved Moment of Inertia (rotation) I = m·r 2 Axis 22-Jun-12 8 P.Ratan (MPT, Ortho & Sports)

9. Kinetics Force: push or pull that tends to produce acceleration Important factor in injuries Vector 22-Jun-12 9 P.Ratan (MPT, Ortho & Sports)

10. Kinetics Idealized force vector Force couple system d = d F F F F’ = d F M=Fd 22-Jun-12 10 P.Ratan (MPT, Ortho & Sports)

11. Kinetics: Force Force & Injury factors Magnitude Location Direction Duration Frequency Variability Rate 22-Jun-12 11 P.Ratan (MPT, Ortho & Sports)

12. Kinetics: Force System Linear Parallel Concurrent General Force Couple 22-Jun-12 12 P.Ratan (MPT, Ortho & Sports)

13. Center of Mass ( COm ) or Gravity (COG) It is an imaginary point where there is intersection of all 3 cardinal plane. Imaginary point where all the mass of the body or system is concentrated Point where the body’s mass is equally distributed 22-Jun-12 13 P.Ratan (MPT, Ortho & Sports)

14. Pressure P = F/A Units (Pa = N m 2 ) In the human body also called stress Important predisposing factor for injuries 22-Jun-12 14 P.Ratan (MPT, Ortho & Sports)

15. Moments of Force (Torque) Effect of a force that tends to cause rotation about an axis M = F ·d (Nm) If F and d are  Force through axis 22-Jun-12 15 P.Ratan (MPT, Ortho & Sports)

16. Moments of Force (Torque) Force components Rotation Stabilizing or destabilizing component 22-Jun-12 16 P.Ratan (MPT, Ortho & Sports)

17. Moments of Force (Torque) Net Joint Moment Sum of the moments acting about an axis Human: represent the muscular activity at a joint Concentric action Eccentric action Isometric 22-Jun-12 17 P.Ratan (MPT, Ortho & Sports)

18. Moments of Force (Torque) Large moments tends to produce injuries on the musculo-skeletal system Structural deviation leads to different MA’s 22-Jun-12 18 P.Ratan (MPT, Ortho & Sports)

19. NEWTONIAN LAWS of Motion 22-Jun-12 P.Ratan (MPT, Ortho & Sports) 19

20. 1 st Law of Motion A body a rest or in a uniform (linear or angular) motion will tend to remain at rest or in motion unless acted by an external force or torque Whiplash injuries 22-Jun-12 20 P.Ratan (MPT, Ortho & Sports)

21. 2 nd Law of Motion A force or torque acting on a body will produce an acceleration proportional to the force or torque F = m ·a or T= I ·  F 22-Jun-12 21 P.Ratan (MPT, Ortho & Sports)

22. 3 rd Law of Motion For every action there is an equal and opposite reaction (torque and/or force) Contact forces: GRF, other players etc. GRF 22-Jun-12 22 P.Ratan (MPT, Ortho & Sports)

23. Equilibrium Sum of forces and the sum of moments must equal zero  F = 0  M = 0 Dynamic Equilibrium Must follow equations of motions  F = m x a  T = I x  22-Jun-12 23 P.Ratan (MPT, Ortho & Sports)

24. Work & Power Mechanical Work W= F ·d (Joules) W= F ·d·cos ( ) Power: rate of work P = W/ t (Watts) P = F ·v P = F ·(d/t) d W W 22-Jun-12 24 P.Ratan (MPT, Ortho & Sports)

25. Mechanical Energy Capacity or ability to do work Accounts for most severe injuries Classified into Kinetic (motion) Potential (position or deformation) 22-Jun-12 25 P.Ratan (MPT, Ortho & Sports)

26. Kinetic Energy Body’s motion Linear or Angular KE=.5·m·v 2 KE  =.5 ·I· 2 22-Jun-12 26 P.Ratan (MPT, Ortho & Sports)

27. Potential Energy Gravitational: potential to perform work due to the height of the body E p = m·g·h Strain: energy stored due to deformation E s = .5·k·x 2 22-Jun-12 27 P.Ratan (MPT, Ortho & Sports)

28. Total Mechanical Energy Body segment’s: rigid (nodeformable), no strain energy in the system TME = Sum of KE, KE  , PE TME = (.5·m ·v 2 )+(.5 ·I ·  2 )+(m ·g ·h ) 22-Jun-12 28 P.Ratan (MPT, Ortho & Sports)

29. Momentum Quantity of motion p=m ·v (linear) Conservation of Momentum Transfer of Momentum Injury may result when momentum transferred exceeds the tolerance of the tissue Impulse = Momentum P 22-Jun-12 29 P.Ratan (MPT, Ortho & Sports)

30. Angular Momentum Quantity of angular motion H=I ·  (angular) Conservation of angular momentum Transfer of angular momentum 22-Jun-12 30 P.Ratan (MPT, Ortho & Sports)

31. Collisions Large impact forces due to short impact time Elastic deformation Plastic deformation (permanent change) Elasticity: ability to return to original shape Elastoplastic collisions Some permanent deformation Transfer and loss of energy & velocity Coefficient of restitution e= Rv post / Rv pre 22-Jun-12 31 P.Ratan (MPT, Ortho & Sports)

32. Friction Resistance between two bodies trying to slide Imperfection of the surfaces Microscopic irregularities - asperities Static friction f <  s ·N Kinetic f=µ k ·N N f 22-Jun-12 32 P.Ratan (MPT, Ortho & Sports)

33. Friction Rolling : Lower that static and kinetic friction (100-1000 times) Joint Friction - minimized Blood vessels - atherosclerosis 22-Jun-12 33 P.Ratan (MPT, Ortho & Sports)

34. FLUID MECHANICS Branch of Mechanics Dealing with the Properties & Behaviors of Gases & Fluids

35. Fluid Flow Laminar Turbulent Effects of friction on arterial blood flow 22-Jun-12 35 P.Ratan (MPT, Ortho & Sports)

36. Fluid Forces Buoyancy Drag Surface Pressure Wave Lift Magnus forces Viscosity Biological tissue must have a fluid component 22-Jun-12 36 P.Ratan (MPT, Ortho & Sports)

37. Fluid Forces 22-Jun-12 37 P.Ratan (MPT, Ortho & Sports)