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

2. P.Ratan (MPT, Ortho & Sports)
BIOMECHANICS
Biology
Skeletal system
Muscular system
Nervous system
Physics
Mechanics
Kinetics
Kinematics
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P.Ratan (MPT, Ortho & Sports)

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

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

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

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

7. P.Ratan (MPT, Ortho & Sports)
Kinematics Formulas
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P.Ratan (MPT, Ortho & Sports)

8. P.Ratan (MPT, Ortho & Sports)
Kinetics
Explains causes of motion
Mass
amount of matter (kg)
Inertia: resistance to being moved
Moment of Inertia (rotation) I = m·r2
Axis
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P.Ratan (MPT, Ortho & Sports)

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

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

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

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

14. P.Ratan (MPT, Ortho & Sports)
Pressure
P = F/A
Units (Pa = N m2)
In the human body also called stress
Important predisposing factor for injuries
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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
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P.Ratan (MPT, Ortho & Sports)

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

19. NEWTONIAN LAWS of Motion
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20. P.Ratan (MPT, Ortho & Sports)
1st 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
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P.Ratan (MPT, Ortho & Sports)

21. P.Ratan (MPT, Ortho & Sports)
2nd 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
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P.Ratan (MPT, Ortho & Sports)

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

23. P.Ratan (MPT, Ortho & Sports)
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 
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P.Ratan (MPT, Ortho & Sports)

24. P.Ratan (MPT, Ortho & Sports)
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
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P.Ratan (MPT, Ortho & Sports)

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

26. P.Ratan (MPT, Ortho & Sports)
Kinetic Energy
Body’s motion
Linear or Angular
KE=.5·m·v2
KE=.5 ·I·2
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P.Ratan (MPT, Ortho & Sports)

27. P.Ratan (MPT, Ortho & Sports)
Potential Energy
Gravitational: potential to perform work due to the height of the body
Ep= m·g·h
Strain: energy stored due to deformation
Es= .5·k·x2
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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 ·v2)+(.5 ·I ·2)+(m ·g ·h )
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P.Ratan (MPT, Ortho & Sports)

29. P.Ratan (MPT, Ortho & Sports)
Momentum P
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
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P.Ratan (MPT, Ortho & Sports)

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

31. P.Ratan (MPT, Ortho & Sports)
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=Rvpost/Rvpre
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P.Ratan (MPT, Ortho & Sports)

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

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

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

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

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

37. P.Ratan (MPT, Ortho & Sports)
Fluid Forces
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P.Ratan (MPT, Ortho & Sports)