Biomechanics is the study of biological systems using mechanical principles. It draws from biology and physics to describe the movement of living organisms. Biomechanics aids in understanding human movement through analyzing kinetics, which examines causes of motion like forces and torques, and kinematics, which describes motion in terms of displacement, velocity and acceleration. Proper biomechanical analysis is important for understanding injuries and designing rehabilitation.

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

2. Biology Physics
Skeletal Muscular Nervous Mechanics
system system system
Kinetics Kinematics
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3. HUMAN MOVEMENT ANALYSIS
BIOMECHANICS KINESIOLOGY
KINETICS KINEMATICS FUNCTIONAL
Linear Angular Linear Angular
Position Position
Velocity Velocity Force Torque
Acceleration Acceleration
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4. Basic types of Motion
 Linear
 Rectilinear
 Curvilinear
 Angular or rotational
 Combined or general
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5. Human Analysis
 Internal: mechanical factors
creating and controlling
movement inside the body
 External: factors affecting
motion from outside the body
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6. Kinematics
 Describes motion
 Time
 Position
 Displacement
 Velocity
 Acceleration
 Vectors
 Angular and linear quantities
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7. Kinematics Formulas
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8. Kinetics
 Explains causes of motion Axis
 Mass
 amount of matter (kg)
 Inertia: resistance to being moved
 Moment of Inertia (rotation) I = m·r2
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9. Kinetics
 Force: push or pull that tends to
produce acceleration
 Important factor in injuries
 Vector
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10. Kinetics
 Idealized force vector
 Force couple system
F
F’ F M=Fd
d d d
= =
F F
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11. Kinetics: Force
 Force & Injury factors
 Magnitude
 Location
 Direction
 Duration
 Frequency
 Variability
 Rate
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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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14. Pressure
 P = F/A
 Units (Pa = N m2)
 In the human body also
called stress
 Important predisposing
factor for injuries
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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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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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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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19. NEWTONIAN
LAWS of Motion
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20. 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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21. 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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22. 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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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=mxa
 T=Ix
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24. Work & Power
 Mechanical Work
 W= F ·d (Joules)
 W= F ·d·cos ( )
 Power: rate of work
d
 P = W/ t (Watts)
W W
 P = F ·v
 P = F ·(d/t)
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25. 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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26. Kinetic Energy
 Body’s motion
 Linear or Angular
 KE=.5·m·v2
 KE =.5 ·I· 2
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27. 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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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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29. 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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30. Angular Momentum
 Quantity of angular
motion
 H=I · (angular)
 Conservation of angular
momentum
 Transfer of angular
momentum
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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=Rvpost/Rvpre
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32. Friction
 Resistance between two bodies
trying to slide
 Imperfection of the surfaces
 Microscopic irregularities -
asperities
 Static friction
 f< s·N
f
 Kinetic
 f=µk·N N
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33. Friction
 Rolling: Lower that static and kinetic
friction (100-1000 times)
 Joint Friction - minimized
 Blood vessels - atherosclerosis
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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
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36. Fluid Forces
 Buoyancy
 Drag
 Surface
 Pressure
 Wave
 Lift
 Magnus forces
 Viscosity
 Biological tissue must have a fluid component
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37. Fluid Forces
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