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

P.Ratan (MPT, Ortho & Sports) BIOMECHANICS Biology Skeletal system Muscular system Nervous system Physics Mechanics Kinetics Kinematics 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

HUMAN MOVEMENT ANALYSIS BIOMECHANICS KINESIOLOGY KINETICS KINEMATICS FUNCTIONAL Linear Angular Linear Angular Position Velocity Acceleration Position Velocity Acceleration Force Torque 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

P.Ratan (MPT, Ortho & Sports) Basic types of Motion Linear Rectilinear Curvilinear Angular or rotational Combined or general 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

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 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

P.Ratan (MPT, Ortho & Sports) Kinematics Describes motion Time Position Displacement Velocity Acceleration Vectors Angular and linear quantities 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

P.Ratan (MPT, Ortho & Sports) Kinematics Formulas 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

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 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

P.Ratan (MPT, Ortho & Sports) Kinetics Force: push or pull that tends to produce acceleration Important factor in injuries Vector 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

P.Ratan (MPT, Ortho & Sports) Kinetics Idealized force vector Force couple system d F F’ F M=Fd d d = = F F 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

P.Ratan (MPT, Ortho & Sports) Kinetics: Force Force & Injury factors Magnitude Location Direction Duration Frequency Variability Rate 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

Kinetics: Force System Linear Parallel Concurrent General Force Couple 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

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 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

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 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

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 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

Moments of Force (Torque) Force components Rotation Stabilizing or destabilizing component 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

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 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

Moments of Force (Torque) Large moments tends to produce injuries on the musculo-skeletal system Structural deviation leads to different MA’s 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

NEWTONIAN LAWS of Motion 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

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 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

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 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

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 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

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  6-Dec-18 P.Ratan (MPT, Ortho & Sports)

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 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

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) 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

P.Ratan (MPT, Ortho & Sports) Kinetic Energy Body’s motion Linear or Angular KE=.5·m·v2 KE=.5 ·I·2 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

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 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

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 ) 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

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 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

P.Ratan (MPT, Ortho & Sports) Angular Momentum Quantity of angular motion H=I · (angular) Conservation of angular momentum Transfer of angular momentum 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

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 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

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 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

P.Ratan (MPT, Ortho & Sports) Friction Rolling: Lower that static and kinetic friction (100-1000 times) Joint Friction - minimized Blood vessels - atherosclerosis 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

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

P.Ratan (MPT, Ortho & Sports) Fluid Flow Laminar Turbulent Effects of friction on arterial blood flow 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

P.Ratan (MPT, Ortho & Sports) Fluid Forces Buoyancy Drag Surface Pressure Wave Lift Magnus forces Viscosity Biological tissue must have a fluid component 6-Dec-18 P.Ratan (MPT, Ortho & Sports)

P.Ratan (MPT, Ortho & Sports) Fluid Forces 6-Dec-18 P.Ratan (MPT, Ortho & Sports)