3 biomechanical concepts - 420 050
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BiomechanicsTRANSCRIPT
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Basic Biomechanical Factors and ConceptsAnatomy and Physiology of Human Movement420:050
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OutlineIntroductionLeversAnatomical LeversLaws of Motion
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BiomechanicsBiomechanics - study of the mechanics as it relates to the functional and anatomical analysis of biological systems and especially humansNecessary to study the bodys mechanical characteristics & principles to understand its movements
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BiomechanicsMechanics - study of physical actions of forcesMechanics is divided into:Statics Dynamics
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BiomechanicsStatics - study of systems that are in a constant state of motion, whether at rest with no motion or moving at a constant velocity without accelerationStatics involves all forces acting on the body being in balance resulting in the body being in equilibriumDynamics - study of systems in motion with accelerationA system in acceleration is unbalanced due to unequal forces acting on the body
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BiomechanicsKinematics & kineticsKinematics - description of motion and includes consideration of time, displacement, velocity, acceleration, and space factors of a systems motionKinetics - study of forces associated with the motion of a bodyMechanical advantageLoad/effort or load divided by effortIdeally using a relatively small force, or effort to move a much greater resistance
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OutlineIntroductionLeversAnatomical LeversLaws of Motion
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Introduction to LeversLever: Simple machine that operates according to principle of torquesTorque: The turning effect of a forceT = Fd
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FdHow can you change torque?1. Change F2. Change d3. Change direction of F
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FdOptimal direction = 90 degrees
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Function of LeversTwo functions:1. Force2. Speed/ROM
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Function of LeversForceExamples?Common traits?Rigid barFixed pointLever movement vs. resistance movement
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FR
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Function of LeversSpeed/ROMExamples?Common traits?Rigid barFixed pointLever movement vs. resistance movement
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FR
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Components of a Lever SystemLever: Rigid barFulcrum: Axis of rotation/fixed pointForce:Applied force (F)Resistance force (R)Moment arm: dApplied forceResistance
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More ConceptsMechanical advantageLevers designed for forceMechanical disadvantageLevers designed for speed/ROM
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FRMechanical advantage or disadvantage?How does mechanical advantage affect movement of the lever?
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Advantage: Small effort moves big resistanceDisadvantage: Big movement required to move resistance a small distance
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Human Application?Lever?Bones (Not always a bar)Fulcrum?JointsApplied force?MusclesResistance force?Weight of limb, external resistance
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Classification of LeversLever classification based on the relative location of:1. Axis of rotation/fulcrum (A)2. Resistance force (R)3. Applied force (F)
A R F
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First Class LeverCenter: (A) Axis of rotation/fulcrumMechanical advantageMechanical disadvantageExamplesCrow barSeesaw
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Advantage or disadvantage?
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Second Class LeverCenter: (R) Resistance forceMechanical advantageAlwaysMechanical disadvantageNeverExamplesWheelbarrowNutcracker
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Third Class LeverCenter: (F) Applied forceMechanical advantageNeverMechanical disadvantageAlwaysExamplesRowingShovelingBat, tennis racket
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Baseball, tennis?
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Human ApplicationFirst class leverElbow extension against a resistance
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(A) Axis of rotation/fulcrum(F) Applied force(R) Resistance forceMechanical advantage or disadvantage
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Human ApplicationSecond class leverAnkle plantar flexion
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Mechanical advantage or disadvantage?Not many in the body
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Human ApplicationThird class leverElbow flexion
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Mechanical advantage or disadvantage?Many of these in body
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In general, is the human body built for force application or speed/ROM?