Biomechanics Basics
اسلاید 1: Biomechanics BasicsChapter 3
اسلاید 2: Random Interesting Fun FactsMichael Jordan makes more money from Nike annually than all of the Nike factory workers in Malaysia combined.Right-handed people live, on average, nine years longer than left-handed people do.It’s physically impossible for you to lick your elbow.
اسلاید 3: OverviewWhat is biomechanics?Levers & their classificationFactors impacting force production of leversLaws of motion and their influence on sport movementEquilibrium, balance, & stabilityFactors influencing balance
اسلاید 4: What is Biomechanics?Bio= life; Mechanics= physical actionsStatics: form of mechanics that analyzes systems in constant state of motionCould be no movement at allCould be constant velocity with no accelerationDynamics: form of mechanics that analyzes systems in motion and accelerating
اسلاید 5: What could a biomechanist do to improve sport performance?Technique analysisIncrease speedIncrease strengthIncrease powerMinimize risk of injury (primarily overuse)
اسلاید 6: What does biomechanics have to do with anatomical kinesiology?Anatomical kinesiology is the whatMuscle origins, insertions, and actionsBiomechanics is the howMechanical principles that dictate the manner those muscles work
اسلاید 7: LeversWhat do levers have to do with human movement?EVERYTHING!Levers are rigid bars (in the body, bones) that move around an axis of rotation (a joint) or fulcrumForces (supplied by muscles) cause the movement to occur
اسلاید 8: Lever FunctionsMagnify a forceA simple crow barIncrease speed and range-of-motion (ROM)Small amount of muscular contraction proximally can produce lots of movement distally
اسلاید 9: Lever FunctionsBalance torquesA triple beam scaleChange direction of forceA seesaw or a pulley of a weight machine
اسلاید 10: Lever TypesFirst, second, and third classArrangement of the applied force, the fulcrum, and the resistance determines the classificationClassification determines the lever’s strengths and weaknesses
اسلاید 11: First ClassFARWhen axis close to force, produces speed and ROM, when close to resistance, produces powerAbout 25% of the muscles in your body operate as first class leversForceAxisResist.
اسلاید 12: AxisFRRFAxis
اسلاید 13: AxisForceResist.Example: Neck extension
اسلاید 14: Second ClassARFVery few occurrences in the bodyGain resultant force (you can lift more), lose distance Force
اسلاید 15: ForceResist.Axis
اسلاید 16: Third ClassRFAAs much as 85% of the muscles in the body function as third class leversUsually produce speed at the expense of forceGreater lever length = greater speed (ex.)Force
اسلاید 17:
اسلاید 18: Factors Impacting Force ProductionTorque: turning effect of an eccentric forceT= Applied Force * Force ArmForce arm is the perpendicular distance between the applied force and the axis of rotationEccentric force: applied in a direction not in line with center of rotation of non-moving axis
اسلاید 19: Factors Impacting Force ProductionResistance arm: distance between axis and point of resistance (NOT the perpendicular distance) Inverse relationship between force and force armInverse relationship between resistance and resistance armForce components and resistance components proportionalF * FA = R * RA
اسلاید 20: Factors Impacting Force ProductionAngle of pullRotary component, dislocating component, and stabilizing componentWhen line of force (inserting tendon) is perpendicular to the bone it is inserting on (90 deg.), dislocating and stabilizing components = 0, therefore all force is rotary
اسلاید 21: Laws of MotionInertiaAccelerationReaction
اسلاید 22: Law of Inertia (Newton’s First Law)“A body in motion tends to stay in motion at the same speed in a straight line unless acted upon by a force; A body at rest tends to remain at rest unless acted upon by a force”English translation: unbalanced forces cause motion; Balanced forces don’t change anything
اسلاید 23: Law of Inertia (Newton’s First Law)Mass is the measure of inertiaGreater mass = greater inertiaImplications for sport movementDecreased mass USUALLY means you are easier to move (less inertia)Agonist/antagonist reciprocal inhibition
اسلاید 24: Law of Acceleration (Newton’s Second Law)“The acceleration of an object is directly proportional to the force causing it, is in the same direction as the force, and is inversely proportional to the mass of the object”F = ma
اسلاید 25: Law of Acceleration (Newton’s Second Law)ImpulseFt = m(vf-vi)Without time, it is impossible to generate force and change velocityMomentumFt = (mvf-mvi)If masses are different, deficiencies can be compensated for by increasing speed
اسلاید 26: Law of Acceleration (Newton’s Second Law)Implications for sport movementClub/racket/bat weightFollow throughAthlete body weight
اسلاید 27: Law of Reaction (Newton’s Third Law)“For every action there is an equal and opposite reaction”Ground reaction forceImplications for sport movementArtificial turf
اسلاید 28: Equilibrium, Balance, & StabilityEquilibrium is the state of zero acceleration (static or dynamic)Balance is the ability to control equilibriumStability is a resistance to the disturbance of equilibrium
اسلاید 29: Factors Influencing BalanceLocation of the center of gravity in relation to the base of supportSize of the base of supportMass of the personHeight of the center of gravityTraction/frictionSensory perceptio
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