KINESIOLOGY CH 9 Biomechanics.ppt
CHAPTER 9The Science of BiomechanicsKinesiology Books Publisher1TABLE OF CONTENTSTypes of Study Quantitative vs Qualitative Analysis Kinematics Versus KineticsMotion Concepts Mass, Gravity, and Inertia Types of Motion Causes of Motion Lever Systems and Motion MechanicsNewton’s Laws of Motion Law of Inertia Law of Acceleration Law of Action–ReactionFluid Dynamics Fluid Drag Forces: The Dynamics of AirBody Balance and Stability Control Equilibrium Balance StabilityQualitative Analysis of Human Motion Skill Objective Analyzing a Skill Observation of Performance Error Detection and CorrectionTHE SCIENCE OF BIOMECHANICS Study of internal and external forces actingon human body and their effects Relatively young Extremely diverse and multifaceted Contributes significantly to our knowledge ofhuman movementKinesiology Books Publisher31
TYPES OF STUDY Quantitative versus Qualitative AnalysisKinematics Versus KineticsKinesiology Books Publisher4QUANTITATIVE VS. QUALITATIVE ANALYSIS Depends on Environment Availability of high-tech equipmentKinesiology Books Publisher5QUANTITATIVE ANALYSIS Using high-tech instrumentation Usually intended for researchers Measuring variables to optimize athletic performance Foot forces on sprinter’s blog Muscle contraction sequence during running 3-D body segment movements during a high jump6Kinesiology Books Publisher62
7Kinesiology Books Publisher7QUALITATIVE ANALYSIS Using sight and hearing Usually done by coaches and teachers To identify and correct errors: “Observe, analyze and correct.” Requires framework and a set of principles8Kinesiology Books Publisher8KINEMATIC VS. KINETICS Two ways to describe humanmotion1. Without reference to forcescausing motion2. Describing motion in terms offorces that cause itKinesiology Books Publisher93
KINEMATICS Describing human motion without its forces Focusing on motion’s spatial and timing characteristics Measurements: Time Displacement Velocity Acceleration10Kinesiology Books Publisher10KINETICS Describing forces leading to motion Internal forces Muscles pulling on bones Bone-on-bone, inside joints External forces acting on the body Without contact (e.g., gravity) From contact with ground,opponent or equipment11Kinesiology Books Publisher11MODELS OF HUMAN MOTION Understanding and observing humanmovements is complex All body tissues undergo shape deformation Most movements occur in three dimensions 3 models, simplify the study of humanmovements: Particle model Stick figure model Rigid body segment model12Kinesiology Books Publisher124
Stick FigureModelParticle Model Dot representscentre of mass Body segments sticks Used when body orobject is airborneand in flight Used when body incontact with otherobjects i.e., projectilemotion Describe grossmotor skills in 2-DRigid BodySegment Model Body segments irregular 3-Dvolume Used forsophisticated 3-Danalyses Includes shapedeformation ofbody segments 13Kinesiology Books Publisher1314Kinesiology Books Publisher14MOTION CONCEPTS Mass, Gravity, and InertiaTypes of MotionCauses of MotionLever Systems and Motion MechanicsKinesiology Books Publisher155
MASS, GRAVITY, INERTIAMass Amount of matter in an object Objects are reluctant to go change state of motion A measure of inertiaMoment of Inertia Reluctance of rotating object to change state ofmotion Depends on mass and its distribution around axis ofrotationGravity Force of attraction between two bodies E.g., human body and planet earthKinesiology Books Publisher1617Kinesiology Books Publisher1718Kinesiology Books Publisher186
19Kinesiology Books Publisher19TYPES OF MOTION Human movement composed of a numberof fundamental types of motion: Linear motion / translation Angular motion / rotation General motionKinesiology Books Publisher All body parts movesame distance anddirection, at the sametime Translation: linearmotion of the whole body Body / segmentsmove linearly androtate at the sametimeLinearmotion True for mostathletic and everyday activitiesGeneralmotion Body moves on a circularpath and rotates aboutaxis of rotation Body segments rotateabout their joints E.g., twisting somersault20Angularmotion E.g., gymnasticsfloor routine, diverfalling downwardand at the sametime rotating in asomersault21Kinesiology Books Publisher217
CAUSES OF MOTION Application of internal or external forces Force is any action, push or pull, that tends to cause anobject to change is state of motion by experiencingacceleration or as state of constant velocity Linear motion force acting on centre of mass/ pivotpoint Angular motion force not acting on centre of mass/pivot point and result in torque (moment of force)Kinesiology Books Publisher2223Kinesiology Books Publisher23LEVER SYSTEMS AND MOTION MECHANICSLever system Mechanical device performing angular motion Components: Axis of rotation Fulcrum (pivot) Lever attached to fulcrum Human muscles, bones and joint work togetheras lever systemsKinesiology Books Publisher248
25Kinesiology Books Publisher25HOW DO LEVERS WORK Force is applied and if greater than resistance Rotation at the axis / fulcrum occurs To determine force amount, consider the length of force arm and resistance armKinesiology Books Publisher26HOW DO LEVERS WORK When lever rotate around and axis / fulcrum: Moment of force or torque is produced How much torque occurs? Therefore, with a longer force arm: Less force is needed Greater torque is produced27Kinesiology Books Publisher279
No rotation: F R, FA RARotation: F R, FA RAHow do you rotateteeter-totter in yourdirection?Rotation: F R, FA RA28Kinesiology Books Publisher28TYPES OF LEVERS Levers perform different functions Three basic types of lever exist First class Second class Third class Differ based on mechanics and howthese components are positioned Axis Resistance Force29Kinesiology Books Publisher29FIRST CLASS LEVERS Applied force and resistance on opposite side of axis, at un/equaldistance from one another Example: crowbar Human body: head flexionRResistanceAAForceFKinesiology Books Publisher3010
SECOND CLASS LEVERS Applied force and resistance on same side of axis; resistance closerto axis Example: wheelbarrow Human body - hard to find: toe raiseResistanceRForceFAA31Kinesiology Books Publisher31THIRD CLASS LEVERS Applied force and resistance on same side of axis; force closer to theaxis Example: fishing Human body – many: forearm flexionResistanceFForceRAAKinesiology Books Publisher3233Kinesiology Books Publisher3311
34Kinesiology Books Publisher34NEWTON’S LAWS OF MOTION Law of InertiaLaw of AccelerationLaw of Action–ReactionKinesiology Books Publisher35Kinesiology Books Publisher36SIR ISAAC NEWTON 300 years ago Explained effect offorces acting on anobject Through 3 laws12
LAW OF INERTIANewton’s First Law“Objects will not change their state ofmotion unless acted on by anunbalanced external force”Kinesiology Books Publisher37LAW OF ACCELERATIONNewton’s Second Law“Objects will experience a change in velocityor acceleration proportional to theunbalanced external force”Kinesiology Books siology Books Publisher3913
LAW OF ACTION-REACTIONNewton’s Third Law“For every action there is an equal andopposite reaction; forces act in pairs that areequal in magnitude and opposite in direction”Kinesiology Books Publisher4041Kinesiology Books Publisher41FLUID DYNAMICS Fluid Drag Forces: The Dynamics of AirKinesiology Books Publisher4214
FLUID DYNAMICS Knowledge of the forces generated by a fluidenvironment such as Water Air Water Air All athletic event take place in a fluid environment Unaffected: gymnastics, dancing Affected: running, cycling, skiing, speed skating,swimming, badminton, baseball, etc.Kinesiology Books Publisher43DRAG FORCES: AIR Drag is a type of fluid force Profile drag; caused by object’s size and shape Surface drag; cause by object’s roughness Acts in opposite direction to body’s travel and slowsit down relative to body’s Velocity Size and shape Roughness Fast-speed sports especially affected velocity drag2 (10x faster, 100 x more drag)Kinesiology Books Publisher4515
SURFACE DRAG Body size and surface roughness surface drag Boundary layer Thin layer of fluid adjacent to skin and carried along with body’s motion,towing along outer fluid layers Laminar flow Small, streamlined, smooth, slow-moving bodies Smooth, layered flow pattern with no disturbance Turbulent flow Most human activities Disturbed flow pattern that changes flow conditionsLaminar flowTurbulent flow4748Kinesiology Books Publisher4816
PROFILE DRAG Main form of drag in fast-moving sports Characterized by turbulent flow Velocity of air flow past object is too fast for air to follow body’s contour Backflow occurs at object’s surface causing large, turbulent lowpressure zone behind the body This zone is continually formed and increases object’s work Profile drag-reducing strategies frontal surface area (e.g., lugers are supine) sources of turbulence (e.g., speed skaters with arms behind back) DraftingMAGNUS EFFECT A rotating body carries a boundary layer thatinteracts with surrounding air Boundary layer flow opposite to relative airflow Air is slowed by friction Zone of increased pressure created Boundary layer flow same as relative airflow Air is not slowed down Zone of increased pressure created Net difference in pressure on opposite sides ofrotating object Magnus force Magnus effect is mostly found in ping pong,tennis, soccer, and baseball50Top spin:downwardsMagnusforceBack spin:upwardsMagnusforce5117
52Kinesiology Books Publisher52BODY BALANCE AND STABILITY CONTROL EquilibriumBalanceStabilityKinesiology Books Publisher53EQUILIBRIUM Equilibrium is a state of a system notexperiencing change in direction andspeed Static equilibrium: body’s at rest Dynamic equilibrium: body’s moving atconstant velocityKinesiology Books Publisher5418
BALANCE Balance: process where body’s equilibrium iscontrolled for a purpose Affected by two factors:1. Base of support; area of contact between bodyand surface Wider base, greater balance2. Location of line of gravity; imagery vertical linethat passes through centre of mass Has to pass through base of support for balanceKinesiology Books Publisher55STABILITY Stability is a measure of the difficulty with whichequilibrium can be disturbed Net internal force required to overcome static ordynamic equilibrium During critical performance times there is a tradeoff between maximizing stability and acquiringspeedKinesiology Books Publisher56 StabilityStatic Equilibrium base size body sizeLower centre ofgravity distancebetween gravityline intersectingbase andoutside baseedgeKinesiology Books Publisher5719
58Kinesiology Books Publisher58 StabilityDynamic EquilibriumWiden basetowardsoncomingexternalhorizontal forceMove centre ofgravity towardsbase edgeduring quickaccelerationShift centre ofgravity towardsoncoming forceUse reflexmovement toregain loss ofbalanceKinesiology Books Publisher5960Kinesiology Books Publisher6020
QUALITATIVE ANALYSIS OF HUMAN MOTION Skill ObjectiveAnalyzing a SkillObservation of PerformanceError Detection and CorrectionQUALITATIVE ANALYSIS Subjective yet systematic evaluation of humanmotion without measuring and using numbers Based on visual observation or video recording Allows discovery of movement tendencies andgenerates immediate and specific feedback Depends on coach’s understanding of skill Based on a model integrating 4 aspects of qualityinstructionKinesiology Books Publisher62Kinesiology Books Publisher6321
SKILL OBJECTIVE Can be described and identified for all skills E.g., blocking a lineman Secondary objectives may exist, referring tospeed or accuracy required Skills with similar overall objectives are governedby similar biomechanical principles Throwing, striking, kicking object for maximalhorizontal surfaceKinesiology Books Publisher64ANALYZING SKILLDividing skill into phases Should make sense to the coach and how the skillis being defined and taughtIdentifying key movements for each phase Their execution determines successfulaccomplishment of biomechanical purpose of thephase and overall performance of the skillKinesiology Books Publisher65Kinesiology Books Publisher6622
OBSERVATION OF PERFORMANCE Difficult task because of skill speed Observation plan beforehand identifies what, why,where and how observation will occur Coaches must use vision (dominant), hearing andfeeling as well as look for tracks and traces Confirm observation accuracy with athlete andvideo recording (if possible)Kinesiology Books Publisher67ERROR DETECTION AND CORRECTION Error sources Mental: concentration lapse or fear Physical: lack of strength, poor habits Detection is visual via direct observation videoanalysis, or traces/marks observation Correction Should keep in mind athlete's physical and mentalabilities, competition level, age and developmentlevel Verbal, demonstration, video Ongoing; 1-2 errors at a time starting with earlierKinesiology Books Publisher68PUTTING IT ALL TOGETHER Biomechanics is the physics of human movement with the maingoal to optimize performance by focusing on movement kinematicsand kinetics Motion results from internal and external forces in ways that can beunderstood via Newton’s laws Fluid affects athletic performance via surface and profile drag andMagnus effect By manipulating base and centre of gravity characteristics athletescan increase stability and reach equilibrium Coaches and athletes use qualitative analysis to evaluate skills anddetect and correct errorsKinesiology Books Publisher6923
Kinematics Versus Kinetics Motion Concepts . Two ways to describe human motion 1. Without reference to forces causing motion 2. Describing motion in terms of forces that cause it KINEMATIC VS. KINETICS Kinesiology Books Publisher 9. 4 10 Describing human motion without its forces
– Exercise physiology – Motor learning – Motor development Sport Books Publisher 18 Motor development – Biomechanics Human movement is a good starting point – Movement experienced daily . Microsoft PowerPoint - PPT CH 1 Introduction to Kinesiology.ppt [Compatibility Mode]
Principles of Kinesiology 1 Principles of Kinesiology 4 Principles of Kinesiology 2 Brain Formatting Principles of Kinesiology 3 Chakra Metaphors The NK Foundation Training is comprised of the units we consider will give you enough skills to facilitate powerful healing change in your friends, family and acquaintances.
Swimming biomechanics, Biomechanics in Rowing, Biomechanics, Biomechanics in Strength and Conditioning and Data analysis in Biomechanics. The conference programme will also include the David Waddell Memorial Keynote Lecture. In addition to the very full scientific schedule, conference will a
Swimming biomechanics, Biomechanics in Rowing, Biomechanics, Biomechanics in Strength and Conditioning and Data analysis in Biomechanics. The conference programme will also include the David Waddell Memorial Keynote Lecture. In addition to the very full scientific schedule, conference will a
Self Administered Applied Kinesiology Applied Kinesiology is a method of checking the truth about a particular statement, belief, or thing. There is much research to support the use of applied kinesiology (AK), also known as muscle checking. For example, one person gave his audience envelopes that had either pure organic vitamin C powder
Division of Kinesiology . Department of Movement Science . The University of Michigan, Ann Arbor . 2002-present Visiting Professor, Faculty of Kinesiology . The University of Zagreb, Zagreb, Croatia. 1994-1996 Associate Director for Research . and Scholarly Activities . Division of Kinesiology
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Performance (UP) Kinesiology tape. The guide contains general advice developed in consultation with various taping experts who work closely with UP. UP Kinesiology tape can be applied in a variety of methods which are flexible and adjustable to suit your needs. Kinesiology tape can be applied by you, health professionals or
