9/4biomechanicsMr. Ryan Wedge Room 21, totman [email protected]. Russell Johnson21, [email protected] lab handout – lab quiz next week!Learning management systemMoodle: http:://moodle.umass.edu/Course name: kin430-sec01 fa14What is biomechanics?The study of forces and motion in biological systemsThe application of mechanical principles in the study of living organismsThe science concerned with internal and external forces acting on the human body, and the effects produced by those forcesKinesiology-study of human movementincludes: biomechanics, exercise physiology, athletic training…What about “sports medicine”?“exercise science”a broad term that encompasses all clinical and scientific aspects of sports and exercise-team doctor biomechanics-organismal biology anatomy & physiology gross anatomy & systems physiology*this is why A&p is a pre-req“Mechanics”-physics mechanics  statics & dynamics   kinematics and kineticsstatics – objects at restdynamics – objects in motionkinematics – linear, angularkinetics - ?^ what is the difference? We will learn later in classhistory of biomechanics-farthest back is to GreeksAristotle wrote about observations of humans/animals doing activities such as running, jumping, etc.He identified that when someone is running they push against ground and it pushes back against themOthers:Galen – personal physician of roman emperor, team doctor for gladiatorsScientific approach to anatomyBefore then, people hadn’t seen inside of human bodyConsidered sacrolidge to open human bodyMedicine at time wasn’t very effectiveGalen introduced dissectionBorelliEquilibriumTorqueLimited access to measurementsVery consistent with how we understand the body works todayNewtonSame forces come into play in terms of how we move, our limitations, etc.Marey & MuybridgeMotion analysisRecord movement of humans doing movement in order to analyzeMarey – scientific, how body functionsMuybridge – artist, photography, created procedure for taking sequential imagesPut a person in handstand, try to figure out the forces in place to keep them balanced-take multiple shots in quick successiontons of images of people/animals doing all kinds of activitiesalmost all pictures of humans were in the nudeloved gambling and drinking, shot a man, paid off the judge-horses can run faster because it always has at least one hoof on the ground pushing itself forward.. is this true?Muybridge proved this wrong with his picturesClaimed they have a flight phaseImpossible to tell with naked eyeSet up multiple cameras, proved that horses have a flight phaseWhy study biomechanics?Central to understanding how the body functionsNeural control piece, mechanical piece, Important for:HealthPerformance-cerbral palsy: allow them to walk around without becoming incredibly fatiguedOlder folks: osteoarthritis, knees really hurt when exercisingMinimize load on joints to lessen problemApplications:-sports injury mechanisms-analysis of sports performance-gait analysisclinical service labcomplete evaluationuses information to choose interventionfollow up, to see how successful intervention wasclosest example: shriner’s hospital in Springfield-orthopaedicsfracture sustained in certain situationunder what conditions do they break easily/hold up better?Klap skateDutch studied speed skatingBecause of structure,Extend hip and knee, you are inclined to plantarflex anklePlantarflex = point toeSpeed skaters prematurely taking foot off iceKlap skate allows skaters to point toeEvery record was broken in the next yearVirtually everyone uses itIntroduced more than 10 years ago-allows skaters to skate fasterforensicsCSI –People with biomechanics called on as expert witnessesCourt casesPeople claim they were injured in a certain way by a deviceSometimes people make things up to get money out of a companyEquine biomechanicsSecretariatBiomechanics at Umass?-4 in kinesiology department-biomechanical engineering-gait changes with age, injuryosteoarthritis affects walkingrunning injuries, using orthotic devices-hitting people in back, seeing how well they withstand balanceolder people can’t withstand as big of a thump in the backdegradation of nervous systemcomputer stimulation workdimensions and unitsmass & length & timemass – M – kilogramlength – L – metertime – T – secondderived quantities:force – MLT^-2 – Newtonwork – ML^2T^-2 – jouledefinition of force:F = m * a (mass x acceleration)Read through textbook to refresh on conceptsForms of motionLinearAngularGeneral – combined linear and angularLinear motionTranslation/translational movementMovement of a body such that all parts of it travel exactly the same distance, in the same direction, in the same timeimportant to knowpick two points on body and track them as movement occurs*a skater holding a position as they glide across the ice*form two parallel, straight lines-rectilinear motion-curvilinear motion-linear motion in a curved motionlines that are the same length except curvedAngular motionRotation/rotational motionMovement of body along circular path about a line is space such that all parts of the body travel through the same angle, in the same direction, in the same timeThis line, which may or may not pass through the body itself, is know as the axis of rotation and lies at right angles to the plane of motion of the bodyEx. flexion/extension of elbowOther examples:Internal axis, imaginary lineLeg lifts, around the impaginary line through the hipAngular vs. curvilinear motionTrack 2 points on bodyIf they form curved lines that are the same length, = curvilinearAngular motion – lines are different lengthsGeneral motionGeneral motion = linear + angular motionMost human activities involve both linear and angular movement and are thus formsof general motionWalking/running, both forms of motion happening- Translation (moving body from point a to point b on a flat path by rotating joints around each other-Basic kinetic conceptsStatics – study of forces acting on a body:-at rest; velocity is zero-in uniform motion; velocity is constant but not zero (uncommon in human movement)dynamics – study of bodies in motion:kinematics: description of motion, independent of the causekinetics: the actual causes of motioninertia – the property of a body causing a resistance to change in state of motionmass – the quantity of matter making up an object; measure of resistance to change