UMass Amherst KIN 430 - 9.4 biomechanics class notes (6 pages)

9 4 biomechanics Mr Ryan Wedge Room 21 totman building rwedge kin umass edu Mr Russell Johnson 21 totman russellj kin umass edu Read lab handout lab quiz next week Learning management system Moodle http moodle umass edu Course name kin430 sec01 fa14 What is biomechanics The study of forces and motion in biological systems The application of mechanical principles in the study of living organisms The science concerned with internal and external forces acting on the human body and the effects produced by those forces Kinesiology study of human movement includes 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 kinetics statics objects at rest dynamics objects in motion kinematics linear angular kinetics what is the difference We will learn later in class history of biomechanics farthest back is to Greeks Aristotle 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 them Others Galen personal physician of roman emperor team doctor for gladiators Scientific approach to anatomy Before then people hadn t seen inside of human body Considered sacrolidge to open human body Medicine at time wasn t very effective Galen introduced dissection Borelli Equilibrium Torque Limited access to measurements Very consistent with how we understand the body works today Newton Same forces come into play in terms of how we move our limitations etc Marey Muybridge Motion analysis Record movement of humans doing movement in order to analyze Marey scientific how body functions Muybridge artist photography created procedure for taking sequential images Put a person in handstand try to figure out the forces in place to keep them balanced take multiple shots in quick succession tons of images of people animals doing all kinds of activities almost all pictures of humans were in the nude loved 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 pictures Claimed they have a flight phase Impossible to tell with naked eye Set up multiple cameras proved that horses have a flight phase Why study biomechanics Central to understanding how the body functions Neural control piece mechanical piece Important for Health Performance cerbral palsy allow them to walk around without becoming incredibly fatigued Older folks osteoarthritis knees really hurt when exercising Minimize load on joints to lessen problem Applications sports injury mechanisms analysis of sports performance gait analysis clinical service lab complete evaluation uses information to choose intervention follow up to see how successful intervention was closest example shriner s hospital in Springfield orthopaedics fracture sustained in certain situation under what conditions do they break easily hold up better Klap skate Dutch studied speed skating Because of structure Extend hip and knee you are inclined to plantarflex ankle Plantarflex point toe Speed skaters prematurely taking foot off ice Klap skate allows skaters to point toe Every record was broken in the next year Virtually everyone uses it Introduced more than 10 years ago allows skaters to skate faster forensics CSI People with biomechanics called on as expert witnesses Court cases People claim they were injured in a certain way by a device Sometimes people make things up to get money out of a company Equine biomechanics Secretariat Biomechanics at Umass 4 in kinesiology department biomechanical engineering gait changes with age injury osteoarthritis affects walking running injuries using orthotic devices hitting people in back seeing how well they withstand balance older people can t withstand as big of a thump in the back degradation of nervous system computer stimulation work dimensions and units mass length time mass M kilogram length L meter time T second derived quantities force MLT 2 Newton work ML 2T 2 joule definition of force F m a mass x acceleration Read through textbook to refresh on concepts Forms of motion Linear Angular General combined linear and angular Linear motion Translation translational movement Movement of a body such that all parts of it travel exactly the same distance in the same direction in the same time important to know pick 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 motion lines that are the same length except curved Angular motion Rotation rotational motion Movement 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 time This 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 body Ex flexion extension of elbow Other examples Internal axis imaginary line Leg lifts around the impaginary line through the hip Angular vs curvilinear motion Track 2 points on body If they form curved lines that are the same length curvilinear Angular motion lines are different lengths General motion General motion linear angular motion Most human activities involve both linear and angular movement and are thus forms of general motion Walking 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 concepts Statics 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 cause kinetics the actual causes of motion inertia the property of a body causing a resistance to change in state of motion mass the quantity of matter making up an object measure of resistance to change in linear motion not the same as weight force a push pull on a body center of mass of body point about which all of mass is evenly