Foundation Year Program An introduction to Biomechanics and

Foundation Year Program An introduction to Biomechanics and Sports Physiology Lecture 1 – The Mechanics in Biomechanics 2015 -16

Foundation Year Program Biomechanics Lecture 1 Objectives: Understand be able to explain: What is Biomechanics? Why am I studying Biomechanics? The structure and function of The amazing human body Mechanics and its application to the human body • Forms of motion • Levers • Balance and center of gravity • • • 2015 -16

Foundation Year Program What is Biomechanics? • From the Ancient Greek βίος bios "life" and μηχανική, mēchanikē " mechanics", to refer to the study of the mechanical principles of living organisms, particularly their movement and structure. (Oxford English Dict. ) Biomechanics studies forces and their impact on living systems. 2015 -16

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Foundation Year Program Why Study Biomechanics? • Applying the concepts of physics and mechanics to the way the body moves and how it applies force to itself and other objects • Understanding biomechanics can help improve performance and reduce injuries in sport. • Possible job in future as equipment designer, in Biomechanics Analysis research labs, Research and design in sports or prosthetic companies, Work related strength and flexibility testing, Design of man-machine interfaces, Research and testing of athletes 2015 -16

Foundation Year Program A few subfields of applied biomechanics include: • Ergonomy, making the things we use work better for us. • Sports Equipment and Sport Surfaces • Sport technique and performance, Sport Safety, • Musculoskeletal biomechanics, Repair and replicate muscles and bones • Cardiovascular biomechanics, repair and replicate the heart, • Rehabilitation, Mobility and longevity, Muscle mechanics, • Control aging related pains and injuries, • Video Game Design 2015 -16

Foundation Year Program The Human Body An amazing organism with bones, muscles, tendons and organs, all working together. To understand how we move, we have to understand how these parts fit together and allow us to move. Today we focus on the physics of motion. 2015 -16

Foundation Year Program Forms of Motion Linear motion: motion along a line • Rectilinear motion: (along a straight line) • Curvilinear motion: (along a curved line) • Angular motion: rotation around an axis 2015 -16

Foundation Year Program Forms of Motion Angular motion Curvilinear motion Rectilinear motion 2015 -16

Foundation Year Program Levers • Humans move using a system of levers – lever is a rigid bar that turns about an axis of rotation or a fulcrum – axis is the point of rotation about which lever moves – levers can be utilized more or less efficiently 2015 -16

Foundation Year Program Levers • Levers rotate when a force (effort, E) is being applied against a resistance or weight • In the body – bones are the bars – joints are the axes – muscles contract to apply force – weights or external loads are the resistance 2015 -16

Foundation Year Program Why Use Levers? Levers perform two main functions: To increase the resistance or load) that can be moved with a given effort e. g. a crowbar. To increase the velocity at which an object will move with A given force. e. g. a golf club or tennis racket. 2015 -16

Foundation Year Program The Three Classes of Levers Three possible orientations of the fulcrum, force and resistance determine the types of lever • Axis “O”- fulcrum - the point of rotation • Applied force “FE” (usually muscle contraction) • Resistance force “FR” (can be weight or/and external loads) 2015 -16

Foundation Year Program The First Class of Levers Effort Arm length Resistance Arm length EA RA FE O FR • In a first class lever the fulcrum is between the effort and the resistance. • This type of lever can increase or decrease the effects of the effort and the speed. Often used for keeping balance. • Ex. Skull-Neck, Tricep-Elbow Joint 2015 -16

Foundation Year Program Mechanical Advantage Effort Arm length EA Resistance Arm length RA O FR FE The mechanical advantage of a lever is the ratio of how much effort force you have to apply relative to how much resistance force you are able to exert. When the mechanical advantage is less than 1, you have to apply an effort force greater than the resistance force in order to move the resistance object. 2015 -16

Foundation Year Program First Class Lever O O 2015 -16

Foundation Year Program The Second Class of Levers FE EA FR O RA • Here the resistance is between the fulcrum and the effort. • The fulcrum is at one end, the effort at the other and the load lies between them. • This type of lever is generally thought to increase only the effect of the effort force. (Describe the Mechanical Advantage here) 2015 -16

Foundation Year Program Second Class Lever FE O FR 2015 -16

Foundation Year Program The Third Class of Levers • Third class Levers FE FR EA O RA • Here the effort is between the fulcrum and the resistance and can be seen in the. • They can increase the body’s ability to move quickly but in terms of applying force they are very inefficient. (Describe the Mechanical Advantage here) 2015 -16

Foundation Year Program Third Class Lever FE O FR 2015 -16

Foundation Year Program Human Body Levers • Human’s levers are mostly built for speed and range of movement at expense of force • Thus, short force arms and long resistance arms require great muscular strength for movement • Examples: biceps and triceps attachments – biceps force arm is about 5 cm – triceps force arm is less than 2. 5 cm 2015 -16

Foundation Year Program Example 1. How much force (in kg) needs to be applied to move 45 kg when the RA is 0. 25 m and the EA is 0. 05 meters? • Use the formula • FE x EA = FR x RA • Note: kgs are not units of force, but sometimes force is divided by g(9. 8 m/s 2) and expressed in kilograms. EA 2. What is the Mechanical Advantage here? RA 2015 -16

Foundation Year Program Example Solution • FE x 0. 05 meters = 45 kg x 0. 25 meters • FE x 0. 05 = 11. 25 kg • FE = 225 Kg RA = 0. 25 ? FA O EA = 0. 05 45 FR 2015 -16

Foundation Year Program Lever Length • Where is the velocity or speed the greatest; at A’ or B’? B’ A’ O A B • How can this principle be applied to tennis? 2015 -16

Foundation Year Program Lever Length • In general, a longer lever increases the speed at the end of the racquet. • However, with longer levers, it is harder to be accurate. 2015 -16

Foundation Year Program Stability • Center of gravity (CG): Point at which all parts of a body are equally balanced • Base of support (BOS): Area within an object’s point of contact with the ground • Line of gravity (LOG): Direct line from the center of gravity to the ground 2015 -16

Foundation Year Program Center of Gravity • The center of gravity can be shifted by stretching, bending, changing position • The center of gravity can be outside of the body • Low center of gravity is typical for more stable positions 2015 -16

Foundation Year Program Base of support • The BOS area can be changed • Larger BOS area is typical for more stable positions • In humans, wide BOS is usually accompanied by low CG 2015 -16

Foundation Year Program Line of Gravity • The line of gravity is always vertical • The LOG must outside the base of support to initiate or continue movement • The further away the LOG from the BOS, the greater the tendency to move in that direction 2015 -16

Foundation Year Program Stability low gravity stable wide support within Someone is more _____when they have a _______centre of _______, a ______ base of _____ and a line of gravity that falls _______the body. 2015 -16

Foundation Year Program Advantages/Disadvantages to Bipedal Locomotion What about strength? Animals vs humans? • Disadvantages – Loss of speed – Loss of agility – Loss of stability • Advantages – Carry food – Carry tools – Increased ability to nurture/protect offspring 2015 -16

Foundation Year Program Interesting Fact: T Rex Arms How much could T Rex lift with its arm? (50 x 6=300 lbs 136 kg) ? (160 -200 kg) 2015 -16

Foundation Year Program Open Question for the Seminar • Do artificial legs provide an unfair advantage? • If yes, how? • If no, why? 2015 -16

Foundation Year Program Also For The Seminar… Review the lecture materials and know: • The basic definition of Biomechanics, and its importance. • The three different classes of levers and • Examples of where each type is found in the human body. • Mechanical advantage and why having M. A. <1 can be required in some muscle groups. • Please, make sure your understand how each type of lever works. Also: Refresh your problem solving skills in statics 2015 -16

Foundation Year Program Summary • Mechanics and its application to biological systems • Scope of biomechanics • Types of motion • Levers in human body • Stability and center of gravity 2015 -16