PTY1016 Biomechanics (Kinematics) PDF

PTY1016 Foundation of Physiotherapy 1: Movement Biomechanics Seah Jianxing [email protected] References Dutton, M. (2020). Dutton’s introduction to physical therapy and patient skills (Second edition.). McGraw Hill. Chapter 3 https://acces...

PTY1016 Foundation of Physiotherapy 1: Movement Biomechanics Seah Jianxing [email protected] References Dutton, M. (2020). Dutton’s introduction to physical therapy and patient skills (Second edition.). McGraw Hill. Chapter 3 https://accessphysiotherapy.mhmedical.com/content.aspx?bookid=2976&sectionid=250229067#1176134695 Biomechanics of the body. (2008). Video Education Australasia. https://singaporetech.primo.exlibrisgroup.com/permalink/65SIT_INST/1i4buil/alma991000741070204056 https://fod-infobase-com.eu1.proxy.openathens.net/p_ViewVideo.aspx?xtid=129227 Nordin, M., & Frankel, V. (2012). Basic biomechanics of the musculoskeletal system (4th ed., International ed.). Wolters Kluwer Health/Lippincott Williams & Wilkins. https://singaporetech.primo.exlibrisgroup.com/permalink/65SIT_INST/1vcvbdp/alma991000504529704056 Neumann, D. A., Kelly, E. R., Kiefer, C. L., Martens, K., & Grosz, C. M. (2017). Kinesiology of the musculoskeletal system : foundations for rehabilitation (Third edition.). Elsevier. Chapter 4, pp 77-114 https://singaporetech.primo.exlibrisgroup.com/permalink/65SIT_INST/1i4buil/alma991000614999804056 Hall, S. (2017). Basic Biomechanics. In Basic Biomechanics (8th ed.). McGraw-Hill Education LLC. https://singaporetech.primo.exlibrisgroup.com/permalink/65SIT_INST/1qe4ih4/cdi_mcgrawhill_accessphysiotherapy_sc n00360082 Richards, J. (2018). The comprehensive textbook of clinical biomechanics (2nd edition.). Elsevier. https://singaporetech.primo.exlibrisgroup.com/permalink/65SIT_INST/1i4buil/alma991000694999404056  Figure 1. Model of elastic energy storage Arm-cocking and acceleration phases of the overhand throw (A). Humans (left) and chimpanzees (right) differ in arm abduction and elbow flexion during throwing (B) because of differences in shoulder orientation, which alters the major line of action of the Pectoralis major (C). Aligning the long axis of the humerus with the major axis of P. major and flexing the elbow maximizes inertia to shoulder flexion torque and loads the elastic ligaments in the shoulder. However, chimpanzee morphology is compromised between maximizing humeral rotation or elbow extension. Signatures of shoulder orientation found in the scapula (D) can be used to reconstruct hominin shoulder orientation. Roach, N. T., Venkadesan, M., Rainbow, M. J., & Lieberman, D. E. (2013). Elastic energy storage in the shoulder and the evolution of high-speed throwing in Homo. Nature, 498(7455), 483-486. https://www.bbc.com/news/science-environment-23061016 Why study biomechanics? Provides foundational understanding of mechanical principles and how they can be applied in analyzing human movement. Address problems related to human health, healthcare and performance. Even at a basic level of analysis, this information can be used to guide treatment decisions and to understand mechanisms of injury. Who apply biomechanics? Physiotherapists Podiatrists Biomedical engineers Personal trainer / instructor /coaches Orthopaedic surgeons  Sub-branches of biomechanics Statics: study of systems in constant motion, including zero motion. 2 Dynamics: study of systems subject to acceleration. Kinematics: study of the appearance or description of motion, mainly the time and spatial factors of motion. Kinetics: study of the actions of forces acting on a body that influence its movement. What is kinematics? What we visually observe of a body in motion is called the kinematics Shoulder horizontal abduction Shoulder extension of the movement. Kinematics is the study of the size, Shoulder internal rotation sequencing, and timing of movement, without regard for the forces that cause or result from the motion. Thi s Photo by Unknown Author i s licensed under CC BY-NC The kinematics of an exercise or a sport skill is known, more commonly, as form or technique.  Resultant muscle force Free body diagram of the shank-and-foot at the instant of heel contact during walking. The segment What is kinetics? Joint reaction force is isolated by figuratively “cutting through” the knee joint. Relevant forces are drawn in as shown. The X- Y coordinate reference frame is placed so the X axis Kinetics is the study is parallel with the shank. of forces, including internal forces Neumann, D. A., (muscle forces) and Weight of shank Weight of foot (2017). Kinesiology of the external forces (the musculoskeletal system : foundations for rehabilitation forces of gravity and Ground reaction force (Third edition.). Elsevier, pp. 84-85 the forces exchanged by bat and ball). Van Houwelingen, J., Schreven, S., Smeets, J. B., Clercx, H. J., & Beek, P. J. (2017). Effective propulsion in swimming: grasping the hydrodynamics of hand and arm movements. Journal of applied biomechanics, 33(1), 87-100. Kinematics vs Kinetics Kinematics Kinetics Distance, displacement, speed, Force, pressure, velocity, acceleration/deceleration torque, work, How far? How fast? How quickly? impulse, momentum, power Thi s Photo by Unknown Author i s licensed under CC BY Thi s Photo by Unknown Author i s licensed under CC BY Qualitative vs Quantitative data descriptive Qualitative Quantitative For example: strong, skillful, agile, For example: flexible, fast running speed = 5 m/s height = 1.75 m mass = 68.2 kg Qualitative vs Quantitative Long jump: (Carl Lewis vs Mike Powell, 1991) Observer 1: Good jump, great lift. Observer 2: Carl Lewis – 8.91 metres, Mike Powell – 8.95 metres. Biomechanical researchers rely heavily on quantitative techniques to answer questions related to mechanics of living organisms. Physiotherapists, clinicians and coaches employ qualitative observations of their patients, athletes, or students to provide opinions and advice. https://www.youtube.com/watch?v=AxvDku19_IM motion capture electrical goniometer isokinetic madine How do we measure movements quantitatively? Neumann, D. A., (2017). Kinesiology of the musculoskeletal system : foundations for rehabilitation (Third edition.). Elsevier, pp. 104-106 Tools for Measuring Human Movement Quantities Videography Video of 30 pictures per second sufficient for most human movements. Clarity of the captured images. Number of cameras to use (to ensure all movements can be viewed and recorded). Movement Monitoring Systems Real-time tracking of reflective body markers (linked to computer for online calculation of kinematics/kinetics quantities). Goniometer or electrogoniometer Accelerometer Force plates – measures ground reaction forces. Electromyography (EMG) – measures muscle activities.  PTY1011 Foundation of Physiotherapy: Movement Biomechanics Kinematics of Human Movement Seah Jianxing [email protected] Kinematics vs Kinetics of movements (e.g. gait) Kinematics is the study of the geometry, pattern or form of motion with respect to time (not concerned with forces, but rather the details of the movement itself). Kinetics is the study of the forces associated with the motion. Knowledge of the patterns of the forces is necessary for an understanding of the cause of any https://www.tekscan.com/blog/medical/what-are-various-types- movement. gait-analysis Forms of Motion Most human movement is a combination of linear and angular motions. Linear motion: motion along a line, with all parts of the body moving in the same direction at the same speed (also: translatory motion or translation). Rectilinear: along a straight line. Curvilinear: along a curved line. Muscolino, J. E. (2017). Kinesiology : the skeletal system and muscle function (3rd edition.). Elsevier, chapter 18. Angular motion: rotation around a central imaginary line known as the axis of rotation, which is orientated perpendicular to the plane where the rotation occurs. Gymnast performs a circle on a bar. Springboard diver executes a somersault in midair. http://clipart-library.com/free/back-handspring-silhouette.html Spatial Reference Systems Spatial reference system used to standardize the measurements to be taken. Cartesian coordinate system: most commonly used. Movements primarily in a single direction, can be analyzed using a 2-dimensional Cartesian coordinate system (x - horizontal, y - vertical) 3-dimensional movement can be Nedeljković, Z., & Sekulić, A. (2015). Concept of spatial coordinate systems, their defining and implementation as a precondition in geospatial applications. Glasnik Srpsk og geografsk og analyzed by adding a z-axis. društva, 95(4), 77-102. Coordinate systems Cartesian coordinate system The rectangular or cartesian coordinate system that is composed of three mutually perpendicular directions (x,y,z) is the reference frame for describing linear movements. Polar coordinate system The polar coordinate system is suited for analyzing angular motions. As shown, the polar coordinate of point P2 are defined by parameters r and θ. r is the distance between the origin O of the coordinate frame and point P2, and θ is the angle line OP2 makes with the horizontal. 2 https://www.skillsyouneed.com/num/cartesian-coordinates.html Linear Kinematic Quantities Visually observable aspects of technique or form. The appearance of a motion. The pattern or sequencing of movement with respect to time. Linear Kinematic Quantities: Displacement What is linear displacement? Change in location Direct distance from initial to final location Vector equivalent of linear distance, i.e. direction is important, not just magnitude Measured in units of cm, m, km https://sciencestruck.com/difference-between-distance-displacement Linear Kinematic Quantities: Speed What is linear speed? Distance covered over the time taken Speed = A scalar quantity Measured in units of Linear Kinematic Quantities: Velocity What is linear velocity? velocity = Vector equivalent of linear speed Measured in units of Linear Kinematics: Resultant Velocity The resultant is the sum of two or more single vectors. * Plane velocity + Wind velocity = Resultant velocity The velocity of a swimmer in a river is the vector sum of the velocities of swimmer and current.  The swimmer is swimming at speed 5 m/s north and the current velocity is 3 m/s east, what is the resultant velocity? Secondary school Maths revision: Pythagoras’ theorem a2 + b2 = c2 c = =+ 32 = 5. 8 m/s a c b 25 + 9 = 34; √34 = 5.8 m/s Linear Kinematic Quantities: Acceleration What is acceleration? Rate of change in linear velocity Acceleration = final -- initial v time Measured in units of https://www.khanacademy.org/science/physics/one-dimensional- motion/acceleration-tutorial/a/acceleration-article * Increasing speed Increasing speed Negative acceleration Positive acceleration Decreasing speed Decreasing speed Positive acceleration Negative acceleration Motion in a negative direction Motion in a positive direction Acceleration may be positive, negative, or equal to zero, based on the direction of motion and the direction of the change in velocity.  Is a soccer kick accelerating or decelerating? the ball acceleration after decelerate contact Thi s Photo by Unknown Author i s licensed under CC BY-NC-ND So far, we have been discussing linear kinematics. Let’s look at angular kinematics. Linear kinematics Angular kinematics Displacement (s) Angle (θ) Velocity (v) Angular velocity (ω) Acceleration (a) Angular acceleration (α) Thi s Photo by Unknown Author i s licensed under CC BY-SA Thi s Photo by Unknown Author i s licensed under CC BY-NC-ND Angular Kinematics – what types of angles? Absolute angle: Angle measured with reference to an absolute reference line, either horizontal or vertical. Relative angle: Angle at a joint formed between Also known as joint angle. longitudinal axes of adjacent body segments. The straight, fully extended position at a joint is regarded as zero degrees. Joint Angles Kim, J. H., & Won, B. H. (2019). Kinematic on Ankle and Knee Joint of Post-Stroke Elderly Patients by Wearing Newly Elastic Band-Type Ankle–Foot Orthosis in Gait. Clinical interventions in aging, 14, 2097. When a patient is in the anatomical position, all joint angles are zero degrees. This is used as the reference to determine joint angles. Relevance: in goniometry ROM measurements, consider the two segments about the joint the movement takes place to be in anatomical position, then you will know which is the joint angle. Joint Angles It is important that the body position does not influence the way the joint angles are measured/defined, so long the anatomical position is adopted as reference. Image source: https://www.youtube.com/watch?v=KZ40yziHPmY Ima ge source: http://voxmdweb.com/knee-exercises/active-range-motion-hip-flexion-supine-knee-bent/ Tools for Measuring Joint Angles Goniometer Essentially a protractor with two long arms attached. Direct measurement of relative joint angles on a human subject. One arm is fixed Other arm is free to rotate Center of goniometer is aligned over the joint center Two arms are aligned over the longitudinal axes Electrogoniometer Halo digital goniometer Angular Kinematics Angular kinematics – the description of the circular motion or rotation of a body / body segment. Motion is described in variables of: Angular distance (ϕ) and angular displacement (θ) Angular speed (σ) and angular velocity (ω) Angular acceleration (α) Angular Kinematics i. Angular distance (ϕ:phi) and angular displacement (θ: theta) Counterclockwise is positive Clockwise is negative & [units: degrees, radians, or revolution (rev)] O Initial A B Final C * What is a Radian? The size of the angle subtended at the centre of a circle by an arc equal in length to the radius of the circle. Radian measure: radius radius 2 radians = 360o 1 radian Radians = Degrees (2) / 360 Radians = Degrees x  / 180 radius What are Radians? https://www.youtube.com/watch?v=cgPYLJ-s5II Units of angular measure # 90 degrees 180 degrees 270 degrees  3 radians  radians radians 2 2 1 1 3 revolution revolution revolution 4 2 4 Angular Kinematics ii. Angular speed (σ: sigma) Angular speed = Angular velocity (ω: omega) Angular velocity = [units: deg/s, rad/s, rev/s, rpm (revolution per minute)] Angular Kinematics iii. Angular acceleration (: alpha ) Question Cristiano Ronaldo kicks the soccer ball, the change in the angular velocity of the knee Angular acceleration = joint is 3.6 rad/s in 1.2 s, what is the angular acceleration of his knee? [units: deg/s2, rad/s2, rev/s2 ] Thi s Photo by Unknown Author i s licensed under CC BY-NC-ND  Relationships Between Linear and Angular Motion * The larger the radius of rotation (r), the greater the curvilinear distance (s) traveled by a point on a rotating body. s2 s = r 2 2 where s is the curvilinear distance travelled, m s1 r is the radius of rotation, m 1 1  is the angular distance, radian r2  r1  Relationships Between Linear and Angular Motion * Since velocity is displacement over time, linear and angular velocity are related by the same factor that relates displacement: the radius of rotation (r). v = r where v is the linear (tangential) velocity, m/s r is the radius of rotation, m  is the angular velocity, rad/s Relationships Between Linear and Angular Motion The linear acceleration of a body in angular motion can be resolved into two perpendicular linear acceleration components. Tangential acceleration Radial acceleration at ar * Tangential acceleration Component of acceleration of angular motion directed along a tangent to the path of motion. Represents change in linear velocity. at = 𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦 = 𝑉𝑓 −𝑉 at 𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑡𝑖𝑚𝑒 𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑡𝑖𝑚𝑒 r = = r 𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑡𝑖𝑚𝑒 where at is the tangential acceleration, m/s2 v is the tangential velocity, m/s r is the radius of rotation, m  is the angular velocity, rad/s  Is the angular acceleration, rad/s2 * Radial acceleration Component of acceleration of angular motion directed toward the centre of curvature. Represents change in direction. v2 ar = r = r 2 ar where ar is the radial (centripetal) acceleration, m/s2 v is the tangential velocity, m/s r is the radius of rotation, m  is the angular velocity, rad/s  summary * Relationships Between Linear and Angular Motion Tangential acceleration: 𝑉𝑓−𝑉𝑖 r𝑓 - ri at = = = r 𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑡𝑖𝑚𝑒 𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑡𝑖𝑚𝑒 at ar Radial or centripetal acceleration: a v2 ar = = r 2 r 2 2 Linear (total) acceleration: a = a t + a r Example : A softball pitcher executes a pitch in 0.65 secs. If her pitching arm is 0.7 m long, what are the magnitudes of the tangential and radial accelerations on the ball just before ball release, when tangential ball speed is 20 m/s? What is the magnitude of the total.. acceleration on the ball at this point? Solution: at = (Vf – Vi) / t at = (20 – 0) / 0.65 = 30.8 m/s2 a ar = v2 / r = (20)2 / 0.7 = 571.4 m/s2 r = 0.7 m v = 20 m/s a=√ (30.8)2 + (571.4)2 = 572.2 m/s2 ar Levers and Pulleys Conceptualizing the human body as machines in terms of levers, wheel and axle and pulleys. Thi s Photo by Unknown Author i s licensed under CC BY-SA Thi s Photo by Unknown Author i s licensed under CC BY-SA Advantages of ‘machines’ Increases range of motion, e.g. levers. Provides speed, e.g. levers. Changes direction of applied force, e.g. pulleys. Increases magnitude of a force, i.e. less effort need to overcome load. Force to overcome resistance or load. Axis of movement. Resistance or load to be overcome. FAR 1st Class 2nd Class ARF - more a lot BUT weight little ROM 3rd Class AFR Houglum, P. A., & Bertoti, D. B. (2012). Brunnstrom's Clinical Kinesiology. (6th ed.). Philadelphia: F. A. Davis Company. G Mechanical Advantage Mechanical advantage (MA) of a lever refers to the ratio between the length of the force arm and the length of the resistance arm. Assuming forces to be equal in magnitude… First-class lever: MA =/>/< 1 Second-class lever: MA > 1 (Advantage, less force need to lift huge weight, but lesser range of motion) Third-class lever: MA < 1 (Disadvantage, more force needed but more speed, larger range of motion) Most muscle systems are third class levers  - axis of ⑧ rotation Sorce resistance Pulleys Houglum, P. A., & Bertoti, D. B. (2012). Brunnstrom's Clinical Kinesiology. (6th ed.). Philadelphia: F. A. Davis Company.  A fixed pulley system changes direction of a force’s pull without providing any mechanical advantage. This may be useful clinically when it is desirable to create more or less force as a specific range of motion. Levangie, P. K., & Norkin, C. C. (2011). Joint structure and function a comprehensive analysis. (5th ed.). Philadelphia: F.A. Davis. Anatomical Pulleys Muscle fibres or tendons may wrap around a bone or are deflected by a bony prominence. Altering the direction of pull of a muscle is caused by the bone or bony prominence resulting in deflection or an anatomic pulley. Pulleys change the direction without changing the magnitude of the applied force. Change in action line produced by an anatomic pulley will have implications for the ability of the muscle to produce torque. Levangie, P. K., & Norkin, C. C. (2011). Joint structure and function a comprehensive analysis. (5th ed.). Philadelphia: F.A. Davis. Anatomical Pulleys Levangie, P. K., & Norkin, C. C. (2011). Joint structure and function a comprehensive analysis. (5th ed.). Philadelphia: F.A. Davis.