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How Do I Move? Chapter 8

How Do I Move? Chapter 8. The Science of Biomechanics. Objectives:. Identify the external forces acting on the human body. Describe the resulting motion. Describe the expected path and motion of any projectile. Differentiate between throw-like and push-like skills.

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How Do I Move? Chapter 8

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  1. How Do I Move?Chapter 8 The Science of Biomechanics

  2. Objectives: • Identify the external forces acting on the human body. • Describe the resulting motion. • Describe the expected path and motion of any projectile. • Differentiate between throw-like and push-like skills. • Determine the degree of stability possessed by an athlete. • Understand the causes and effects of somersaulting. • Qualitatively analyze simple sport skills that involve throwing, striking, or hitting an object. Sport Books Publisher

  3. Biomechanics • Examines the internal and external forces acting on the human body and the effects produced by these forces. • Aids in technique analysis and the development of innovative equipment designs. • Draws on knowledge from sports medicine, physical therapy, kinesiology, and biomechanical engineering. Sport Books Publisher

  4. golf swing Quantitative Analyses • Involves measurement of variables that are thought to optimize or maximize performance • For Example: • Pattern of forces using a force platform • Sequence of muscle activity using electromyography (EMG) • Three-dimensional (3D) movements of each body segment using high speed cinematography Sport Books Publisher

  5. Qualitative Analyses • Involves obtaining visual or aural information to asses performance It requires: • A framework within which skilled performance can be observed • A set of principles with which movement can be analyzed • A checklist to use when identifying errors • Techniques to use for error detection and correction Sport Books Publisher

  6. Kinematics Study of Motion • The study of time and space factors of a body in motion. • The variables used to describe motion are time, displacement, velocity, and acceleration. • These variables are used to describe both linear and angular motion (angular displacement, angular velocity, and angular acceleration). Sport Books Publisher

  7. Kinematics Variables • Time: temporal characteristics of a performance, either of the total skill or its phases • Displacement: length and direction of the path an athlete takes from start to finish • Angular Displacement: direction of, and smallest angular change between, the rotating body’s initial and final position • Velocity: displacement per unit of time • Angular Velocity: angular displacement per unit of time • Acceleration: rate of change of velocity • Angular Acceleration: angular velocity per unit of time Sport Books Publisher

  8. Kinetics Study of Motion • Focuses on the various forces that are associated with a movement Internal Forces: • Generated by muscles pulling via their tendons on bones, and to bone-on-bone forces exerted across joint surfaces External Forces: • Acting from without, such as the force of gravity or the force from any body contact with the ground, environment, sport equipment, or opponent Sport Books Publisher

  9. Human Body Models Particle Model: • Used when the object of interest (the human body or an object) is airborne after being thrown, struck, or kicked Stick Figure Model: • Used when the object is in contact with its environment Rigid Segment Model: • Used for more sophisticated quantitative analyses Sport Books Publisher

  10. Particle Model Stick Figure Model Rigid Segment Model Three models used to represent the diver Sport Books Publisher

  11. Particle Model • The drawing consists of a single point, representing the body’s center of mass • The body is isolated from its surroundings • The only external forces acting on the body are gravity and air resistance (when a large velocity is involved) • Limited to bodies that are in flight (projectile motion) Sport Books Publisher

  12. Preliminary Steps for Analyzing Human Motion Step 1 • Identify the system to be studied, which is to separate the object of interest from its surroundings. Step 2 • Identify the frame of reference in which the movement takes place. Step 3 • Identify the type of motion that is occurring, the body planes in which movement takes place (sagittal, frontal, or transverse). • Identify the axes of rotation about which rotational motion occurs (sagittal, frontal, or vertical). Sport Books Publisher

  13. General motion Angular motion Types of Motion Linear motion Sport Books Publisher

  14. Curvilinear Motion • When all parts of the body move the same distance, in the same direction, at the same time • Translation refers to movement of the body as a unit without individual segment parts of the body moving relative to one another • Rectilinear motionoccurs when movement follows a straight line • Curvilinear motionoccurs when the movement path is curved Sport Books Publisher

  15. Angular and General Motion Angular Motion (rotation) • Occurs when a body moves along a circular path, through the same angle, in the same direction, and at the same time • The axis of rotationis the point about which movement occurs • All joint motions are angular motions General Motion • A combination of linear and angular motion • Includes most athletic and many everyday activities Sport Books Publisher

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