Unit #2: Human Performance

1. Unit #2:Human Performance Biomechanical Principles and Applications Chapter: 15 Pages: 225 - 239

2. Biomechanics What is biomechanics? • The science that takes the principles of physics and applies them to human movements.

3. Biomechanics What is the focus of biomechanics? 1. How the bones move 2. How the muscles work 3. How the skeleton is propelled by the muscular system

4. Biomechanics Why is biomechanics important? Biomechanics is used to: 1. Improve efficiency of a movement. Eg. Improving an athlete’s technique 2. Design sport and office equipment. (more efficient and reduced risk of injury) Ergonomics – Health and Safety Board

5. Biomechanics Why is biomechanics important cont’d? • Design prosthetic devices such as artificial hips, knees, limbs and orthopedic footwear 4. Identify the causes of physical injuries and provides the corrective actions required for injuries. Eg. Carpal Tunnel Syndrome

6. Biomechanics Who Uses Biomechanics? Doctors, surgeons, physiotherapists, occupational therapists, coaches, athletes, physical education teachers, nurses, dentists, kinesiologists, sports scientists, health and safety boards

7. Biomechanics The Six Basic Human Movements 1. Walking 2. Running 3. Jumping 4. Throwing 5. Striking/Kicking 6. Swimming

8. “Biomechanical Innovations”Exercise Science Textpage: 228 Fosbury Flop Questions: • Who was the “Fosbury Flop” named after? • When was the “Fosbury Flop” introduced to track and field? • How did high jumpers clear the bar prior to the introduction of the “Fosbury Flop?” • Use the diagram at the bottom of the page to describe the “Fosbury Flop” technique. • What accomplishment did Fosbury achieve using this technique? • Explain why this method is better than the Western Roll technique. • What innovation permitted the use of the Fosbury Flop? • What was used before foam mats?

9. “Biomechanical Innovations”Exercise Science Textpage: 228 Jump Serve Questions: • Describe the Jump Serve. • When was the Jump Serve introduced? • How fast can top players serve a ball using the Jump Serve? • Describe how this technique increases the speed of the volleyball serve.

10. Definitions • Mass– the property of an object that measures its resistance to change in speed or direction. Eg. 64kg • Weight - The force that attracts a body to earth. Weight=mass×acceleration due to gravity (9.8 m/s²)

11. Linear Motion Force– is a push or pull (that causes motion) - the unit of measurement is the Newton (N) F = m × a where: F = force m = mass a = acceleration

12. Linear Motion Velocity– the rate of change in position. (speed) - the unit of measurement for velocity (in this class) will bemeters/second. (m/s) v= d÷twhere: v= velocity d= distance t = time

13. Linear Motion Acceleration– rate of change of velocity - it is usually measured in m/s² a = (v² – v¹) (t² – t¹)

14. Biomechanics The study of biomechanics is based on two assumptions: 1. The Law of Conservation of Energy– Energy can never be created or destroyed, it can only be converted from one form to another. Examples of forms of energy: thermal, radiant, electrical, chemical, gravitational, nuclear, motion, sound 2. Equilibrium– a body will not move, or change its velocity, if the sum of all the forces acting on the body is zero.

15. Newton’s Laws of Motion Three Laws of Motion govern all human motion; these laws are named in honour of the scientist who created them, Sir Issac Newton. 1. The Law of Inertia 2. The Law of Acceleration 3. The Law of Reaction

16. Newton’s First Law of Motion: 1. The Law of Inertia (Lazy Law): Every body will remain in a state of constant motion or rest unless acted upon by an outside force. Inertia– an objects resistance to change in motion. Resistance (inertia) is dependant on an objects mass. The greater the mass the greater the objects resistance (inertia).

17. Newton’s Second Law of Motion: 2. Law of Acceleration: When a force is applied to an object it will accelerate in the direction of the force. F = m × a ORa = F ÷ m F= force m= mass a= acceleration

18. Newton’s Third Law of Motion: 3. The Law of Reaction: For every action there is an equal and opposite reaction. When an object exerts a force on a second object, the second object exerts an equal force but in the opposite direction on the first object.

19. Definitions • Centre of Mass – the imaginary point at which a person or an object’s mass is focused.

20. Definitions cont’d • Force as a Vector– a push or pull of a certain magnitude in a particular direction.

21. Rotational Motion

22. Rotational Motion • Rotational movement involves the movement of a body about an axis

23. Rotational Terminology • Angular Displacement– the change in position about an axis. • Angular Velocity– the rate of change of angular displacement with respect to time.

24. RotationalTerminology cont’d • Angular (Rotational) Acceleration– the change in angular velocity a rotating object experiences per unit time. • Moment of Force (Torque)– the push or pull applied to an object that rotates.

25. RotationalTerminology cont’d • Moment of Inertia (Rotational Inertia)– an objects resistance to rotate or change the speed of rotation. • The moment of inertia depends on the distribution of mass in relation to the axis of rotation.

26. Moment of Inertia • The further the mass is from the axis, (the greater the moment of inertia) the less likely an object is to rotate OR the more difficult it is to stop the object from rotating.

27. Moment of Inertia • The closer the mass is to the axis, (the smaller the moment of inertia) the easier it is to rotate the object or stop it from rotating.

28. Comparison of Linear and Rotational Motion

29. Lever Systems • Levers are considered the simplest machines. • Machines are instruments designed to perform work. • Every movable bone in the human body, acting alone or in concert with others, is part of a lever system.

30. Lever Systems • There are three classes of levers. • Class 1 Levers • Class 2 Levers • Class 3 Levers

31. Lever Systems Class 1 Levers The fulcrum (axis) is located between the force (effort) and the resistance (load). Eg. Teeter-totter

32. Class 1 Lever

33. Lever Systems Class 2 Levers The resistance is in between the force and the fulcrum. Eg. wheelbarrow

34. Class 2 Lever

35. Lever Systems Class 3 Levers The force is in between the fulcrum and the resistance. Eg. Shovelling

36. Class 3 Lever

37. Lever Activity In pairs, complete the lever activity.

38. Seven Principles of Biomechanical Analysis • The Seven Principles of Biomechanical Analysis can be grouped into four broad categories. 1. Stability 2. Maximum Effort 3. Linear Motion 4. Rotational Motion

39. Stability Principle #1: The lower the center of mass; the larger the base of support; the closer the center of mass to the base of support; and the greater the mass, the more stability increases.

40. Stability The center of massis an imaginary point at which a person or an object’s mass is concentrated. Thebase of supportis the area between the supporting limbs. Theline of gravityis an imaginary vertical line that passes straight down the center of mass to the ground. Massis the measure of resistance to linear motion.

41. Maximum Effort Principle #2: The production of maximum force requires the use of all possible joint movements that contribute to the task’s objective.

42. Maximum Effort Principle #3: The production of maximum velocity requires the use of joints in order – from largest to smallest.

43. Linear Motion Principle #4: The greater the applied impulse, the greater the increase in velocity. Impulse refers to the application of force over a segment of time that results in a change of momentum. Impulse = F (tf-ti)

44. Linear Motion Principle #5: Movement usually occurs in the direction opposite that of the applied force.

45. Rotational Motion Principle #6: Rotational motion is produced by the application of a force acting at some distance from an axis, that is , by torque.

46. Rotational Motion Principle #7: Angular momentum is constant when an athlete or object is free in the air.