Principles of Biomechanics and Exercise

Principles of Biomechanics and Exercise

1. Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training Principles of Biomechanics and Exercise

2. Biomechanics: “…. The study of forces and the effects of those forces on living things. A force is not clearly defined..Only the effects of a force Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

3. Effect of a force ? Movement, Deformation, Biological change “Any action which tends to cause a change in motion/shape of a body Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

4. First Law “Every object will remain at rest or continue in its state of uniform motion unless it is acted upon by an external force” Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

5. Law of Inertia Inertia = body’s reluctance to change Resistance to change its state of motion Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

6. Second Law “When a net force acts on an object the change in motion that is produced (the acceleration) takes place in the direction of the net force. This acceleration is proportional to the net force and inversely proportional to the mass of the object” Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

7. Law of Acceleration Force = mass x acceleration (F = ma) Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

8. Third Law “Every action has an equal and opposite reaction” Law of Action-Reaction Forces come in pairs of equal and opposite forces Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

9. Most mechanical forces acting on the skeleton are generated either through impact with the ground (i.e., gravitational loading) or through muscle contractions (i.e., muscle loading) Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

10. People who participate in sports that involve weight-supported (e.g., non–weight-bearing) exercise, such as cyclists and swimmers, have commonly been found to have low BMD levels. Because these activities generate relatively high levels of muscle forces but no impact forces Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

11. I mpact activities, through either ground- or joint-reaction forces they generate, confer a unique benefit on bone strength Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

12. Physical activities that involve impact forces, and therefore generate both gravitation and muscle loading, are most likely to have beneficial effects on bone metabolism and reduce fracture risk Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

13. Newton’s Law of Gravitation: Force is proportional to the product of their masses and inversely proportional to the distance between them Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

14. Gravity Perpendicular & down Toward center of earth g = -9.81 m/s2 (sea level) Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

15. Weight (Force) Gravitational force of the earth on a body Fwt = m x g Where; wt = weight m = mass g = gravitational constant (~ 9.81 m/s2) Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

16. Reaction Forces Newtons third law “Every action has an equal and opposite reaction Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

17. Friction Forces Resistance to movement between two surfaces in contact Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

18. Maximum friction depends on a) Magnitude of force pressing surfaces together b) Surface factors Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

19. What is motion ? Motion is a change in position with time Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

20. Linear motion Translation All of the parts of a body move the same distance in the same direction at the same time Units = Metres (m), can also be curvilinear Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

21. Angular motion Rotation Occurs when all of the parts of a body move through the same angle, in the same direction, at the same time Units = Radian (rad) or degree (°) Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

22. Rotation about an axis Axis (internal or external) The central line through point of rotation, perpendicular to the plane of the rotary motion Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

23. General motion Combination of linear and angular Most human motion is general motion Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

24. Distance vs Displacement Distance = length or angle actually travelled Scalar Displacement = length or angle b/w start & end Vector - length and direction Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

25. Angular displacement ( θ) Angular position (θ) angular position of a body relative to zero angle Angular displacement change in angular position vector quantity + ve anticlockwise - ve clockwise Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

26. Angular Displacement Formula. The angular displacement is defined as the angle through which an object moves on a circular path. It is the angle, in radians, between the initial and final positions Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

27. Linear velocity (v) Linear Velocity (vector) Rate at which a body moves from one location to another. Units = meters per second (m.s-1) v = s/t Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

28. Linear velocity (v) Linear Acceleration (vector) Change in velocity occurring over a given time interval Units = metres per second per second (m.s-2) a = (v2-v1)/ t Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

29. Angular velocity ( ω) Average angular velocity: Units: °.s-1, rad.s-1, rev.s-1 Vector Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

30. Angular velocity ( ω) Average angular speed: Units: °.s-1, rad.s-1, rev.s-1 Scalar Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

31. Angular velocity formula When an object is traveling along a circular path, the central angle corresponding to the object's position on the circle is changing. The angular velocity, represented by w, is the rate of change of this angle with respect to time. Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

32. Angular Acceleration Formula. The angular acceleration of a rotating object is the rate at which the angular velocity changes with respect to time. It is the change in the angular velocity, divided by the change in time Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

33. Absolute Vs. Relative joint angles Absolute joint angles Right-hand* horizontal OR vertical to distal end of segment Relative joint angles Between segments Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

34. Linear & angular motion Segment rotations produce linear motion of Whole body Point on a body Body segment Implement or equipment Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

35. Linear & angular motion Key concept: The motion of any point on a rotating body (e.g. wheel) can be described in linear terms Key information: Axis of rotation Radius of rotation Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

36. Linear & angular velocity Linear variables for a point on a rotating body are related to the angular variables for that body Linear velocity; v = r  v = m.s-1  = rad.s-1 Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

37. linear angular acceleration formula In rotational motion, tangential acceleration is a measure of how quickly a tangential velocity changes. It always acts perpendicular to the centripetal acceleration of a rotating object. It is equal to the angular acceleration α, times the radius of the rotation. Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training

38. linear angular acceleration formula In rotational motion, tangential acceleration is a measure of how quickly a tangential velocity changes. It always acts perpendicular to the centripetal acceleration of a rotating object. It is equal to the angular acceleration α, times the radius of the rotation. Stephan BetterBodyz van Breenen Aquatic Fitness Therapy Training