1. Biomechanics Is a study of forces and their effects on the human body during movement.

2. Newton’s Laws of Motion Sir Isaac Newton was a famous seventeenth- century scientist who developed three laws to explain the relationship between the forces acting on a body and the motion of a body.

3. Law 1: The law of inertia An object at rest tends to remain at rest unless acted upon by some external force. In order to get a body moving, a force must overcome the object’s tendency to remain at rest or inertia. The amount of inertia an object has depends on its mass. http://www.youtube.com/watch?v=by-7kkAu2Pg

4. Law 2: Acceleration When a force acts upon a mass, the result is acceleration of that mass. The object will move in the direction the force was applied. Depending on the size of the force and the size of the object, the object will accelerate accordingly. Smaller object = faster Bigger object = slower

5. Law 3: Action Reaction For every action there is an equal and opposite reaction. E.g. If an athlete exerts a force onto the ground in order to push off (Action Force), the ground will exert an equal and opposite force on the athlete (Reaction Force), pushing them up in the air. The two forces always work in pairs

6. ACTION – REACTION A runner exerts a force against the ground. This creates an equal and opposite reaction force which moves the body over the ground.

7. FORCE SUMMATION The summation (sum) of forces that have accumulated throughout the bodies muscles during an action. Allows maximal force to be produced by the muscles and then transferred into physical movements

8. Force summation can be maximised by: Using larger muscles first, smaller muscles last Ensuring that the athlete is balanced and stable so therefore the athlete can generate a maximum force. Correct order of muscles Timing of muscles

9. COG Centre of Mass in the centre line of body. Provides person wCentre of Mass in the centre line of body. Provides person with high level of balance ith high level of balance Centre of mass outside midline of body provides person with less balance. More likely to fall over.

10. Line of Gravity Line of gravity is the vertical line that passes through the centre of gravity to the ground. The line of gravity is important when determining stability: If the line of gravity falls within the object/person’s base of support [area in contact with the ground] the object is relatively stable. If the line of gravity falls outside the object/person’s base of support they are not

11. Base of Support Base of support is the area within an object or person’s point of contact with the ground. The larger / wider the base of support = more stable Narrow base of support = less stable

12. Stability Stability is vital for all movements. Improved stability often allows skills to be executed more effectively. Stability can be improved through increasing abdominal strength. This improves body control and speed as a person is able to move their centre of gravity in a direction more effectively.

13. Stability is improved through: Widening the base of support

14. Stability is improved through: Lowering the centre of gravity

15. Stability is improved through: Keeping the line of gravity within the base of support

17. LEVERS: Are simple machines which apply force and speed more easily. Levers help to move loads at greater speeds Muscles and bones act together to form levers. A lever is a rigid rod (usually a length of bone) that turns about a pivot (usually a joint). Levers can be used so that a small force can move a much bigger force.lever pivotforce

18. External levers vs internal levers EXTERNAL: External levers allow force and speed to be applied from outside the body E.g. paddles or oars in boats, pole in pole-vaulting

19. Internal levers For human movement the most important levers are internal, within the body These levers are made up of: – bones act as lever arms (resistance) – joints act as pivots (Fulcrum) – muscles provide the effort forces to move loads (effort)

20. SHORT TO LONG Moves from short lever to a long lever in kicking Short lever allows more speed Long lever allows more force

21. SHORT TO LONG…

22. Maximising lever length to improve performance Shortening the lever arm (by bending at the joint) allows the lever arm to GENERATE force Once this has been achieved the lever arm can be lengthened (straighten the joint) to maximise speed and force applied.

23. Kicking a rugby ball Back swing: Kicking leg is bent, creating a short lever to swing towards the ball at speed Forward swing: Kicking leg straightens creating a longer lever allowing the ball to be kicked with more force (and speed)