1. Biomechanical Principles

2. Overview NEWTONS THREE LAWS FORCE SUMMATION STABILITY AND BALANCE
Inertia
Force
Action and reaction
FORCE SUMMATION
Generating momentum
Stretching muscles
Sequencing
Timing
Full range of motion
STABILITY AND BALANCE
Line of Gravity (LOG)
Centre of Gravity (COG)
Base of Support (BOS)
LEVERS
First Class
Second Class
Third Class
PROJECTILE MOTION
Height of Release
Angle of Release
Speed of Release
Spin

3. Newton’s First Law of Motion INERTIA
“An object at rest tends to remain at rest unless acted upon by some external force. {inertia}”
Having a great deal of inertia is an advantage when bulk is important.
It can be a disadvantage
Require a lot of force to get moving, decrease agility.
If inertia is the objects resistance to movement which barbell has the greatest inertia?

4. Newton’s Second Law of Motion FORCE
“When a force acts upon a mass, the result is acceleration of that mass.”
Force = mass x acceleration
F= ma
1. The greater the force, the greater the acceleration.
2. The smaller the mass, the greater the acceleration when a constant force is applied.
3. The mass will accelerate in the direction the force is applied.
Applying the rule to a soft ball throw:
The more force you apply through your muscles when pitching the softball the further the softball will go

5. Newton’s Third Law of Motion Action and Reaction
“For every action, there is an equal and opposite reaction.”
When we apply a force to something, this is known as action force.
The object we apply a force to, applies a force back, a reaction force.
These two forces always work in pairs.
When a ball is bounced it bounces back in a direction opposite to which it is dropped.

6. STABILITY AND BALANCE
There are three aspects that help us to maintain stability and balance
CENTRE OF GRAVITY
LINE OF GRAVITY
BASE OF SUPPORT

7. CENTRE OF GRAVITY
Centre of Gravity (COG) is defined as the centre of weight distribution in the body
When we are standing COG is around our belly button
COG moves depending on how our bodies are positioned

8. LINE OF GRAVITY
Line of Gravity (LOG) is an imaginary line that runs through the centre of gravity to the base of support

9. BASE OF SUPPORT
Base of Support (BOS) is defined as how the person is standing
If their feet are wide apart they have a large BOS which means they have better stability
If their feet are close together they have a small BOS which means they are less stable
If a person wants to produce speed which BOS would be better and why??

10. BOS, COG, LOG

11. PROJECTILE MOTION A projectile is an object that is moving in the air.
Factors that effect projectile motion:
Gravity
Air resistance
Speed of Release
Angle of Release
Height of Release
Spin

12. SPEED, HEIGHT AND ANGLE OF RELEASE
The speed, height and angle of release of a projectile have important implications for the projectiles flight path and distance
Speed of release is largely determined by muscle force and leverage of the body
Angle of release is the angle (measured from the horizontal) that a projectile is released from.
Activities requiring large angle of release usually projected from ground level. e.g. golf
Activities requiring small angle of release usually have a larger height of release (above ground level) e.g. diving or throwing a cricket ball.

13. PROJECTILE MOTION AND DISTANCE
When projecting for maximal distance apply the following:
The greater the speed of release, the more distance is covered
The greater the height of release, the more distance is covered.
Optimal angle of release is around 45o.

14. HORIZONTAL AND VERTICAL RELEASE
Almost all projectile sports require both horizontal and vertical velocity, the amount of each is dependant on the desired outcome and the nature of the sport.
You need enough horizontal velocity to ensure that the projectile travels in the desired direction
You need enough vertical velocity to ensure that the projectile covers the desired distance through the air

15. ANGLE OF RELEASE
Projectiles require different angles of release depending on the sport.
The optimal angle of release is 45 degrees
VERTICAL ANGLE OF RELEEASE
HORIZONTAL ANGLE OF RELEASE

16. HEIGHT OF RELEASE
Increasing the height of release increases the horizontal distance covered
Which sports would this be important in??
Achieving maximum height of release usually involves creating long levers by straightening body segments involved in releasing the projectile.

17. Height of release of a projectile affects the speed and angle of a projectile

18. SPIN
A spinning object will follow a different path as a non spinning object
spin gives projectiles stability in the air.
Spin determines how an object will rebound after landing/or be manipulated to travel a certain path.

19. FORCE SUMMATION
Force Summation is the amount of force produced by the body’s muscles to produce a force
There are five aspects that determine the accuracy of force summation
Segments
Stretching out
Timing
Sequencing
Full range of motion

20. BODY SEGMENTS
We should use as many body segments as possible to generate as much force as we can so that the projectile’s horizontal and/or vertical distance increases
To maximise the muscular force that each muscle group associated with each segment can generate
Which body segments are used to execute the hockey flick?
Legs, hips, shoulder, elbow , wrist

21. STRETCHING OUT MUSLCES
Before we begin the sequence of movements, such as the throwing action, we should stretch muscles out to their optimal length.
It allows the muscles to be contracted with optimum force
For example: Softball throw
Large step forward
Extension of shoulder and arm behind

22. SEQUENCING
Generally we use larger muscle groups first and then the smaller muscle groups
This creates more force and generates more movement on the projectile – WHY??
JUMPING FOR HEIGHT
With straight legs hands on hips
With straight legs arms swinging
Bend legs, straighten legs, arms swinging

23. TIMING OF BODY SEGMENTS
We need to use the right muscle groups at the right time to so the movement is not uncoordinated
We use larger muscle groups first and then smaller muscle groups

24. FULL RANGE OF MOTION
To give maximum momentum in throwing, kicking and striking we need to move the body segments through the greatest range of motion.
The greater the range of motion the greater the horizontal and vertical distance covered
ACTIVITIES:
Ball pass from ground, knees, and feet with minimal to full range of motion.
Record distances…..What happened and why??

25. LEVERS There are three classes of levers
First Class , Second Class, Third Class
First-class Lever
Eg see-saw, crow bar, rowing
Second-class Lever
Opening a door, wheelbarrow
Third-class Lever
Bicep curl

26. THIRD CLASS LEVER This is the main lever humans use TERMINOLOGY:
FULCRUM = Also known as pivot point.
FORCE = The direction you are pulling or pushing the load
LOAD = The weight that you are pushing or pulling against

27. LEVERS AND PERFORMANCE
Levers (arm or leg) can be lengthened or shortened to created speed and force
Shortening the lever (by bending the joint) allows lever to generate force and more speed
Then the lever can be lengthen (by straightening the joint) to maximise speed at the end of the lever.
How does this work with the softball pitch??

28. Maximising force and speed in a rugby kick
Back-swing
Kicking leg is bent, creating a short lever to swing towards the ball with force and speed
Forward swing
Kicking leg straightens, creating a long lever, allowing the ball to be kicked with more speed
Follow-through
Leg follows through, to improve accuracy and allow the leg to slow down safely.