Download Biomechanical Principles

Overview
NEWTONS THREE
LAWS
• Inertia
• Force
• Action and reaction
FORCE SUMMATION
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•
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•
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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)
PROJECTILE MOTION
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•
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Height of Release
Angle of Release
Speed of Release
Spin
LEVERS
• First Class
• Second Class
• Third Class
Newton’s First Law of Motion
INERTIA
“An object at rest tends to remain at rest
unless acted upon by some external force.
{inertia}”
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•
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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?
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
Newton’s Third Law of Motion
Action and Reaction
“For every action, there is an equal and opposite
reaction.”
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•
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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.
STABILITY AND BALANCE
 There are three aspects that help us to maintain
stability and balance
 CENTRE OF GRAVITY
 LINE OF GRAVITY
 BASE OF SUPPORT
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
LINE OF GRAVITY
 Line of Gravity (LOG) is an imaginary line that runs
through the centre of gravity to the base of support
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??
BOS, COG, LOG
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
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.
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.
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
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
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.
 Height of release of a projectile affects the speed
and angle of a projectile
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.
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
1. Segments
2. Stretching out
3. Timing
4. Sequencing
5. Full range of motion
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
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
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
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
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??
LEVERS
 There are three classes of levers
 First Class , Second Class, Third Class
First-class
Lever
Second-class
Lever
Third-class
Lever
Eg see-saw,
crow bar,
rowing
Opening a
door,
wheelbarrow
Bicep curl
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
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??
 Maximising force and speed in a rugby kick
Back-swing
Forward swing
Follow-through
Kicking leg is bent,
creating a short lever
to swing towards the
ball with force and
speed
Kicking leg
straightens, creating a
long lever, allowing the
ball to be kicked with
more speed
Leg follows through,
to improve accuracy
and allow the leg to
slow down safely.