Transcript Achievement Standard 2.2 Demonstrate understanding of how

Achievement Standard 2.2
Demonstrate understanding of how
and why biophysical principles relate
to the learning of physical skills
Back to basics…
SKELETAL SYSTEM
• Bones are living structures with 5
functions:
• protect internal organs
• support the body
• make blood cells
• store minerals
• provide for muscle attachment
IDENTIFYING BONES
• Label the bones on the skeleton, or a
partner!
• Which bones make up the:
Elbow joint?
Knee joint?
Shoulder joint?
Hip joint?
Joints
• Movement of the skeleton is helped by joints. These
are particularly helpful for sporting actions and
activities. These can be separated into five
categories of joints.
• Ball and Socket Joint
• Hinge Joint
• Pivot Joint
• Gliding Joint
• Saddle joint/condyloid
Synovial joints of the
body
Anatomy of the knee
joint
Ankle anatomy
Ball and Socket Joint
• Two examples of this joint in the human body are
the hip and shoulder joints.
• The rounded head of one bone fits into a cupshaped socket of another. This joint allows the
greatest range of movement.
Hinge Joint
Two examples of this type of joint include those found at the
knee and elbow.
1.) Anatomically speaking, hinge joint movement is flexion and
extension. Flexion is when you decrease the angle of the
joint and extension is when you increase the angle of the
joint.
2) If you move your leg as if you were about to kick a ball.
You will find that the movement of the joint can only occur in
one way/plane (direction) just like the hinge of a door.
Pivot Joint
• Atlas and Axis in the
cervical vertebrae
• Allows rotation and flexion
Joints in Action
Movement Patterns
The Elbow Joint
• Is a hinge joint, with the distal end of the humerus
articulating with the proximal ends of the radius and
ulna
• Movement is possible in one plane only, allowing
flexion and extension to take place.
• Also within the elbow joint capsule, the radius
articulates with the ulna to form a pivot joint.
• The radioulnar joint allows pronation and supination of
the lower arm.
Muscles/movement of the
Elbow joint
Movement
Prime mover
Antagonist
Flexion
Biceps
Triceps
Extension
Triceps
Biceps
Radioulnar (Pivot)
Pronation
Pronator teres
Supination
Supinator muscle
• Think of a sporting example, when each prime mover of the elbow
would be in action. For example, during the shot putt, elbow
extension is caused by the triceps.
The Shoulder Joint
• The shoulder joint is a ball and socket joint, with the head of
the humerus fitting into a very shallow cavity on the scapula.
• The shoulder joint is the most mobile joint in the body, but
also one of the most unstable.
• The movements possible at the shoulder joint are flexion,
extension, abduction, adduction, internal and external rotation
and circumduction.
• For some skills analysis of the shoulder movement is quite
straighforward, for example, lifting the arms above the head
in preparation for a handstand, clearly involves flexion of the
shoulder joint
• Unfortunately, most of the actions we perform in sport, for
example a serve in volleyball, are a combination of several
movements and are therefore quite difficult to analyse.
• I do not expect you to attempt complex movement analysis,
but have a go at the next activity…
Muscles/movement of the
Shoulder Joint
Movement
Agonist/Prime Mover
Antagonist
Flexion
Anterior deltoid
Posterior deltoid
Extension
Posterior
deltoid/latissimus
dorsi
Anterior deltoid
Abduction
Medial deltoid
Pectoralis major
Adduction
Pectoralis major
Medial deltoid
Activity
• Describe the movement patterns at the shoulder and elbow
joints during each phase of the javelin throw.
• Remember to use preparation, execution and recovery.
Knee Joint
• The knee joint is a hinge joint.
• The proximal end of the tibia articulates with the
distal end of the femur.
Movement
Agonist
Antagonist
Flexion
Hamstrings (Biceps
femoris)
Quadriceps (Rectus
femoris)
Extension
Quadriceps
Hamstrings
The Hip Joint
• The hip joint is another ball and socket joint.
• The head of the femur articulates with the pelvis.
• Although it is desirable to have a wide range of
mobility at the joint, it is perhaps more desirable to
have stability.
• Movements possible at the hip include flexion,
extension, abduction, adduction and circumduction.
The Hip Joint
Movement
Prime mover
antagonist
Flexion
iliopsoas
Gluteus maximus
Extension
Gluteus maximus
Iliopsoas
Abduction
Gluteals
Adductor muscle
Adduction
Adductor muscle Gluteals
The Ankle Joint
• The ankle joint is a hinge joint, where the talus
articulates with the distal ends of the tibia and
fibula.
Movement
Prime mover
Antagonist
Dorsiflexion
Tibialis anterior
Soleus/gastrocnem
ius
Plantarflexion
Gastrocnemius
Tibialis anterior
• Identify the movement patterns
at the shoulders, hip, knee and
ankles
Muscles/movement of the
Spine
• The movements of the spine are flexion, extension,
lateral flexion and rotation.
Movement
Prime mover
Antagonist
Flexion
Rectus
abdominus
Sacrospinalis
Extension
Sacrospinalis
Rectus abdominus
Rotation/Lateral
flexion
Internal obliques External obliques
Recap
• What have we established so far….? What can you do?
1.
2.
3.
4.
5.
Name the bones of the skeleton…all 206 of them?
Name the joints in the body?
Classify the joints (hinge, ball and socket, etc)
Name the bones that articulate at the joints.
Identify the movement pattern happening at the
joint (flexion, extension etc)
6. Antagonistic muscle action.
Muscles
There are 3 different types of muscle
Smooth
Cardiac
Skeletal
Controlled by nerves (some voluntary, some
involuntary)
• Contract (shorten) – which brings bones closer
together, therefore for movements to occur in both
directions the muscles must work together in pairs
e.g. bicep & triceps, hamstrings & quadriceps.
Hopefully, this is familiar to you?!
• Extend
•
•
•
•
•
Muscles in Action
A closer look at leg
muscles
How muscles move
• Muscles are attached to two different bones by
tendons. When the muscle contracts only one bone
moves.
• The place where the muscle is attached to the
stationary bone is called the ORIGIN. The place
where the muscle is attached to the moving bone is
called the INSERTION
When you analyse your
player….
• You need to be able to:
1. Identify the joint, eg. Knee
2. Classify the joint, eg. Hinge
3. Name the bones that articulate at the joint.
4. Movement patterns
5. Antagonistic muscle action. Explain what it is and
identify agonist and antagonist working at the
identified joints.
• Identify the antagonistic muscle pairings at the back, hip,
shoulder, elbow and knee joints
Biomechanics
• An ability to analyse movement is extremely helpful to
both performer and coach.
• A basic understanding of the principles of movement
can help identify and correct problems with
technique.
• We will study the basic mechanics of movement.
•
•
•
•
Force summation
Newton’s Laws of Motion
Levers
Centre of gravity
Newton’s Laws of Motion
• Sir Isaac Newton studied the effect of the forces on
movement and from his observations developed three
laws of motion to explain the relationship between
motion and applied force.
The Law of Inertia
This law states that:
‘A body continues in its state of
rest or of uniform motion unless
a force acts on it”
A body or an object is said to be in a
state of inertia and a force must be
applied to it before any change in
velocity can occur. The greater the
mass of the body, the more force is
required to overcome its inertia. You
can throw a 5kg weight further than a
you can throw a 10kg weight using the
same force.
For a body to get moving the force has
to be greater than the inertia acting
upon it (inertia = a bodies tendency to
remain at rest. The greater the mass
of the body = greater the inertia
The law of acceleration
• ‘The acceleration of an object is directly proportional
to the force causing it and is inversely proportional to
the mass of the object.’
• The speed that a person can throw a tennis ball is
proportional to the amount of force applied by the
muscles. It also depend on the inertia of the ball.
• In sport, we often refer to the momentum of an
object. This is a product of velocity times mass. A
defender in hockey usually uses a heavier stick than a
forward because it allows him or her to transfer more
momentum to the ball and consequently hit it further.
• Momentum can also be built up and transferred from
one body part to the rest of the body, resulting in
more force…FORCE SUMMATION! EG?
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 and opposite force
back on the first.
The most common sporting example
of this is when an athlete pushes
back against the starting blocks at
the beginning of a sprint race,
(exerting a force on the blocks)
Force Summation
Many skills performed in sport require maximum
speed or force to be generated.
Some skills require maximum force to get a result,
while others require maximum speed or velocity.
In order to do this, an athlete needs to involve as
many body parts as is technically possible.
Force Summation
• To gain maximum momentum, the force needs to be
generated by:
• Using as many segments of the body as possible.
• In the correct sequence, using large muscles first and
then the smallest muscles last but fastest.
• With the correct timing.
• Through the greatest range of motion.
Example
An athlete competing in a discuss competition
would generate less force and therefore less
horizontal distance, if only the arm and shoulder
are used.
Another competitor using force built up from
using legs, hips, back, shoulder, arm and wrist in
order would throw further
Centre of Gravity
• The centre of gravity, sometimes referred to as the
point of balance, is the point in an object where all its
mass is concentrated.
• The centre of gravity of a performer is continually
changing as the body position changes.
• As the centre of gravity is the point of balance of the
body, we commonly refer to performers being
‘balanced’ or ‘off-balance’.
• To be in a state of balance, the centre of gravity
must be over the area of support.
• The larger the area of support, the easier it is to
maintain balance.
• Lowering or raising the centre of gravity will affect
stability.
Levers
• When we think of levers, crowbars and wheelbarrows
spring to mind, rather than ulnas and femurs.
• The skeleton forms a system of levers that allows us
to move.
• A LEVER is a rigid bar that rotates around a fixed
point FULCRUM and is used to apply FORCE/EFFORT
around a RESISTANCE.
• In the human body, the bones are the levers, the
joints the fulcrums, the muscles act as the effort and
the weight of the body part, plus anything that it
holds, is the resistance.
Classification of levers
• There are three different types of lever in the body,
but we are just concerned with the third class lever.
• In the third order lever, the effort lies between the
fulcrum and the resistance. This is the most common
form of lever in the body. It generates speed and
range of movement. Arms and legs.
• The longer the lever, the greater the change of
momentum and consequently change in velocity that
can be imparted on an object.
• This can be an advantage in sports in which you hit
objects.
• For example, a volleyball can be hit harder when the
elbow is fully extended rather than
flexed!(application)
Use of levers in Sport
In many sports the equipment
you use act as an extension of
the levers in your body and
helps to generate greater
force or sped. Two good
examples of levers used in
sport can be seen in rowing or
golf.
Force
• Forces can be used to make something move, stop
something moving that is already moving, or to
prevent something from moving altogether.
• A force might be internal or external. In the
human body, the muscles act as the internal
forces, whereas the effect of gravity is external.
• The effect that a force has on a body is
influenced by 3 factors:
• 1. The size or magnitude of the force
• 2. The direction of the force. If a single force is
applied to a body through its centre of gravity,
the body will move in the same direction as the
force.
• 3. The position of application of the force
Application of force to
volleyball serve/dig
• In volleyball, the player must gauge how much force
to apply to the serve/dig.
• If you are performing a closed skill, for example, the
serve, you are at an advantage that the amount of
force, the direction of the application of the force
required are the same each time you perform the
serve.
• IN open skills, the situation will vary each time and
errors can be made. For example, not connecting with
the ball correctly will cause it to veer off to one side.
How do we put it all into
practice…?
• So, we need to apply all that we have learned so far
and make a start.
• This is how I see it working…
• Put in your reflective diary your research on a
‘perfect’ overhead serve and a perfect dig.
• Include the analysis of breaking the skill down into
preparation, execution and recovery.
• Then compare the perfect example with your student.
Movement Analysis
• To complete an anatomical and biomechanical analysis
(kinesiological analysis) of a motor skill, you need to
be able to:
1. Describe the skill and its purpose
2. Evaluate the performance in terms of:
• Joint action, muscle action and function
• Biomechanical principles
Correct faults by again applying the above and
Psychological/Skill principles
Projectile Motion
FACTORS AFFECTING PROJECTILE MOTION
Any object released into the air is termed a
projectile.
The flight path of a projectile consists of a
vertical and horizontal component.
What does this mean?
Principles that affect
projectiles
• Regardless of the type of object that is being
released, or by what means it is being projected,
they are all governed by the same principles.
1.
2.
3.
4.
5.
6.
Gravity.
Air resistance.
Speed of release.
Angle of release.
Height of release.
Spin.
Speed of Release
Generally, the greater the speed of release, the
greater the distance gained.
In many game situations this is a factor that must
be under constant control.
Can you give me an example?
Angle of Release
For any given speed of release, the optimum angle of
release is always 45 degrees.
Is this the case in many sports? Why?
What would happen if the angle of release were to
high for a given activity?
Poor distance gained
What would happen if the angle of release were too
low for a given activity
Poor flight time and possibly poor distance.
Height and angle of
release
• The inter-relationship between height of release and angle
of release is important to consider.
• As the height of release increases, the angle of release
decreases.
• As the height of release decreases, the angle of release
increases.
Application of Projectile
motion to the volleyball
serve
• Firstly the speed or the force that the ball is
struck/released at is important. The speed at which the
ball is struck will determine how far the ball will travel. The
striking force must be sufficient enough to allow the ball
to cross the net but not enough to mean the ball goes out
of play.
• The height of release also influences the horizontal
distance covered, too high and the ball may go to far, too
low and the ball may strike the net. The angle is also
important in conjunction with this. The angle and height of
release must be judged correctly in order that the serve is
successful. Spin can also be applied in order to make the
ball dip after the net-making it harder for teams to return.
Most skill classification systems are based on
the view that motor skills are affected by
:
three main factors
1.
Whether the movement has a definite
beginning and end
2. How precise the movement is
3. Whether the environment affects the
performance of the skill
The following words or phrases are often used in
the classification of skills according to a continuum
because this reflects the true, although complex
nature of the skill.
The Gross-Fine continuum
This is concerned with the precision of movement.
Gross skills involve large muscle movements. These
skills are not very precise and may include many of
the fundamental movement patterns such as
walking and jumping. EG?
Fine skills: involve more intricate movements using
small muscle groups. They tend to be precise in
nature and generally involve a high degree of handeye coordination. EG?
The open-closed continuum
This is concerned with the effects of the
environment on skills
• Open skills are affected by the environment and
are therefore predominantly perceptual.
Movements have to be adapted to the
environment and the skill is most externally
paced – for example a pass in football.
• Closed Skills are not affected by the
environment and are predominantly habitual.
Movement follows a set pattern and have a
definite beginning and end. These skills tend to
be self-paced. Eg. Free pass in basketball.
The Pacing Continuum
• This is often used in conjunction with the open-closed
continuum and refers to the timing of the movements.
• Self-paced skills: The performer controls the rate at
which the skill is executed. Self-paced skill are
usually closed skills and an example is a javelin throw.
• Externally-paced skills: The environment, which may
include your opponent controls the rate of performing
the skill. This type of skill involves reaction and is
usually and open skill such as receiving a serve in
badminton.
Discrete, Serial, Continuous
• This is concerned with how well defined the beginning and
end of the skill are.
• Discrete skills have a clear beginning and a clear end. The
skill can be repeated but the performer must start again
from the beginning. It is a single, specific skill. A penalty
flick in hockey is an example of such a skill.
• Serial skills have several discrete elements which are put
together to make an integrated movement or sequence of
movements, for example the series of skills in a triple
jump.
• Continuous Skills have no obvious beginning or end- the end
of one cycle of movement is the beginning of the next. The
skill is repeated as a set pattern, for example, cycling.
So…..the volleyball serve is…
• A gross motor skill, engaging large muscle groups. It
is a closed, self-paced, discrete skill, as it is not
really affected by the environment, the movements
are habitual and follow a set pattern and have a
definite beginning and end. The student controls the
rate at which it is executed.