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 cup-

shaped socket of another. This joint allows the greatest range of movement.

Hinge JointTwo 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 PatternsThe 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/gastrocnemius

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. Name the bones of the skeleton…all 206 of them?

2. Name the joints in the body?3. Classify the joints (hinge, ball and socket, etc)4. Name the bones that articulate at the joints.5. 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. Knee2. Classify the joint, eg. Hinge3. Name the bones that articulate at the joint.4. Movement patterns5. 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 InertiaThis 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.

ExampleAn 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 purpose2. 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 MotionFACTORS 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. Gravity.2. Air resistance.3. Speed of release.4. Angle of release.5. Height of release.6. 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 end2. How precise the movement is3. Whether the environment affects the

performance of the skillThe 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 continuumThis 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 hand-eye coordination. EG?

The open-closed continuumThis 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.