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SKILLS AND TECHNIQUES 5

Mechanical Principles

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Mechanical Principles are the facts which affect how we perform skills.

Balance

Transfer of weight

Application of force

Rotation

Resistance

Follow through

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5.0 Balance

Balance is the ability of the body to maintain the centre of gravity over your base of support. This means using body tension and specific muscle groups to remain stable or balanced.

Maintaining a balance can be made easier by lowering your centre of gravity and/or increasing the size of your base of support.

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There are two types of balance

1. Static – a balance which is required to be held still

2. Dynamic – a balance which is required to be maintained under constantly changing conditions

STATIC

STATIC

DYNAMIC

DYNAMIC DYNAMIC

STATIC

STATIC

Look at the pictures, decide whether they are static or dynamic balances

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When performing a static balance body tension is important. The balance requires the control of different muscle groups.

Stability of a balance is increased by a lowering the centre of gravity, maintaining the centre of gravity over the centre of the bas of support and enlarging the base of support.

Which gymnast is the most stable?

The handstand has a smaller base of support and a higher centre of gravity.

The headstand has a larger base of support and a lower centre of gravity.

The gymnast performing the headstand is therefore more stable balance.

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Hurdling in athletics, an ongoing continuous action, involves adjusting your body shape to ensure you remain in dynamic balance when running over each hurdle.

When batting in cricket, a dynamic balance, you need to adjust your body position to remain in balance

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5.1 Transfer of weight

Transfer of weight is the movement of weight from one body part to another.

Transfer of weight is used when completing several skills and techniques in order to produce an effective performance.

Often this can be seen as a single action such as: - throwing - catching - striking or at other times when single actions are repeated, for example when running.

A transfer of weight can help create power in actions such as throwing a javelin, striking a shuttlecock or tennis ball or even kicking a football.

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ActivityTransfer of weight

From To

GymnasticsHandstand

Feet

Hockey Push pass

Front foot

Shot puttBack foot

Football throw in

Complete the table below to show how weight was transferred.

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5.2 Application of Force 5.2 Application of Force

In Physical Education, when performing skills and techniques in any activity different forces are applied and resisted.

Newton’s Third Law states that for every action there is an equal and opposite reaction.

An example of this is a sprinter starting to run off the blocks when the gun is fired.

The sprinter applies a force backwards against the blocks.

The blocks, which are secured to the track, push back with exactly the same force, resulting in the sprinter travelling forwards.

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This means that in Physical Education, if a force is applied in one direction the body will move in the opposite.

If speed or power is needed in the activity then the greater the force applied the faster or more powerful the action.

Activity Skill Direction of force applied

Direction of movement

Benefit

Athletics (running)

Sprint start Backwards against the blocks

Forwards along the track

Faster result in getting to the finish line

Basketball Rebounding (jumping)

Down against the floor

Jumping high Securing possession of the ball

Swimming Front crawl Backwards against the water

Forwards through the water

Gliding through the water quickly

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5.3 Rotation5.3 RotationIn different activities rotation helps perform skills and techniques more effectively.Rotation is the movement of a body part, or the whole body, around a central axis

Think of some activities you have participated in in PE. Do any of them have some form of rotation involved? YES!

Gymnastics – rotation is a key part to gymnastics. It occurs in many ways. Turning head over heels (forward roll/somersault). Sideways in the form of a cartwheel where you turn over from your feet to your hands before returning to your feet again in a dynamic balance.

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Trampolining – when completing a front or back somersault in trampolining you turn head over heels. The smaller the tuck shape whilst turning, the quicker the rotation. The bigger the body shape the slower the rotation.

Discus – when throwing the discus you turn around your body in a spinning technique from back to front in order to gain power.

Swimming – when completing a tumble turn in order to turn around, again the smaller the tuck the quicker the rotation.

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5.4 Resistance5.4 Resistance• Apart from the forces we apply in order to make our body move, there are other forces which have an effect on our performance. This is called resistance.• Sometimes resistance can be an advantage where resistance aids our performance and sometimes it can be a disadvantage and we try to overcome it.

Lets look at a sprinter:The sprinter starts in the blocks which are stuck to the track, this is an advantage when when gun goes as by powerfully straightening the legs against the blocks the printer can gain speed quickly.

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The sprinter wears special trainers which have spikes on the sole which give a better grip on the track giving more resistance on the track so as the athlete does not slip and fall.

However, if the athlete is running into a headwind this causes more resistance and is a disadvantage.

Think of other activities where resistance can be an advantage.

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ions In some activities participants have to reduce the amount of resistance.

Ice Skaters want to minimise the friction to allow gliding on the ice.

Cyclists try and stay in a streamlined position to reduce the air resistance. They wear skin tight clothing and a streamlined helmet.

A swimmer needs to be streamlined to reduce water resistance also known as drag. They do this by wearing special costumes and sometimes men even shave their body hair! Their body shape also changes when gliding through the water.

By reducing drag or resistance, the ice skater, cyclist and swimmer can travel faster.

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5.4 Follow Through5.4 Follow ThroughFollow through follows on from the preparation and action phases of skills and techniques. It can be categorised under the recovery stage.

To complete any kicking, throwing, hitting or striking action effectively it is important to have a good follow through.

Skills where follow through occurs includes:

Kicking

Throwing

Hitting/Striking

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Follow through can either involve one body part or the whole body.

In some cases the the follow through action involves rotation. The hip and shoulder joints rotate in actions such as striking a tennis ball, hitting a golf ball and striking a baseball.

In many throwing actions the direction of follow through is the same as the direction of the throw.

An effective follows through produces accuracy and power when completing the skill.

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Created for Physical Education in Glasgow Secondary Schools

by

E.Gordon – Kings Park Sec. School

C.McGourty – Holyrood Sec. School

You have now completed Skills and Techniques 5