© folens 2009 for edexcel 1.2.4 a healthy, active lifestyle and your muscular system muscular...

© Folens 2009FOR EDEXCEL 1.2.4 A healthy, active lifestyle and your muscular system

Muscular functions 1

Muscular functions


What you will learn about in this topic:

1. Muscle fibre types

2. Types of muscle contraction




Learning objectives

By the end of this presentation you should be able to:

•Understand the different types of muscle fibres

•Describe how muscles work

•Explain muscle contractions


How muscles work

Muscle can only pull.

Because they cannot push, to make joints work they are arranged in pairs called antagonistic pairs.

For muscles to move limbs, one muscle must pull (contract) and one must relax.



The pulling muscle is called the prime mover (or agonist).

The muscle relaxing is called the antagonist.

When a muscle contracts it becomes shorter.

When a muscle relaxes it becomes longer.



Synergists are muscles also involved indirectly with the action. They hold the body position so that the prime mover can operate.



Muscle fibresThere are two different types of fibre in muscles:

1. Fast twitch muscle fibres (FTMF)

2. Slow twitch muscle fibres (STMF)

Everyone has a natural combination of these fibres in their body. Although the amount of fibres cannot be changed, they can be trained to work to their maximum capability.



Each type is suited to different activities.

Fast twitch muscle fibres are used for more explosive activities, which need quick reactions, or short bursts of energy, such as in discus and javelin.



Fast twitch muscle fibres contract fast and produce a powerful action but have a limited oxygen supply so tire quickly.



Slow twitch muscle fibres are used for endurance activities which are slow and prolonged, such as running, cycling and swimming.



Slow twitch muscle fibres contract many times and stay efficient over long periods of time.



Muscle contraction

There are two different types of muscle contraction:

1. Isotonic

2. Isometric



Isotonic muscle contractions occur when there is movement of the body. They happen frequently in games play.



The ends of the muscles move closer to make the action. As a muscle contracts (shortens and fattens), it causes concentric movement. When it relaxes, it is an eccentric movement (lengthens and flattens).



Working the muscles isotonically improves dynamic (moving) strength.

It develops cardiovascular and cardiorespiratory systems and increases power and endurance.



Isometric muscle contractionstake place when the muscle length stays the same and improves static strength.

It is used for stabilizing parts of the body and holding it steady so that movement can take place elsewhere, such as a gymnast on a beam.



It does not develop power or muscular endurance; the cardiovascular and cardiorespiratory systems are not improved.

Few sports require this type of contraction alone.



Task

Take a look at the following photographs and decide which muscle contractions are being used.



Exam questions

1. Describe slow twitch muscle fibres.

2. Describe fast twitch muscle fibres.




What you have learntin this topic:

1. Muscle fibre types

2. Types of muscle contraction



Learning objectives

You should now be able to:

•Understand the different types of muscle fibres

•Describe how muscles work

•Explain muscle contractions

© folens 2009 for edexcel 1.2.4 a healthy, active lifestyle and your muscular system muscular...

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