Muscular system: Fibre types and contractions

1. Muscular system: Fibre types and contractions BTEC L3 Sport Kevin Browne

2. Aims of the lesson • Outline the types and difference of fibre types • To identify the main function of the muscular system • Outline and describe the roles of muscle in order to provide it main function

3. Task • Individually write your own description of what a slow twitch fibre • Key words may include • Contraction • Endurance • Energy production • Force production

4. Slow twitch fibre • These will be red in colour as they have good blood supply. They will have a dense network of blood vessels making them suited to endurance work and they are slow to fatigue • They contain many mitochondria to make them more efficient at producing energy using oxygen

5. Individually write your own description of what a fast twitch fibre • Use the same keywords as before • FTF will contract as twice as quick as STF and are thicker in size. They have a poor blood supply and are whiter in appearance and will fatigue quickly. • They are harder faster contractions making them suitable for sprinters

6. What's the difference between type 2a and 2b • The type that is used depends upon the chosen activity. Type 2b fibres work when a person is very close to their maximum intensity. • Type 2a work at slightly lower intensities but still much higher than slow twitch fibres • Can you give me an example of this?

9. Contracting muscles • What is the main function of muscles? • Simply movement • When a muscle contracts it pulls on the tendon which in turn pulls the bone and makes the bone • When muscles contract they work as a group in that the muscles contracting is dependent on the other muscles doing their job • A muscle can play one of the four roles

10. 4 roles • Agonist (prime mover): the muscle contracts to produce the desired movement • Antagonist : this muscle relaxes to allow the agonist to contract • Synergist : this muscle assists the agonist in producing the desired movement • Fixator :these muscles will fix joints and the body in position to enable the desired movement to occur.

11. During the upward phase of the bicep curl the biceps are the agonist and are contracting concentrically. During the downward phase the biceps are still the agonist but this time they are contracting eccentrically. They are in effect acting as a brake, resisting gravity to control the downward phase of the exercise. • This is sometimes a difficult concept to understand and you may find it useful to try the exercises and feel how the muscles are working.

14. Summary • Questions • You tell me! • True or false