Muscle Fibre Types

Question 1

Describe slow twitch fibres

Answer 1

• red in colour with a good blood supply
• recruited mainly for aerobic exercise, eg: walking, jogging etc.
• slow to fatigue
• high capillary density
• lots of mitochondria

Question 2

Describe fast twitch fibres

Answer 2

• AKA Type 2 fibres
• white in colour
• relatively poor blood supply
• recruited mainly for anaerobic exercise
• quick to fatigue
• low capillary density
• not many mitochondria
• can be sub-divided into Type 2A and Type 2B

Question 3

What are the differences between Type 2A and 2B fast twitch fibres?

Answer 3

• Type 2B are true fast twitch fibres

- Type 2A are sometimes known as pink or intermediary fibres as they have a mix of characteristics

Question 4

What are the two muscle fibre types?

Answer 4

• slow twitch fibres

- fast twitch fibres