Muscle fibres

Question 1

What are type I muscle fibres?

Answer 1

• Slow twitch fibres (slow-oxidative fibres)
• Designed for stamina or aerobic ativities

Question 2

What are some structural characteristics of type I muscle fibres?

Answer 2

• High number of/larger mitochondria
• High level of myoglobin
• High capillary density
• High levels of triglyceride
• High levels of oxidative enzymes

Question 3

What are type II muscle fibres and what are the two different types?

Answer 3

Fast twitch fibres designed for increased speed and anaerobic/strength
- Type IIa - fast oxidative (explosive endurance activity eg 100m sprint)
- Type IIb - Fast glycolytic (single explosive activity eg high jump)

Question 4

What are some structural characteristics of type II muscle fibres and what are their functional characteristics?

Answer 4

• More PC stores - increased use of ATP-PC system
• More glycogen - More energy stored for anaerobic exercise
• More anaerobic enzymes - More breakdown of glucose for respiration
• Large diameter of fibre - More force/explosive strength for activity
• Large/faster motor neurone - faster speed for activity