Muscle fibre types

Question 1

What are the structural characteristics of slow oxidative (type 1) muscle fibres?

Answer 1

RED
> thin diameter - short diffusion gradient - high O2 supply
> high capillary density
> high myoglobin and mitochondria
> slow firing nerve fibres
> high aerobic enzyme activity

Question 2

What are the functional characteristics of slow oxidative (type 1) muscle fibres?

Answer 2

> high resistance to fatigue
slow speed and low strength of contraction
maintains force production for long periods of time
high rate of aerobic energy production

Question 3

What are the positives of slow oxidative (type 1) muscle fibres?

Answer 3

+
> high aerobic capacity
> high resistance to fatigue
> benefits endurance athletes

Question 4

What are the negatives of slow oxidative (type 1) muscle fibres?

Answer 4

-
> low speed and force of contraction
> low anaerobic capacity

Question 5

What are the structural characteristics of fast oxidative glycolytic (type 11a) muscle fibres?

Answer 5

PINK
> wider in diameter than type 1, but narrower than type 11x
> large amounts of myoglobin and mitochondria
> less capillaries than type 1, but more than type 11x
> relatively high ATP and PC levels

Question 6

What are the functional characteristics of fast oxidative glycolytic (type 11a) muscle fibres?

Answer 6

> moderate resistance to fatigue
high speed and strength of contraction
relatively large nerve conduction

Question 7

What are the positives of fast oxidative glycolytic (type 11a) muscle fibres?

Answer 7

+
> high speed/force of contraction
> good strength/speed endurance
> allows injection of faster pace to be sustained for short durations
> (400m, 800m, games players)

Question 8

What are the negatives of fast oxidative glycolytic (type 11a) muscle fibres?

Answer 8

-
> not as fatigue resistant as type 1
> not as powerful as type 11x

Question 9

What are the structural characteristics of fast glycolytic (type 11x) muscle fibres?

Answer 9

WHITE
> high in ATP and PC
> high in actin and myosin
> large motor neurone and motor unit size
> wide in diameter
> high in glycogen
> low in capillaries, mitochondria, and myoglobin

Question 10

What are the functional characteristics of fast glycolytic (type 11x) muscle fibres?

Answer 10

> very high speed and force of contraction
low resistance to fatigue
high glycolytic capacity (fast ATP re-synthesis)
high rate of contraction and relaxation
fast nerve conduction

Question 11

What are the positives of fast glycolytic (type 11x) muscle fibres?

Answer 11

+
> very high speed and force of contraction
> very high anaerobic capacity
> sprinter, short, explosive events

Question 12

What are the negatives of fast glycolytic (type 11x) muscle fibres?

Answer 12

-
> very low fatigue resistance
> lactic acid build up
> short durations