Muscular System- Muscle Fibres

Question 1

Name three types of muscles?

Answer 1

Type 1 (slow twitch)
Type 2a (Fast twitch)
Type 2x (Fast twitch)

Question 2

Can you describe three characteristics of Type 1 muscle fibres?

Answer 2

Type 1 are slow twitch
They contract slowly
They contract with less force
They are the most resistant to fatigue
They are suited to longer duration, aerobic activities
They have a rich blood supply
They contain many mitochondria (site for aerobic respiration)
They have a high capacity for aerobic respiration

Question 3

Can you describe three characteristics of Type 2a muscle fibres?

Answer 3

They are known as fast twitch fibres/fast-oxidative fibres
They are able to produce a great force when contracting
They are resistant to fatigue
They fatigue faster than type 1 fibres
They use oxygen
They are suited to speed, power and strength activities

Question 4

Can you describe three characteristics of Type 2x muscle fibres?

Answer 4

They are known as fast twitch fibres/fast-glycolytic fibres
They produce the greatest force when contracting
They contract rapidly
They least resistant to fatigue (fatigue the quickest)
They are suited to anaerobic activities
They depend upon anaerobic respiration
Recruited for high intensity/short duration activities

Question 5

What is the all or none law?

Answer 5

In order for a muscle to contract, it must receive a nerve impulse. This impulse must be sufficient to activate the motor unit.
Once activated, all the muscles fibres within the motor unit contract. If the impulse is not strong/ sufficient at the motor unit, then none of the muscles contract.

Question 6

How would a basketball player utilise all muscle fibre types during a game?

Answer 6

Type 1 (slow twitch)- needed for aerobic respiration due to game being over a longer duration (four quarters)
Type 2a (Fast twitch)- There may be periods of the game where it is end to end resulting in a player working anaerobically for longer and having to resist the effects of lactic acid.
Type 2x (Fast twitch)- For explosive movements within the game e.g. jumping in a lay-up/ dunk.

Question 7

TRUE or FALSE
Marathon runners only have Type 1 (slow twitch) muscle fibres as they work aerobically.

Answer 7

FALSE
Every athlete will have fast and slow twitch muscle fibres. Their genetics may determine if one muscle fibre outweighs the other.

Question 8

TRUE or FALSE
Type 2a fibres can be trained to resist the effects of fatigue

Answer 8

TRUE

Question 9

TRUE or FALSE
Type 2a fibres are also known as fast-glycolytic fibres

Answer 9

FALSE
Type 2a fibres are known as fast-oxidative fibres
Type 2x fibres are known as fast-glycolytic fibres

Question 10

How would a rugby player utilise all muscle fibre types during a game?

Answer 10

Type 1 (slow twitch)- needed for aerobic respiration due to game being over a longer duration (80 minutes)
Type 2a (Fast twitch)- There may be periods of the game where it is end to end resulting in a player working anaerobically for longer and having to resist the effects of lactic acid.
Type 2x (Fast twitch)- For explosive movements within the game e.g. tackling