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HMS, BM EQ-Bank 830

Compare and contrast the characteristics and functions of slow-twitch and fast-twitch muscle fibres in relation to different sporting activities.   (5 marks)

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Sample Answer

Similarities:

  • Both fibre types
    • exist in all skeletal muscles, working together for varied movement demands.
    • contract through the sliding action of actin and myosin filaments.
    • can be trained to improve performance within their genetic limitations.
    • contribute to overall muscle function, with most activities requiring some combination of each type.

Differences:

  • Structure:
    • Slow-twitch fibres contain abundant mitochondria and capillaries, appearing red from high myoglobin content.
    • Fast-twitch fibres have fewer mitochondria and limited blood supply, appearing white.
  • Energy systems:
    • Slow-twitch fibres use aerobic metabolism efficiently for sustained energy.
    • Fast-twitch fibres rely on anaerobic pathways for rapid ATP production.
  • Contraction characteristics:
    • Slow-twitch fibres contract slowly but resist fatigue for hours.
    • Fast-twitch fibres generate explosive force but fatigue within seconds.
  • Sporting applications:
    • Marathon runners and cyclists benefit from predominant slow-twitch fibres for endurance events.
    • Sprinters and weightlifters require fast-twitch dominance for power and speed.
    • Team sports like soccer utilise both – slow-twitch for continuous running, fast-twitch for sprinting and jumping.
  • Training adaptations:
    • Endurance training enhances slow-twitch oxidative capacity.
    • Power training increases fast-twitch force production, though fibre type proportions remain largely genetic.
Show Worked Solution

Sample Answer

Similarities:

  • Both fibre types
    • exist in all skeletal muscles, working together for varied movement demands.
    • contract through the sliding action of actin and myosin filaments.
    • can be trained to improve performance within their genetic limitations.
    • contribute to overall muscle function, with most activities requiring some combination of each type.

Differences:

  • Structure:
    • Slow-twitch fibres contain abundant mitochondria and capillaries, appearing red from high myoglobin content.
    • Fast-twitch fibres have fewer mitochondria and limited blood supply, appearing white.
  • Energy systems:
    • Slow-twitch fibres use aerobic metabolism efficiently for sustained energy.
    • Fast-twitch fibres rely on anaerobic pathways for rapid ATP production.
  • Contraction characteristics:
    • Slow-twitch fibres contract slowly but resist fatigue for hours.
    • Fast-twitch fibres generate explosive force but fatigue within seconds.
  • Sporting applications:
    • Marathon runners and cyclists benefit from predominant slow-twitch fibres for endurance events.
    • Sprinters and weightlifters require fast-twitch dominance for power and speed.
    • Team sports like soccer utilise both – slow-twitch for continuous running, fast-twitch for sprinting and jumping.
  • Training adaptations:
    • Endurance training enhances slow-twitch oxidative capacity.
    • Power training increases fast-twitch force production, though fibre type proportions remain largely genetic.

HMS, BM EQ-Bank 829 MC

Which characteristic of fast-twitch muscle fibres makes them most suitable for high-intensity, short-duration activities?

  1. High myoglobin content
  2. Abundant mitochondria
  3. High glycolytic capacity
  4. Slow contraction velocity
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\(C\)

Show Worked Solution
  • C is correct: Fast-twitch fibres use high glycolytic capacity for rapid energy production.

Other Options:

  • A is incorrect: Characteristic of slow-twitch fibres
  • B is incorrect: Characteristic of slow-twitch fibres
  • D is incorrect: Fast-twitch fibres have fast contraction velocity

HMS, BM EQ-Bank 828 MC

A marathon runner is more likely to have a higher percentage of which type of muscle fibres in their leg muscles?

  1. Fast-twitch fibres
  2. Slow-twitch fibres
  3. Intermediate fibres
  4. Explosive fibres
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\(B\)

Show Worked Solution
  • B is correct: Slow-twitch fibres have greater endurance for marathon running.

Other Options:

  • A is incorrect: Fast-twitch fibres suit short, explosive activities
  • C is incorrect: Not a standard muscle fibre classification
  • D is incorrect: Not a standard muscle fibre classification

HMS, BM EQ-Bank 37

Describe TWO characteristics and functions of fast twitch muscle fibres.   (3 marks)

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Sample Answer – ANY 2 of the following

  • Fewer mitochondria: Contains limited mitochondria compared to slow-twitch fibres. Relies on anaerobic energy production rather than oxygen-dependent pathways.
  • Rapid contraction: Contracts quickly to generate explosive force. Enables powerful movements but for short durations only.
  • Quick fatigue: Depletes energy rapidly due to anaerobic metabolism. Limits sustained activity to approximately 10 seconds of maximum effort.
  • Larger diameter: Fast-twitch fibres are larger than slow-twitch fibres. Greater size enables more forceful contractions for explosive movements like jumping and sprinting.
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Sample Answer

  • Fewer mitochondria: Contains limited mitochondria compared to slow-twitch fibres. Relies on anaerobic energy production rather than oxygen-dependent pathways.
  • Rapid contraction: Contracts quickly to generate explosive force. Enables powerful movements but for short durations only.
  • Quick fatigue: Depletes energy rapidly due to anaerobic metabolism. Limits sustained activity to approximately 10 seconds of maximum effort.
  • Larger diameter: Fast-twitch fibres are larger than slow-twitch fibres. Greater size enables more forceful contractions for explosive movements like jumping and sprinting.

HMS, BM EQ-Bank 36

Explain the relationship between muscle fibre types and the production of movement.   (4 marks)

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Sample Answer

  • Muscle fibres have different structural characteristics that determine their function in movement production.
  • Type I fibres contain abundant mitochondria and myoglobin, which enable them to use oxygen efficiently for sustained contractions. As a result, these fibres are recruited for endurance movements like distance running.
  • Type II fibres are larger with fewer mitochondria. Due to their structure, they rely on anaerobic energy systems. Consequently, they produce powerful, explosive movements but fatigue quickly.
  • The reason for selective recruitment is that the nervous system activates specific fibre types based on movement demands. Therefore, slow movements primarily use Type I fibres, while explosive movements recruit Type II fibres. Such coordination ensures the body produces appropriate movements efficiently.
Show Worked Solution

Sample Answer

  • Muscle fibres have different structural characteristics that determine their function in movement production.
  • Type I fibres contain abundant mitochondria and myoglobin, which enable them to use oxygen efficiently for sustained contractions. As a result, these fibres are recruited for endurance movements like distance running.
  • Type II fibres are larger with fewer mitochondria. Due to their structure, they rely on anaerobic energy systems. Consequently, they produce powerful, explosive movements but fatigue quickly.
  • The reason for selective recruitment is that the nervous system activates specific fibre types based on movement demands. Therefore, slow movements primarily use Type I fibres, while explosive movements recruit Type II fibres. Such coordination ensures the body produces appropriate movements efficiently.

HMS, BM EQ-Bank 35

Compare the basic characteristics of fast and slow twitch muscle fibres.   (4 marks)

Sample Answer

Similarities

  • Both fibre types exist in all skeletal muscles and contract through the sliding action of actin and myosin filaments.

Differences

  • Contraction speed differs: Fast-twitch fibres contract quickly for explosive movements, whereas slow-twitch fibres contract slowly for sustained activities.
  • Energy systems vary: Fast-twitch fibres rely on anaerobic metabolism, while slow-twitch fibres use aerobic metabolism efficiently.
  • Structural differences exist: Fast-twitch fibres are larger with fewer mitochondria, in contrast to slow-twitch fibres which are smaller with abundant mitochondria.
  • Fatigue resistance contrasts: Fast-twitch fibres fatigue rapidly, however slow-twitch fibres resist fatigue during prolonged exercise.
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Show Worked Solution

Sample Answer

Similarities

  • Both fibre types exist in all skeletal muscles and contract through the sliding action of actin and myosin filaments.

Differences

  • Contraction speed differs: Fast-twitch fibres contract quickly for explosive movements, whereas slow-twitch fibres contract slowly for sustained activities.
  • Energy systems vary: Fast-twitch fibres rely on anaerobic metabolism, while slow-twitch fibres use aerobic metabolism efficiently.
  • Structural differences exist: Fast-twitch fibres are larger with fewer mitochondria, in contrast to slow-twitch fibres which are smaller with abundant mitochondria.
  • Fatigue resistance contrasts: Fast-twitch fibres fatigue rapidly, however slow-twitch fibres resist fatigue during prolonged exercise.

HMS, BM EQ-Bank 34

Outline TWO structural characteristics of slow twitch muscle fibres.  (3 marks)

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Answers could include TWO of the following:

Slow twitch fibres have:

  • Abundant mitochondria
    • They contain numerous mitochondria throughout the muscle fibre to support aerobic metabolism.
    • These organelles enable efficient ATP production through oxidative pathways, allowing sustained energy generation for prolonged endurance activities.
  • Rich blood supply:
    • Possess an extensive capillary network surrounding each fibre, providing continuous oxygen delivery for aerobic respiration.
    • This vascular density supports the high oxygen demands of endurance activities and contributes to their red appearance.
  • High myoglobin content:
    • Store significant amounts of myoglobin, an oxygen-binding protein within the muscle fibres.
    • This gives them their characteristic red colour and provides an oxygen reserve for sustained aerobic metabolism during prolonged activities.
  • Smaller diameter:
    • Slow twitch fibres have a smaller cross-sectional area compared to fast-twitch fibres.
    • While this limits maximum force production, the smaller size allows for more efficient oxygen diffusion throughout the fibre, enhancing endurance capacity.
Show Worked Solution

Answers could include TWO of the following:

Slow twitch fibres have:

  • Abundant mitochondria
    • They contain numerous mitochondria throughout the muscle fibre to support aerobic metabolism.
    • These organelles enable efficient ATP production through oxidative pathways, allowing sustained energy generation for prolonged endurance activities.
  • Rich blood supply:
    • Possess an extensive capillary network surrounding each fibre, providing continuous oxygen delivery for aerobic respiration.
    • This vascular density supports the high oxygen demands of endurance activities and contributes to their red appearance.
  • High myoglobin content:
    • Store significant amounts of myoglobin, an oxygen-binding protein within the muscle fibres.
    • This gives them their characteristic red colour and provides an oxygen reserve for sustained aerobic metabolism during prolonged activities.
  • Smaller diameter:
    • Slow twitch fibres have a smaller cross-sectional area compared to fast-twitch fibres.
    • While this limits maximum force production, the smaller size allows for more efficient oxygen diffusion throughout the fibre, enhancing endurance capacity.

HMS, BM EQ-Bank 33 MC

Which statement about Type I (slow twitch) muscle fibres' physiological adaptations is INCORRECT?

  1. They have high oxidative capacity
  2. They produce rapid, powerful contractions
  3. They have high fatigue resistance
  4. They support endurance activities
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\(B\)

Show Worked Solution
  • B is correct: Type I (slow twitch) muscle fibres do not produce rapid, powerful contractions – this is a characteristic of Type II (fast twitch) muscle fibres.

Other Options:

  • All other options are correct statements about Type I (slow twitch) muscle fibres.

HMS, BM EQ-Bank 32 MC

Which characteristic best describes Type IIb (fast twitch) muscle fibres?

  1. High mitochondrial density
  2. Slow contraction speed
  3. Rapid force production
  4. High fatigue resistance
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\(C\)

Show Worked Solution
  • C is correct: Type IIb fibres produce rapid, powerful contractions.

Other Options:

  • A is incorrect: Characteristic of Type I (slow twitch) fibres.
  • B is incorrect: Type IIb fibres have fast contraction speeds
  • D is incorrect: Type IIb fibres fatigue quickly