Muscle Fibre Types

• How many different types of muscle fibre can one skeletal muscle contain?

  Three different types
• What determines the duration and intensity of exercise in muscle fibres?

  The characteristics of each fibre type
• What are the three types of muscle fibres?

  • Type 1 – Slow Oxidative
  • Type 2a – Fast Oxidative Glycolytic
  • Type 2b – Fast Glycolytic
• What is the primary function of slow oxidative muscle fibres?

  To store oxygen in myoglobin and process it in the mitochondria
• How do slow oxidative muscle fibres generate ATP?

  By breaking down fats and glucose in the mitochondria
• What is the only usable form of energy in the human body?

  ATP
• Why do slow oxidative fibres have a high density of mitochondria and myoglobin?

  To efficiently process oxygen for energy production
• What is the role of capillaries in slow oxidative muscle fibres?

  To provide a dense network for oxygen transport
• What type of muscle fibres work aerobically and can withstand fatigue for long periods?

  Slow oxidative muscle fibres
• What are the three types of muscle fibres mentioned?

  Type I, Type II A, and Type II B fibres
• Why can slow oxidative muscle fibres only produce a small amount of force in contraction?

  Because they are designed for endurance rather than strength
• What are the functional characteristics of muscle fibres?

  • Speed of Contraction
  • Force of Contraction
  • Resistance to Fatigue
  • Activity Used For
  • Anaerobic Capacity
  • Aerobic Capacity
• How does the composition of muscle fibres affect an individual's athletic performance?

  It determines the type of activity they are successful at
• What are the structural characteristics of muscle fibres?

  • Mitochondrial Density
  • Capillary Density
  • Myoglobin Content
  • Motor Neuron Size
  • Fibres per Neuron
  • Phosphocreatine Stores
• What is the speed of contraction for Type I fibres?

  Slow
• What percentage of slow oxidative fibres might a long distance runner's gastrocnemius contain?

  About 70%
• What is the force of contraction for Type I fibres?

  Low
• What type of events are fast glycolytic muscle fibres suited for?

  Explosive, power events such as Shot Put and 100m sprint
• How do Type I fibres resist fatigue?

  They have high resistance to fatigue
• What is a key difference between fast glycolytic muscle fibres and slow oxidative muscle fibres?

  Fast glycolytic fibres can exert a large force and have a fast contraction and relaxation time
• What type of activity are Type I fibres primarily used for?

  Aerobic activity
• What energy source do fast glycolytic muscle fibres have large stores of?

  Phosphocreatine
• What type of respiration do fast glycolytic muscle fibres use?

  Anaerobic respiration
• How does phosphocreatine benefit fast glycolytic muscle fibres?

  It enables an immediate energy supply
• What is the anaerobic capacity of Type I fibres?

  Low
• Why do fast glycolytic muscle fibres fatigue quickly?

  Because they work anaerobically and can only last a short duration before fatigue
• What is the aerobic capacity of Type I fibres?

  High
• What is the size comparison of fast glycolytic muscle fibres to other types?

  They are the largest type of fibre
• What is the mitochondrial density in Type I fibres?

  High
• How do fast glycolytic muscle fibres contribute to force of contraction?

  They have large neurons with many fibres connected to one neuron, which helps exert a larger force of contraction
• What is the capillary density in Type I fibres?

  High
• What is the myoglobin content in Type I fibres?

  High
• Which type of athlete would most likely have a high percentage of type 2b fibres?

  A shot putter
• What is the motor neuron size for Type I fibres?

  Small
• In which muscles would a shot putter likely have a high percentage of type 2b fibres?

  Deltoids, pectoralis majoris, and quadriceps
• What is the primary function of fast oxidative glycolytic muscle fibres?

  To produce a large amount of force relatively quickly while resisting fatigue
• How many fibres per neuron are there in Type I fibres?

  Few
• What are the phosphocreatine stores like in Type I fibres?

  Low
• How are fast oxidative glycolytic muscle fibres similar to type 2b muscle fibres?

  They both have large neurons that innervate many muscle fibres at once
• What role do large stores of phosphocreatine play in fast oxidative glycolytic muscle fibres?

  They help to maintain a good anaerobic capacity