fast v slow twitch

• fast twitch

  • contract rapidly - found in limbs and eyelids
  • short burst of energy- unstable /not sustainable-fatigue rapidly and increase lactate formation
  • rely on anaerobic respiration for ATP
  • increased rate of ATP hydrolisis in myosin heads
  • fewer and smaller mitochondria
  • fewer capillaries-flow supply of oxygen and glucose(aerobic)
• slow twitch

  • contract slower for sustained activities
  • aerobic respiration for ATP
  • fatigue slower-less lactate formation-good endurance
  • denser network of capillaries-supply 02 and glucose
  • more myoglobin, haemoglobin and mitochondria= increased 02 supply, absorption and aerobic respiration
  • slower rate of ATP hydrolisis in myosin head
  • small calcium ion store