muscular system

• 1. smooth muscle – found in the internal organs and blood vessels - this is involuntary
  2. cardiac muscle – found only in the heart - this is involuntary
  3. skeletal muscle – attached to the skeleton - this is voluntary

  Involuntary muscles are not under our conscious control which means we can't make them contract when we think about it.

  Voluntary muscles are under our conscious control so we can move these muscles when we want to.
• A sprinter would need a high percentage of type IIx fibres so that their muscles can contract very quickly and produce a lot of force so that they can run very fast over a 100 m distance. However, these muscles tire very quickly so the sprinter will not be able to run at this speed for very long.