Functional Roles of Muscles & Types of Contraction

• Points of Attachment

  • insertion - point of muscular attachment to a moveable joint/bone which gets closer to the origin during muscular contraction
  • origin - point of muscular attachment to a stationary bone which stays relatively fixed during muscular contraction
• Antagonistic Muscle Action

  muscles work in pairs/groups to produce coordinated movement
• Agonist

  muscle responsible for creating movement at a joint, primer mover
• Antagonist

  muscle that opposes the agonist providing resistance for coordinated movement
• Fixator

  muscle that stabilises one part of the body while another causes movements
• Types of Muscle Contraction

  • isometric
  • isotonic
  • isotonic concentric
  • isotonic eccentric
• Isometric Contractions

  when the muscle contracts without lengthening or shortening whilst producing tension

  holds the body in a stationary position, no movement occurs

  
  

  e.g crucifix on rings in gymnastics
• Isotonic Contractions


  muscular contraction which changes length during its contraction

  either eccentric or concentric
• Eccentric Contraction


  muscular contraction which lengthens while under tension

  a type of isotonic contraction which causes extension

  e.g bicep brachii in the downwards phase of bicep curl
• Concentric Contraction 


  muscular contraction which shortens while producing tension

  a type of isotonic contraction which causes flexion

  e.g bicep brachii in the upwards phase of bicep curl