PE GCSE - Muscular system

• Slow twitch muscle fibres

  Contracts slowly with less force. Fatigues slowly, uses oxygen well. Can keep going for a long time. Adapted to aerobic respiration
• Fast twitch muscle fibres

  Contracts quickly with more force. But Fatigues quickly as does not use oxygen well. Adapted to anaerobic respiration
• How long can recovery time take?

  Up to 48 hours
• How does rest allow the body to recover?

  Can recover from minor injuries, stiffness and soreness. Allows for lost fluids to be replaced. Refill glycogen stores.
• Long term effects of excersie on the muscular system

  Muscle hypertrophy, which improves strength. Increased tolerance to lactic acid. Increased strength of tendons and ligaments.
• Short term effects of excersie on the muscular system

  Increase in temperature of the muscles. Increased elasticity. Muscle fatigue. Muscle soreness.
• Eccentric Contractions

  Lengthens
• Concentric Contractions

  Shortens
• muscle contracts and changes length. Eg. the tricep lengthens and the bicep shortens during the upward phase of a dumbell.

  Isotonic contractions:
• muscle contracts but stays the same length. Eg. Plank, Wall sit, a scrum in rugby, muscles in use but don't move.

  Isometric contractions:
• Antagonist muscle

  The muscle opposite the agonist, which must relax and lengthen during contraction of the agonist.
• Agonist muscle


  muscle doing the work, contracting. The muscle in agony.
• Antagonistic muscles


  Muscles that work in pairs to produce movement. They sit back to back, opposite each other.