There are two kinds of endurance:


  • Your muscles can continue to exert a lot of force for a long period
  • The feeling of heaviness and weakness means your muscles are fatiguing
  • Athletes with high muscular endurance have higher proportions of slow twitch muscle fibers
  • Muscular endurance can be increased through weight training



  • Your heart and lungs can keep your muscles supplied with Oxygen throughout exercise
  • The harder your muscles work the more oxygen they need, so the heart and breathing rates rise
  • The better your CV system is, the slower your heart rate is because you pump more blood with each beat
  • You can improve your CV endurance through aerobic training
  • The graph below will help you work out what heart rate you should train at to get the best results




The aerobic zone is where you should be working if you are looking to improve your CV endurance. You can work out your maximum predicted heart rate by taking your age away from 220 (220 - your age).

Aerobic vs Anaerobic

Respiration is the way in which energy is released from the food we eat. Respiration can be either aerobic or anaerobic:


  • Means with Oxygen
  • Your heart and lungs supply enough Oxygen to the muscles to maintain the level of exercise
  • This equation explains the process of respiration:


Glucose + Oxygen = Carbon dioxide + Water + Energy


  • The Carbon dioxide and water are breathed out. Water is also lost through sweat
  • As long as you get enough Oxygen to the muscles, this can continue for long periods


  • Means without Oxygen
  • Your heart and lungs do not supply enough Oxygen to the muscles to maintain exercise
  • This is the equation:


Glucose = Lactic acid + Energy


  • Lactic acid builds up in the muscles because there isn't enough Oxygen
  • Lactic acid makes your muscles feel very tired and heavy
  • Soon enough you have to slow down or stop altogether