C7 - Energy Systems

• Stores of Adenosine Triphosphate (ATP) and Phosphocreatine (PC):

  • There are increased levels of ATP and PC in the muscle and an increased capacity to generate ATP by the ATP-PC energy system
  • This is partly due to the increased activity of the enzymes which break down PC
  • ATP production by anaerobic glycolysis is increased as a result of enhanced activity of the glycolytic enzymes
  • There is also an increased ability to break down glycogen in the absence of oxygen
• Stores of Glycogen:

  • When glucose is stored it is in the form of glycogen which is bound to water (1g of glucose need 2.7g of water) for storage
  • However, the glycogen molecule is bulky and difficult to store in large amounts
  • The body can store around 1600 kcals of glycogen, which would enable us to run for around 2 hours
• Stores of Triglyceride:

  • Triglycerides are dietary fats in that they are how the fats we ingest are packaged
  • A triglyceride is defined as 'three fatty acid attached to a glycerol backbone'
  • Glycerol is actually a carbohydrate which the fatty acids attach to; during digestion the fatty acids will be broken off from the glycerol backbone to be used by the body as required
  • The glycerol will be used as all carbohydrate are used to produce energy
• Number and Size of Mitochondria:

  • Aerobic endurance exercise leads to the increase in number of mitochondria in the muscles that are used in exercise
  • There is also an increase in the numbers of enzymes required in the process for ATP production in the mitochondria which results in the mitochondria being able to produce ATP more quickly
• Onset of Blood Lactate Accumulation (OBLA):

  • As lactate accumulates it decreases the pH levels of the blood, making it more acidic
  • This increased levels of hydrogen ions will eventually prevent the glycolytic enzyme functioning
  • However, anaerobic training increases the buffering capacity of the body and enables the body ti work for longer in periods of high acidity so OBLA will increase
• Aerobic and Anaerobic Enzymes:

  • The enzymes required to produce ATP during anaerobic and aerobic exercise increase which means the energy systems can produce ATP much more quickly after appropriate exercise training
• Lactate Buffering:

  • Anaerobic training increases the buffering capacity of the body and enables the body to work for longer in periods of high intensity
• Respiratory Exchange Ratio (RER):

  • The RER is ratio of carbon dioxide produced in relation to the amount of oxygen consumed by a person in each breath and is used to work out which fuels a person is using when they exercise
  • RER = Volume carbon dioxide produce/volume of oxygen consumed
  • This is also known as the Respiratory Quotient (RQ)
  • The fuel used to supply energy during exercise will determine RER value
  • Carbohydrate = 1, Fat = 0.7, Protein = 0.8
  • An RER greater than 1 shows that a person is working anaerobically, as more carbon dioxide is being produced compared to oxygen being consumed