Energy Systems

• 3 Types of Energy Systems

  • ATP-PC system
  • glycolytic system
  • aerobic system
• ATP-PC System

  • also known as the alactacid phosphocreatine system
  • breakdown of PC releases energy (exothermic) & this energy is used to resynthesise ATP (endothermic)
  • uses a coupled reaction
  • duration is 3-10s
  • anaerobic reaction
  • fuel used is PC
  • enzyme that breaks down PC is creatine kinase
  • site of reaction is the sarcoplasm of muscle cells
  • 1:1 energy yield
  • waste product is creatine
• ATP-PC System Evaluation

  + provides energy for very high intensity activity, no fatiguing by-products, no delay for oxygen, ATP can be resynthesised rapidly

  _ low ATP yield, only good for anaerobic events, only lasts 8-10s, limited supply of PC in muscle cells
• ATP-PC System Sporting Examples

  • very high intensity activity
  • 100m sprint
  • long jump
  • javelin throw
  • gymnastics vault
• Glycolytic System

  • also known as the lactic acid system
  • consists of the breakdown of glycogen/glucose to pyruvic acid & then this pyruvic acid is then converted into lactic acid
  • duration of up to 3 mins
  • anaerobic reaction
  • fuel used is glycogen/glucose
  • enzymes used are GPP, PKF & LDH
  • site of reaction is the sarcoplasm of muscle cells
  • 1:2 energy yield
  • waste product is lactic acid
• Glycolytic System Evaluation

  + relatively large amounts of glycogen stored in the body, no delay for oxygen, ATP can be regenerated quickly due to few chemical reactions being needed

  _ lactic acid produced reduces pH & enzyme activity, relatively low ATP yield, OBLA occurs earlier & recovery takes longer
• Glycolytic System Sporting Examples

  • 400m sprint
  • 100m freestyle swim
• Aerobic System

  there are 3 distinct stages to this energy system:

  1. aerobic glycolysis
  2. Kreb's cycle
  3. Electron Transport chain

  • duration is anything longer than 3 minutes
  • aerobic reaction
  • fuels used are glycogen/glucose & triglycerides
  • enzymes used are GPP, PFK & ACETYL CO-A
  • 1:38 energy yield
  • waste products are CO2 and H2O
• Aerobic System - Aerobic Glycolysis

  • site of reaction is sarcoplasm of muscle cells
  • converts glucose into pyruvic acid using the enzyme PFK
  • resynthesises 2 ATP
• Aerobic System - Kreb's Cycle

  • site of reaction is matrix of mitochondria
  • Acetyl CoA combines with oxaloacetic acid to form citric acid
  • this is oxidised through a cycle of reactions
  • resynthesises 2 ATP
• Aerobic System - Electron Transport Chain

  • site of reaction is the cristae of mitochondria
  • NAD & FAD split hydrogen atoms into ions & electrons
  • hydrogen ions are oxidised & removed as H2O
  • resynthesises 34 ATP
• Aerobic System Evaluation


  + high ATP yield, long duration of energy production, no fatiguing by-products, large fuel stores

  _ slow energy production limits activity to sub-maximal intensity, delay for oxygen delivery, complex series of reaction
• Aerobic System Sporting Examples

  • marathon
  • football game