A2 PE physiology



  • Energy systems rarely work in isolation eg games player have high and low intensity 
  • Energy is provided by each system 
  • The contribution id determined by intensity and duration of exercise

Shotputter- 90% ATP/PC System 

Marathon Runner- 5% Lactic Acid System 95% Aerobic System 

800m Runner- 30% ATP/PC System 65% Lactic Acid System 5% Aerobic System 

Tennis Player- 70% ATP/PC System 20% Lactic Acid System 10% Aerobic System

Netball Player- 60% ATP/PC System 20% Lactic Acid System 20% Aerobic System 

To measure intensity- 

  • Calculate % of max HR ( 220-age = max ) 
  • Or vO2 max- Amount of O2 taken on in 1 min 
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  • Threshold of ATP/PC 10 seconds 
  • Threshold of Lactic Acid 3 minutes
  • When aerobic system can nolonger supply energy quick enough it goes back to anaerobic 
  • This is called blood lactate accumulation 
  • The conc of blood lactic acid in the blood increases quickly 
  • norm- 1-2mm of LA per L of blood 
  • 4mm + is when OBLA is reached 
  • This point varies due to aerobic fitness
  • Untrained- OBLA at 50% of vO2 max 
  • Trained- OBLA at 85% of vO2 max 
  • Trained athletes can get rid of LA and supply O2 to working muscles
  • Stores of fuels vary according to fitness levels
  • Increased muscle size , Increased aerobic metabolism , Increased enzyme activity 
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  • Doesnt require 02
  • PC stored in the muscle cells as a readily avaliable energy source
  • Small compound so quick reaction
  • Automatically stimulated by a decrease in ATP and increase in ADP
  • Provides energy for high intensity actions
  • No fatiguing by-products
  • PC can be resynthesised quickly 


  • Only small amounts of ATP/PC stored in muscles 
  • 1;1 ratio 
  • Lasts 8-10 seconds 
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  • Large glycogen stores in muscle/liver 
  • 2;1 ratio 
  • Fewer reactions than the aerobic system 
  • Quicker supply of energy 
  • GGP and PFK enzyme activated due to decrease in PC
  • Lasts between 10-180 seconds 
  • Can work areobically and anaerobically 


  • Not as quick as ATP/PC system 
  • Produces lactic acid ( fatiguing by-product)
  • Reduced pH , inhibits enzymes 
  • Stimulates pain receptors 
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  • Large glycogen and FFA stores avaliable 
  • Efficient ATP resynthesis with O2 
  • 38 ATP 1 glucose 
  • low intensity high duration exercise 
  • No fatiguing by-products 


  • Slower resynthesis 
  • Requires more O2 
  • More complex reactions 
  • Delay of resynthesis as O2 required 
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