1. LESSON 4 Aerobic Energy System
ENERGY SYSTEMS
LESSON 4
Aerobic Energy System

2. LEARNING OBJECTIVES Am I able to explain the Aerobic System?
Can I evaluate the Aerobic System?

3. STARTER
Explain the facts about the Lactic Acid System

4. FACTS OF THE LACTIC ACID SYSTEM
There is NO Oxygen present!! Therefore, the Lactic Acid System works under Anaerobic conditions
The fuel for this system is Carbohydrates (in the form of Glycogen)
The reactions take place in the sarcoplasm of the muscle cells
The main limitation of this system is the Onset of Blood Lactate Accumulation (OBLA) – which lowers the pH and inhibits enzymes
The Lactic Acid system is the predominant energy system for the 400m sprint and for midfield games players that have lots of high intensity sprints with no time for recovery

5. AEROBIC ENERGY SYSTEM Look at sheet provided about the Aerobic System
Explain what is happening during:
Aerobic Glycolysis
Krebs Cycle
Electron Transport Chain

6. AEROBIC GLYCOLYSIS
This is the same reactions as Lactic Acid System, apart from Pyruvic Acid combines with coenzyme A to form Acetyl CoA due to oxygen being present

7. KREBS CYCLE
The Acetyl CoA combines with oxaloacetic acid to form Citric Acid
Citric acid is then taken into the Krebs Cycle where:
CO2 is produced and removed via the lungs
Hydrogen atoms are removed (oxidation)
Energy is produced to re-synthesis 2 molecules of ATP
Oxaloacetic acid is regenerated

8. ELECTRON TRANSPORT CHAIN
The Hydrogen atoms (from Krebs Cycle) Combine with the coenzymes NAD and FAD to form NADH and FADH
These are then carried down the Electron Transport Chain where hydrogen is split into H+ and e
This takes place in the cristae of the mitochondria where three important events take place:
The hydrogen electron (e‾) splits from the hydrogen atom and passes down the ETC
This provides sufficient energy to re-synthesise 34 ATP molecules
The hydrogen ion (H+) combines with oxygen to form water (H2O)

9. TASK Explain how ATP is re-synthesised in the Aerobic System
You must include information on the following:
Aerobic Glycolysis
Krebs Cycle
Electron Transport Chain

10. FATS
Triglycerides (fats) are broken down by enzymes termed lipases into free fatty acids (FFA) and glycerol and used as an energy fuel within the aerobic system
FFA are broken down into Acetyl CoA, which enters and is broken down by the Krebs Cycle and the ETC in the process termed beta-oxidation
FFA produce more Acetyl CoA and consequently produce far greater energy than the breakdown of glycogen/glucose
However, FFA’s require 15% more O2 than that required to break down glucose
Therefore, glycogen and glucose are the preferred energy fuel during moderate or high intensity activity

11. TRAINING ADAPTATIONS
Aerobic training causes a number of beneficial adaptations which help to improve the aerobic energy system’s efficiency to re-synthesise ATP:
Increased storage of muscle and liver glycogen
Increased metabolism of aerobic enzymes
Earlier use of FFA’s as a fuel thereby helping to conserve glycogen stores
The net effect of the above adaptations is that they increase/prolong the aerobic threshold thereby increasing the potential intensity of performance
This delays muscle fatigue by increasing the intensity at which the onset of blood lactate accumulation is reached and by maximising its efficiency to remove lactate during periods of recovery

12. ADVANTAGES OF THE AEROBIC ENERGY SYSTEM
Large potential glycogen and Free Fatty Acids (FFA) stores available as an efficient energy fuel
Efficient ATP re-synthesis when good O2 supply guarantees breakdown of FFA
Large ATP re-synthesis. 38 ATP from one molecule of glucose, compared to 2 from LA system and 1 from ATP/PC system
Provides energy for low/moderate intensity, high duration exercise (3 minutes to 1 hour)
No fatiguing by-products. CO2 and H2O are easily removed

13. DISADVANTAGES OF THE AEROBIC ENERGY SYSTEM
Slower rate of ATP re-synthesis compared with LA system
Requires more O2 supply (15% more for FFA)
More complex series of reactions
Cannot re-synthesise ATP at the start of exercise due to initial delay of O2 from the cardiovascular system
Limited energy for ATP during high intensity, short duration work

14. FACTS OF THE AEROBIC SYSTEM
The Aerobic System works under Aerobic conditions
The fuel for this system is Glycogen or Fat as well as requiring Oxygen to function
The reactions take place in the sarcoplasm of the muscle cells, Matrix of the Mitochondria and Cristae of the Mitochondria

15. PLENARY
Explain how the three energy systems would work throughout a Football match