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Aerobic and anaerobic pathways – an introduction to the energy systems. Aerobic and anaerobic pathways – an introduction to the energy systems. Text Reference Nelson Physical Education VCE Units 1 &2 – Chapter 3 . What do I need to know?. Key Knowledge - PowerPoint PPT Presentation
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Aerobic and anaerobic pathways – an introduction to the energy systems
Aerobic and anaerobic pathways – an introduction to the energy systems
Text Reference1. Nelson Physical
Education VCE Units 1&2 – Chapter 3
.
What do I need to know?
Key Knowledge Introduction to the characteristics of aerobic and anaerobic
pathways (with or without oxygen) and their contribution to movement and dominant fibre type associated with each pathway.
Key Skills Identify the dominant energy pathway utilised in a variety of
aerobic or anaerobic activities determined by the intensity and duration of the activity. Collect, analyse and report on primary data related to responses to exercise and anaerobic and aerobic pathways.
Food FuelsFood fuels and the three energy systems
Food Fuels for Energy1. Carbohydrates
(CHO) – Preferred source of fuel during exercise (Glycogen)
2. Fat – Concentrated fuel used during rest and prolonged sub-maximal exercise.
3. Protein – Used for growth and repair (Negligible use during exercise)
Energy
VCE Physical Education - Unit 3
Foods High in CHO, Fats and Proteins
VCE Physical Education - Unit 3
Adenosine Triphosphate (ATP)
Food fuels and the three energy systems
Food Fuels at RestRest (Aerobic) Fat and glucose are the preferred fuelsDuring Exercise1. Short duration / high intensity – Anaerobic systems used using
carbohydrates.2. Long duration / low intensity – Aerobic system using carbohydrates.
However, fats are used once glycogen stores are depleted.
Maximal and Sub-maximal Activity
Contributions of Carbohydrates, Fats and Protein to Energy Production
Food fuels and the three energy systems
Energy Demands - Intensity
Low intensity ATP requirements are met aerobically using the aerobic
system.High Intensity Explosive movements require instant supply of ATP which can’t
be met aerobically, therefore the ATP-PC and lactic acid systems need to be used anaerobically.
Aerobic Anaerobic
Intensity increases
Carbohydrate Contributions
Storage (Based on 80kg person)
Muscle glycogen – 400g Liver glycogen – 100gIntake of Carbohydrates
depends on the intensity and duration of exercise bouts.
Normal contribution to diet is 55-60% CHO
Carbohydrate loading (80% CHO intake) is used for endurance activities.
Carbohydrate rich diet; Increases glycogen stores Glycogen is used in
rebuilding ATPCHO preferred fuel over fats
during exercise due to requiring less oxygen to release energy.
Athletes need to be aware of their dietary intakes of CHO. Excess CHO is converted to fat.
Fat ContributionsStorage of fats Adipose tissue Triglycerides (Broken down into free fatty
acids)Aerobic metabolism of fat is; Slow as it requires more
oxygen than CHOs. Adds stress to the oxygen
transport system ATP yield is much higher
from fat (460 molecules) in comparison to glucose (36).
At rest 50% of energy supplied by
fats Oxygen demand is easily
met to burn fatsBenefits of fat Large energy store Transport medium for fat
soluble vitaminsNegative aspects of fat Adverse health effects Obesity, heart disease etc.
Protein ContributionsRole of protein (Amino acids) in the body; Growth and repair Speed up reactions in the body (Enzymes) Produces hormones and antibodiesProtein and exercise1. Not used as a fuel, therefore low priority.2. Only used in extreme circumstances3. Normal diet contains enough protein (15%).Excess protein can lead to; Less intake of CHO Increase in fat intake from animal products Increase in fluid waste
VCE Physical Education - Unit 3
Prolonged Endurance Events
During prolonged endurance events such as marathon running and triathlons;
Body uses a combination of CHO and fats.
Trained athletes are able to ‘spare’ glycogen and use free fatty acids.
Fats cannot be used alone as a fuel (poor solubility in the blood).
‘Hitting the wall’ occurs when glycogen stores are depleted. This is called ‘hypoglycaemia’.
VCE Physical Education - Unit 3
Glycemic Index (GI)
Glycemic index; Rating of CHO effect
on blood glucose Quick breakdown with
immediate effect on blood glucose levels are labelled high GI
Slow breakdown are labelled low GI
Before exercise you should eat;
Food that maintains blood glucose levels ie.low GI food
Avoid high GI food prior to exercise.
High GI cause an insulin surge, effecting the performance of an athlete
The Three Energy SystemsFood fuels and the three energy systems
Aerobic Exercise Aerobic exercise includes lower intensity activities
performed for longer periods of time. Activities like walking, jogging, swimming, and
cycling require a great deal of oxygen to make the energy needed for prolonged exercise.
The energy system that is used in aerobic exercise is called the aerobic system. It can also be called ‘oxygen system’ or the ‘aerobic glycolysis system’.
Anaerobic Exercise The term "anaerobic" means "without air" or "without oxygen." Anaerobic exercise uses muscles at high intensity and a high
rate of work for a short period of time. Anaerobic exercise helps us increase our muscle strength and
stay ready for quick bursts of speed. Examples of anaerobic exercise include heavy weight lifting, sprinting, or any rapid burst of hard exercise.
These anaerobic exercises cannot last long because oxygen is not used for energy and fatiging metabolic by-products
There are two energy systems which use the anaerobic pathways; ATP-PC and the Lactic Acid systems
Common Mistake The three energy
systems do not turn on and off like a traffic light.
They are always in operation – the relative contribution of each system varies depending on factors such as intensity, type of activity and duration. X
The ATP-PC SystemFood fuels and the three energy systems
Anaerobic Most rapidly
available source of ATP
Depends on simple short chemical reactions
Stored PC last for 10 seconds at max intensity
The ATP-PC SystemHow does the system
work? PC releases a free
phosphatePC = P + C ADP + P = ATP
Body has a larger storage of PC compared to ATP
PC stores can be replenished through aerobic recovery.
Once PC stores are depleted, they body must use glycogen through the anaerobic pathway.
The Lactic Acid SystemFood fuels and the three energy systems
The Lactic Acid System
The lactic acid system; Activated at the start of
intense exercise More complex reactions
than the ATP-PC system Peak power until it fatigues
(2-3 minutes) Predominant energy
supplier in events 85% max HR eg. 200m sprint.
How the system works; Glycogen is broken down in
the absence of oxygen (Anaerobic glycolysis)
This produces a fatigue causing by product called lactic acid.
Lactic acid makes the muscle pH decrease (More acidic), reducing ATP resynthesis.
The lactic acid system; Provides twice as much
energy for ATP resynthesis than the ATP-PC system.
Fatiguing metabolic by-products produced at the lactate inflection point (LIP)
The Aerobic SystemFood fuels and the three energy systems
The Aerobic System
The aerobic system Slowest contributor to ATP
resynthesis However, produces much more
energy than the anaerobic systems
Becomes major contributor once the lactic system decreases.
Major contributor in prolonged exercise eg. Endurance events.
Aerobic system does contribute in maximal intensity exercise (Eg. Between 55-65% in 800m)
table 4.4 p.101 and 4.5 p.102
How the system works;1. CHOs and Tryglycerides (FFA
+ glycerol) broken down to release energy. This produces pyruvic acid.
2. Pyruvic acid is further broken down producing carbon dioxide (Kreb’s cycle)
3. Further breakdown via the electron transport chain. It requires hydrogen ions and oxygen, producing water and heat.
Comparing the Three Energy SystemsFoods, Fuels and Energy Systems
VCE Physical Education - Unit 3
Energy System InterplayFoods, Fuels and Energy Systems
Interplay Between Energy Systems
All activities use some energy from all three systems.The energy systems overlap – they never work
independently.It it’s the relative contribution of each system that
varies.
Anaerobic v Aerobic Contributions