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WHAT DO WE NEED TO BE ABLE TO MOVE?CHAPTER 3
PAGE 45-60
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LEARNING GOALS SUCCESS CRITERIA
• To be able to explain the characteristics of
aerobic and anaerobic pathways and their
contribution to movement and dominant fibre
type associated with each pathway
• I can identify and explain the dominant energy
pathway utilised in a variety of aerobic or
anaerobic activities
• I can collect, analyse and report on data related to
responses to exercise and anaerobic and aerobic
pathways
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MOVEMENT REQUIRES ENERGY!
Nutrients in food are converted into the body’s energy currency which is called ATP. This allows a muscle to
contract.
The energy released from the breakdown of foods cannot be transferred directly to our cells, so it has to be
stored.
ATP can only be stored in limited amounts, whether you’re a couch potato or an Olympic athlete.
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MUSCULAR WORK
How we move determines our energy requirements and associated processes:
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ENERGY DEMAND
Two factors determine the energy (ATP) demand of an event:
Exercise intensity – determines rate of ATP resynthesis needed
Exercise duration – determines yield of ATP resynthesis needed
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Energy Systems
WHAT? 1
WHY? 2
HOW? 3
WHEN? 4
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WHAT?
Energy systems break the bonds of different body fuels via a series of complex reactions to extract chemical
energy. This energy is used to resynthesise ATP for muscle contraction.
A car engine uses one type of fuel (petrol), skeletal muscle has the advantage of obtaining energy from breaking
down as many as four different fuel sources:
Creatine Phosphate (CP) or Phosphocreatine (PC)
Carbohydrates (CHO)
Lipid (fat)
Protein
These are mainly found in our diets and are stored in our bodies including our muscles, liver, adipose tissue and
blood.
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WHAT?
The energy systems work together to meet the ATP requirements.
We have three energy systems or pathways that work together to supply the body with ATP, our universal energy
currency.
Anaerobic or “O2 independent”
ATP-PC system
Anaerobic glycolysis system
Aerobic or “O2 dependant”
Aerobic system
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ATP-PC SYSTEM (F1 POWER)
This system provides the fastest rate of ATP resynthesis as it
uses the fuel creatine phosphate (CP) or phosphocreatine
(PC) already stored in the muscle.
This system has the fastest rate of ATP resynthesis, therefore is
used as the predominant energy system by athletes competing in
short duration, high-intensity ‘power’ events.
This is the most powerful system, but has a limited capacity to
generate ATP as it fatigues rapidly.
This can only be used as the predominant energy system for up
to 6 – 10 seconds. The first 2 – 3 seconds of maximal effort work
will rely on the breakdown of existing ATP stores in the muscle.
You may also hear this system being referred to as the alactacid
system or the phosphagen system.
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ANAEROBIC GLYCOLYSIS SYSTEM (V8 SUPERCAR)
This system involves more complex chemical reactions that breakdown the fuel known as muscle
glycogen to release energy via the process of anaerobic glycolysis. This results in the formation of the by-
product lactic acid.
This system can resynthesise ATP at a fast rate allowing for the continuation of high-intensity effort. This system is
normally used in activities that last between 10 and 75 seconds.
Anaerobic glycolysis literally means ‘the breakdown of sugar independent of oxygen’.
ATP is resynthesised from the breakdown of carbohydrates mainly in the form of muscle glycogen (some can come
from blood glucose)
As oxygen is not present, glycogen is not completely broken down and pyruvic acid is formed which then ferments to
produce lactate.
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AEROBIC SYSTEM (SMARTCAR)
This system is the most complex and involves the greatest number of chemical reactions. It has three
distinct stages and is able to use either carbohydrate (CHO) or lipids (fat) fuels stored inside and
outside of the working muscles. The by-products formed as a result of using this system include CO2,
H2O and heat.
The three stages are known as:
1. Glycolysis
2. Kreb’s Cycle
3. Electron Transport System (ETS)
This system has a considerably slower rate of ATP resynthesis due to a reduction in intensity, but has an unlimited
capacity for resynthesis and is therefore the predominant energy system used at rest and during events lasting
over 75 seconds.
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Energy Systems
WHAT? 1
WHY? 2
HOW? 3
WHEN? 4
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WHY?
We require ATP for muscle contraction and movement everyday. ATP is the body’s universal energy currency
used by all systems: cardiac, respiratory, muscular.
Actual ATP store (70kg)
50gRequired ATP for 1 day
190kg
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Energy Systems
WHAT? 1
WHY? 2
HOW? 3
WHEN? 4
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HOW?
Energy systems resynthesise ATP using energy released from fuels stored in the body.
Food Fuels Chemical fuels (substrates) Energy system
Lipids
(Fat)
Free Fatty Acids – FFA (blood)
Triglycerides (adipose tissue, muscle)
Aerobic
Carbohydrate
(CHO)
Glucose (blood)
Glycogen (muscle, liver)
Aerobic
Anaerobic Glycolysis
Creatine
(Cr)
Phosphocreatine – PC or CP (muscle) ATP-PC
Protein
(AA)
Amino acids – AA (blood, muscle) Aerobic
Substrate: is a fuel stored in the body in a chemical form that is broken to release energy for ATP.
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Energy Systems
WHAT? 1
WHY? 2
HOW? 3
WHEN? 4
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WHEN?
Energy
System
Predominant
fuel(s)
Predominant Power
(rate)
Capacity
(yield)
By-products Fatigue
mechanism
Event
ATP-PC Phosphocreatine
(PC)
6 – 10 sec Fastest Smallest None Fuel depletion (PC) 100m sprint, field
events,
weightlifting
Anaerobic
Glycolysis
Muscle glycogen
Glucose
30 to 60 sec Fast Small H+, lactate Accumulation of
by-products (H+)
400m sprint, 100m
freestyle
Aerobic Muscle
glycogen/glucose
Muscle triglyceride
Free Fatty Acids
1-2 mins to 3
hours
4 hours +
Medium
Slow
Large
Largest
CO2, H2O,
heat
Accumulation of
by-products (H+)
Fuel depletion
(MG)
Thermoregulation
1500m freestyle,
800m run
Ironman
(triathalon)
Aerobic glycolysis
Aerobic lipolysis
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ENERGY SYSTEM INTERPLAY
The energy systems do not work in isolation. The way they work together is referred to as interplay.
The energy system said to be contributing the most to ATP resynthesis is referred to as the predominant energy
system.
Energy systems are not switched on or off, but instead increase and decrease their contributions.
At the start of any event, all 3 systems will contribute with ATP.
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RELATIVE CONTRIBUTIONS TO MEET THE REQUIREMENTS OF HIGH-
INTENSITY EFFORTS.
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Match the bars in
the graph with the
following events.
a) 400-metre sprint
b) 200-metre run
c) 3-kilometre run
d) 100-metre sprint
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Refer to the graph.
a) Identify which graph best represents a 3-
kilometre run. Justify your answer.
b) Identify the times at which the anaerobic
systems would have been predominant.
c) Explain the contribution of the anaerobic
energy systems in the activity.
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EXAM QUESTIONS
Question 1
Christine Ohuruogu ran a time of 49.62 seconds to win the gold medal in the 400-metre event at the 2008 Beijing Olympics. Identify the predominant fuel her body used for this event.
1 mark
Question 2
Identify the three by-products of the aerobic energy system.
1 mark
Question 3
Carbohydrates, fats and proteins are the three main food groups. Identify the chemicals that these three food groups are stored as in the muscles.
1 mark
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Sport or event A B C D E F G H I
Percentage anaerobic energy contribution 10 20 30 40 50 60 70 80 90
Percentage aerobic energy contribution 90 80 70 60 50 40 30 20 10
Question 4
The table below shows the percentage of energy contribution for various activities
a) Which of the following would best match the letters A, E and H from the table in relation to the percentage
contribution of anaerobic and aerobic energy systems for that particular sport or event?
• Steve Hooker's pole vault world record attempt
• John Van Wisse's winning 48-kilometre swim around New York's Manhattan Island
• An AFL centre player's first quarter of football
• An Australian soccer striker attempting a shot on goal
• Olympic standard shot-put event
• Elite male 400-metre running event
• School cross-country run
• Secondary school swimming team 50-metre freestyle swimming race
3 marks
For each of the events selected, justify your choice.
3 marks
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ENERGY SYSTEMS AND MUSCLE FIBRE TYPE
Muscle Fibre Characteristics Fuel Source used ATP
generation
Event type
Slow Twitch High resistance to fatigue
Large capacity to resynthesise
ATP
Red
Muscle glycogen
Blood glucose
FFA
Triglycerides
Aerobic Endurance
Fast Twitch (IIa) Resynthesise ATP at a fast rate
Fast oxidative fibres
Red
(Mixture of both) Aerobic
Anaerobic
Many team sports e.g.
hockey, netball
Fast Twitch (IIb) Contract rapidly
Large force
White
Phosphocreatine
Muscle glycogen
Anaerobic Short
Explosive
Powerful
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KEY TERMS
ATP
Energy systems
Interplay
Resynthesis
ADP
Pi
High-energy phosphate
Phosphocreatine (PC)
Carbohydrate (CHO)
Lipid (Fat)
Protein
Adipose Tissue
Anaerobic
Aerobic
Predominant
Glycogen
Triglycerides
Amino Acids
Power
Capacity
Glycolysis
Oxygen-independent
Aerobic glycolysis
Aerobic lipolysis
Free Fatty Acids (FFA)