Transcript Chapter5

Chapter 5
Foods, fuels and energy systems
Text Sources
1.
Nelson Physical
Education VCE Units
3&4: 5th Edition –
Malpeli, Horton, Davey
and Telford 2010.
2. Live It Up 2: 2nd Edition –
Smyth, Brown, Judge,
McCallum and Pritchard
2006.
VCE Physical Education - Unit 3
Glossary Words
 Interplay
 Glycolysis
 Aerobic
 Anaerobic
 Carbohydrate loading
 Glycamic index (GI)
 Hypoglycaemia
 Mitochondria
 Glycogen sparing
 Lactate inflection point (LIP)
 Onset of anaerobic blood lactate (OBLA)
VCE Physical Education - Unit 3
Foods, fuels and energy systems
Food for Exercise
Food is the source of energy for the human body and it also provides nutrients for
growth and repair. When food is eaten, this is what happens…

The food is broken down into soluble chemicals (e.g. glucose) by digestion in
the gut.

The soluble chemicals pass through the gut wall into the blood.

The blood carries the soluble food chemicals to all of the body’s cells, where
they will be used for:
Energy
Growth
VCE Physical Education - Unit 3
Repair
Food Fuels for Energy
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)
See fig 5.2 p.118
1.
VCE Physical Education - Unit 3
p.87
Carbohydrate Contributions
Intake of Carbohydrates depends
on the intensity and duration of
exercise.
Normal contribution to diet is
55-60% CHO
Carbohydrate loading (80%
CHO intake) is used to
endurance activities.
Carbohydrate rich diet;
Increases glycogen stores
Glycogen is used in rebuilding
ATP
CHO preferred fuel over fats
during exercise due to requiring
less oxygen to release energy.
Excess CHO is converted to
adipose tissue (Fat).
VCE Physical Education - Unit 3
Body Cells
Glucose diffuses
easily into the
cells and is used
to meet their
energy demands.
Skeletal Muscle
Glucose is stored here as
glycogen and is used
when the body is working
harder.
VCE Physical Education - Unit 3
Liver
Here some of the
glucose is stored as
glycogen and used
to maintain blood
sugar levels.
Fat Contributions
Storage of fats
Adipose tissue
Triglycerides
(Broken down into free fatty
acids)
At rest
50% of energy supplied by fats
Oxygen demand is easily met to
burn fats
Aerobic metabolism of fat is;
Slow
Requires more oxygen
Adds stress to the oxygen
transport system
ATP yield is much higher from
fat (460 molecules) in
comparison to glucose (36).
Benefits of fat
Large energy store
Transport medium for fat
soluble vitamins
Negative aspects of fat
Adverse health effects
Obesity, heart disease etc.
VCE Physical Education - Unit 3
VCE Physical Education - Unit 3
Protein Contributions
Role of protein (Amino acids) in
the body;

Growth and repair

Speed up reactions in the
body (Enzymes)

Produces hormones and
antibodies
Protein and exercise
1.
Not used as a fuel, therefore
low priority.
2. Only used in extreme
circumstances
3.
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
VCE Physical Education - Unit 3
VCE Physical Education - Unit 3
VCE Physical Education - Unit 3
 Using student netbook




go to www.heartfoundation.org.au
Click on Healthy eating
Click on Food and nutrients facts
Students are to write down the 5 tips for healthy eating
Students are then to use the website to answer Think things
through Page 123 Nelson
VCE Physical Education - Unit 3
VCE Physical Education - Unit 3
Food Fuels in the Body and Recommended Dietary Intake
Food Fuel
Stored
As
Site(s)
The proportions of
essential nutrients
contained in a
balanced diet
Carbohydrates
Example
foods
High GI:
Med GI:
Low GI:
Fat
Protein
VCE Physical Education - Unit 3
VCE Physical Education - Unit 3
HOMEWORK ACTIVITY
 Complete Thinking Things Through pg 117
VCE Physical Education - Unit 3
QUIZ
 Complete quiz filling in table on food fuels
VCE Physical Education - Unit 3
VCE Physical Education - Unit 3
Adenosine Triphosphate (ATP)
Our mechanical energy required
for muscular contractions,
require the chemical breakdown
of the ATP molecule (Forms
ADP).
Our ATP stores are very limited,
therefore it must continually be
rebuilt.
Nutrients assist in rejoining the
split molecule
VCE Physical Education - Unit 3
VCE Physical Education - Unit 3
Test Your Knowledge
1.
2.
3.
4.
5.
Carbohydrates are the most important nutrient in energy production.
Name two foods rich in carbohydrates?
When comparing glycogen and fats, which requires more oxygen to
produce the same amount of ATP?
Describe the intensity of a physical activity where fats are the
predominant energy source. Give one example?
Give one reason why fats should not be included in a meal just prior to
an extended endurance event such as a triathlon.
Kaila McKnight is Australia’s leading female middle distance runner
with a personal best time of 4:10:01 for 1500m event.
a)
b)
c)
What is the predominant energy system used to supply ATP to the muscles for this
event?
Identify one by-product of the above energy system
What is the predominant food fuel used to provide the ATP for this event?
VCE Physical Education - Unit 3
The Three Energy Systems
The systems used to
resynthesis of ATP depend
on a number of factors
including;
Duration
Intensity
If oxygen is present
Availability and
restoration of
chemical/food fuels
Systems and their names
1. ATP-PC
2. Anaerobic Glycolysis
(Lactic Acid (LA))
3. Aerobic
The three energy systems do not
function independently or
one at a time, but work
together via the process of
interplay to supply energy
and rebuild ATP.
VCE Physical Education - Unit 3
Foods, fuels and energy systems
The ATP-PC System pg 125-6
Quickest system
Breaks down phosphocreatine (PC) to form ATP
anaerobically.
However, PC stores require time to replenish.
Dominant system for the first 10 seconds of high
intensity exercise
Used in fast, powerful movements.
How does the system work?
PC releases a free phosphate
PC = P + C
ADP + P = ATP
VCE Physical Education - Unit 3
Body has a larger storage of PC compared to ATP
PC stores can be replenished through aerobic
recovery/passive recovery. Passive recovery for
maximum ATP resynthesis, also increase removal of
H+
Once PC stores are depleted, the body must use
glycogen through the anaerobic pathway.
Anaerobically trained athletes can resynthesise
ATP faster
As resynthesis decreases, intensity must decrease
VCE Physical Education - Unit 3
VCE Physical Education - Unit 3
The ATP/PC system during the interplay of energy systems
 Handout ‘Phosphate Creatine’
 Read as a class and explain the graph
VCE Physical Education - Unit 3
 Using the e-learning disc. Show students ‘Sports
predominantly powered by the ATP/PC system and
also the 30 second video clip on ‘Carl Lewis’ competing
in long jump.
 Read summary as a class page 126 Nelson text
‘Summary of the ATP-PC energy system’
VCE Physical Education - Unit 3
Foods, fuels and energy systems
Anaerobic Glycolysis System
The anaerobic glycolysis
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.
VCE Physical Education - Unit 3
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 as more H+), reducing ATP resynthesis.
The lactic acid system;
Provides twice as much energy for ATP resynthesis
than the ATP-PC system.
Experiences problems at the anaerobic threshold.
VCE Physical Education - Unit 3
How Anaerobic Respiration Happens
1
Glucose is transported
to the muscles of the
body via the blood.
2
Glucose passes into
the muscles cells and
is used to produce
energy for muscular
contractions.
3
Anaerobic respiration
produces lactic acid
as a waste product.
Facts about Anaerobic Respiration



During anaerobic respiration, your muscles are not
supplied with enough oxygen.
The lactic acid builds up due to the shortage of
oxygen. This is known as an oxygen debt, which
needs to be paid back once exercising has
finished.
The lactic acid build-up will soon make your
muscles feel tired and painful, so exercising
anaerobically can only be carried out for
short periods of time.
VCE Physical Education - Unit 3
Anaerobic Respiration is how sprinters produce the energy that is used in
short periods of ‘all out effort’ - high intensity.
Oxygen cannot reach the muscles fast enough, so anaerobic respiration is
used.
Glucose produces…
Lactic acid quickly
builds up & makes
the muscles feel
The rest is
tired & painful. ‘All
converted into heat
out effort’ cannot
to warm
- Unit 3the body.
last for very long! VCE Physical Education
Some is used for
muscle contractions,
creating movement.
VCE Physical Education - Unit 3
 Read page 127 ‘Summary of the Lactic acid (LA) energy
system’
 Handout ‘How Anaerobic Glycolysis works’
 Read as a class and explain graph
 Students are to answer the following question in their
workbooks
 List 4 sports that are predominantly powered by anaerobic
glycolysis? Make sure you include the value of the sport for example
200m sprint.
 Answer: 200m sprint. 100m swim, 500m kayak and consecutive
sprints in intermittent sports such as netball, football, basketball,
squash, hockey and water polo
VCE Physical Education - Unit 3
ANAEROBIC METABOLIMS /
PATHWAY
ATP-PC
Fuel Source
Fuel Location
Dominant
ATP Rate
ATP Amount
VCE Physical Education - Unit 3
ANAEROBIC
GLYCOLYSIS
ANAEROBIC METABOLIMS /
PATHWAY
ATP-PC
ANAEROBIC
GLYCOLYSIS
Fuel Source
ATP-PC
Glycogen/Glucose
Fuel Location
Skeletal Muscle
Skeletal Muscle
Dominant
0-6sec
6-60sec
ATP Rate
High (3.6 mM/Min)
Moderate (1.6mM/min)
ATP Amount
Low (1 ATP/PC)
Moderate (2/3 ATP per
mole glucose)
VCE Physical Education - Unit 3
 Complete “Energy System During a Maximum Sprint”
Lab pg 131-2
VCE Physical Education - Unit 3
Foods, fuels and 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 anaerobic
glycolysis decreases.
Major contributor in prolonged exercise eg.
Endurance events.
Aerobic system does contribute in maximal
intensity exercise (Eg. Between 55-65% in 800m)
See table 5.4 p.129
VCE Physical Education - Unit 3
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.
VCE Physical Education - Unit 3
VCE Physical Education - Unit 3
VCE Physical Education - Unit 3
How Aerobic Respiration Happens…
1
Glucose and
oxygen are carried
by the haemoglobin
in the
red blood cells.
2
Glucose and oxygen
pass into all the muscle
cells of the body and is
used to help produce
energy for muscular
contractions.
Facts about Aerobic Respiration



During aerobic respiration, the heart and lungs
supply the muscles with plenty of oxygen.
The carbon dioxide is breathed out via the
lungs, while the water is lost as sweat, urine or
in the air we breathe out as water vapour.
As long as the muscles are supplied with
enough oxygen, exercising aerobically can be
carried out for a long period of time.
VCE Physical Education - Unit 3
3
Aerobic respiration
produces carbon
dioxide & water as
waste products.
Aerobic respiration is how marathon runners produce the energy that is
used in long periods of less intensive effort.
Some is used for
muscle contractions,
creating movement.
Glucose and
oxygen produce…
The rest is converted
into heat to warm
the body.
Water, which is
Carbon dioxide,
carried away by the
which is carried
blood and excreted
away by the blood
through the lungs,
& excreted through sweat and urine.
VCE Physical Education - Unit 3
the lungs.
Energy and Types of Physical Activities
Each physical activity or sport you undertake requires a different
energy system…

Some use mainly aerobic respiration.

Others use mainly anaerobic respiration.

Most use a combination of the two.
Track Events and their use of Aerobic Respiration
Event
Percentage of
Aerobic Respiration
Marathon
100%
10,000 m
95%
5,000 m
83%
1,500 m
60%
800 m
50%
400 m
20%
200 m
10%
100 m
Less than 1%
VCE Physical Education - Unit 3
Basketball players
use both systems
 Students Are to copy Table 5.4 page 129 Nelson Text and
answer the following question into their workbooks
 By comparing anaerobic and aerobic energy what is
occurring at approximately 1 minute of maximal- intensity
exercise?
 Answer: the energy being released is almost equal by the anaerobic and
aerobic systems.
 When are the two systems at the 50-50 mark?
 Answer: at around the 75 second mark
VCE Physical Education - Unit 3
 As a class read ‘ Summary of the aerobic energy
system’ page 129-130
 As a class read the ‘real world focus’ on ‘Michael
Johnson’ page 130 Nelson text
 Discuss
 After the 200m mark, the speed of running decreases,
even though PC isn’t totally depleted and lactate
concentration is not maxed.
 Students are to complete ‘Think things through’
page 131 Nelson text
VCE Physical Education - Unit 3
COMPARING THE THREE SYSTEMS
 Give handout summarising each system
 Complete lab activity pg 132-3
VCE Physical Education - Unit 3
 Thinking Things Through pg 138-9
 Thinking Things Through pg 141
VCE Physical Education - Unit 3
Food Fuels at Rest vs Exercise
Rest (Aerobic)

Fat and glucose are
the preferred fuels
During Exercise
1.
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.
VCE Physical Education - Unit 3
VCE Physical Education - Unit 3
Foods, fuels and 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 anaerobic
glycolysis systems need to
be used anaerobically.
Aerobic
Anaerobic
VCE Physical Education - Unit 3
Interplay Between Energy Systems
All energy systems start at the same point, but each system will peak at
different times.
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.
VCE Physical Education - Unit 3
Duration and Intensity
Duration of event
Intensity of event
Primary energy system(s)
0-6 seconds
very intense
ATP-PC
6-30 seconds
intense
ATP-PC and Lactic Acid
30 sec. - 2 minutes
heavy
Lactic Acid
2-3 minutes
moderate
Lactic Acid and Aerobic
> 3 minutes
light
Aerobic
VCE Physical Education - Unit 3
VCE Physical Education - Unit 3
VCE Physical Education - Unit 3
High Intensity Competition
VCE Physical Education - Unit 3
VCE Physical Education - Unit 3