Download 1 Chapter 4

Chapter 4
Foods, fuels and energy systems
Text Sources
1.
Nelson Physical
Education VCE Units
3&4: 4th Edition –
Malpeli, Horton, Davey
and Telford 2006.
2. Live It Up 2: 2nd Edition –
Smyth, Brown, Judge,
McCallum and Pritchard
2006.
VCE Physical Education - Unit 3
Foods, fuels and energy
systems
The Importance of Energy
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
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Repair
The
 Carbohydrates
muscles
of the
inbody
the
form
both
of
starch
carbohydrates
gained
and foods
fats
to
such
produce
as
The
glucose
enters
theuse
small
intestine
where itfrom
passes
into
energy.
pasta,
The
bread
following
and potatoes
diagram are
shows
eaten.
how carbohydrates are used.
the
blood.
 The starch is digested in the gut and turned into glucose molecules.
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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.
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Liver
Here some of the
glucose is stored as
glycogen and used
to maintain blood
sugar levels.
Food Fuels and ATP
Foods, fuels and energy systems
Food Fuels for Energy
p.87
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 4.2 p.86
1.
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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
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Energy for Muscular Activity
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The Three Energy Systems
Foods, fuels and energy systems
Energy Systems
The systems used to
resynthesis of ATP
depend on a number of
factors including;
•Duration
•Intensity
•If oxygen is present
•Urgency of energy
required
•Athletes level of training
Systems and their
alternative names
• ATP-PC
• Alactacid
• Creatine Phosphate
• Phosphogen system
2. Lactic Acid (LA)
• Anaerobic glycolysis
• Lactacid
3. Aerobic
• Oxygen system
• Aerobic glycolysis
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Fuels at Rest
Foods, fuels and energy systems
Food Fuels at Rest
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.
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Contributions of Carbohydrates,
fats and Protein to Energy
Foods, fuelsProduction
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 lactic acid
systems need to be used
anaerobically.
Aerobic
Anaerobic
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Carbohydrate Contributions
Storage (Based on 80kg
person)
•Muscle glycogen – 400g
•Liver glycogen – 100g
Intake 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 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.
Athletes need to be aware of
their dietary intakes of CHO.
Excess CHO is converted to
adipose tissue (Fat).
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Fat Contributions
Storage of fats
•Adipose tissue
•Triglycerides
(Broken down into free fatty
acids)
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).
At rest
•50% of energy supplied by fats
•Oxygen demand is easily met
to burn fats
Benefits of fat
•Large energy store
•Transport medium for fat
soluble vitamins
Negative aspects of fat
•Adverse health effects
•Obesity, heart disease etc.
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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
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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’.
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p.92
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
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p.94
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The ATP-PC System
Foods, fuels and energy systems
The ATP-PC System
•Quickest system
•Breaks down phosphocreatine
(PC) to form ATP anaerobically.
•However, PC stores require time
to replenish.
•Dominant system for the first 1015 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
•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.
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The Lactic Acid System
Foods, fuels and 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.
•Experiences problems at the
anaerobic threshold.
Data analysis 4.1 p.99-100
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Anaerobic Respiration
Anaerobic respiration involves the release of a little energy, very
quickly from the incomplete breakdown of glucose without using oxygen,
The Process of Anaerobic Respiration
inside the cells.
1. Glucose is made available by the breakdown of glycogen stored
Energy for muscles to contract
in the working muscles.
and create movement
2. The glucose
is
used
by
the
muscles
of the body to produce energy,
Glucose
without the use of oxygen.
Lactic
Acidpasses
3. This process creates lactic
acid,Education
which
back into the blood
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for removal.
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
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
tired & painful. ‘All
out effort’ cannot
last for very long!
Some is used for
muscle contractions,
creating movement.
The rest is
converted into heat
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to warm the body.
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The Aerobic System
Foods, fuels and energy systems
VCE Physical Education - Unit 3
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)
See 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.
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The Process
Aerobic respiration
involves of
theAerobic
release ofRespiration
energy from the slow
breakdown of glucose using oxygen, inside the cells.
Water
Glucose
1. Glucose and oxygen are transported to the working muscles by
Energy for Muscles
the blood.
contract
2. Glucose and oxygen areto
then
used byand
the muscles of the body
create Movement
to produce energy.
Carbon
3. ThisOxygen
process creates carbon dioxide and water.
Dioxide
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4. The carbon dioxide passes
back
into the
for removal.
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
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sweat and urine.
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
100 m
10%
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Less than 1%
Basketball players
use both systems
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Energy System Interplay
Foods, fuels and energy systems
The Three Energy Systems
VCE Physical Education - Unit 3
Figu re 1. Three energy systems and their percentage contribution (Y-axis) to
total energy output during all-out exerc ise of different durations (X-axis).
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.
VCE Physical Education - Unit 3
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
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Comparing the Three Energy
Systems
Foods, fuels and energy systems
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Comparing the Energy Systems and Interplay
Energy Production
•ATP-PC – 5.7 to 6.9 kcal
•Lactic Acid – 10 to 12 kcal
•Aerobic – 980kcal
See table 4.6 p.107
Note 10kcal = 1 mole
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High Intensity Competition
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Web Links – Chapter 4
•VCE Board of Studies – additional information about energy systems:
http://vcaa.vic.edu.au/vce/studies/physicaledu/EnrgSys.pdf
•Heart Foundation Australia: http://www.heartfoundation.com.au
•Australian Institute of Sport – sports nutrition:
http://www.ais.org.au/nutrition/
•Nutrition Australia: http://www.nutritionaustralia.org/
•Dietician's Association of Australia: http://www.daa.asn.au/
•Sports Coach UK – energy pathways:
http://www.brianmac.demon.co.uk/energy.htm
•‘How stuff works’ – How exercise works:
http://health.howstuffworks.com/sports-physiology6.htm
Info about the glycemic index: http://www.glycemicindex.com/
•Australian Sports Commission: http://www.ausport.gov.au
•Find 30 promotion (Government of WA Department of Health): http://www.find30.com.au
•Walking School Bus promotion (UK): http://www.walkingbus.com
•Ministry of Health (New Zealand) toolkits: http://www.newhealth.govt.nz
•The 10,000 Steps Rockhampton project: http://www.10000steps.org.au/rockhampton/
•Travelsmart Australia: http://www.travelsmart.gov.au
•World Health Organisation: http://www.who.int
•Heart Foundation Australia: http://www.heartfoundation.com.au
•VicHealth (The Victorian Health Promotion Foundation): http://www.vichealth.vic.gov.au
•Be Active promotion (Government of South Australia): http://www.beactive.com.au
•Go For Your Life: http://www.goforyourlife.vic.gov.au
•Physical Activity Resources for Health Professionals – Introduction (Centre for disease control and prevention – USA):
http://www.cdc.gov/nccdphp/dnpa/physical/health_professionals/index.htm
•Health Promotion (Public Health Agency of Canada): http://www.phac-aspc.gc.ca/hp-ps/index.html
•Strategic Inter-Governmental Forum on Physical Activity and Health (SIGPAH): http://www.nphp.gov.au/workprog/sigpah/
•Healthy youth (Centre for disease control and prevention (USA): http://www.cdc.gov/HealthyYouth/
•America On The Move promotion: http://www.americaonthemove.org
•Papers from the International Journal of Behavioural Nutrition and Physical Activity: http://www.ijbnpa.org/home
•Department of health and aging (Australian government): http://www.health.gov.au/internet/wcms/publishing.nsf/content/home
•Building a healthy, active Australia (Australian government): http://www.healthyactive.gov.au
•National Public Health Partnership: http://www.nphp.gov.au
•Be Active promotion (Government of South Australia): http://www.beactive.com.au
•Sport and Recreation Australia: http://www.sport.vic.gov.au
•
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