Transcript Chapter 4 - DKinghamVCEPE

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.
The Importance of Energy
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
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.
Body Cells
Glucose diffuses
easily into the
cells and is used
to meet their
energy demands.
Skeletal Muscle
Glucose is stored here as
glycogen (400grams)
and is used when the
body is working harder.
Liver
Here some of the
glucose is stored as
glycogen
(100grams) and
used to maintain
blood sugar levels.
Food Fuels and ATP
Foods, fuels and energy systems
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 4.2 p.86
1.
p.87
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
The Three Energy Systems
Foods, fuels and energy systems
Energy Systems
Which of the 3 systems
that operate during
exercise depends on a
number of factors
including;
•Duration
•Intensity
•If oxygen is present
•Urgency of energy
required
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
Energy Systems
The ATP-PC systems
and the Lactic Acid
system are anaerobic,
meaning they can work
in the absence of
oxygen.
The Aerobic system, is
aerobic, therefore
requires the use of
oxygen
During the start of
exercise all three
energy systems are
in use. Their
contribution is
dependent on the
intensity and
duration of the
exercise..........
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.
Contributions of Carbohydrates, fats
and Protein to Energy Production
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 lactic acid
systems need to be used
anaerobically.
Aerobic
Anaerobic
Carbohydrate Contributions
Storage (Based on 80kg
person)
•Muscle glycogen – 400g
•Liver glycogen – 100g
•(enough to fuel a 25km
run!!!)
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).
Fat Contributions
Storage of fats
•Adipose tissue
•Triglycerides
(Broken down into free fatty
acids which in turn are
broken down to provide
energy)
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 A,D,E & K
Negative aspects of fat
•Adverse health effects
•Obesity, heart disease etc.
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
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 (this is know as
glycogen sparing).
•Fats cannot be used alone
as a fuel (poor solubility in
the blood - hydrophobic).
•‘Hitting the wall’ occurs
when glycogen stores are
depleted. This is called
‘hypoglycaemia’.
•This is why athletes
consume Gatorade, Glucose
supplements etc...
p.92
Glycemic Index (GI)
p.94
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 eg
lollies prior to exercise
(can impair CNS function
and accelerate glycogen
depletion).
•High GI cause an insulin
surge, effecting the
performance of an athlete
The ATP-PC System
Foods, fuels and energy systems
The ATP-PC System
•Quickest system
•Dominant system for the first
10-15 seconds of high intensity
exercise
•Used in fast, powerful
movements.
•Examples................???
•Breaks down phosphocreatine
(PC) to form ATP anaerobically.
•However, PC stores require time
to replenish.
*** Read Summary of the ATP-PC
system pg 96 of TEXT
How does the system work?
•PC releases a free phosphate
molecule
PC = P + C
ADP + P = ATP
•Body has a larger storage of PC
compared to ATP (4 times as
much in the muscles)
•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 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
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.
Acidpasses back into the blood
3. This process creates lactic Lactic
acid, which
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.
READ Summary of Lactic Acid system pg.98
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
to warm the body.
Lactate Inflection Point (LIP)
•
•
•
•
•
LIP is a term which is used to describe
the relationship between the entry and
removal of lactate in the blood stream
it has been created to replace the
several terms which have come to
dominate the area of physical
education which can confuse the
actual definition of Anaerobic
Threshold
activity levels above the LIP are
associated with fatigue and an
increase of lactic acid within the body
The greater the intensity above the LIP
the faster the fatigue will set in
The LIP can also help predict the
speed and power a person can sustain
and for how long
There are only a few methods that can test
for the LIP and they are either through
blood tests or ventilation
The Aerobic System
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 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 (aerobic
glycolysis);
1st STAGE: CHOs andTryglycerides
(FFA + glycerol) broken down
to release energy. This
produces pyruvic acid. Energy
is released
2nd STAGE: Pyruvic acid is further
broken down producing
carbon dioxide (Kreb’s cycle)
3rd STAGE: Further breakdown via
the electron transport chain. It
requires hydrogen ions and
oxygen, producing water and
heat.
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
4. The carbon dioxide passes back into the blood 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.
READ Summary of Aerobic System pg. 104
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.
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%
Basketball players
use both systems
Energy System Interplay
Foods, 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.
Interplay – Game of Netball / Basketball
Which energy systems are at use as you
play a game of basketball or netball?????
Read bottom of page 108-109
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
Comparing the Three Energy Systems
Foods, fuels and energy systems
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
High Intensity Competition
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
•