Chapt 4

VCE Physical Education - Unit 3

Chapter 4Foods, fuels and energy systemsText 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.

Food Fuels

Foods, Fuels and Energy systems


Food Fuels for Energy

1. 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


Foods High in CHO, Fats and Proteins




Complete questions 1-4 page 87 of Nelson Physical Education VCE Units 3 & 4.

Checkpoints

Adenosine Triphosphate (ATP)Foods, fuels and energy systems


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.


Fuel use at Varying Intensities and Duration



Food Fuels at Rest

Rest (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

ProductionFoods, 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

Intensity increases


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 fat.


Fat Contributions

Storage 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 fats

Benefits of fat Large energy store Transport medium for fat

soluble vitamins

Negative aspects of fat Adverse health effects Obesity, heart disease etc.



Checkpoints


Crossover Concept


Protein Contributions

Role 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


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’.


Glycemic Index (GI)

Glycaemic 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

http://www.glycemicindex.com/


Glycemic Index of Common Foods


Comparative Results for High and Low GI Meals



Checkpoints

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 a by-product, called lactic acid, is produced.

There are two energy systems which use the anaerobic pathways; ATP-PC (Alternatively called; ‘Alactacid’, ‘Creatine Phosphate’ or ‘Phosphogen system’) and the Lactic Acid systems (Also called ‘Anaerobic glycolysis’ or ‘Lactacid’)


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 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

10-15 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.


The Lactic Acid System



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.



Complete the data analysis task on page 99-100 of Nelson Physical Education VCE Units 3 & 4.

Coursework 4.1

The Aerobic System



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.


Anaerobic and Aerobic Glycolysis




Complete the laboratory tasks on page 104 and 105-6 of Nelson Physical Education VCE Units 3 & 4.

Coursework 4.2 and 4.3

Energy System Interplay



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.


Aerobic Contributions


Anaerobic v Aerobic Contributions


Complete the data analysis task on page 109-111 of Nelson Physical Education VCE Units 3 & 4.

Complete the laboratory task on page 111-3 of Nelson Physical Education VCE Units 3 & 4.

Coursework 4.4 and 4.5


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




High Intensity Competition



Checkpoints


Complete the review questions 1-9 page 116 of Nelson Physical Education VCE Units 3 & 4.

Test Your Knowledge


Complete the chapter questions on page 20-28 of Nelson Peak Performance Physical Education VCE Units 3 & 4.

Peak Performance


Read the summarised information of pages 38-46 of PHYS ED Notes and complete the revision questions.

PHYS ED Notes


VCAA Questions - 2006






Web Links – Chapter 4•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

•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/

http://www.ausport.gov.au/

http://www.find30.com.au/

http://www.walkingbus.com/

http://www.newhealth.govt.nz/

http://www.10000steps.org.au/rockhampton/

http://vcaa.vic.edu.au/vce/studies/physicaledu/EnrgSys.pdf

http://www.heartfoundation.com.au/

http://www.ais.org.au/nutrition/

http://www.nutritionaustralia.org/

http://www.daa.asn.au/

http://www.brianmac.demon.co.uk/energy.htm

http://health.howstuffworks.com/sports-physiology6.htm

http://www.glycemicindex.com/

Chapt 4

Technology