Chapter 4 Foods, fuels and energy systems VCE Physical Education - Unit 3 Text Sources 1.Nelson Physical Education VCE Units 3&4: 4 th Edition – Malpeli,

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  • Chapter 4 Foods, fuels and energy systems VCE Physical Education - Unit 3 Text Sources 1.Nelson Physical Education VCE Units 3&4: 4 th Edition Malpeli, Horton, Davey and Telford 2006. 2. Live It Up 2: 2 nd Edition Smyth, Brown, Judge, McCallum and Pritchard 2006.
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  • The Importance of Energy Foods, fuels and energy systems
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  • VCE Physical Education - Unit 3 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 bodys cells, where they will be used for: EnergyGrowthRepair 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 Food for Exercise
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  • VCE Physical Education - Unit 3 The muscles of the body use both carbohydrates and fats to produce energy. The following diagram shows how carbohydrates are used. Carbohydrates in the form of starch gained from foods such as pasta, bread and potatoes are eaten. The starch is digested in the gut and turned into glucose molecules. The glucose enters the small intestine where it passes into the blood.
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  • VCE Physical Education - Unit 3 Here some of the glucose is stored as glycogen and used to maintain blood sugar levels. Glucose is stored here as glycogen and is used when the body is working harder. Glucose diffuses easily into the cells and is used to meet their energy demands. Skeletal Muscle LiverBody Cells
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  • Food Fuels and ATP Foods, fuels and energy systems
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  • 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) See fig 4.2 p.86 VCE Physical Education - Unit 3 p.87
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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 VCE Physical Education - Unit 3
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  • Energy for Muscular Activity VCE Physical Education - Unit 3
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  • The Three Energy Systems Foods, fuels and energy systems
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  • 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)Lactic Acid (LA) Anaerobic glycolysis Lactacid 3. AerobicAerobic Oxygen system Aerobic glycolysis VCE Physical Education - Unit 3
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  • Fuels at Rest Foods, fuels and energy systems
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  • 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. VCE Physical Education - Unit 3
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  • Contributions of Carbohydrates, fats and Protein to Energy Production Foods, fuels and energy systems
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  • Energy Demands - Intensity Low intensity ATP requirements are met aerobically using the aerobic system. High Intensity Explosive movements require instant supply of ATP which cant be met aerobically, therefore the ATP-PC and lactic acid systems need to be used anaerobically. VCE Physical Education - Unit 3 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). VCE Physical Education - Unit 3
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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. VCE Physical Education - Unit 3
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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 VCE Physical Education - Unit 3
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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. VCE Physical Education - Unit 3 p.92
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  • 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 p.94
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  • The ATP-PC System Foods, fuels and energy systems
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  • 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. VCE Physical Education - Unit 3
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  • The Lactic Acid System Foods, fuels and energy systems
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  • 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 VCE Physical Education - Unit 3
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  • Anaerobic respiration involves the release of a little energy, very quickly from the incomplete breakdown of glucose without using oxygen, inside the cells. 1.Glucose is made available by the breakdown of glycogen stored in the working muscles. 2. The glucose is used by the muscles of the body to produce energy, without the use of oxygen. 3. This process creates lactic acid, which passes back into the blood for removal. Anaerobic Respiration The Process of Anaerobic Respiration Glucose Energy for muscles to contract and create movement Lactic Acid
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  • VCE Physical Education - Unit 3 Glucose is transported to the muscles of the body via the blood. How Anaerobic Respiration Happens Glucose passes into the muscles cells and is used to produce energy for muscular contractions. 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. 123
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  • Anaerobic Respiration is how sprinters produce the energy that is used in short periods of all out effort - high intensity. Glucose produces Lactic acid quickly builds up & makes the muscles feel tired & painful. All out effort cannot last for very long! The rest is converted into heat to warm the body. Oxygen cannot reach the muscles fast enough, so anaerobic respiration is used. Some is used for muscle contractions, creating movement.
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  • The Aerobic System Foods, fuels and energy systems
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  • 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 (Krebs cycle) 3.Further breakdown via the electron transport chain. It requires hydrogen ions and oxygen, producing water and heat. VCE Physical Education - Unit 3
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  • 1.Glucose and oxygen are transported to the working muscles by the blood. Aerobic respiration involves the release of energy from the slow breakdown of glucose using oxygen, inside the cells. 2.Glucose and oxygen are then used by the muscles of the body to produce energy. 3.This process creates carbon dioxide and water. 4.The carbon dioxide passes back into the blood for removal. The Process of Aerobic Respiration Energy for Muscles to contract and create Movement Water Carbon Dioxide Glucose Oxygen
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  • VCE Physical Education - Unit 3 Facts about Aerobic Respiration How Aerobic Respiration Happens Glucose and oxygen are carried by the haemoglobin in the red blood cells. Glucose and oxygen pass into all the muscle cells of the body and is used to help produce energy for muscular contractions. Aerobic respiration produces carbon dioxide & water as waste products. 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. 123
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  • VCE Physical Education - Unit 3 Aerobic respiration is how marathon runners produce the energy that is used in long periods of less intensive effort. Glucose and oxygen produce Carbon dioxide, which is carried away by the blood & excreted through the lungs. Water, which is carried away by the blood and excreted through the lungs, sweat and urine. Some is used for muscle contractions, creating movement. The rest is converted into heat to warm the body.
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  • VCE Physical Education - Unit 3 Energy and Types of Physical Activities Each physical activity or sport you undertake requires a different energy system Track Events and their use of Aerobic Respiration Basketball players use both systems Some use mainly aerobic respiration. Others use mainly anaerobic respiration. Most use a combination of the two. Event Percentage of Aerobic Respiration Less than 1%100 m 10%200 m 20%400 m 50%800 m 60%1,500 m 83%5,000 m 95%10,000 m 100%Marathon
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  • Energy System Interplay Foods, fuels and energy systems
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  • The Three Energy Systems VCE Physical Education - Unit 3
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  • Interplay Between Energy Systems All activities use some energy from all three systems. The energy systems overlap they never work independently. It its the relative contribution of each system that varies. VCE Physical Education - Unit 3
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  • Duration and Intensity VCE Physical Education - Unit 3 Duration of eventIntensity of eventPrimary energy system(s) 0-6 secondsvery intenseATP-PC 6-30 secondsintenseATP-PC and Lactic Acid 30 sec. - 2 minutesheavyLactic Acid 2-3 minutesmoderateLactic Acid and Aerobic > 3 minuteslightAerobic
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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 VCE Physical Education - Unit 3
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  • High Intensity Competition VCE Physical Education - Unit 3
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