Energy Systems Explain the factors that contribute to a performer’s VO2 max. (7 marks) • VO2 max definition – maximum volume of oxygen that can be utilised per minute/unit of time • Relative VO2 max definition – takes into account body weight/ ml.kg1.min-1 • Lifestyle – lack of exercise/smoking/poor diet/fitter/equiv • Training – continuous/aerobic/fartlek improves VO2 max/stamina/ endurance training • Age – VO2 max decreases with age • Physiology – number of slow twitch fibres/capillary density/number of mitochondria/haemoglobin content/surface area of alveoli/red blood cell count/efficiency of heart or equivalent • Genetics – inherited factors of physiology limit possible improvement • Gender - men generally have approx. 20% higher VO2 max than women • Body composition – higher percentage of body fat decreases VO2 max/poor diet reduce VO2 max/overweight/obese Using your knowledge of energy systems, outline and explain the relationship between energy sources and intensity of exercise. (7 marks) A. At low level of exercise energy comes from a mixture of fats and carbohydrates; B. Broken down aerobically/using oxygen/aerobic system; C. Glycolysis/Anaerobic Glycolysis – glucose broken down/pyruvic acid/pyruvate formed D. Beta oxidation breaks down fats/tri-glycerides/free fatty acids E. Krebs Cycle – oxidation of acetyl-coenzyme-A/Citric acid production F. Electron transport/transfer chain – water formed/hydrogen ions/protons used G. At high levels of intensity carbohydrates are only energy source/as intensity increases, more carbohydrates used; H. At high intensity fat use limited by oxygen availability/no fats used anaerobically/lack of oxygen; I. Slower energy release from fats/quick release of energy from carbohydrates; J. (Carbohydrate break down) Lactic Acid System/Lactate anaerobic system K. No oxygen used/anaerobic L. Glycolysis/Anaerobic Glycolysis – glucose broken down/pyruvic acid/pyruvate formed/lactate/lactic acid formed Explain how the majority of energy is provided for gymnastic events. (7 marks) A. Anaerobic/without oxygen B. (during first few seconds) stored ATP splits/breaks down initially/ATP breaks down to ADP + P + energy C. ATP-PC/system/phosphocreatine system/alactic system D. PC = C + P(i) + energy/creatine + phosphate/PC broken down; E. Energy used for ATP resynthesis/ADP + P + energy = ATP/ADP + PC = ATP + C; F. Lasts 5-10 seconds/limited supply G. Lactic acid system/Lactate anaerobic system H. Glycogen/glucose breakdown I. Glycolysis J. To pyruvate/pyruvic acid K. Lactate/lactic acid formed Outline the function and process of the fast component of the recovery process. (4 marks) A. EPOC explanation – volume of oxygen consumed in recovery above the resting rate B. The alactacid/alactic (debt/component) C. Re-saturation of myoglobin/haemoglobin with oxygen D. Re-synthesise ATP/PC levels E. Uses 2-4 litres of oxygen F. Completed in 2-3 minutes G. 50% PC stores replenished within 30 seconds/75% within 60 seconds At the 2008 Beijing Olympic Games, David Davies won the silver medal in the swimming 10 kilometre marathon event, in a time of 1 hour 51 minutes and 53.1 seconds. Explain how the majority of energy used during the race would be provided. (7 marks) A. Majority produced by the aerobic system/oxygen B. Glycolysis/Anaerobic glycolysis C. Carbohydrates/glycogen/glucose D. broken down into pyruvate/ pyruvic acid E. Some ATP produced/2 ATP F. Krebs cycle G. Fats/triglycerides/fatty acids/glycerol H. Beta oxidation I. Oxidation of acetyl-coenzyme-A/Citric acid/ production of CO2 J. Electron transport chain K. Water/H2O formed/hydrogen ions formed (H+)/ hydrogen/protons L. Large quantities of ATP produced or resynthesised/34- 36 ATP Competitive swimmers will often compete in several events and suffer from fatigue due to limited recovery time. Explain the possible causes of fatigue during a race. (3 marks) A. Build up of lactic acid /accumulation of hydrogen ions/OBLA B. Glycogen depletion/needed for glycolysis C. Dehydration/reduces blood flow/loss of electrolytes/increase body temperature D. Reduced levels of calcium E. Reduced levels of acetylcholine/slows nerve impulse and inhibits contraction F. Lack of PC stores Elite swimmers follow structured training programme to develop exceptional levels of fitness. Outline the relationship between ‘VO2 max’ and ‘lactate threshold’. (3 marks) A. VO2 max – the maximum amount of oxygen utilised/equiv per unit of time/per minute B. Lactate threshold – the point at which lactic acid starts to accumulate in the blood/OBLA C. Lactate threshold is a percentage of VO2max D. The higher the VO2 max, the more the delay in lactic acid build-up/as VO2max increases, so does lactate threshold E. Trained athletes can exercise for longer periods at the same/higher intensity compared to an untrained athlete/lactate threshold a much higher percentage of VO2 max Explain how lactate is removed from the blood by the body. (4 marks) • Used as respiratory substrate/for respiration/energy/using oxygen (O2)/lactate to • replenish ATP; • Converted to pyruvate/pyruvic acid; • Then to Carbon Dioxide (CO2) and water; • In inactive muscle and various tissues/organs; • Converted to glycogen/glucose; • In liver; • Some excreted in sweat/urine/conversion to protein Elite games players require high levels of fitness and psychological preparation, therefore regular fitness testing and after-match performance analysis are common. (a) Figure 1 illustrates the relationship between the concentration of blood lactate and the workload. Use Figure 1 to identify the workload level at which lactate threshold occurs, and explain why lactate (lactic acid) tends to be produced when a player is exercising. (3 marks) • • • • • • Lactate threshold correctly identified as between 500 and 800 Watts; Lactate from anaerobic (glycolosis)/lack of oxygen (O2)/high demand/lack of supply; Greater demand for ATP resynthesis during exercise; Excess Hydrogen ions produced during glycolysis and Kreb’s cycle; Join with pyruvate to form lactic acid (when oxygen is no longer available) High intensity/workload exercise/equiv. What do you understand by the term lactate threshold? (2 marks) • Lactic acid accumulates in blood; • 2 mmol of lactic acid per litre of blood; • Exercise has become anaerobic. Explain how knowing blood lactate levels during a swim might assist an elite performer. (2 marks) • Accurately measures intensity of training; • Elite performers need to train close to their Lactate threshold/VO2 max; • Accuracy in determining Lactate threshold/VO2 max is difficult. Describe the changes that occur in the body to make the aerobic energy systems more efficient following prolonged endurance training. (4 marks • • • • • • • • • Cardiac hypertrophy Increased resting stroke volume Decreased resting heart rate Increased blood volume and haemoglobin levels Increased muscle glycogen stores Increased myoglobin content in muscles Increased capilliarisation of muscle Increased number and size of mitochondria Resulting increase in VO2 max (maximal oxygen consumption) The triathlon is an athletic event that involves performers undertaking a long distance swim, immediately followed by a cycle race and then finally a run of several kilometres. (a) What would be the major energy sources used by a triathlete? (3 marks) (b) Briefly explain how these energy sources are used for regeneration of ATP. (5 marks) (a) 1. Fats; 2. Fatty acids; 3. Glycerol; 5. Carbohydrates; 6. Glycogen; 4. Triglycerides. 7. Glucose; 8. Protein/lactate. (b) 1. Carbohydrates/glycogen/glucose broken down into pyruvate; 2. Anaerobic/glycolysis; 3. Some ATP produced; 4. Fats/triglycerides/fatty acids/glycerol broken down into variety of compounds; 5. Beta oxidation; 6. Into mitochondria; 7. Krebs cycle; 8. Electron transport chain; 9. Oxidation/aerobic; 10. Large quantities of ATP produced. (i) Describe and explain the effects of a two-hour period of intense exercise and recovery periods on the levels of glycogen in the elite performer. (4 marks) (ii) How might this elite performer prepare for a competition that will last longer than 2 hours? (3 marks) (i) 1. Glycogen levels decrease during training and restored during recovery 2. Above resting; 3. It takes 24 hours to recover; 4. Glycogen used for energy/ATP formation/production; 5. Aerobic/oxygen; 6. Mitochondria/Kreb’s cycle/pyruvate; 7. Supercompensation/overcompensation/adaptation; (4 marks) (ii) 1. Carboloading/glycogen loading/supercompensate/overcompensate/ glycoloading ; 2. Dietary restriction of carbohydrate; 3. Modified training programme/tapering; 4. Increase carbohydrate intake 24hrs prior to event 5. To store more glycogen than normal; 6. Carbohydrate intake during event; (3 marks) It has been said that the winner of a 100m race is the runner who slows down the least. Explain, using your knowledge of energy systems, why this might be the case. (7 marks) • Predominant energy system used in 100m race is ATP-PC system. • ATP stores only supply energy for 2-3 seconds. • PC stores only supply energy for 5-8 seconds. • Speed of muscle contractions and therefore runners speed will decrease when ATP-PC stores are depleted. • Once ATP-PC stores have been depleted the predominant energy system will be the anaerobic (lactic acid) system. • This system produces energy at a slower rate and runner will slow down. • Athletes who can continue for longer before resorting to the lactic acid sytem will maintain top speed for longer. • Training allows the ATP-PC to become more efficient, supplying energy for a greater period of time. Research has been conducted into activity cycles of intermittent sports such as soccer, hockey and rugby, which are reliant on efficient energy systems. a) Identify the principle energy source for each of the following activity cycles in these types of physical activities: (i) Walking (ii) Sprinting (iii) Jogging (4 marks) b) What are the disadvantages of using fat as an energy source during exercise? (3 marks) a) (i) Fats (ii) Glucose / phosphocreatine (iii) Fats / glucose b) • Extra weight requires greater amounts energy to be produced for movement. • Reduces flexibility. • Fat can only be used as an energy source when oxygen is present / requires oxygen to be broken down / only used during aerobic activity. • Excess fat causes overheating and problems associated with this (dehydration, cardiovascular drift etc) • Cannot be used during explosive activities. What do you understand by the term VO2 max? (2 marks) • Max amount of oxygen that can be consumed and used by the body per minute. • Greater VO2 max means greater aerobic fitness / capacity. • Predominantly genetically determined. During a game of hockey a performer accumulates a lactic acid concentration of 8 mmol. Two minutes later in the game their lactate concentration is 4.8 mmol. a) Suggest reasons why the performer’s level of lactic acid had risen to 8 mmol. (4 marks) b) Give an explanation as to why their lactate concentration had fallen two minutes later. (3 marks) a) • • • • Increased energy requirement due to high intensity of activity. Anaerobic energy systems used. Insufficient oxygen available due to high intensity of activity. Excess Hydrogen produced during breakdown of glucose in glycolysis and Kreb’s cycle. • Joins with pyruvate when oxygen no longer available. • Forms lactic acid. • Lactate threshold (2 mmol) and OBLA (4 mmol) passed as lactic acid accumulates. b) • Levels may have dropped due to decrease in exercise intensity / break in play. • Reduced requirement for ATP resynthesis. • Reduced levels of Hydrogen being produced reduces the production of lactic acid. • Slow component of EPOC (lactacid component). • Oxidation of lactic acid into carbon dioxide and water (and pyruvate) to continue through Kreb’s cycle. An 800m runner undertakes aerobic training to improve their VO2 max. Why might this improve their 800m personal best? (7 marks) • VO2 max is the maximum amount of O2 that can be consumed and used in one minute. • Greater VO2 max means more O2 available for aerobic energy production. • Allows for greater use of fats as an energy source thus saving glucose stores for later in the race. • More energy produced aerobically reduces reliance on anaerobic systems and therefore delays lactate threshold. • Hydrogen produced during glycolysis and Kreb’s cycle joins with oxygen rather than joining pyruvate to form lactic acid. • Prevents build up of lactic acid which would hinder energy production. • Greater availability of O2 helps to speed up EPOC. • This results in faster resynthesis of ATP and PC stores. • Allows for sprint finish. After a period of intense exercise a performer shows evidence of heightened ventilation rate and heart rate two minutes after the end of exercise. a) In terms of recovery, why does the performer exhibit these raised heart and ventilation rates? (4 marks) b) Why should the organisers of world championship athletics meetings allow at least three days between 1500m races? Use your knowledge of recovery in your answer. (3 marks) a) • Increased heart rate and ventilation rate to increase supply of oxygen to working muscles. • O2 required for EPOC. • Fast (alactacid) component of EPOC involves reloading myoglobin with O2. • Also replenishes ATP and PC stores. • 50% of PC stores replenished within one minute, 100% within 3-4 mins. • Increased O2 supply also involved in conversion of lactic acid back into pyruvate (and water) to rejoin Kreb’s cycle as an energy source. b) • Slow (lactacid) component of EPOC requires time to deal with excess lactic acid. • Lactic acid can be converted to pyruvate and water / glycogen / protein / glucose. • Time is needed to replenish glucose stores depleted from a 1500m race. • Muscle cells need time for repair after 1500m race.