3.1.1.6 – Energy systems

1. 3.1.1.6 – Energy systems Learning objectives To describe how ATP is released and regenerated. To explain the ATP-PC and anaerobic glycolytic systems. To understand the stages of the aerobic energy system To understand the energy continuum and examples of sports placed on it.

2. 3.1.1.6 – Energy systems Learning objectives To describe the energy transfer process during high and low intensity exercise. To be able to explain the factors affecting VO2 max. To understand the different measurements of energy expenditure. To evaluate the impact of specialist training methods on the energy system used.

3. Energy systems Watch me How does the body continually provide energy for exercise?

4. Energy transfer in the body We need a constant supply of energy so that we can perform everyday tasks. The more exercise we do the more energy is required. The intensity and duration of an activity play an important role in the way in which energy is provided.

5. ATP – (Adenosine Triphosphate) ATP is the usable form of energy in the body. The energy from foods that we eat, such as carbohydrates, has to be converted into ATP before the potential energy in them can be used. An ATP molecule consists of adenosine and 3 Phosphates Adenosine P P P

6. ATP breakdown Energy is released from ATP by breaking down the bonds that hold this compound together. Enzymes are used to break down ATP. ATP-ase is the enzyme used to break down ATP into ADP (adenosine diphosphate) and a single phosphate. Adenosine ENERGY P P P This type of reaction is an exothermic reaction. Think. Pair. Share – What is meant by an exothermic reaction?

7. ATP resynthesis ATP within muscle fibres are used up very quickly (2-3 seconds) and therefore needs to be replenished immediately. For ATP to be rebuilt an endothermic reaction has to occur. This is a chemical reaction which absorbs energy. ADP P P P Resynthesis of ATP is done through the joining of ADP and a single phosphate. This energy regeneration is only possible through one of three energy systems.

8. CONCENTRATION OF ATP TIME 3 SECS 10 SECS 60 SECS 2 HRS ATP ATP can provide several powerful contractions lasting only 2-3 seconds. This can be shown on a graph similar to the one below. ATP STORE

9. Energy systems • There are three energy systems that regenerate ATP: • ATP-PC system • Glycolytic system • Aerobic system Each energy system is suited to a particular type of exercise depending on the intensity and duration and whether oxygen is present.

10. ATP-PC system Depleted ATP stores trigger the release of creatine kinase which causes phosphocreatine (PC) to be broken down anaerobically. Phosphocreatine is an energy-rich chemical produced naturally by the body. This compound found in the sarcoplasm of the muscles. This rapid availability of PC is important for providing contractions of high power, such as in the 100 m or in a short burst of intense activity during a longer game i.e. a fast break in basketball.

11. CONCENTRATION OF ATP TIME 3 SECS 10 SECS 60 SECS 2 HRS ATP-PC system However, there is only enough PC to last for up to 10 seconds and it can only be replenished when the intensity of the activity is sub-maximal. ATP-PC SYSTEM

12. ATP-PC system Think. Pair. Share – Discuss and write down all the advantages and disadvantages of the ATP-PC System.

13. ATP-PC system For every one molecule of PC broken down there is enough energy released to create one molecule of ATP. This is not very efficient system but it does have the advantage of not producing by-products and its use is important in delaying the onset of the lactic anaerobic system. This breaking down of PC to release energy is a coupled reaction.

14. Anaerobic glycoltic system Once PC is depleted (at around 10 seconds) the anaerobic glycoltic system takes over and regenerates ATP from the breakdown of glucose. Glycogen The breakdown of glucose is only possible in the presence of an enzyme Phosphofructokinase (PFK) Enzyme: Phosphofructokinase Glycolysis 2 ATP Glucose ENERGY

15. Anaerobic glycoltic system The process of glucose breakdown in the absence of oxygen is called anaerobic glycolysis and causes the production of pyruvic acid. The longer exercise continues the higher the rise in lactic acid and pH levels. The slowly inhibitsenzyme activity causing fatigue and eventually OBLA. Glycogen Enzyme: Phosphofructokinase (PFK) Glycolysis 2 ATP Glucose ENERGY Enzyme: Lactate dehydrogenase (LDH) Lactic Acid Pyruvic Acid

16. Anaerobic glycoltic system Glycoltic ATP resynthesis will continue for up to 3 minutes but peaks at 1 minute. This is particularly useful for cycling sprint events or a counter attack in football. Think. Pair. Share – What other events will predominantly use this system?

17. CONCENTRATION OF ATP TIME 3 SECS 10 SECS 60 SECS 2 HRS Anaerobic glycoltic system The graph below shows the glycoltic system ATP concentration over time. GLYCOLTIC SYSTEM

18. Anaerobic glycoltic system Think. Pair. Share – Discuss and write down all the advantages and disadvantages of the anaerobic glycoltic system.

19. Aerobic system Aerobic system of energy production needs oxygen to function. The complete oxidation of glucose can produce up to 38 molecules of ATP and has 3 distinct stages.

20. Aerobic system 1st Stage – Glycolysis: This process is the same as anaerobic glycolysis but occurs in the presence of oxygen. Lactic acid is not produced and the pyruvic acid is converted into a compound called acetyl-coenzyme-A (acetyl CoA). Glycogen 2 ATP ENERGY Glycolysis Pyruvic Acid

21. Aerobic system Acetyl Co-A moves to the mitochondria within the muscle cell where the remaining stages are activated.

22. Aerobic system 2nd Stage – Kreb/citric acid cycle: Once the pyruvic acid diffuses into the matrix of the mitochondria a complex cycle of reactions occurs in a process known as the Krebs cycle. The reactions produces two molecules of ATP, as well as carbon dioxide. Hydrogen is taken to the electron transport chain. Acetyl-CoA Hydrogen 2 ATP yielded Carbon Dioxide Citric Acid

23. Aerobic system 3rd Stage - Electron transport chain: Hydrogen is carried to the electron transport chain by hydrogen carriers. This occurs in the cristae of the mitochondria. The hydrogen splits into hydrogen ions and electrons and these are charged with potential energy. The hydrogen ions are oxidised to form water, while providing energy to resynthesise ATP. Throughout this process, 34 ATP molecules are formed. Hydrogen H+ H- H+ H- 34 ATP yielded Water

24. Aerobic system Total energy yield from the aerobic system is.... 38 molecules of ATP

25. Aerobic system and Free Fatty Acids Fats can also be used as an energy source in the aerobic system. The Krebs cycle and the electron transport chain can metabolise fat as well as carbohydrate to produce ATP. Triglycerides (stored fat in muscle) Metabolised aerobically Enzyme: Lipase Glycerol and Free Fatty Acids Beta Oxidation Kreb’s Cycle Acetyl Coenzyme A

26. Aerobic system and Free Fatty Acids More ATP can be made from one molecule of fatty acids than from one molecule of glycogen but the intensity must be low. This is why in long duration exercise, fatty acids will be the predominant energy source.

27. CONCENTRATION OF ATP TIME 3 SECS 10 SECS 60 SECS 2 HRS Aerobic system The graph below shows the aerobic system ATP concentration over time. AEROBIC SYSTEM

28. Aerobic system Think. Pair. Share – Discuss and write down all the advantages and disadvantages of the aerobic system.

29. Energy Continuum of Physical Activity All the energy systems contribute during all types of activity but one of them will be the predominant energy provider. The intensity and durationof the activity are the factors that decide which will be the main energy system in use. Think. Pair. Share – What energy system/s would an 800m runner utilise during their race?

30. Energy Continuum of Physical Activity • 800m race: • ATP-PC System – Start of race. • Aerobic System – Majority of race. • Glycoltic System – Sprint finish.

31. Energy Continuum of Physical Activity Think. Pair. Share – How many other sports can you place on the energy continuum?

32. Energy Continuum of Physical Activity This is where the exercise intensity changes frequently. i.e. a basketball player is required to walk, run, sprint and jump at various points in the game.

33. Energy Continuum of Physical Activity The point at which an athlete moves from one energy system to another is known as a threshold. This depends on the exercise intensity and fuel available. ATP-PC Glycoltic Aerobic % energy supplied Time

34. Energy Continuum of Physical Activity The ATP-PC/glycoltic threshold is the point at which the ATP-PC energy system is exhausted and the glycoltic system takes over. As a midfielder, performers would need to make short 3 second sprints to get free or beyond a defender (ATP-PC) but will also need the glycoltic system to make recovery runs back to help defend.

35. Energy Continuum of Physical Activity The glycoltic/aerobic threshold – this would occur when the ball is in phases of play away from the player. A performer will still track and scan players movement but at a lower intensity. Sufficient oxygen will be available throughout to allow for ATP resynthesis.

36. Energy transfer during long duration/lower intensity exercise For exercise at a low intensity over a long period of time the aerobic system is the preferred method of energy production. Oxygen consumption is the amount of oxygen we use to produce ATP and referred to as VO2.

37. Oxygen consumption during exercise The difference between sub-maximal and maximal exercise is linked to the level of oxygen deficit at the start of physical activity. When we start to exercise, it takes time for the circulatory system to respond to the increased demand for oxygen and the mitochondria to adjust to the rate of respiration needed.

38. Oxygen consumption during recovery Watch me What do athletes do to aid the recovery process after exercise and why?

39. Oxygen consumption during recovery The recovery process involves returning the body to the state it was in before exercise. The reactions that occur and how long the process takes depend on the duration and intensity of the exercise undertaken and the individual's level of fitness. Post exercise the body is in a state of fatigue and enters a period of recovery. To do this, aerobic energy is required and is termed excess post-exercise oxygen consumption (EPOC)

40. Oxygen consumption during recovery Oxygen Deficit: The amount of oxygen that the performer requires to complete an activity aerobically. Oxygen debt is the amount of oxygen needed to return the body to a resting state. Oxygen debt results from EPOC.

41. Excess Post-exercise Oxygen Consumption (EPOC) • After strenuous exercise there are 4 main tasks that the body needs to be completed before the muscle can operate efficiently again: • Replacement of ATP and phosphocreatine (the fast component) • Replenishment of myoglobin with oxygen • Removal of lactic acid (the slow component) • Replacement of glycogen

42. Excess Post-exercise Oxygen Consumption (EPOC) • Oxygen deficit and EPOC can be plotted against time. There are two distinct stages during EPOC. • The fast component of recovery • The slow component of recovery

43. Excess Post-exercise Oxygen Consumption (EPOC) EPOC will always be present but the size of the oxygen deficit and EPOC will differ depending on the activity intensity and duration. Low intensity exercise High intensity exercise Low intensity exercise results in a small deficit limiting the use of the anaerobic energy systems and therefore lactic acid accumulation.

44. Excess Post-exercise Oxygen Consumption (EPOC) Fast component of recovery: This first stage of EPOC recovery is also known as the alactacid component. The increased rate of respiration continues to supply oxygen to the body and myoglobin stores. EPOC helps replenish these stores and takes up to 2-3 minutes.

45. Excess Post-exercise Oxygen Consumption (EPOC) Fast component of recovery: Resynthesis of ATP and PC stores also occurs within the first 3 minutes of EPOC. After this time, phosphocreatine stores, are completely restored but 50% of PC can be replenished after only 30 seconds.

46. Excess Post-exercise Oxygen Consumption (EPOC) Second component of recovery: This stage is also known as the lactacid component. It is the slowest of the replenishment processes and full recovery may take up to an hour, depending on the intensity and duration of the exercise.

47. Excess Post-exercise Oxygen Consumption (EPOC) Post exercise respiratory rate (ventilation) and depth along with heart rate (circulation) remain high to aid removal of by-products such as CO2 and carbonic acid. Body temperature rises during exercise and will remain elevated during EPOC. This accounts for about 60% of the slow lactacid component of EPOC.

48. Excess Post-exercise Oxygen Consumption (EPOC) Lactic acid (the slow component) can be removed in four ways: Performing a cool-down accelerates lactic acid removal because exercise keeps the metabolic rate of muscles high and keeps capillaries dilated. This means that oxygen can be flushed through, removing the accumulated by products.

49. Excess Post-exercise Oxygen Consumption (EPOC) The stores of glycogen in relation to the stores of fat are relatively small. The replacement of glycogen stores depends on the type of exercise undertaken. It may take a number of days to complete the restoration of glycogen after a marathon. Eating a high-carbohydrate meal will accelerate glycogen restoration, and should be done within 1 hour post exercise.

50. Energy transfer during short duration/high intensity exercise For exercise at a higher intensity energy must be produced rapidly. This is reliant on the anaerobic respiration system.