PDH/PE

1. PDH/PE Personal Development, Health and Physical Education Core 2: Factors affecting Performance

2. FACTORS AFFECTING PERFORMANCE • How does training affect performance? • energy systems • analyse each energy system by exploring: • source of fuel • efficiency of atp production • duration that the system can operate • cause of fatigue • by-products of energy production • process and rate of recovery

3. FACTORS AFFECTING PERFORMANCE • The human body is an incredible machine which requires energy to do vast amounts of work to meet the demands placed on it by everyday living. • Energy is found in food, and the energy content of food is measured in kilojoules. • A person’s base metabolic rate (bmr) is the minimum amount of kilojoules the body requires for it to function and stay alive; any extra activity will need extra energy.

4. FACTORS AFFECTING PERFORMANCE • Foods can be broken down into carbohydrates, fats and proteins. Each source of nutrient supplies a different amount of kilojoules to the body: • protein contains 17 kilojoules per gram • fat contains 37 kilojoules per gram • carbohydrate contains 16 kilojoules per gram

5. FACTORS AFFECTING PERFORMANCE • The kilojoule content of foods depends on the amount of carbohydrates, fats and proteins present in the food. • Fat supplies around twice the kilojoules as the same amount of carbohydrate and protein, so it is a longer lasting source of energy but it also takes longer to digest.

6. Carbohydrates • Carbohydrates are an ideal source of energy for the body, and are the main nutrient which fuel exercise of a moderate to high intensity. They can be easily broken down into glucose, a form of sugar that is easily used by the body. • This breakdown into glucose is called glycolysis. Any glucose not needed immediately gets stored in the muscles and the liver in the form of glycogen. Once these glycogen stores are filled up, any extra gets stored as fat. • Carbohydrates can take the form of simple carbohydrates, such as sugars, or complex carbohydrates. Natural sugars are found in fruit and vegetables and refined sugars are found in soft drinks, biscuits and snack bars.

7. Carbohydrates • Complex carbohydrates are starch-based foods and are available in root vegetables like potatoes, wholemeal breads and in refined foods, such as white flour based foods like pizza and sugary processed breakfast cereals. • Carbohydrates stored as glycogen are easily used for exercise. • It normally supplies the energy for the first few minutes of any activity, either as the main energy source or it may be needed to break down fats for longer lasting sports. Athletes should always ensure they have full stores of carbohydrates prior to competition.

8. Carbohydrates

9. Fats • Fats are the main energy source for long and low to moderate exercise, such as cycling. • Fats are not used initially when supplying energy, as oxygen is needed to break down fats; so it takes some time for fat to be converted to energy. Foods high in fat stay in the stomach for a long period of time and as such can become detrimental to performance if consumed too close to competition. • The major energy component from fats in the body is triglycerides, which aid to insulate the body. • Triglycerides need to be broken down, through a process called lipolysis, into glycerol and free fatty acids to provide energy for activity.

10. Fats • These free fatty acids are then broken down into glucose, which requires oxygen. This process is also known as oxidation. When the body is digesting fats blood is needed, which can cause cramping and discomfort when performing. • Most adults have enough stored fat in the form of adipose tissue to fuel activity for hours or even days as long as there is sufficient oxygen to allow fat metabolism to occur.

11. Protein • Proteins are not normally used for energy, but will do so in extreme circumstances after all the fats and carbohydrates have been exhausted. • If protein was used as energy this would stress the kidneys because they have to work harder to eliminate the by-products of this protein breakdown. • Proteins are primarily used for repairing and rebuilding muscle used during exercise. Strength athletes, such as weightlifters, require more protein than endurance athletes, such as marathon runners, and the average adult due to isolated muscle use. Proteins are broken down into amino acids.

12. How the body uses energy • By having a basic understanding of how food provides energy for athletes it is important to understand how the energy is used by the body. • Food provides energy in the form of chemical energy, which must be converted to mechanical energy. • The breakdown of food produces energy that is stored in the body for later use. • Adenosine triphosphate (ATP). ATP is an energy-rich compound that the body uses to maintain the survival of essential processes, such as heart beating and temperature regulation, as well as to meet the demands of any exercise requirements.

13. How the body uses energy • Energy for activity is stored in the muscles in the form of ATP. ATP is stored in small amounts in the body, which is sufficient to provide energy for a short burst of muscular effort before it fully breaks down. • However, through a process of resynthesis the body has the ability to produce more ATP to continue the exercise effort, depending on the type and length of activity.

14. How the body uses energy • The ATP molecule is made up of a large molecule called an adenosine molecule and three smaller molecules called phosphates • When the bond between phosphate 2 and phosphate 3 breaks it provides energy, which is then transferred to the cells and allows for movement to occur. • The energy released allows muscle cells to contract. ENERGY

15. How the body uses energy • At this point the molecule has only two phosphate groups attached and is called adenosine diphosphate and may also break down to a lower form of energy supply of adenosine monophosphate. • An average adult may break down or metabolise up to 40 kilograms of ATP per day to maintain bodily functions. • This can rise to 0.5 kilogram per minute during strenuous exercise. • The breakdown of glycogen and creatine phosphate (PC) will supply energy to resynthesise adenosine triphosphate (ATP) to provide energy. Short-term energy supplies do not require oxygen to replenish ATP, so the ATP/PC and lactic acid systems are called the anaerobic systems.

16. How the body uses energy • Fuel sources needed to provide ATP for longer duration activities will require oxygen to be present and as such are called the aerobic energy system. • There are three energy pathways in which the body uses and replenishes ATP molecules to facilitate the requirements of physical activity. The energy supplied is a combination of energy systems dependent on the intensity and duration of the exercise, determining which method gets used and when. • The body cannot easily store ATP (and what is stored gets used up within a few seconds), so it is necessary to continually create ATP during exercise. In general, the two main ways the body converts nutrients to energy are aerobic and anaerobic energy systems.

17. Alactacid system (atp/pc) • The alactacid system (ATP/PC) uses the stored ATP molecules in the muscle, usually for a few seconds or one explosive movement. The ATP molecule is then unable to provide energy to the working muscles. • To continue the muscular movement, the body now relies on creatine phosphate (PC) in a secondary reaction • The creatine phosphate separates into two molecules of creatine and phosphate.

18. Alactacid system (atp/pc) • The energy derived from this reaction is enough to rejoin or resynthesise the floating phosphate groups. • The body is not using new ATP molecules but rather resynthesising the ones that had previously been broken down. • This system is used for short bouts of exercise, especially those lasting for only up to 12 seconds, such as 100-metre sprint, shot put and discus.

19. Source of fuel • This process of resynthesis of ATP goes on continually until the creatine phosphate molecules are broken down, which normally takes between 10–12 seconds. • Creatine phosphate thus provides the fuel for the alactacid energy system.

20. Efficiency of atp production • This is an efficient form of energy production as the chemical reactions occur very quickly and are very simple. • The fuel for this system is already stored in the muscle as is the ATP molecule. • It allows for immediate production or resynthesis of ATP molecules and as such does not rely on oxygen to resynthesise ATP molecules.

21. Efficiency of atp production • The recovery time for this system is also very short. The creatine phosphate molecules will replenish themselves completely if the body is at rest for a minimum of two minutes (approximately 50% of PC will be restored in the first 30 seconds of rest). • Without the ATP/PC system, fast, powerful movements could not be performed, as these activities demand a rapidly available supply of energy. For each molecule of PC there is one molecule of ATP resynthesised.

22. Duration that the system can operate • In this system, ATP is only stored in the muscles for 1–2 seconds of activity. • Creatine phosphate (PC) molecules are also stored in the muscle and will last for a further 10–12 seconds. • This means that the total duration for this energy system is approximately 10–12 seconds.

23. Cause of fatigue • Fatigue in the ATP/PC system is mainly due to the inability of the body to continually resynthesise ATP molecules. • This occurs when the body has used up all of its stored supply of PC.

24. By-products of energy production • The only by-product given off in this energy system is heat, as a result of the reactions breaking phosphate groups off PC and ATP.

25. Process and rate of recovery • The rate of recovery is relatively short from activity. • After full depletion of ATP and PC the body will take approximately two minutes to fully regain its normal levels of PC.

26. Lactic acid system • If muscular contraction is continually required beyond the limit of the alactacid system, the lactic acid system will continue providing the ATP molecules to create required energy. • This system produces lactic acid as a waste product in the chemical breakdown of glucose and glycogen (called glycolysis). • After the lactic acid system has used all of the PC, the body needs to find a new fuel in the form of blood glucose or glycogen stored in the muscle to keep going. • Anaerobic glycolysis provides energy by the partial breakdown of glucose without the need for oxygen.

27. Lactic acid system • As glycolysis occurs the glucose is broken down into pyruvic acid, but due to a lack of oxygen it then transforms to lactic acid. This lactic acid then builds up in the cell and is transferred into the blood stream where the body tries to get rid of it. • Anaerobic glycolysis provides energy by the partial breakdown of glucose without the need for oxygen. • As glycolysis occurs the glucose is broken down into pyruvic acid, but due to a lack of oxygen it then transforms to lactic acid. This lactic acid then builds up in the cell and is transferred into the blood stream where the body tries to get rid of it.

28. Source of fuel • The major source of fuel for this system is carbohydrates in the form of sugar travelling in the bloodstream, known as blood glucose, and the glycogen stored in the muscles, known as muscle glycogen.

29. Efficiency of atp production • This is a very efficient system as it continues to resynthesise ATP molecules after the ATP/PC system has ceased. • The breakdown of glucose and glycogen provides energy which will result in the resynthesis or regeneration of ATP molecules to be used for muscular contraction in a short time.

30. Duration that the system can operate • Anaerobic metabolism produces energy for short, high-intensity bursts of activity lasting approximately one minute at high intensity or up to three minutes for moderate intensity. • If intensity is sub-maximal, then this energy system can last longer than three minutes.

31. Cause of fatigue • It was formerly thought that lactic acid was the major cause of fatigue when using this system. • Lactic acid is produced as a by-product of this system and has to be transported out of the body’s cells by the blood. If high-intensity exercise is maintained for quite a long time (40–60 seconds) the blood cannot transport all the lactic acid out of the system and so it builds up. • This is where the onset of blood lactate accumulation (OBLA) occurs and causes the muscles to fatigue. • This is also known as the lactic acid threshold or anaerobic threshold. At this point the athlete’s performance decreases as does intensity and muscles start to tire and performance is affected.

32. Cause of fatigue • This is clearly evident at the end of a 400-metre race where an athlete appears to be running quicker than other athletes, but in fact the other athletes are slowing down faster due to lactic acid build up. • When lactate was produced in the absence of oxygen, hydrogen ions were also produced. • The presence of hydrogen ions, not lactate, makes the muscle acidic as they alter the pH component of the cell and that will eventually halt muscle function. • As hydrogen ion (H+) concentrations increase, the blood and muscle become acidic. • The higher than normal acid content in the cell will alter the breakdown of glucose.

33. Cause of fatigue • Acidic muscles will aggravate associated nerve endings causing pain and increase irritation of the central nervous system. • When the acid content of the cell increases, nerve endings are stimulated and the perception of burning is encountered by the athlete. • Fatigue is due to the increased hydrogen ion concentration and not the lactic acid.

34. By-products of energy production • The by-product of the lactic acid system is pyruvic acid which, in the absence of oxygen, produces lactate and hydrogen ions (H+). • The lactate is then used by the cells, of which 65% is converted to carbon dioxide and water, 20% into glycogen, 10% into protein, and 5% into glucose.

35. Process and rate of recovery • It takes 20 minutes to 2 hours for lactic acid to be removed from the blood. Depending on the body’s needs at a particular time, lactic acid is also capable of being converted into glycogen. • The body’s recovery from using this system will be enhanced if an active cool down is completed; this will aid the transfer of lactic acid around the body where it can be reused. • However, the active cool down should be below the effort that would produce more lactic acid, for example, 40–50% of maximum heart rate.

36. Aerobic system • The aerobic system requires oxygen to make the ATP molecules needed for exercise. • Aerobic exercise is known as steady state exercise, because the energy demands meet the energy being supplied by the body. As the oxygen is transferred around the body via the circulatory system, it eventually reaches the working muscles. • As the body reaches its anaerobic threshold, the body starts to slow down and the oxygen has time to reach the working muscles and change pyruvic acid into carbon dioxide, water and ATP. • As a result, no more lactic acid is produced due to the presence of oxygen.

37. Aerobic system • Aerobic glycolysis occurs when oxygen (O2) is available to break down pyruvate, which produces ATP through chemical reactions that occur in the Krebs Cycle and the ‘electron transport system’. • The body now starts to break down glucose and fats, as well as convert pyruvic acid so it can be used to regenerate ATP using oxygen. • To begin the long-winded process of creating ATP molecules via the aerobic energy system the glycerol portion of fat as well as pyruvic acid are converted to acetyl coenzyme A (Acetyl CoA), which is necessary for the next step in creating energy. • The free fatty acids are also converted to acetyl co enzyme through a different process, called beta oxidation.

38. Aerobic system • At this point both the glycerol and the fatty acids have been converted to Acetyl CoA and are now ready for the Krebs Cycle to take place in the cells of the mitochondria. • As the Acetyl CoA is broken down, carbon dioxide and hydrogen are removed. The energy from the breakdown of this is used to regenerate ATP. • Once again the carbon dioxide exits the body through the lungs. However, the hydrogen moves on to • the final stage of the electron transport system where it combines with oxygen to form water (H2O).

39. Source of fuel • The fuel for the aerobic system is primarily glucose and free fatty acids. • Most humans have fats available to be used and so have a limitless supply of fuel to keep creating ATP molecules, these fats are broken down into glycerol and free fatty acids. • This is essential in changing the structure of fat so it can be broken down in the presence of oxygen.

40. Efficiency of atp production • For longer slower duration of exercise, the aerobic system is very efficient in being able to provide an endless supply of energy to resynthesise ATP for an extended period of time. • Compared to glucose, fats can supply up to 10 times as many ATP molecules.

41. Duration that the system can operate • The aerobic energy system can supply energy to the body from 2–3 minutes to a few hours. • However, it is used primarily during endurance exercise, which is generally less intense and can continue for long periods of time. If a person is exercising at a low intensity (that is, below 50% of maximum heart rate), their body has enough stored fat to provide energy for hours or even days, provided there is enough oxygen for reactions to occur. • Obviously the higher the intensity of the exercise, it will be easier to become exhausted because all of the supplies in the body will be used up. • The aerobic system is the same system the body predominantly uses to maintain its everyday bodily functions.

42. Cause of fatigue • The main cause of fatigue in this system is due to the depletion of glucose to the working muscles. • Poor respiration or circulation where it is difficult for oxygen and nutrients to get to working muscles and subsequent poor removal of waste products can also lead to fatigue.

43. By-products of energy production • The by-products formed from using this system are carbon dioxide (CO2) and water (H2O), as a result of chemical reactions. • The water is lost through sweat or expiration and is also made available to other cells in the body. • The carbon dioxide is breathed out as exercise takes place. These by-products are not harmful to the athletic performance.

44. Process and rate of recovery • The rate of recovery is dependent on the type of activity that has taken place. High-intensity activity for an extended period of time will take a longer time for recovery, than if the activity was low intensity. • The main factor to be aware of is to replenish lost glucose and glycogen, which could take days for the food to be fully digested. • Note that the time taken for oxygen to reach the working muscles is between 2–4 minutes before ATP is supplied predominantly by the aerobic system.

45. Pathways of energy systems • During exercise an athlete will move through the various energy pathways. • As exercise begins, ATP is produced through anaerobic metabolism from both the ATP/PC system and the lactic acid system. • With an increase in breathing and heart rate, there is more oxygen available and aerobic metabolism begins and continues to resynthesise ATP molecules over an extended period of time. • The energy systems do not work independently of each other but rather have some contribution to all sports. The amount of contribution depends on the intensity of the activity, the duration of the activity and how explosive the activity is.

46. Types of training and training methods • Assess the relevance of the types of training and training methods for a variety of sports by asking questions such as: • which types of training are best suited to different sports? • which training method(s) would be most appropriate? why? • how would this training affect performance? • The type of training undertaken by an athlete should meet the specific needs of the activity being trained for. The three main types of training are strength, aerobic and flexibility training.

47. Aerobic, eg continuous, fartlek, aerobic interval, circuit • The main objective of aerobic training is to make the athlete’s body more efficient at using oxygen. • This involves training the larger muscle groups—the arms, chest and legs—to efficiently combine with the cardiovascular system to supply oxygen to the athlete and their working muscles.

48. Aerobic, eg continuous, fartlek, aerobic interval, circuit • Any training that will build cardiorespiratory endurance is termed aerobic training when the majority of the energy in the athlete is derived aerobically. • Aerobic training should follow the FITT principle, which is at least three times a week for 20 minutes and between 65–85% maximum heart rate. • There are many different types of aerobic training, such as continuous, Fartlek, aerobic, interval and circuit.

49. Continuous training • This is the simplest form of aerobic training where there is no rest, but rather continual effort and at an intensity where the heart rate will be in the aerobic training zone for at least 20 minutes. • Some examples include jogging, swimming or cycling. • This training can vary from long slow duration of between 60– 80% maximum heart rate aimed at aerobic endurance, to higher intensities of approximately 80–90% maximum heart rate, which will train the body’s ability to deal with lactic acid for long periods of time and possibly increase the OBLA. • If there is too much continuous training an athlete would run the risk of overuse injuries.

50. Fartlek training • Fartlek training involves alternating bursts of high-intensity activity while still maintaining the longer slower style of training. • This training is less structured than interval training with no predetermined structure to follow. • The athlete can then concentrate on feeling the pace and their physical response to it, so that they’re able to develop self-awareness and pace judgment skills to set their own pace. • Work–rest intervals can be based on how the body feels. Beginners tend to enjoy Fartlek training because it is more flexible and can be done on all types of terrains, not specifically just on a track. This is a good form of training for the aerobic energy system.