chapter 6 & 7 unit 3 pe slides

• Energy systems


  Resynthesise ATP
• ATP


  Provides energy for movement, is broken down and rebuilt 24/7, is broken down to provide energy for muscular contractions, energy comes from breaking the bond holding the three phosphates together

  
• ATP resynthesis


  Using PC, CHOs, fats and sometimes proteins, when these are broken down they release energy to enable ATP to be recharged/rebuilt

  
• Aerobic metabolism


  ATP resynthesis occurs via energy systems or pathways that require the presence of oxygen
• Anaerobic metabolism


  ATP resynthesis occurs via energy systems or pathways that do not require oxygen
• 3 energy systems


  • ATP PC system
  • Anaerobic glycolysis system
  • Aerobic system
• ATP PC system


  • Maximal Intensity, very short duration, during O2 deficit
• Anaerobic glycolysis system


  • High Intensity, short duration, during O2 deficit
• Aerobic system


  • Low intensity, long duration
• PC/CP


  Creatine phosphate or phosphocreatine, stored within the muscles to provide energy for ATP resynthesis for about 10 seconds, extremely high rate, low yield 0.8 ATP/molecule

  
• Fats


  Preferred fuel source at rest/low intensities, higher yield of ATP, can only be broken down aerobically, take a long time to recharge ATP
• Carbohydrates


  Preferred fuel source during exercise, produce ATP at a faster rate compared to fats, more efficient with oxygen, stored as glycogen in liver and muscles, undergo glycolysis to release energy, excess CHO is converted to fat and stored as adipose tissue, glycogen stores depleted after 1.5-2 hours of exercise, can be broken down anaerobically and aerobically
• Protein


  Rarely used as a major fuel source, minimal contribution, slow to recharge ATP, only used predominantly in extreme circumstances such as starvation and very long duration/ultra-endurance events, include enzymes that are used to break down other chemicals, stored as muscle tissue, made up of amino acids, very high oxygen cost so are not optimal for use during exercise
• Carbohydrates


  Preferred source of fuel during exercise (Glycogen)
• Fats


  Concentrated fuel used during rest and prolonged sub-maximal exercise
• Carbohydrate is a more efficient fuel source than fat when you consider the amount of ATP produced per unit of oxygen consumed, carbohydrate can be broken down both anaerobically and aerobically, carbohydrates have fewer bonds that need to be broken down to release energy than fats, so the rate of ATP production is faster than when using fats
• During prolonged endurance events such as marathon running and triathlons, the 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'
• Cross-over concept and glycogen sparing


  Involve the delay of carbohydrates becoming the major fuel rebuilding ATP, this means that fats are used for longer from the start of continuous activities
• Fats take a lot of oxygen away from working muscles in order to rebuild ATP and they require many more chemical reactions than carbohydrates to be broken down in order to "recharge/rebuild" ATP
• Fat is an essential fuel source for aerobic energy production, fat is the main fuel source during rest and prolonged sub-maximal intensity exercise, fats require greater amounts of oxygen to be broken down, aerobic respiration involves more complex reactions, fats produce a high yield of ATP per molecule, fats produce ATP at a slower rate, therefore suitable for low intensity exercise when energy demand is low
• ATP breakdown and energy release

  Adenosine triphosphate (ATP) is broken down to adenosine diphosphate (ADP) and inorganic phosphate (Pi), releasing energy which is used to power muscular contractions

  
• ATP-PC system


  • Anaerobic, high intensity, very short duration, very fast rate, low yield (approx 1 ATP), uses phosphocreatine (PC) to form ATP anaerobically, peak power 2-4 seconds, replenished through passive recovery

  
• Anaerobic glycolysis system


  • Anaerobic, high intensity, short duration, fast rate, low yield (approx 2 ATP), uses glycogen, produces hydrogen ions (H+) causing muscle fatigue, peak power 5-15 seconds, fatigues after 2-3 minutes

  
• Aerobic system


  • Aerobic, low intensity, long duration, slow rate, high yield (approx 36-38 ATP), uses carbohydrates, fats, protein, slowest contributor to ATP resynthesis
• As one energy system increases its contribution

  The other two energy systems are also affected
• Marathon runner


  Completed in around 2 hours and 15 minutes, undertaken at submaximal intensity, the rate of ATP required is much lower, the yield (total amount) of ATP required is much, much greater & glycogen is utilised
• 100m Sprinter


  Completed in around 10 seconds, high-intensity activity, the rate of ATP expenditure is very rapid, the rate of ATP resynthesis must also be very rapid, the yield (total amount) of ATP required is low
• The graph shows the approximate relative contributions of the three energy systems to energy production at maximum sustainable exercise intensity for varying durations
• Energy system interplay


  1. After approximately 10 seconds of intense muscular activity, the energy system providing the majority of the energy shifts from the ATP-PC system to the anaerobic glycolysis system

  2. After about 1 minute of maximal intensity effort, the main supplier of ATP shifts from the anaerobic glycolysis system to the aerobic system
• Steady state


  Oxygen supply equals oxygen demand
• Oxygen deficit


  Oxygen demand exceeds oxygen supply
• EPOC


  The period after exercise stops when heart rates remain above resting levels
• VO2 maximum


  The maximum oxygen that can be taken up, transported and used by working muscles
• Oxygen deficit


  Associated with anaerobic ATP production
• Oxygen uptake


  Associated with aerobic ATP production
• Energy system training


  • ATP-PC: Up to 10 secs, maximal intensity, 1:3 to 1:5 work:rest, passive recovery
  • Anaerobic Glycolysis: 10-90 secs, >85% max HR, 1:2 to 1:3 work:rest, active recovery
  • Aerobic: Interval 2-3+ mins, continuous 30+ mins, 70-85% max HR, 1:1 to 1:0.5 work:rest, active recovery
• Training the ATP-PC system

  Short-interval, sprint training or plyometrics, maximal-intensity efforts up to 10 secs followed by adequate time for PC replenishment, resistance/weight training with maximal effort up to 5 secs
• Training the anaerobic glycolysis system


  Training sessions above 85% max HR, repeated efforts of 30-90 secs, 1:3 or 1:2 work:rest (medium interval training)
• Training the aerobic system


  Continuous training 70-75% max HR for 30+ mins, interval training of 2-4 mins at 70-85% max HR, 1:1 or 1:0.5 work:rest
• All 3 energy systems contribute to ATP production throughout an event/race/match, with intensity and duration determining the major contributor at any time