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ENERGY SYSTEMS

ENERGY SYSTEMS. What you need to know…. ATP-PC, Lactic Acid, Aerobic systems Key points, how they work Summary of the three energy systems Energy systems interplay. The Three Energy Systems.

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ENERGY SYSTEMS

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  1. ENERGY SYSTEMS

  2. What you need to know… • ATP-PC, Lactic Acid, Aerobic systems • Key points, how they work • Summary of the three energy systems • Energy systems interplay

  3. The Three Energy Systems • There are three pathways or energy systems responsible for the resynthesis (___________) of ATP and supply of energy • Which of the three energy systems operates during exercise depends on: • ___________ of exercise • How urgently the energy is required • ___________ of exercise • Whether or not ___________ is present

  4. The Three Energy Systems • The energy for muscular contractions is produced either anaerobically or aerobically via three energy systems • Anaerobic systems 1. ATP-PC system 2. Lactic Acid system • Aerobic system 3. Aerobic system

  5. The Three Energy Systems • The three energy systems do not function independently or one at a time; all three energy systems are activated at the start of exercise and their relative contribution is determined by intensity and duration of exercise • At rest, our demands for ATP are ___________ and can be met ___________ • As we start to exercise, the demand for ATP ___________ rapidly, especially during maximal activities and the ATP demands are met ___________ • However, if the exercise is less intense and longer ATP demands can be mostly met aerobically

  6. Energy for Rest and Activity • The body can create energy (ATP) under two main conditions • Rest: where there is enough (sufficient) oxygen available for the body to continue to function at a resting level • Activity: where physical exertion means there is not enough (insufficient) oxygen available for the body to continue to function at a particular level without a large increase in oxygen intake

  7. At Rest • The body has lots of oxygen available • 2/3 energy comes from ___________ • More ___________ is contained in fat than carbohydrate • 1/3 energy comes from ___________ • The end products of aerobic metabolism are: • Carbon dioxide (CO2), water (H2O) and heat

  8. During Activity • Increased oxygen supply needed to go to working ___________ • Exercise of short duration and high intensity the ___________ systems supply most of the required energy • Carbohydrate main fuel • Exercise of longer duration and low intensity ___________ system supplies energy • Carbohydrate initial fuel, then fat main fuel once CHO is used

  9. ATP-PC System • Also known as: phosphate, PC, CP, phosphocreatine systems • It’s an anaerobic system = no oxygen • A small amount of ___________ is stored in the muscles • Primary system for maximal intensity efforts of 1-10 seconds duration • Eg:

  10. ATP-PC SystemHow it works • Once ATP (stored in muscles) is used ATP needs to be ___________ • As we learnt earlier ATP is reformed using ADP and a free phosphate molecule (Pi) • This process requires energy • Phosphocreatine (PC) is the chemical compound that provides this energy • There is ~4 times the amount of PC in muscles than ATP • So, PC is broken down to create energy and this energy is used to reform ATP from ADP • PC releases a free phosphate: • PC = P + C • ADP + P = ATP

  11. ATP-PC SystemSummary • Provides most rapidly available source of ATP for energy because it depends on short and simple chemical reactions • Anaerobic system so it doesn’t rely on ___________ to release energy • ATP & PC both stored in ___________ and available for immediate energy release • Although, after 5 seconds ~50% is depleted • Once PC is completely used, ATP must be reformed in other ways • Usually via glycogen (stored in muscles and liver) using anaerobic glycolysis from the lactic acid system

  12. Lactic Acid System • Also know as: anaerobic glycolysis, lactacid systems • It’s an anaerobic system = no oxygen • Provides bulk of ATP production for high intensity, sub-maximal efforts • Eg: • Duration: 10 sec – 2-3 mins • Intensity: 85 – 95% max HR

  13. Lactic Acid SystemHow it works • As we know, there is not enough PC in the muscles to continuously repair ADP  ATP • In the lactic acid system this resynthesis of ATP is done differently • This energy comes from the breakdown of ___________ (process is known as glycolysis) • Because oxygen is not present the glycogen is not totally broken down • Pyruvic acid is created and because there is no oxygen it is converted to lactic acid • Hydrogen ions also released • See figure 2.10, p.69 • As by-products (lactic acid and hydrogen ions) increase in the muscles it decreases the rate of ATP rebuilding and leads to ___________

  14. Lactic Acid SystemSummary • Requires no oxygen • More complex reactions than the ATP-PC system to release energy • Requires glycogen to be broken down to release energy (glycolysis) • Produces lactic acid, which contributes to fatigue • Is the system used for sub-maximal activities when the PC is depleted until the aerobic system can be used

  15. Aerobic System • Also known as: aerobic glycolysis, oxygen systems • Creates the most energy out of all three systems • Is the ___________ at creating energy • Contributes majority of ATP production in sub-maximal, longer efforts • Eg: • Duration: >30 sec • Intensity: <85% max HR

  16. Aerobic SystemHow it works • Stage 1: Carbohydrates (glycogen) is broken down into glucose and pyruvic acid using oxygen (aerobic glycolysis) • Occurs in the mitochondria (aerobic powerhouse) • See figure 2.11, p.70 • Because oxygen is present a more complete breakdown of glycogen occurs resulting in no lactic acid • Stage 2: Instead of pyruvic acid becoming lactic acid it is further broken down in the citric acid cycle (Kreb’s cycle), releasing ___________ and CO2 • Stage 3: The electron transport chain also produces large amounts of ATP along with ___________ and ___________ • See figure 2.12, p.71

  17. Aerobic SystemSummary • Requires oxygen • Dominant system for sub-maximal activities • Many more complex reactions than the ATP-PC & lactic acid systems • Prefers to break down CHO rather than fats • Although ___________ can produce more ATP • However, fats require more oxygen to produce the same amount of ATP as CHO • Releases no toxic by-products and can be used indefinitely • Produces far more ATP than the anaerobic systems • However, still contributes significant amounts of energy during high intensity efforts lasting 1-2 minutes

  18. Comparing the Three Energy Systems • Complete the summary table

  19. ATP (Energy) Production • The ___________ and ___________ of the physical activity determine which of the energy systems is the dominant contributor to ATP (energy) production • See figure 2.14, p.74 and figures 2.15 & 2.16, p.75

  20. Energy System Interplay • Virtually all physical activities receive energy from each of the three energy systems • Each system is best suited to supplying energy for specific types of events or activities • They overlap each other depending on the type of activity and exercise demands • They do not turn themselves on and off

  21. REVISION QUESTIONS 1/ The ATP-PC system is the quickest to supply energy because it: A has an indefinite supply of stored ATP B does not use oxygen C is immediately available, is the simplest and quickest system for breaking down PC to create ATP, and is stored in muscle cells D is more powerful than fats 2/ Marcus runs a 100m heat at his school athletics carnival, qualifying for the final in 12 secs. Most of the PC depleted during the 100m will be resynthesised during: A the first 3 minutes of an active recovery B 1 minute of active recovery and eating high GI food C 30 seconds D the first part of EPOC

  22. REVISION QUESTIONS 3/ Discuss the energy system contribution for a 200m swimming event lasting 1 minute 45 seconds. 4/ What are triglycerides? (2 marks) 5/ What are they broken down to? (1 mark) 6/ Why and when would a recreational marathon runner possibly rely on fat as a fuel? (2 marks)

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