LGA507 Exercise Physiology

1. LGA507 Exercise Physiology Energy Systems III Image by Frederic de Villamil

2. Aims and Objectives

3. Oxidative Background Anaerobic reactions of glycolysis release only about 10% of the energy within the original glucose molecule. Thus extracting the remaining energy requires an additional pathway Image by matt coates Image by Diamondduste

4. Glucose / Glycogen Breakdown and Synthesis A Molecule of Glucose • This system will supply energy indefinitely • Bi-products of breakdown are CO2 and H2O Image by Klaas 1978 • Teach people new skills, techniques and strategies • Variety of different teaching methods and styles specific to athlete • Have suitable knowledge and experience Decreasing exercise intensity to increase fat utilisation will prolong exercise. Oxygen stops pyruvate turning to lactic acid Uses pyruvate as a fuel • You have enough carbohydrates in your body to run approximately 24 miles • You have enough fats in your body to run approximately 300 miles

5. Oxidative System Image by Bas Van Uyen • Relies on oxygen to breakdown fuels for energy • Produces ATP in mitochondria of cells • Can yield much more energy (ATP) than anaerobic (oxygen independent) systems • Is the primary method of energy production during endurance events

6. Oxidative Production of ATP 1. Glycolysis - cytoplasm Oxygen consumption relates to the O2 that is ‘consumed’ by muscles. O2 is required for the reactions that supply energy for steady rate exercise. 2. Krebs cycle—mitochondria 3. Electron transport chain - mitochondria Image byakunamatata • Teach people new skills, techniques and strategies • Variety of different teaching methods and styles specific to athlete • Have suitable knowledge and experience For example as exercise intensity increases, oxygen uptake increases to the same extent, however, this is only true at low and moderate intensities. For many years, scientists believed that the relationship between oxygen and uptake and exercise intensity was linear up to VO2max. Image by Alan Wong Image by Tinojasontran

7. Glycolysis, Krebs Cycle and Electron Transport Chain Images owned by Human Kinetics

8. Krebs Cycle Images owned by Human Kinetics

9. Oxidation of Carbohydrate 1. Pyruvic acid from glycolysis is converted to acetyl coenzyme A (acetyl CoA). 2. Acetyl CoA enters the Krebs cycle and forms 2 ATP, carbon dioxide, and hydrogen. 3. Hydrogen in the cell combines with two coenzymes (NAD and FAD) that carry it to the electron transport chain. • Teach people new skills, techniques and strategies • Variety of different teaching methods and styles specific to athlete • Have suitable knowledge and experience 3. Hydrogen in the cell combines with two coenzymes (NAD and FAD) that carry it to the electron transport chain. 4. Electron transport chain recombines hydrogen atoms to produce ATP and water. 5. One molecule of glycogen can generate 37 molecules of ATP.

10. Electron Transport Chain Images owned by Human Kinetics

11. Glycolysis Has Two Phases • Anaerobic phase • Glucose/glycogen is broken down to pyruvate in a series of enzymatic reactions • If insufficient O2 is present the pyruvate will receive H+ and become lactic acid • Often dependent upon the rate of energy production (eg. high intensity events result in high lactate concentrations) • Aerobic phase • Complete breakdown of CHO - in the presence of O2 pyruvate will be converted to acetyl Co-A and enter Krebs cycle • broken down further where H+ are donated to co-enzymes and taken to the ETC… energy from electrons are used to resynthesise ATP

12. Total ATP yield from 1 molecule of glucose / glycogen

13. Oxidation of Fat • Lipid breakdown can not produce ATP anaerobically • Acetyl CoA enters the Krebs cycle and the electron transport chain. • Fat oxidation requires more oxygen and generates more energy than carbohydrate oxidation. • During exercise lipid mobilisation is mediated by catecholamine • Lypolysis—breakdown of triglycerides into glycerol and free fatty acids (FFAs) by lipase. • FFA are transported by albumin to the muscles • FFAs travel via blood to muscle fibres and are broken down by enzymes in the mitochondria into acetic acid which is converted to acetyl CoA.

14. Total ATP yield from 1 molecule of fat (palmitic acid)

15. Protein Metabolism  Body uses little protein during rest and exercise (5% to 10%). Images by er1danus • Teach people new skills, techniques and strategies • Variety of different teaching methods and styles specific to athlete • Have suitable knowledge and experience  The nitrogen in amino acids (which cannot be oxidized) makes the energy yield of protein difficult to determine.  Some amino acids that form proteins can be converted into glucose.

16. Interaction of the Energy Systems Images owned by Human Kinetics

17. Factors Affecting Energy Metabolism Images by AS Les Volcans - Niger Exercise intensity determines rate of energy demand and therefore metabolic pathways • Anaerobic vs aerobic • Carbohydrates vs fats • Substrate availability • Metabolic acidosis

18. Factors Affecting Energy Metabolism Image by Reytan Oxidative enzyme activity within the muscle Fibre-type composition and number of mitochondria Endurance training Oxygen availability and uptake in the lungs Cardiac output Your parents

19. Key Points  The ATP-PCr and glycolytic systems produce small amounts of ATP anaerobically and are the major energy contributors in the early minutes of high-intensity exercise.  The oxidative system uses oxygen and produces more energy than the anaerobic systems. • Teach people new skills, techniques and strategies • Variety of different teaching methods and styles specific to athlete • Have suitable knowledge and experience  Carbohydrate oxidation involves glycolysis, the Krebs cycle, and the electron transport chain to produce up to 37 ATP per molecule of glycogen aerobically. 3. Hydrogen in the cell combines with two coenzymes (NAD and FAD) that carry it to the electron transport chain. 5. One molecule of glycogen can generate 37 molecules of ATP.

20. Key Points  Fat oxidation involves -oxidation of free fatty acids, the Krebs cycle, and the electron transport chain to produce more ATP than carbohydrate, but it is O2-limited.  Protein generally contributes little to energy production (less than 5%), and its oxidation is complex because amino acids contain nitrogen, which cannot be oxidized. . • Teach people new skills, techniques and strategies • Variety of different teaching methods and styles specific to athlete • Have suitable knowledge and experience  The oxidative capacity of muscle fibers depends on their oxidative enzyme levels, fiber-type composition, how they have been trained, and oxygen availability. 3. Hydrogen in the cell combines with two coenzymes (NAD and FAD) that carry it to the electron transport chain. 5. One molecule of glycogen can generate 37 molecules of ATP.

21. References McArdle, W, D., Katch, F, I. and Katch, V, L. (2006). Exercise Physiology: Energy, Nutrition and Human Performance.  6th Edition.  USA: Lippincott Williams and Wilkins Powers ,S. and Howley, S, T. (2006). Exercise Physiology: Theory and Application to Fitness and Performance. 6th Edition. New York:  McGraw-Hill Wilmore, J. and Costill, D. (2005). Physiology of Sport and Exercise.  3rd Edition, Illinois: Human Kinetics

22. Energy Systems III Glossary

23. Energy Systems III Quiz