Bioenergetics Slides: ATP, Energy Systems & Metabolism - PDF

Bioenergetics Introduction  ATP Usage During Exercise 2  Assuming 1 ATP molecule is broken down for each actin-myosin powerstroke, then:  There are 300 myosin heads per sarcomere  100,000 sarcomeres per fiber...

Bioenergetics Introduction  ATP Usage During Exercise 2  Assuming 1 ATP molecule is broken down for each actin-myosin powerstroke, then:  There are 300 myosin heads per sarcomere  100,000 sarcomeres per fiber  250,000 fibers in the biceps brachii  A single muscle twitch requires about 7.5 billion ATP molecules! Fig. 18.13. McArdle et al. 2015. Exercise Physiology… LWW Adenosine Triphosphate (ATP) 3  The potential energy within the ATP molecules powers ALL of the cells’ energy-requiring processes  All other energy stores are used to replenish ATP by phosphorylation of ADP Fig. 2.4. Kenney et al. 2012. Physiology of Sport… Hum.Kin. Adenosine Triphosphate (ATP) 4  Cells’ two major energy-transforming activities: 1) Extract potential energy from food and conserve it within the bonds of ATP 2) Extract and transfer the chemical energy in ATP to power biologic work Fig. 2.4. Kenney et al. 2012. Physiology of Sport… Hum.Kin. Bioenergetics Overview 5 Fig. 2.10. Kenney et al. 2020. Physiology of Sport… Hum.Kin. 5  Bioenergetics Key Terms 6  Glycolysis: catabolism of a glucose molecule  Gluconeogenesis: building of a glucose molecule from amino acids or lactate  Glycogenolysis: catabolism of glycogen into glucose molecules  Glycogenesis: combining glucose molecules to store as glycogen Where (in the cell) do these processes take place? Fig. 2.1. Kenney et al. 2015. Physiology of 6 Sport… Hum.Kin.  Bioenergetics Key Terms 7  Lipogenesis: combining 3 fatty acids with a glycerol molecule to form a triglyceride  Lipolysis: breaking a triglyceride into 1 glycerol and 3 fatty acids  Beta oxidation: catabolizing fatty acids into acetyl-CoA molecules  Proteolysis: catabolizing protein to amino acids Where (in the cell) do these processes take place? Fig. 2.1. Kenney et al. 2015. Physiology of 7 Sport… Hum.Kin.  Energy Expenditure 8  4x increase in EE when going from sitting to walking  120x increase in EE when going from walking to sprinting  Average person resynthesizes 75% of their body mass in ATP each day  A person running a 2.5 hour marathon can generate 80 kg (176 lb) of ATP during the run alone! Fig. 6.10. McArdle et al. 2010. Exercise Physiology… LWW  Biological Energy Systems 9 Three basic energy systems exist in muscle cells to replenish ATP: Phosphagen (sarcoplasm) Glycolytic (sarcoplasm) Oxidative (mitochondria)  Fuel Substrates Rate vs. Capacity 10 Characteristics of the Various Energy Supply Systems Energy Oxygen Relative rate of ATP ATP per molecule Available Location System necessary? per second of substrate Capacity Phosphagen Sarcoplasm NO 10 1 100 days * Gross production of 36-39 ATP per molecule of carbohydrate (excludes energy cost of transport through membranes). The net production is slightly lower (net = 32 ATP per glucose). Tab. 2.3; Fig. 2.13. Kenney et al. 2015. Physiology of Sport… Hum. Kin.  Biological Energy Systems 11  Exercise intensity determines the primary energy system utilized  Higher intensity – demands faster production of ATP  Lower intensity – can use slower, more efficient means of ATP production  At no time, during either exercise or rest, does any single energy system provide the complete supply of energy. Tab. 2.3. Baechle et al. 2008. Essentials of Strength… Human Kinetics  Biological Energy Systems 12  This table assumes that you are maintaining that intensity and pacing yourself for the best possible time for a given event.  For example, you shouldn’t sprint the first lap of a mile and then walk the next 3 laps. This table assumes you are maintaining the same intensity.  Also note that the phosphagen system can last up to 15 seconds and does NOT run out after 6 sec Tab. 2.3. Baechle et al. 2008. Essentials of Strength… Human Kinetics Bioenergetics Overview 13 Fig. 2.10. Kenney et al. 2020. Physiology of Sport… Hum.Kin. 13 Review Questions 14  Know the terms from the catabolic and anabolic processes involved in bioenergetics and be able to identify where they take place (cell type and location in the cell)  Ex. Glycolysis takes place in the sarcoplasm of myocytes  Be able to identify ATP’s chemical structure and distinguish it from ADP and AMP.  Know the ATPase reaction  Know how the different energy systems rank in regards to speed of ATP production and efficiency of ATP production.  Efficiency refers to the # of ATP produced per substrate used.  APPLY the bioenergetics information to different exercises and sporting events of varying intensities.  Ex. Which is the predominant energy system(s) for a 40 yd dash?  Ex. Which is the predominant energy system(s) for a 400m race? Figure & Notes References 15  Kenney, Wilmore, & Costill. Physiology of Sport & Exercise, 5th Edition. Human Kinetics, 2015.  McCardle, Katch, Katch. Exercise Physiology: Nutrition, Energy, and Human Performance, 8th Edition. Wolters Kluwer Health, 2015.  Baechle & Earle. Essentials of Strength & Conditioning, 3rd Edition. Human Kinetics, 2009.