Understanding Exercise Physiology: Energy, Metabolism, and Bioenergetics

2. Exercise Physiology: • physiology: the sum of all biologic processes • what happens to these processes when exercise

3. Metabolism: sum total of all processes occurring in living organisms • catabolism: breakdown • anabolism: build up

4. Energy transductions or conversions are limited by the laws of thermodynamics

5. Energy is transferred or converted • food converted to fat • light and CO2 make sugar

6. Measured in kilocalories • amount of energy necessary to raise the temperature of 1 lit of water one degree Celsius

7. Energy then, is related to the ability to perform work

8. Can measure the capacity for maximal work capacity in man • via exercise physiology

9. 1st law of thermodynamics: • energy is neither created nor destroyed • it is converted or transformed from one form to another

10. Energy can be categorized as • potential energy (amount of energy in canoe on top of falls) • can be light, electric, or bound • kinetic energy (amount of energy in canoe at the bottom of falls) • energy of motion

11. Energy-releasing and Energy-conserving processes • must be coupled • exergonic processes release or “frees” energy • downhill • endergonic processes release of “store” energy • uphill

12. Transfer of potential energy is unidirectional, to kinetic energy, lowering the energy to do work

13. This parallels the second law of thermodynamics: • potential energy gradually decreases, entrophy increases • the reactions in the body move towards spontaneity, disorder, and randomness

14. Energy conversions • photosynthesis • respiration (part of energy converted can be utilized for different work in the human body)

15. Biologic work in humans: Bioenergetics • mechanical (muscle contraction) • chemical (biosynthesis of cellular molecules) • transport (concentrating chemicals in intra and extracellular fluids)

16. Factors affecting the rate of bioenergetics: • enzymes • coenzymes • mass action • temperature

17. Hydrolysis and Condensation • hydrolysis: complex organic molecules are catabolized to simpler forms for assimilation • condensation: molecule of water is formed in this anabolic process

18. Oxidation and Reduction rxns • oxidation: transfer of either oxygen or hydrogen atoms, or electrons • loss of electrons, gain of valence • oxidizing agent is electron acceptor • reduction: gain of either oxygen or hydrogen atoms, or elctrons • gain of electrons, loss of valence • reducing agent is electron donor • together are called redox reaction

19. e.g. • NAD to NADH + H or FAD to FADH2

20. Energy Expenditure Measurements: • Direct • bomb calorimetry • Indirect • closed circuit • open circuit

21. ATP, energy currency of the body • stores small amounts, 85g or 3 oz • intermediate compound • part of energy receiver-energy donor cycle • all energy can be transformed or converted to ATP equivalents • ATP equivalent is the energy differential in the conversion of ATP to ADP, and vice versa

22. Cleaving of ATP • the cleaving of ATP, hydrolysis of ATP can occur in the presence or absence of oxygen is termed nonaerobic