EXERCISE AND NUTRITIONAL SCIENCES 632

1. EXERCISE AND NUTRITIONAL SCIENCES 632 PHYSIOLOGICAL CHEMISTRY OF EXERCISE Michael J. Buono, Ph.D. Fred W. Kolkhorst, Ph.D. San Diego State University http://www-rohan.sdsu.edu/~ens632/

2. BIOENERGETICS-how thebody acquires, converts, stores, and utilizes energy First Law of Thermodynamics (conservation of energy) energy cannot be created or destroyed, only converted from one form (chemical, thermal, mechanical, light, etc) to another; thus, the total energy in the universe remains constant. (examples: photosynthesis = light to chemical, exercise = chemical to mechanical) Second Law of Thermodynamics whenever energy is exchanged between forms the exchange is imperfect and some energy is lost as heat (randomness increases) (humans are 25% efficient, 75% heat). Specific heat of the human body is .83 kcal/kg/oC, thus a 60 kg person needs to retain 50 kcal of heat (.83 x 60) to increase the core body temperature 1 oC. Thus, running a mile (100 kcal) theoretically should increase the core body temperature 2 oC if no heat was lost.

3. Exercise Photosynthesis Internal combustion engine Space heater

4. BIOENERGETICS (cont.) • Exergonic Rx • a reaction that gives up (releases) energy (burning of a tree, hydrolysis of ATP, oxidation of carbohydrate, etc.) • Endergonic Rx • a reaction that absorbs (takes in) energy (growth of a tree, resynthesis of ATP, formation of carbohydrate via photosynthesis)

5. Coupled Reactions in Animals • Exergonic Rx  ATP  Endergonic Rx Oxidation of food  ATP  Muscular contraction, ion gradients (CHO, Fat)

6. ATP (adenosine triphosphate) • ATP need in rapidly contracting skeletal muscle is over 100x greater than ATP need at rest. • ATP is needed for: • 1.) myosin ATPase (50%) • 2.) sarcoplasmic reticulum Ca++ ATPase (SERCA) (40%) • 3.) Na+ /K+ ATPase (10%)

7. Sodium-Potassium ATPase Humans have ECF [ Na+] of 140 mM and ICF [Na+] of 10 mM Humans have ECF [ K+] of 4 mM and ICF [K+] of 150 mM

10. Excitation-Contraction Coupling Ca++ cycling

11. Dihydropyridine (DHP) receptor Ryanodine receptor

12. Sarcoplasmic Reticulum ATPase (SERCA)

13. Cross-bridge cycle - Myosin ATPase

14. ATP Structure Electrostatic repulsion ~ = phospho-anhydride bond

15. ATP (cont.) ATP + H20 ADP + Pi + H+ + free energy Free Energy (-G) of ATP = -7.3 kcal/mole exergonic reaction: thus (–) in value (products have less free energy than reactants) kcal = energy needed to raise 1L of water 1 C mole = atomic wt. of substance in grams (6.02 x 1023 molecules)

16. Free energy(-G) of various biological compounds

17. G and ATP

18. Early Studies on ATP • Fletcher (1920s)  believed lactic acid caused muscular contraction • Embden (1920s)  rapid freezing of isolated muscle showed contraction without HLA formation • Cain (1940s)  poisoned CPK with DNFB and showed ATP decreased with each contraction thus showing that hydrolysis of ATP provided the energy needed for muscular contraction.

19. Substrate Level Phosphorylation • PC + ADP + H + ATP + Cr CPK (-7.3 kcal/mole)  G (-10.1 kcal/mole)  G

20. ATP Use During Exercise

21. CP and ATP Use During Exercise Myokinase reaction 2 ADP ATP + AMP

22. Changes in ATP,ADP and AMP

23. Amount of ATP needed to run a Marathon