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Exercise Metabolism

Exercise Metabolism. Chapter 4 pp 53-68. 1. Rest-to-Exercise: Anaerobic. “anaerobic”. 2. Rest-to-Exercise: Aerobic. Example.... Assume standing requires 15 ATP and 0.4 liters/min of oxygen Assume running at 6 mph requires 100 ATP and 1.5 liter/min of oxygen

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Exercise Metabolism

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  1. Exercise Metabolism Chapter 4 pp 53-68

  2. 1. Rest-to-Exercise: Anaerobic “anaerobic”

  3. 2. Rest-to-Exercise: Aerobic • Example.... • Assume standing requires 15 ATP and 0.4 liters/min of oxygen • Assume running at 6 mph requires 100 ATP and 1.5 liter/min of oxygen • A person can go from standing to running 6 mph in a mater of seconds. • But, it takes 2-3 minutes for the oxygen requirement to go from 0.4 to 1.5 liters/min • Where does the ATP needed to run 6 m.p.h come from until adequate oxygen can be supplied?

  4. (anaerobic) (aerobic) Rest-to-Exercise: The Oxygen Deficit

  5. 3. Recovery • What needs to happen in recovery? • ATP-PCr system • P + Cr + energy ➡ PCr • Glycolysis? • Lactic acid removal from muscle fiber Where does the energy comes from?

  6. Lactic Acid Removal • Where? • Heart and Type I Muscle Fibers • How? • Lactic acid ➞ Pyruvic Acid • Pyruvic Acid ➞ Acetyl Co-A • Acetyl Co-A ➞ Krebs Cycle (aerobic system)

  7. Lactate as a Fuel During Exercise • Slow twitch muscle fibers • Heart muscle • Liver via the Cori cycle

  8. EPOC EPOC E.P.O.C • What does E.P.O.C. stand for note: oxygen consumption = energy • What contributes to the excess oxygen consumption?

  9. E.P.O.C. (Used as a fuel)

  10. 4. Prolonged Aerobic Exercise • Aerobic energy requires O2 • oxygen demand • O2 transported via cardioplumonary system • oxygen supply

  11. Prolonged Aerobic Exercise • Deficit: O2 supply < O2 demand • Steady State Exercise • O2 supply = O2 demand • Heart rate? Breathing rate?

  12. 5. Measurement of Aerobic Energy/Performance • Maximal oxygen uptake • Lactate threshold

  13. Oxygen Uptake 79% N 20.97% O2 0.03% CO2 Ventilation (Liters of air per minute) 79% N ~17% O2 ~4% CO2 13

  14. Oxygen Uptake (VO2) 79% N 20.97% O2 0.03% CO2 VO2 79% N ~17% O2 ~4% CO2 14

  15. Oxygen Uptake (VO2) • What does it measure? • How is it expressed? • VO2 ml/kg/min • VO2 liters/min

  16. VO2max Maximum Oxygen Uptake (VO2max) What is VO2max? What does it represent?

  17. VO2max Values Source: ACSM

  18. * General Population, Female, Aged 20-29: 35-43 ml/kg/min * General Population, Male, Aged 20-29: 44-51 * US College Track, Male: 57.4 * College Students, Male: 44.6 * Highest Recorded Female (Cross-Country Skier): 74 * Highest Recorded Male (Cross-Country Skier): 94

  19. VO2max FYI

  20. Bjørn Dæhlie 96 ml/kg/min FYI Steve Prefontaine 84 ml/kg/min

  21. Lactic Acid Production • What happens to pyruvate? • If adequate oxygen… • pyruvate to acetyl CoA • hydrogen to H2O • If inadequate oxygen… • pyruvate and hydrogen to lactic acid • What happens to lactic acid levels as the exercise intensity increases? 1. 2. 2. 1. Acetyl-CoA Hydrogen Mitochondria (Krebs cycle & Electron Transport Chain) Oxygen

  22. Lactate Threshold Lactate (mmols) Light to Moderate Exercise. LA removed Heavy Exercise. LA accumulates 3 4 5 6 7 8 9 10 Speed (mph)

  23. Lactate Threshold VO2max • The Lactate Threshold typically occurs between 50-85% of Vo2max • What is significant about the intensity level at the lactate threshold? 3 4 5 6 7 8 9 10 Running Speed 3 4 5 6 7 8 9 10 Running Speed

  24. 7. Fuel Utilization During Exercise

  25. Measuring Fuel Utilization During Exercise • Respiratory exchange ratio (RER or R) • R = VCO2 / VO2 • Fat (palmitic acid) = C16H32O2 • C16H32O2 + 23O2 ↔ 16CO2+ 16H2O + ATP • R = VCO2/VO2 = 16 CO2/23O2 = 0.70 • Glucose = C6H12O6 • C6H12O6 + 6O2 ↔ 6CO2+ 6H2O + ATP • R = VCO2/VO2 = 6 CO2/6O2= 1.00 It takes more O2 to burn fats so the R value for fats will be lower.

  26. Fuel Utilization During Exercise • Carbohydrates and Fats (very little Protein) Resting Low Intensity High Intensity Max. Intensity High Intensity

  27. Fuel Utilization During Exercise Which fuel is used more as the exercise INTENSITY increases? Why the shift towards carbohydrates?

  28. Fuel Utilization During Exercise What fuel is used more as the exercise DURATION increases? Why the shift towards fats?

  29. 8. Fuels for Exercise

  30. Sources of Carbohydrate During Exercise • Muscle glycogen • Liver glycogen • Total of about 2,000 kcals (1.5-2 hrs) • Systems • Glycolysis • Lactic acid • Aerobic

  31. Sources of Fat During Exercise • Adipose tissue • Triglycerides to fatty acids • Muscle cells • Total of 50,000-100,000 kcals • System: aerobic

  32. Protein for Energy During Exercise • Skeletal muscle • Amino acids and the Cori cycle • Why is protein not an optimal fuel source?

  33. The Glucose-Alanine Cycle

  34. Gluconeogensis • The Cori cycle and the Glucose-Alanine cycle • What do they have in common? • Gluconeogensis

  35. Energy Related Fatigue • Glycogen depletion • Hypoglycemia

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