1. Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Chapter 7 Energy Transfer in Exercise

2. Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Immediate Energy The ATP-PCr system –Provides ATP for short-term high-intensity movements –Is rapidly depleted

3. Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Nuclear Magnetic Resonance Spectroscopy Nuclear magnetic resonance (NMR) –Study exercise muscle metabolism –Is noninvasive –Measurements are taken at regular intervals –Determines concentrations of bioactive compounds Pi ATP PCr

4. Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Short-Term Energy The lactic acid system Glycolysis resulting in lactate formation Lactate accumulation –Blood lactate threshold Lactate production exceeds clearance Average for untrained = ~ 55% max aerobic capacity Training increases lactate threshold.

5. Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

6. Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Lactate-Producing Capacity Increases with anaerobic training –Improved motivation –Increased intramuscular glycogen stores Allows for increased glycolysis –Increased glycolytic enzymes Training increases ~ 20%

7. Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Oxygen Consumption during Exercise Oxygen consumption –Pulmonary oxygen uptake –Oxygen is measured at lung, not tissues. –Steady state When oxygen demand is met by oxygen delivery Blood lactate doesn’t accumulate. Exercise may continue at this rate until limitations other than oxygen alter performance.

8. Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Oxygen Deficit As exercise begins –Oxygen demand increases immediately. –Oxygen consumption lags behind. Oxygen deficit –Quantitative expression of difference between oxygen consumed and the amount that would have been consumed had steady state been reached right from the start

9. Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

10. Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Oxygen Deficit Trained individuals –Reach steady state more rapidly –Have a smaller oxygen deficit More rapid increase in cardiac output Larger percentage of blood directed to active muscle Training-induced cellular adaptations

11. Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Maximal Oxygen Consumption Oxygen consumption plateaus with increase in intensity O 2max Maximal oxygen uptake Maximal aerobic power Aerobic capacity Provides a quantitative measure of capacity for aerobic ATP resynthesis

12. Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

13. Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Muscle Fiber Types Fast- and slow-twitch muscle fibers –Slow-twitch = type I Highest aerobic capacity Lowest glycolytic capabilities –Fast-twitch = type II Type IIa –Medium glycolytic and aerobic capabilities Type IIb –Highest glycolytic capacity –Lowest aerobic capacity

14. Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Energy Spectrum of Exercise Each energy system’s relative contribution to maximal exercise duration –ATP-PCr and lactic acid systems Half the energy for intense exercise for 2 minutes –Aerobic energy transfer Intense exercise for 5 – 10 minutes –Aerobic energy Long-duration exercise Energy allocations progress on a continuum.

15. Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Oxygen Consumption during Recovery Metabolic dynamics of recovery oxygen consumption –Traditional concepts Alactacid oxygen debt Lactacid oxygen debt Experiments suggest that most lactate oxidizes for energy, leading to contemporary concepts.

16. Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Contemporary Concepts Excess postexercise oxygen consumption (EPOC) may be accounted for by –Anaerobic metabolism in previous exercise –Adjustments that exert metabolic influence Respiratory Circulatory Hormonal Ionic Thermal

17. Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Implications of EPOC Optimal recovery depends upon type of exercise. –Steady-rate exercise Passive recovery –Non-steady-rate exercise Active recovery –Working ~ 30 to 45% if cycling –Working ~ 55 to 60% if running

18. Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

19. Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Intermittent Exercise Interval training –Preestablished work & rest intervals –Manipulating the intervals allows for maximal overload of specific energy systems. –Blood lactate levels remain low.