1. Basic Energy Systems (Bioenergetics) The systems used to degrade fuels to provide the energy to form ATP are: l The Oxidative system l The Glycolytic system l The ATP-PCr system Muscle cells can produce ATP using any one or a combination (IN MOST CASES) of the three systems Anaerobic

2. The Energy Continuum Copyright © Pearson Education, Inc. publishing as Benjamin Cummings Figure 4.1

3. ATP-PCr System l Relies on stored phosphagens as fuel - namely phosphocreatine (PCr) - also called creatine phosphate (CP) l PCr + ADP ATP + Cr creatine kinase

4. Characteristics of ATP-PCr l Anaerobic – occurs whether or not oxygen is present l Creates immediate ATP (high rate ATP production) –One enzyme reaction

5. Characteristics of ATP-PCr l Limited in ATP production capabilities –Can provide ATP for only 3 to 15 seconds of high intensity exercise because stores of PCr are limited

6. ATP AND PCr DURING SPRINTING

7. ATP-PCr System l Dominates ATP production: –During short-term, very high-intensity or all-out exercise (< 15 secs.) l Tennis serve, high jump, power lifts, etc.

8. Glycolytic System Glycolysis (lactic anaerobic) l Glycolysis is an anaerobic pathway that uses energy transferred from glucose to rejoin P i to ADP to form ATP

9. Glycolytic System Glucose 10 steps 10 steps Pyruvic Acid (aerobic conditions) Lactic Acid (anaerobic conditions) ATP

10. Glycolytic System l Dominates ATP production from 15 seconds to 2 minutes of high-intensity exercise

11. Glycolytic System Characteristics l Anaerobic l Less immediate than ATP-PCr, but can provide ATP for longer (up to 2-3 minutes of high intensity exercise) –Further contraction limited by lactic acid accumulation

12. Illinois State University Lactic Acid l Lactic acid levels in blood are a balance between production and clearance l At low intensities, clearance = production, and levels remain at or near resting (1-2 mmol/L) l At high intensities, the shuttle molecules cannot clear all the lactate produced, and accumulation occurs l Maximal value = ~ 8 mmol/L, but values as high as 32 mmol/L have been reported

13. Anaerobic ATP Production l ATP-PCr and Glycolysis, collectively called the ANAEROBIC energy systems, work together to provide ATP during exercise that is too intense for all the needed ATP to be made aerobically (supramaximal exercise) –Aerobic systems also begin to contribute (minorly) within the first 10 seconds of exercise

14. Oxidative System l Aerobic breakdown of food fuels (CHO, FATS, some PRO) Aerobic Glycolysis or Beta Oxidation Krebs Cycle Electron Transport Chain

15. AEROBIC GLYCOLYSIS AND THE ELECTRON TRANSPORT CHAIN

16. Oxidative System Characteristics l Has a much higher ATP yield than either anaerobic system –Can produce ATP almost indefinitely provided adequate fuel and oxygen are available l Responds more slowly than either anaerobic system (low rate of ATP production, but high capacity) –Can’t produce enough ATP quickly enough to support high-intensity exercise

17. Major Differences between Energy Systems l Fuel(s) used l Oxygen requirement l Rate of ATP production –High (ATP-PCr) –Moderate (glycolytic) –Low (oxidative) l Amount of ATP produced (and therefore the length of time each can fuel activity)

18. Copyright © Pearson Education, Inc. publishing as Benjamin Cummings Figure 4.2

19. Key Point to Remember l When discussing energy systems, it is important to remember that the time ranges on the continuum for each energy system are based upon maximal or all-out efforts at optimal paces l Longest distance in a given time period

20. Example l The ATP-PCr system will dominate ATP production for the first 15 seconds of an activity that can only be performed for 15-30 seconds because it is such a high intensity activity that it cannot be performed for a longer time period l Walking for 15-30 seconds does not require a maximal effort and so is NOT predominately fueled by the ATP-PCr system even though it only lasts for only 15 seconds.

21. Example l Maximal effort and optimal paces will differ between a sprint and a marathon, because the time frame differs (30 seconds vs. 3 hours). One must judge the optimal pace that will elicit the best performance. A sprinter should not jog the first few seconds; nor should a marathon runner sprint the first few seconds. That would not be maximal effort or optimal pacing, and therefore the energy system being used could not be precisely assessed.

22. Illinois State University 1. Laboratory procedures – BIOPSY or blood draws for lactate analysis 2. Tests of anaerobic power and capacity a.Wingate Anaerobic Test (WAT) b.Mararia-Kalamen Stair Climb c.Field tests Measurement of Anaerobic Metabolism Copyright © Pearson Education, Inc. publishing as Benjamin Cummings