C H A P T E R

1. 5 C H A P T E R Bioenergetics of Exercise and Training

2. Objectives • Discuss the role of ATP • Explain the three energy systems • Discuss training effects on bioenergetics • Recognize substrates • Design programs to stimulate growth

3. Energy • The ability or capacity to perform work • Bioenergetics is the flow of energy in a biological system • Digestion of fats, CHO, protein • Synthesis of fats, glycogen, protein • Release of energy stored in fat, CHO, protein

4. Metabolism • Sum of all anabolic and catabolic processes in the body • Series of enzyme controlled chemical reactions to build up and break down substances in the body • Anabolic- to build up (store energy) • Catabolic- to break down (release energy)

5. Control of Metabolism • Protein based enzymes control the rate of metabolism • Substrate is the substance that an enzyme works on • Enzymes work by a “lockandkey” mechanism • Enzymes are notchanged in the reaction

7. Chemical Structures of ATP, ADP, and AMP with phosphates.

8.  Energy stored in the chemical bonds of adenosine triphosphate (ATP) is used to power muscular activity. The replenishment of ATP in human skeletal muscle is accomplished by three basic energy systems: phosphagen, glycolytic, and oxidative.

9. 1. Phosphagen (Anaerobic) System Occurs in the absence of molecular oxygen Provides ATP for short-term, high-intensity activities Is active in the start of all exercise regardless of intensity

10. Substrate Depletion and Repletion • Substrate- starting materials for bioenergetic reactions • Fatigue • Depletion of phosphagens • Depletion of glycogen • Depletion of fatty acids • Depletion of amino acids • Depletion of lactate

11. Glycogen • Glycogen supply is limited; 300-400 grams in muscle, and 70-100 grams in liver • Both aerobic and anaerobic exercise increase glycogen stores, repletion is related to post-exerciseCHO ingestion • The rate of glycogen depletion is related to the intensity of exercise; high intensity intermittent exercise can cause glycogen depletion

12. Restore CHO Stores

13. 2. Glycolytic System Breaks down carbohydrates to produce ATP that supplements the supply from the phosphagen system for high-intensity muscular activity May go in one of two ways: fast glycolysis or slow glycolysis ~4:1 ATP production difference

14.  • During fast glycolysis, pyruvate is converted to lactic acid, providing ATP at a fast rate. • With slow glycolysis, pyruvate is transported to the mitochondria for use in the oxidative system. • ATP-PC 4 moles ATP/min (capacity 1 mole) • FG-2 moles ATP/min (capacity 1.5 moles) • Aerobic-1 mole ATP/min (capacity 90 moles)

16.  Fast glycolysis has commonly been called anaerobic glycolysis. Slow glycolysis has been called aerobic glycolysis. Also a function of fiber type.

17. Glycolysis

18. Lactate Threshold (LT) and Onset of Blood Lactate Accumulation (OBLA)

19. 3. Oxidative (Aerobic) System Requires molecular oxygen Provides ATP at rest and during low-intensity activities Uses primarily carbohydrates and fats as substrates

20.  The oxidative metabolism of blood glucose and muscle glycogen begins with glycolysis. If oxygen is present in sufficient quantities the end product of glycolysis, pyruvate, is not converted to lactic acid but is transported to the mitochondria, where it is taken up and enters the Krebs Cycle.

21. Krebs Cycle

22.  In general, an inverse relationship exists between the relative rate and total amount of ATP that a given energy system can produce. 1. The phosphagen energy system primarily supplies ATP for high-intensity activities of short duration 2. The glycolytic system for moderate- to high-intensity activities of short to medium duration. 3. The oxidative system for low-intensity activities of long duration.

23. Duration Intensity Primary energyof event of event system(s) 0-6 s Very intense Phosphagen 6-30 s Intense Phosphagen and fast glycolysis 30 s-2 min Heavy Fast glycolysis 2-3 min Moderate Fast glycolysis and oxidative system > 3 min Light Oxidative system Table 5.3 Effect of Event Duration on Primary Energy System Used

24.  The extent to which each of the three energy systems contributes to ATP production depends primarily on the intensity of muscular activity and secondarily on the duration. At no time, during either exercise or rest, does any single energy system provide the complete supply of energy.

25. Energy Systems During Exercise

26. The use of appropriate exercise intensities and rest intervals allows for the “selection” of specific energy systems during training and results in more efficient and productive regimens for specific athletic events with various metabolic demands. 

27. Implications for Training and Conditioning • Nutritional implications • Metabolic specificity • Interval training • Combined training

28. Nutrition • Carbohydrate intake • During activity • Following activity • Maximize glycogen storage

29. Metabolic Specificity • Training must be metabolically specific to an activity to elicit maximal performance enhancement • Metabolic profiling • Recovery is aerobic • High intensity anaerobic activities train aerobic metabolism

30. Interval Training • More work can be performed with less fatigue by exercising at high intensities with intermittent rest • Metabolic profile of interval training similar to performance in a variety of sports • 90-100% ATP-PC 5-10 secs 1:12, 1:20 • 75-90% FG 15-30 secs 1:3, 1:5 • 30-75% FG, Ox 1-3 min 1:3, 1:4 • 20-35% Ox > 3 min 1:1, 1:3

31. Combination Training • Aerobic training may reduce anaerobic performance • Decrease strength • Decrease muscle mass • Resistance training has a generally positive effect on aerobic performance • Extensive aerobic training to enhance recovery from anaerobic exercise is not necessary and may be counterproductive

32. Next Class • Chapter 18 anaerobic part 1