1. Fueling physical activity and fatigue
Module 3- Metabolism and Nutrition

3. Energy Production and Capacity
All energy systems are contributing at all times
In general, there is an inverse relationship between a given energy system’s maximum rate of ATP production (i.e., ATP produced per unit of time) and the total amount of ATP it is capable of producing over a long period
As a result, the phosphagen energy system primarily supplies ATP for high-intensity activities of short duration, the glycolytic system for moderate- to high- intensity activities of short to medium duration, and the oxidative system for low-intensity activities of long duration

5. Rate the oxidation of fats and proteins, phosphagen system, aerobic glycolysis, oxidation of carbodydrate and anaerobic glycolysis is terms of rate and capacity of ATP production
ATP Production Rate
Phosphagen
Anaerobic Glycolysis
Aerobic Glycolysis
Oxidation of Carbohydrates
Oxidation of Fats and Proteins
ATP Production Capacity
Oxidation of Fats and Proteins
Oxidation of Carbodydrates
Aerobic Glycolysis
Anaerobic Glycolysis
Phosphagen

6. Key Point
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

7. Lactate Threshold and Onset of Blood Lactate Accumulation
Lactate Threshold (LT)
Represents an increasing reliance on anaerobic mechanisms
LT is often used as a marker of the anaerobic threshold
Occurs because of increased rate of glycolysis, decreased lactate removal rate and insufficient oxygen
Occurs at 50-60% of VO2 max for untrained individuals and 70-80% for trained individuals
Onset of Blood Lactate Accumulation (OBLA)
Occurs when the concentration of blood lactate reaches 4 mmol/L (rest less than 1 mmol/L)

9. Lactate Threshold and Onset of Blood Lactate Accumulation
These two breaks are thought to represent the points at which intermediate and large motor units are recruited
Training at intensities near or above the LT or OBLA pushes these points “to the right”
This shift probably occurs as a result of changes in hormone release and increased mitochondrial content
This shift allows athletes to perform more work before fatigue sets in

10. Oxygen Uptake and the Aerobic and Anaerobic Contributions to Exercise
Oxygen uptake (consumption) is a measure of a person’s ability to take in and use oxygen
Then what is VO2 Max
A person’s maximum ability to take in and use oxygen
Oxygen deficit is the anaerobic contribution to the total energy cost of exercise
This occurs because of the time it takes for the aerobic energy systems to “kick in” (Remember to relative rates of ATP production)
Oxygen debt (excess postexercise oxygen consumption [EPOC]) occurs when the oxygen uptake value is still elevated post-exercise in order to restore the body to return to its pre-exercise state

11. 75% of V02 Max

12. 80% of Maximum Power Output (Anaerobic Exercise)

14. Oxygen Deficit
Due to lack of oxygen early in exercise, anaerobic pathways are needed to produce ATP
Pyruvate and hydrogen from NADH converted to lactate and hydrogen because there was not enough oxygen in the mitochondria
These hydrogen ions
Interfere with calcium binding to troponin
Reduce calcium release from sarcoplasmic reticulum
Decrease the ph, causing phosphofructokinase to slow down glycolysis
Chemical receptors in the cell detect hydrogen (burning sensation), affects the CNS and can eventually cause inhibition of motor unit recruitment by the motor cortex

15. EPOC
Possible factors increasing excess post-exercise oxygen consumption:
Resynthesis of ATP and creatine phosphate stores
Resynthesis of glycogen from lactate
Oxygen resaturation of tissue water, venous blood, skeletal muscle blood and myoglobin
Redistribution of ions within various body compartments
Repair of damaged tissue
Additional cardiorespiratory work
Residual effects of hormone release and hormone accumulation
Increased body temperature

16. Substrate Depletion and Repletion
Phosphagens
Creatine phosphate can decrease markedly (50-70%) during the first stage (5-30 seconds) of high- intensity exercise and can be almost eliminated as a result of very intense exercise to exhaustion.
Postexercise phosphagen repletion can occur in a relatively short period; complete resynthesis of ATP appears to occur within 3 to 5 minutes, and complete creatine phosphate resynthesis can occur within 8 minutes
Half life of creatine phosphate replenshment is 30 seconds
50% recovered in 30 seconds, 75% in 60 seconds, 87.5% in 90 seconds, etc.

17. Substrate Depletion and Repletion
Glycogen
The rate of glycogen depletion is related to exercise intensity.
At relative intensities of exercise above 60% of maximal oxygen uptake, muscle glycogen becomes an increasingly important energy substrate; the entire glycogen content of some muscle cells can become depleted during exercise
Repletion of muscle glycogen during recovery is related to postexercise carbohydrate ingestion.
Repletion appears to be optimal if 0.7 to 3.0 g of carbohydrate per kg of body weight is ingested every 2 hours following exercise