Download Energy Systems for Exercise

April 7, 2006
The Lactic Acid System and
Aerobic Systems for Energy
Production During Exercise
David L. Gee, PhD
www.cwu.edu/~geed
Lactic Acid System
Anaerobic
 Uses
glycolysis
muscle glycogen, blood
glucose, liver glycogen as
substrates (not FAT or PRO)
 High rate of ATP energy production
 Primary fuel in sprint-type activities
(a few seconds - few minutes)
Lactic Acid System
 Important

when:
Activity longer than a few seconds
• creatine-P depleted/limited

Activity too intense for aerobic
metabolism
• oxygen delivery limited
– limited rate of O2 :
• uptake in lung
• transport and delivery to muscle cell
• transport and delivery to mitochondria
Lactic Acid System
Lactic acid is the end product
 Low total energy capacity

• lactic acidosis
• Inhibits glycolytic enzymes

Training effects
• improved aerobic capacity reducing lactate
production
• improved removal of lactate

Ergogenic aids
• bicarbonate loading
Oxygen Energy System
Oxygen Energy Systems
 Aerobic
carbohydrate
metabolism
• glycolysis, Krebs cycle, electron transport
system
lower rate of ATP energy production
 high total energy capacity
 primary source of energy for higher
intensity endurance events (~< 30 min)

09.06 Aerobic Respiration Overview
Slide number: 2
Glucose
Plasma
membrane
Mitochondrion
Cytoplasm
Extracellular fluid
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
09.06 Aerobic Respiration Overview
Slide number: 4
Glucose
Glycolysis
Pyruvate
ATP
NADH
Acetyl-CoA
NADH
Plasma
membrane
Mitochondrion
Cytoplasm
Extracellular fluid
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
09.06 Aerobic Respiration Overview
Slide number: 6
Glucose
Glycolysis
Pyruvate
ATP
NADH
Acetyl-CoA
Krebs
cycle
NADH
H2O
ATP
NADH
Plasma
membrane
Mitochondrion
Cytoplasm
ATP
Extracellular fluid
CO2
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
O2
Oxygen Energy Systems
 Fat
oxidation
• Beta-oxidation, Krebs cycle, Electron
transport system
Lowest rate of ATP-energy production
 Highest total energy capacity
 Primary source of energy during lower
intensity endurance events (~>30 min)

Oxygen Energy Systems
 Protein
oxidation
• Amino acid oxidation, Krebs cycle, Electron
transport system
Low rate of ATP-energy production
 Limited total energy capacity
 significant source of energy during long
endurance events

% Contribution of Aerobic and
Anaerobic Energy Sources