Post on 03-Jan-2016
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Introduction to Nutrition for Exercise and Health
Physiology of Aerobic & Anaerobic Exercise
Prof Jennifer Broxterman, RD, MScFN3373: Nutrition for Physical ActivityLecture 2
What Fuels Physical Activity?
ATP
Hydrolysis of ATP
ATP & Energy Use by Exercising Muscles
Rephosphorylation of ADP to Form ATP
Energy Systems that Replenish ATP
Creatine Phosphate
Anaerobic Glycolysis
Oxidative Phosphorylation
ATP
Characteristics of the 3 Energy Systems
Speed of Action
Amount of ATP
Replenished
Duration of Action
Creatine Phosphate
Very Fast Very Small Very Short
Anaerobic Glycolysis
Fast Small Short
Oxidative Phosphorylation
Very Slow Large Very Long
Energy System 1
Creatine Phosphate
Creatine Phosphate Energy System
The CrP Energy System Rephosphorylates ADP to ATP Rapidly
• Anaerobic reaction• If [ATP] in a muscle ↓ there is an accompanying
↑ in ADP in the cell – ↑ in the activity of CK, allowing the reaction to
proceed faster
• CrP is stored in very small amounts• At very high-intensity exercise it takes ~ 5-10
seconds for CrP in the muscle to be depleted and fatigue to set in
Characteristics of the CrP Energy System
• One chemical step• Catalyzed by creatine kinase (CK)• Very fast reaction• One ATP per CrP molecule• 5-10 second duration• Anaerobic• Fatigue associated with CrP depletion• Predominant energy system in very high-
intensity exercises (power events)
Creatine Phosphate & ADP Rephosphorylation
The Creatine Shuttle
Energy System 2
Anaerobic Glycolysis
Glucose
GLYCOLYSIS
2 Pyruvic Acid molecules
If Oxygen is AbsentIf Oxygen is Present
Anaerobic Metabolism
Aerobic Metabolism
Lactic AcidCO2 + H2O
2 ATP
36-38 ATP
The Anaerobic Glycolysis Energy System
Anaerobic Glycolysis
Cori Cycle
Energy System 3
Oxidative Phosphorylation
Glucose
GLYCOLYSIS
2 Pyruvic Acid molecules
If Oxygen is AbsentIf Oxygen is Present
Anaerobic Metabolism
Aerobic Metabolism
Lactic AcidCO2 + H2O
2 ATP
36-38 ATP
Cellular Respiration Overview
C6H12O6 + 6O2 6CO2 + 6H2O + Energy
(glucose) (heat and ATP)
• The energy in one molecule of glucose yields 36 ATP
• Aerobic respiration involves a series of 3 reactions:– Glycolysis– Krebs Cycle– Electron Transport Chain
Glycolysis
Oxidative Phosphorylation Energy System
Glycolysis, Krebs Cycle, Electron Transport Chain of Oxidative Phosphorylation
Macronutrients as Fuel Sources during Exercise
Beta Oxidation
Respiratory Exchange Ratio
Respiratory Exchange Ratio
Respiratory Exchange Ratio
RER Chart