Energy Systems and
Muscle Fibre Types

In groups of 2 answer the following…
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Why do we eat?
Answer- Nutrients and Energy needed for daily activities/bodily functions

Cont…
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What Foods provide us with Energy?
Answer – The foods that yield Energy are known as Energy Yielding foods and can be classified as Carbohydrates
(CHO’s), Fats, and proteins

Cont…
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How does the body convert these foods into
Energy?
Answer- Bioenergetic Conversion, Foods are broken down into their smallest units
( glucose , fatty acids, and amino acids).
These Units are then eventually converted into a high energy storing molecule called
ATP, which in turn can be broken down by the body’s cells releasing energy!

Exercise Metabolism
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ATP --- ADP + Pi + Energy

Energy Systems
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The body produces Energy aerobically or
Anaerobically through one of it’s three metabolic pathways.
The body prefers to satisfy it’s energy
(work) requirements through aerobic methods (with oxygen)…..eg walking
However, as the intensity of work/activity increases the body will recruit other pathways to help produce the needed
Energy.

ATP
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Adenosine Triphosphate
Captures the chemical energy resulting from the breakdown of food and stores it in the high energy phosphate bonds.
See O.H. (ATP)

Anaerobic Energy
Systems

Aerobic Energy System

Spinning Lab Activity
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See H.O.

Three Energy Pathways
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Anaerobic Alactic (ATP-PC)
Anaerobic Lactic (anerobic glycolysis,
(incomplete))
Aerobic Respiration (aerobic/complete glycolysis)

Anaerobic Alactic (ATP –
CP) System
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Simplest of the energy systems.
Creatine Kinase (enzyme) helps break up
Creatine Phosphate in the muscle into Cr +
Pi + Energy (this energy will be used to bind
Pi + ADP, can not be used for cellular work)
CP is in limited supply within the muscle, thus this system supplies a large amount of energy but CP levels decline rapidly as it is used up as the system replenishes ATP stores.
ATP-CP system only lasts 3-10sec during an all out sprint.

Anaerobic Lactic System
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Production of ATP through the breakdown (Lysis) of glucose via special glycolytic enzymes called glycolysis.
Before either glucose or glycogen can be used to generate energy, they must be converted to G-6-P (glucose 6 phosphate).
This process requires 1 molecule of
ATP for glucose, but not for glycogen.

Anaerobic Lactic System
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Glycolysis begins once G-6-P is formed and ultimately produces pyruvic acid.
This process does not require oxygen but oxygen determines the fate of pyruvic acid
(discuss later)
When oxygen is not present pyruvic acid becomes lactic acid.
This system is much more complex than the
ATP-CP system, but can provided energy for up to 2-3 minutes during intense activity.

Anaerobic Lactic System
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The limitation of this system is the build up of lactic acid, which inhibits further glycogen breakdown, because it impairs glycolytic enzyme function.

Anaerobic Lactic System
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THE CORI CYCLE:
- Process by which lactic acid is transported to the liver and converted back to pyruvate and eventually back to glycogen.
- The cori cycle takes place between skeletal muscle and the liver.

Aerobic Alactic System
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This oxidative production of ATP occurs within the mitochondria.
Unlike anaerobic ATP production the oxidative system has a tremendous energy yield.
Yields about 36 ATP per molecule of glucose.
Oxidative process involves 3 stages:
- Glycolysis,
- Krebs Cycle,
- Electron Transport Chain

Aerobic Alactic System
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GLYCOLYSIS:
- Breakdown glucose or glycogen into pyruvic acid.
- In the presence of oxygen, pyruvic acid is converted into a compound called acetyl CoA, which enters the
Krebs Cycle.
- 2 ATP produced

Aerobic Alactic System
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THE KREBS CYCLE (Citric Acid Cycle):
- Is complex series of chemical reactions that produces CO2, ATP, and hydrogen ions.
- 2 ATP are produced per glucose molecule.

Aerobic Alactic System
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ELECTRON TRANSPORT CHAIN:
- Large amounts of ATP are produced with CO2 and water as the by-products.
- Total of 32 ATP are produced.

Aerobic System Cont…
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What are the limitations of the aerobic system?
Fuel source ( CHO , Fat, Protein) and
Oxygen must be available!
The rate of ATP utilization must be slow enough to allow aerobic system to keep pace otherwize body will turn to other systems to generate ATP

Healthy Heart and Lungs!
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How might a healthy circulatory system benefit you during a sporting event?
OR
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How might an unhealthy circulatory system hinder someone during activity?

Healthy Heart and Lungs!
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If the heart and lungs can not effectively pump enough oxygen to the tissues, then the system will shift to anaerobic pathways!
Training effect!...ability to do more work
(i.e. use ATP with the same effort)
Individuals with healthy hearts and lungs can deliver more oxygen to their tissues and remain aerobic longer or at higher intensities!