Energy Systems

Lesson 5.1

Where do we get Energy for our working muscles?

The Three Energy NutrientsThe Three Energy Nutrients

Carbohydrates

Proteins

Fats©

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Carbohydrates

• Carbohydrates are broken down into glucose and stored into the muscle as glycogen.

• Most easily broken down into this state which is why they are the first thing our body uses as a form of energy.

Proteins

• Proteins are broken down into amino acids.

• Proteins are used for energy when the body is in starvation mode.

Fats

• Fats are broken down in to fatty acids and a glycerol.

• Fats are the LAST energy source which is used.

How does our body use what we eat?

How does our body use what we eat?

• ATP = Adenosine TRI Phosphate– 3 phosphates are present

Adenosine Triphosphate (ATP)Adenosine Triphosphate (ATP)

Adenosine triphosphate (ATP) ATP is a usable form of energy

for the body. Made in the mitochondrion Resynthesized in two ways

Aerobically Anaerobically

ATP ADP + Pi + ENERGY

• ATP is the molecule that gives every cell in our body energy to function.

• All things in our body require energy in order to be able to function properly.– Food metabolism– Heart beat– Muscles contract

• When you need energy it is on.

• When you don’t need energy it is being stored and not used.

2 ways to re-synthesize ATP

Aerobic System

Two Energy SystemsTwo Energy Systems

Aerobic SystemIn the presence of oxygen (O2)

All of its metabolic activity will involve O2

Occurs in the mitochondriaLeads to the complete breakdown of glucose

• With the presence of oxygen you are able to perform an activity over a long period of time with a balanced intensity.

• What is an example of “aerobic activity”– Requires oxygen

• How does your body react?– Heart rate increases– Breathing increases

Aerobic System

• Any activity longer than 90s• Mitochondria of cells

•C6H12O6 + 6O2 +36ADP +36Pi --> 6CO2 + 36ATP 6H2O + E

ETC – the finer detailsETC – the finer details• When oxygen is reduced, it also bonds with 2 H+,

and forms one H2O (inside the matrix)• Oxygen is the final electron acceptor (This is why we need

oxygen to live!)

ATP Synthase

http://www.youtube.com/watch?v=KU-B7G6anqw&feature=fvst

Anaerobic

• Occurs in the muscle fiber, only using chemicals and enzymes readily available.

• Smaller amounts of energy are produced

• No oxygen is needed for this reaction

• Needed for short and medium length activities.– Ex: weight lifting, short shifts in hockey

The two systems do not act as opposing systems.

The two systems co-exist.

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Three Metabolic Pathways

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Three Metabolic Pathways

• Within the ANAEROBIC and AEROBIC systems, there are 3 metabolic pathways by which ATP energy reserves are restored:– ATP-PC pathway (anaerobic alactic)– Glycolysis pathway (anaerobic lactic)– Cellular respiration (aerobic)

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High Energy Phosphate System

CreatineCreatinePP ENERGYENERGY

ADP + Pi ATPADP + Pi ATP

PC + ADP ATP + CREATINE

ATP-PC System (anaerobic alactic)First of two anaerobic

energy pathwaysRelies on the action of

stored ATP and phosphocreatine

Yields enough ATP for 7-12 seconds of energy

Provides highest rate of ATP synthesis

ATP-PC SystemATP-PC System

ATP-PC• Plays an important role in sporting events

which only last a few seconds, but require large bursts of energy.– Ex: Olympic weight lifting, high jump, 50-100 m

dash.

• HOWEVER – muscles do not have large supplies of phosphocreatine, and after about 10-15 seconds, body begins to rely on the seond system.

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High Energy Phosphate System Overview

Primary energy source:

Duration of activity:

Sporting events:

Advantages:

Limiting factors:

Stored ATP, CP

7 to 12 s

Weightlifting, high jump, long jump, 100 m run, 25 m swim

Produces very large amount of energy in a short amount of time

Initial concentration of high energy phosphates (ATP, PC)

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The Anaerobic Glycolytic System

ADP + Pi ATPADP + Pi ATP

ENERGYENERGY

Lactic AcidLactic Acid

GlycogenGlycogen

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Glycolysis

• A biochemical process that releases energy in the

form of ATP from glycogen and glucose

• anaerobic process (in the absence of oxygen)

• The products of glycolysis (per molecule of

glycogen):

- 2 molecules of ATP

- 2 molecules of pyruvic acid

• The by-product of glycolysis (per molecule of

glycogen):

- 2 molecules of lactic acid

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The Anaerobic Glycolytic System • Starts when:

– the reserves of high energy phosphate compounds fall to a low level

– the rate of glycolysis is high and there is a buildup of pyruvic acid

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Anaerobic Threshold• The exercise intensity at which lactic acid begins to accumulate within

the blood

• The point during exercise where a person begins to feel discomfort and burning sensations in the muscles

• Lactic acid is used to store pyruvate and hydrogen ions until they can be processed by the aerobic system

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Substrates for the anaerobic energy system

• The primary source of substrates is carbohydrate

• Carbohydrates: – primary dietary source

of glucose– primary energy fuels

for brain, muscles, heart, liver

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Glucose stored in blood

Glycogen stored in muscle or liver

Complex Carbohydrates

Digestive system

Glycogen

Glucogenesis

Circulation of glucose throughout body

Glucose

Blood Stream

Carbohydrate breakdown and storage

LACTIC ACID CHALLENGE

What is lactic acid challenge?

• This is a class challenge.– Find an place on the wall, and the person who

can perform a wall sit for the longest – will win a prize!

• Describe what you felt that made you want to stop?

What is lactic acid?

• After 2 or 3 minutes of a sustained activity the body can not break down glucose fast enough to keep up.

• Lactic Acid builds up in the muscle fibers

• You are forced to slow down/stop – as it causes pain/discomfort in the muscle.

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The Anaerobic Glycolytic System Overview

Primary energy source:

Duration of activity:

Sporting events:

Advantages:

Limiting factors:

Stored glycogen, blood glucose

12 s to 3 min

Lactic acid build up, H+ ions build up (decrease of pH)

800 m run, 200 m swim, downhill ski racing, 1500 m speedskating

Ability to produce energy under conditions of inadequate oxygen

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The Role of Three Energy Systems During an All-out Exercise Activity of Different Duration