Transcript Energy systems.

Energy systems.
PHYSIOLOGICAL
REQUIREMENTS OF
PHYSICAL ACTIVITY
Foods
Fuel and
Energy Systems
Where does this energy
come from?
A Roger Federer serve takes 1-2 seconds
to perform. It’s fast & explosive. He
might do this hundreds of time over a
game. Plus he has to run fwd, bkwd and
sideways for 1-2 hours. His Muscles
requires ENERGY to do this.
Food Fuels our Body
1. CARBOHYDRATES
(Glycogen)
2. PROTEIN
3. FATS
CARBOHYDRATES
Cereals
Pastas
Rice
Fruit/Veges
Breads
Sugar
Carbohydrates are stored as Glycogen in Muscle & Liver
CHO is the body’s preferred fuel during Exercise
– breaks down easily, uses little oxygen
PROTEIN
Fish
Red Meat
Eggs
Dairy
products
Poultry
GRAINS
Protein is stored as MUSCLE and AMINO ACIDS around the body.
5-10% contribution to endurance events:
Mainly used for growth/repair
FATS
Butter
Oils
Margarine
Cheese
Nuts
Food that we ingest is stored and burnt to fuel
our muscles
This food must be converted
into a chemical compound
called ATP
Without ATP - Muscles
cannot contract
A.T.P.
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Adenosine triphosphate.
This is energy for muscle contraction.
Energy for movement of muscle fibres
is stored in the muscle as a molecule of
ATP.
Adenosine
Adenosine
P
P
triphosphate
P
To use the stored ATP

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To release the energy, ATP is broken
down into ADP + Pi (Adenosine
diphosphate + Phosphate molecule)
The energy released allows for a muscle
contraction.
Adenosine
P
P
+
Pi
Energy
Resynthesis of ATP
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There is only enough stored ATP for about 12 contractions, so….we must resynthesise
ADP back into ATP.
Fuel and energy for this comes from CHO,
Fats, Proteins and Creatine phosphate.
These fuel sources resynthesise the free
Phosphate molecule (Pi) back to the ADP to
reform ATP.
CHO, Fats,
Proteins, CP
Adenosine
P
P
+
Pi
Resynthesises the ADP back to ATP
Adenosine
P
P
Pi
ATP is used in all 3 energy
systems.
The type of energy system used and the
interplay between them depends on the
frequency, duration, intensity of the
activity and fitness levels of the
individual.
The 3 energy systems

The ATP – PC system
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The Lactic Acid Systems
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Aerobic System
For activity lasting:
0-10 SEC
ATP-PC
SYSTEM
10-30/40 SEC
Anaerobic
Glycolytic
SYSTEM
2MINS +
AEROBIC
SYSTEM
High Energy Phosphate System
ATP –PC system cont..
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ATP breaks down to ADP + Pi to release
energy.
The ADP + Pi must be reformed to ATP
for continued muscle function.
PC provides the energy for the free Pi
to be re-attached to the ADP molecule
to form ATP.
ATP –PC system cont..
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PC stored in the muscles breaks down
anaerobically (without O2) to form Phosphate
and Creatine. This releases energy for the
resynthesis of ATP.
It takes 2 PC molecules to resynthesise 1 ATP
molecule (one PC = 0.7 ATP).
NOTE: The resynthesis of PC (Phosphate + Creatine = PC)
occurs in the recovery phase.
ATP-PC
SYSTEM
Used for high
intensity
Jumps, Throws,
Sprints
Uses stores of
CP (Creatine
Phosphate) to
REMAKE ATP
CP instantly
available, but
runs out
quickly
Only have 10
seconds of CP
in muscles
If activity lasts longer than 10 sec, ATP must be
REMADE by some other means…..
Training the High Energy Phosphate System
a) Interval training:
- 20% increase in CP (creatine phosphate) stores
- no change in ATP stores
- increase in ATPase function (ATP -> ADP+P)
- increase in CPK (creatine phosphokinase) function
(CPK breaks down CP molecule and allows ATP
resynthesis)
b) Sprint training:
- increase in CP stores up to 40%
- 100% increase in resting ATP stores
Summary

Each ATP molecule is made up of
an adenosine part and three
phosphate groups.

Besides ATP, there is still another
high-energy compound called
phosphocreatine (PC) inside the
human muscle cells. When PC is
broken down, energy is released
for the resynthesis of ATP.
Summary Cont…
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However, the total amount of PC stored in the human
body is also extremely limited. The energy released
from the breaking down of ATP is also required to
resynthesize PC. Nevertheless, this process will be
carried out when the human body is in the recovery
stage.

The complete ATP-PC system can only supply 5.7 to
6.9 Kcal of energy, which can maintain about 10
seconds of maximal efforts.
Summary cont…
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The importance of the ATP-PC system is that it is the instant
energy source in the human body.
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The ATP-PC system does not require oxygen in the muscles for
proper functioning. Besides, the required fuels (ATP and PC)
have already been stored in the muscle cells
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The chemical reactions involved when PC is broken down are
fewer than the other two energy systems.

The ATP-PC system is particularly important for high-intensity
and high- speed activities that need to be completed in a few
seconds (e.g., starting, jumping, throwing, and weight lifting).
Anaerobic Glycolytic
SYSTEM
Body uses stored fuel of
GLYCOGEN to REMAKE ATP
Need Oxygen to
do this properly
About 2-3
hours of
glycogen
stored in
body.
Downside –
by-product
called Lactate.
Hydrogen
Ions also
released
which inhibit
muscle
contraction
Happens because of lack
of enough Oxygen to
break down Glycogen
400m run, 800m at high intensity
The Anaerobic Glycolytic System
Glycolysis
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A biochemical process that releases energy in the form of
ATP from glycogen and glucose
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Anaerobic process (in the absence of oxygen)
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The products of glycolysis (per molecule of glycogen):
- 2 molecules of ATP
- 2 molecules of pyruvic acid
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The by-product of glycolysis (per molecule of
glycogen):
- 2 molecules of lactic acid
Anaerobic Threshold
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The exercise intensity at which lactic acid begins to accumulate
within the blood
The point during exercise where the person begins to feel
discomfort and burning sensations in their muscles
Lactic acid is used to store pyruvate and hydrogen ions until
they can be processed by the aerobic system
The Anaerobic Glycolytic System
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cont
.
Starts when:
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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
Substrates for the anaerobic energy system
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The primary source of
substrates is
carbohydrate
Carbohydrates:
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primary dietary source
of glucose
primary energy fuels
for brain, muscles,
heart, liver
Carbohydrate breakdown and storage
Complex
Carbohydrates
Digestive
system
Glucose
Blood
Stream
Circulation of glucose
around body
Glucose stored
in blood
Gluconeogenesis
Glycogen
Glycogen stored
in muscle or liver
Effect of Training on the Anaerobic
Glycolytic System
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Rate of lactate accumulation is increased in the trained
individual
This rate can be decreased by:
a) reducing the rate of lactate production
- increase in the effectiveness of the aerobic oxidative system
b) increasing the rate of lactate elimination
- increased rate of lactic acid diffusion from active muscles
- increased muscle blood flow
- increased ability to metabolize lactate in the heart, liver and in nonworking muscle
Review of Anaerobic Systems
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Video Review
AEROBIC SYSTEM
Like the LA system,
the Aerobic uses
Glycogen to
remake ATP.
Will keep suppling ATP
for as long as Fitness
levels allow
Used in
longer, submax
activities.
Long run,
swim, cycle.
Plenty of
Oxygen
available to
remake ATP .
So no LA or H+
is accumulated
Oxygen supply
meets demand
We use this
system at REST
(Now!) – except
we burn…
FAT!!!!
Aerobic Oxidative System
The Aerobic Oxidative System
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The most important energy system in the human body
Primary source of energy (70-95%) for exercise lasting longer
than 10 minutes provided that:
a) working muscles have sufficient mitochondria to meet energy
requirements
b) sufficient oxygen is supplied to the mitochondria
c) enzymes or intermediate products do not limit the Kreb’s cycle
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Primary source of energy for the exercise that is performed at
an intensity lower than that of the anaerobic oxidative system
The Oxidative Phosphorylation System
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Two Pathways: Krebs Cycle & Electron Transport Chain
Biochemical process used to resynthesize ATP by combining ADP
and P in the presence of oxygen
Takes place in mitochondrion (contains enzymes, co-enzymes)
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Energy yield from 1 molecule of glucose is 36
ATP molecules
Energy yield from 1 molecule of fat up to 169
ATP molecules
By-products of this reaction: carbon dioxide, water
Cori Cycle
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Lactic acid is taken to the liver to be
metabolized back into pyruvic acid and then
glucose
Aerobic Review
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Video Review
The Power Of The Aerobic System
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Evaluated by measuring the maximal volume of oxygen that
can be consumed per kilogram of mass in a given amount of
time
This measure is called aerobic power or VO2 max (ml/min/kg)
Factors that contribute to a high aerobic power:
a) arterial oxygen content (CaO2)
- depends on adequate ventilation and the O2-carrying capacity of blood
b) cardiac output (Q = HR x stroke volume)
- increased by elevation of the work of heart and increased peripheral blood
flow
c) tissue oxygen extraction (a-vO2 diff)
- depends upon the rate of O2 diffusion from capillaries and the rate of O2
utilization
The Substrates for the Aerobic System
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Carbohydrates (glycogen and glucose) and fats
(triglycerides and fatty acids)
Fats:
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found in dairy products, meats, table fats, nuts, and some
vegetables
body’s largest store of energy, cushion the vital organs, protect
the body from cold, and serve to transport vitamins
each gram of fat contains 9 calories of energy
Effect of Training on Aerobic Systems

Endurance training is the most effective method (long
duration several times per week):
- increases vascularization within muscles
- increases number and size of mitochondria within
the muscle fibres
- increases the activity of enzymes (Krebs cycle)
- preferential use of fats over glycogen during exercise
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Endurance training increases the max aerobic power of a
sedentary individual by 15-25% regardless of age
An older individual adapts more slowly
During REST
Any rest, short
OR Long, CP is
being
replenished, so
we can ‘sprint’
again.
BUT, need 3
minutes rest to
get all CP
back!
Any Lactate and Hydrogen Ions are
removed from muscles & blood stream
too.
Things to remember:
The 3 Energy
Systems are not like
TRAFFIC LIGHTS.
One does not switch
off and another goes
on.
All 3 turn on at
once no matter
what the
activity.
However, depending on
intensity and duration of the
activity, ONE system will
contribute more than the
other TWO.
Energy Systems Video Overview
The Role of Three Energy Systems During an All-out
Exercise Activity of Different Duration
Discussion Questions:
1. What are the differences between the 3 energy systems?
2. List one advantage and one disadvantage of each of the 3 energy
systems.
3. Give an example of three activities or sports that use each of (a) the
high energy phosphate system, (b) the anaerobic glycolytic system,
and (c) the aerobic oxidative system as their primary source of energy
(one sport for each energy system).
4. What is the most important source of fuel in the body for all types of
energy production - a substance also known as the energy currency of
the body?
5. Define ATP turnover and ATP resynthesis.
6. Describe how each of the three energy systems could be trained most
efficiently.