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Energy Systems
Muscle Fibres
Nervous System
Cardiovascular System
Respiratory System
PSE4U
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Carbohydrates:
 Most abundant
organic substance in
nature they are
essential for human an
animal life

Glucose:
 Is broken down to form ATP
(adenosine triphosphate)
 Is stored in muscles and liver as
GLYCOGEN – can be broken
down under conditions of stress
or the demands of muscular
activity
Created by photosynthesis
CO2 + H2O + sunlight E  C6H12 O6 + O2

Energy is neither created nor destroyed only
transformed from one form to another
▪ Ex. Light energy from the sun is “captured” by plants during
the process of photosynthesis and converted to chemical
energy (food)

CHEMICAL ENERGY (food) – is used to make
ATP (free energy)
ATP
Adenosine
adenosine
Triphosphate
diphosphate phosphate
ATP -------------> ADP
+ P
A-P - P - P ------------->
A- P-P
+
Energy
In
Energy
Out
P
ADP
1.
ANAEROBIC (without oxygen) – short
high intense activity
2.
AEROBIC (with oxygen) – endurance

These two systems coexist, overlap and interact
in various combinations
Most activities rely on a combination of both
systems
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Occurs relatively quickly in the muscle
fibres, utilizing chemical and enzymes
readily at hand for powerful but relatively
short lived activitites

Anaerobic can be broken down into 2
systems:
▪ PATHWAY 1: Anaerobic Alactic (ATP-PC)
▪ PATHWAY 2: Anaerobic Lactic (Glycolosis)
Name
ATP-PC
(Anaerobic Alactic System)
Location of Activity
Cytoplasm
Energy Source
Creatine Phosphate (PC)
Uses Oxygen or Not
Anaerobic (without oxygen)
ATP created
1 molecule
Duration
10-15 seconds
Number of Chemical
Reactions
1-2
By-Products
None
Name
ATP-PC
(Anaerobic Alactic System)
Basic Formula
PC + ADP  ATP + creatine
Type of Activities
Power surges, speed events
Types of exercise that rely on
this system
Sprints, jumps, weightlifting
Advantages
Very quick surge of power
Limitations of energy system
Short duration, muscles store small
amounts of ATP and creatine phosphate
Muscle fibre type recruited
Type IIB (fast-twitch
•Is important as it provides the highest rate of ATP synthesis that
cannot be matched by other, more complex energy systems
•Recovery Period of PC 2-5 min – requires ATP to resynthesize PC
Name
Glycolysis
(Anaerobic Lactic System)
Location of Activity
Cytoplasm
Energy Source
Glucose (Glycogen)
* Glycolysis is the first step in the
breakdown of glucose
Uses Oxygen or Not
Anaerobic (without oxygen)
ATP created
2 molecules per glucose molecule
Duration
15 seconds to 3 minutes
Number of Chemical
Reactions
11
* Has a lot more steps but yields twice as
much ATP over Anaerobic Alactic sytem
By-Products
Lactic Acid
Name
Glycolysis
(Anaerobic Lactic System)
Basic Formula
C6H12O6 + 6O2 + 36ADP + 36 P  6CO2 + 6H2O + 36 ATP
Type of Activities
Intermediate activities/sprint finishes
Types of exercise that
rely on this system
200-800 metre runs, shift in hockey
Advantages
Quick surge of power
Limitations of energy
system
Buildup of lactic acid causes pain and fatigue
Muscle fibre type
recruited
Type IIA (fast twitch)
GLUCOSE
PYRUVATE is the by-product of
glycolysis when oxygen is not present it
continues to breakdown into LACTIC
PYRUVATE (without O2)
LACTIC ACID
ACID
(with O2)

▪ LACTIC ACID –decreases muscles ability to contract
(Kreb’s Cycle)
Name
Cellular Respiration
(Aerobic System)
Location of Activity
Mitochondria
Energy Source
Glycogen, Fats, Proteins
Uses Oxygen or Not
Aerobic (with Oxygen)
ATP created
36 Molecules per glucose molecule
Duration
120 seconds and beyond
Number of Chemical
Reactions
Glycolysis
Kreb’s Cycle
Electron Transport Chain
By-Products
Water and Carbon Dioxide
Name
Cellular Respiration
(Aerobic System)
Basic Formula
C6H12O6 + 6O2 + 36ADP + 36 P  6CO2 + 6H2O + 36 ATP
Type of Activities
Prolonged activities
Types of exercise that Marathons, exercise classes
rely on this system
Advantages
Long duration, complete breakdown of glucose
Limitations of energy Slow, requires large amounts of oxygen
system
Muscle fibre type
recruited
Type I (slow-twitch)
CELLULAR RESPIRATION – 36 ATP
 Glucose fuels this system but,
Glucose
▪ Fats can
be broken down when exercise occurs for longer
than 20 min 2 ATP are
▪ Proteins can beMade
broken down in chronic situations –
starvation
Pyruvate
 Complete
of
(withbreakdown
Oxygen)
glucose, unlike
anaerobic lactic that stops after glycolysis
32 ATP are

2 ATP are
Made
Made
Electron
This system can be sustained as
long Transport
as
oxygen is present and physiologicalChain
limits are
not reached.

Blood Lactate Threshold (anaerobic
threshold)
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Point at which lactate levels in the blood increase
abruptly beyond resting values
Onset of Blood Lactate Accumulation
(OBLA)
▪ Point at which blood lactate levels begin to accumulate
very rapidly.
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Raising the Lactic Acid Threshold – Need to do
power training
▪ Raising the lactic acid threshold will allow you to utilize
your anaerobic lactic system for a longer period of time
as the build up of lactate will be slower.
MUSLCE
LIVER
Glucose
Glucose
Pyruvic Acid
Pyruvic Acid
Lactic Acid
Lactic Acid
Can be
Stored in
liver or
muscles as
glycogen
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FATS – ideal as they contain large quantities of
stored energy
Triglycerides
Fatty Acids
Lipolysis
Fatty Acids
Acetyl CoA
Beta Oxidation
enter KREB’s CYCLE

PROTEIN – same amount of energy as
carbohydrates (glucose) but ½ as much as fat

No protein reservoirs in the body like carbs
and fats, all proteins are part of existing
body tissue or actively engaged as in
metabolic systems

Made up of long chains of amino acids

Individual amino acids are broken down
further and enter energy system

We have different types of muscle fibres in
our body and each type of muscle fibre is
more adapted to a certain energy system.
 Slow Twitch Muscle Fibres
▪ Generate and relax tension slowly but are able to
maintain lower levels of tension for a long period of
time.
 Fast Twitch Muscle Fibres
▪ Have the ability to tense and relax quickly and can
generate large amounts of tension but have low
endurance levels.
Slow - Twitch
Fast – Twitch
Cyclist
61%
39%
Canoeist
61%
39%
Middle – Distance
Runner
59%
41%
Swimmer
58%
42%
Weightlifting
46%
54%
Sprinter
26%
74%
Soccer Player
53%
47%
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The difference in muscle fibre types are
mainly due to the extent to which a particular
muscle relies on oxygen in the production of
energy.

MYOGLOBIN – is the oxygen storage unit
that delivers oxygen to working muscles.

The more a muscle utilizes aerobic processes
for energy production the more myoglobin it
has.
▪ Slow twitch muslce fibres (red) are high in myoglobin
▪ Fast twitch muscle fibres (white) are low in myoglobin
Type I Slow
Oxidative
(SO)
Type IIA
Fast Oxidative
Glycolysis
(FOG)
Type IIB
Fast Glycolysis
(FG)
Colour
Red
Red/White
White
Fibre Diameter
Small
Medium
Large
Contraction Speed
Slow (110ms)
Fast
Very Fast (50ms)
Force Production
Low
Intermediate
High
Energy Efficiency
High
Low
Low
Myoglobin Content High
Moderately high
Low
Myosin ATPase
Low
High
High
Fatigue Resistance
High
Moderate
Low
Aerobic Capacity
High
Moderate
Low
High
High
Anaerobic Capacity Low

Tonic Muscles – assists the body with
maintaining posture or stability during
activities such as standing, walking and
throwing.
▪ High percentage of Type I fibres

Phasic Muscles – characterised by a
higher percentage of Type IIA and Type
IIB