ENERGY SYSTEMS
LESSON 3
Lactic Acid Energy System
LEARNING OBJECTIVES
1.
Am I able to explain the Lactic Acid System?
2.
Can I evaluate the Lactic Acid System?
STARTER
STARTER ANSWERS
1.
2.
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I understand
Man overboard
Undercover agent
Long underwear
Easy on the eyes
I over ate
Circles under his eyes
Going around in circles
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High chair
Flat tyre
Downtown
Cross roads
Sick in bed
Mixed up kid
Running around the
block
Scrambled eggs
LACTIC ACID ENERGY
SYSTEM
Explain what is happening below:
Glycogen
GPH
Glucose
GPH = Glycogen Phosphorylase (converts stored
Glycogen into active Glucose in the blood)
LACTIC ACID ENERGY
SYSTEM
Explain what is happening below:
Glucose
PFK
2ATP
Pyruvic Acid
PFK = Phosphofructokinase (helps to break
Glucose into Pyruvic Acid)
LACTIC ACID ENERGY
SYSTEM
Explain what is happening below:
LDH
Lactic Acid
Pyruvic Acid
LDH = Lactate Dehydrogenase (converts Pyruvic
Acid into Lactic Acid)
LACTIC ACID ENERGY
SYSTEM
Explain what is happening below:
Glycogen
GPH
Glucose
PFK
LDH
2ATP
Lactic Acid
Pyruvic Acid
ENZYMES OF THE LACTIC
ACID ENERGY SYSTEM
GPH = Glycogen Phosphorylase (converts
stored Glycogen into active Glucose in the
blood)
 PFK = Phosphofructokinase (helps to
break Glucose into Pyruvic Acid)
 LDH = Lactate Dehydrogenase (converts
Pyruvic Acid into Lactic Acid)

TASK


Explain how ATP is re-synthesised in the Lactic
Acid System
You must include information on the following:
Use of enzymes
 End products from chemical reactions

TRAINING ADAPTATIONS
Repeated bouts of anaerobic training
which overload the LA system also
increase the body’s tolerance to lactic acid
 This will increase the body’s stores of
Glycogen
 This also delays the effect of OBLA
(Onset of Blood Lactate Accumulation)
and prolongs the Lactic Acid threshold

ADVANTAGES OF THE LACTIC
ACID ENERGY SYSTEM

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Relatively large amount of Glycogen stored in
muscles/liver and is readily available
Re-synthesises two molecules of ATP – more than
ATP/PC System
Requires few chemical reactions than Aerobic System,
so provides a quicker supply of energy
GPH and PFK enzyme activation due to a decrease in
PC
Can work aerobically and anaerobically
Provides energy for high intensity exercise lasting
between 10 and 180 seconds
DISADVANTAGES OF THE
LACTIC ACID ENERGY SYSTEM
Not as quick as the ATP/PC System
 Produces Lactic Acid, which is a fatiguing
by-product
 Reduces pH of muscle cell (making it more
acidic) which inhibits the enzyme action
 Stimulates pain receptors
 Net effect is muscle fatigue and pain

FACTS OF THE LACTIC ACID
SYSTEM
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There is NO Oxygen present!! Therefore, the Lactic Acid
System works under Anaerobic conditions
The fuel for this system is Carbohydrates (in the form of
Glycogen)
The reactions take place in the sarcoplasm of the muscle
cells
The main limitation of this system is the Onset of Blood
Lactate Accumulation (OBLA) – which lowers the pH
and inhibits enzymes
The Lactic Acid system is the predominant energy system
for the 400m sprint and for midfield games players that
have lots of high intensity sprints with no time for recovery
PLENARY
 Discuss
how you think ATP can be resynthesised during exercise lasting
longer than 30 seconds