Exercise Physiology
Studies a range of SYSTEMS in the human body. These systems
allow us to perform the various activities we do, and more
importantly. enable us to live.
Exercise Physiology requires us to understand the following
information:
• Muscular Systems – how they contract & relax and their
•
•
•
•
microscopic structures.
Energy Systems – how we get energy to move.
Circulatory Systems – the heart & blood.
Respiratory System – the lungs
Nervous Systems – the brain & how it controls movement &
processes
In this unit we will learn about
 Energy systems – and how we get energy to move.
 How our body responds to exercise.
 The heart and lungs.
The Energy Systems

1)
2)

1.
2.
3.
Energy for muscle contractions can be supplied in
two ways: Either
Anaerobically – without oxygen, or
Aerobically – with oxygen.
In the body there are three main pathways for the
breakdown of ATP to make energy. These systems
are dependent on the type of activity being
performed.
The Three Pathways Are:
ATP-CP
Anaerobic – (lactic acid)
Aerobic
The ATP-PC System
 This energy system provides energy for the activities of short
duration and high intensity hence it does not require oxygen.
 The ATP-PC system will only last up to 10 seconds when there is
not any recovery time because the ATP & PC becomes
exhausted.
 The ATP-PC system is used during 100m sprints, shot put, high-
jump and other activities that are completed in only a few
seconds.
The Lactic Acid System
 The Lactic Acid system is also anaerobic (ie. No
Oxygen). It is the system that ‘kicks-in’ when the ATPPC system can no longer produce energy.
 The lactic acid system provides energy for up to 3
minutes hence it is used for activities such as 400m &
800m running events or middle distance swimming.
The main source of fuel for this system is
Carbohydrates.
 One problem with the Lactic Acid system is that a byproduct called Lactic Acid builds up in the muscles and
blood. It is this by-product produced during intense
exercise that causes fatigue.
The Aerobic System
 The aerobic system produces ATP in the presence of
oxygen. It is this system that is used during rest &
everyday activities such as mowing the lawns, walking
etc. During intense exercise it is the aerobic system
that ‘kicks-in’ after 2-3 minutes.
 The aerobic system produces far more ATP than any
other system because it is produced when oxygen is
present. Not only this, oxygen being present also
prevents the build-up of Lactic Acid.
The Three Energy Systems
100
% Energy Contribution
Red –
Green –
Pale Blue -
50
0
0 10 20 30
40 50 60
120
180
Running Time (seconds)
240
300
360
Task – Identify the energy system at work.
Activity
Golf Swing
Javelin
Marathon
200m Swim
Volleyball Spike
1500m Run
Walking
30 sec Burst
Power-lifting
Beep Test
ATP-CP
Lactic Acid
Aerobic
Task - Answers
Activity
ATP-CP
Golf Swing
X
Javelin
X
Lactic Acid
Marathon
X
200m Swim
Volleyball Spike
X
X
1500m Run
X
Walking
X
30 sec Burst
X
Power-lifting
X
Beep Test
Aerobic
X
Using your notes on energy systems,
complete the following table:
Description
ATP – CP
(immediate)
Lactic Acid
(short term)
Aerobic
(long term)
Source of
Energy
Time
(predominately
used)
Classification
Example
Answers
Description
Source of
Energy
Time
Classification
Example
(predominately
used)
ATP – PC
(immediate)
Used in high intensity,
extremely short
activities.
ATP stored in the
muscle cells.
0-10 sec
Anaerobic
(Does not require O2,
and so does not cause
a build up of lactic
acid).
Sprint starts, weight
lifting, shot put…
Lactic Acid
(short term)
Used in short term,
high intensity exercise.
Carbohydrates
(glycogen)
30 sec – 2 mins
Anaerobic
(Does not require O2,
but used carbos only,
large amounts of lactic
acid build up-hence
decreased
performance).
200m sprint, sit ups/
press ups…
Aerobic
(long term)
Light – moderate
intensive exercise.
(The body can work
for extended time
without experiencing
fatigue).
Carbohydrates and
fats.
2-3mins + (These
intensive may vary
from very easy to very
hard)
Aerobic
(Because this system
requires oxygen to
burn carbos and fats,
lactic acid does not
build up-hence no
effect on
performance).
Marathon runner or
swimmer…
Summary of Energy Systems
ATP-PC System
Lactic Acid System
Aerobic System
 Anaerobic
Anaerobic
Aerobic
 Very rapid
Rapid
Slow
 Chemical: CP
Food: glycogen
Food: CHO, Fat,
Protein
 Very limited ATP
Limited ATP
Unlimited ATP
 Muscular stores
limited
Lactic Acid causes
fatigue
No fatiguing
by-products
 Explosive, sprint
30 sec to 3 min
Endurance
 100m
400m
Marathon