Changes to the Circulatory System
Stronger heart muscle
Increased cardiac output
Increased stroke volume
Lower resting heart rate
Increased capilliarisation
Changes to the Respiratory System
More efficient gaseous exchange
Increased tidal volume
Increased vital capacity
Better oxygen debt tolerance
Cell Respiration
 In order to exercise we need
energy.
 Cells get energy from
glucose in a process called
cell respiration.
 Two kinds of cell
respiration go on in your
muscle fibres.
AEROBIC RESPIRATION
&
ANAEROBIC RESPIRATION
Cell respiration during exercise.
 Your muscles usually get their
energy from AEROBIC
respiration, e.g jogging,
swimming, cycling.
glucose + oxygen = ENERGY + carbon dioxide + water
Cell respiration during exercise.
 However, our muscles
sometimes need large
amounts of energy very
quickly, e.g when sprinting,
therefore ANAEROBIC
respiration takes over.
Glucose = ENERGY + lactic acid
Cell respiration during exercise.
 Glucose has to be broken
down for it to be used by the
muscles.
 The glucose which has been
stored (from food) in the
muscles and liver as glycogen
is broken down and ATP and
pyruvic acid is formed.
 When there is oxygen the
pyruvic acid is changed into
carbon dioxide and water.
 Without enough oxygen the
pyruvic acid changes into
lactic acid
Lactic acid and oxygen debt.
 After strenuous exercise like




sprinting, your muscles need
extra oxygen quickly.
This extra oxygen is called
the OXYGEN DEBT.
You will pay it off by gulping
air into your lungs
Most of the lactic acid gets
turned into carbon dioxide
and water.
Some is changed back into
glucose and oxygen.
Energy systems used during
exercise - ANAEROBIC
 The CP system
 The ATP that is broken down by the muscle contracting
can be reformed in the presence of creatine phosphate (CP)
which is also stored in muscles.
 If there is enough CP then muscle contractions can take
place even though there is no oxygen.
 This anaerobic system is used by sprinters and throwers. It
is used whenever a large effort is needed for a short time.
CP stores are used up in about 5-10 seconds.
 e.g. 100m sprint, sprinting down the wing in football
Energy systems used during
exercise - ANAEROBIC
 The Lactic Acid System
 Pyruvic acid changes into lactic acid that collects in the





muscles that are working as well as overflowing to the
bloodstream.
Lactic Acid makes muscle contractions difficult and causes
tiredness.
If there is too much the muscles won’t work at all.
This anaerobic system is used by athletes who work as hard
as possible for up to 2 minutes.
After this the body goes into oxygen debt.
e.g. 400m sprint, running back to defend the goal in
hockey
Energy systems used during
exercise - AEROBIC
 The Aerobic System
 If there is enough oxygen and glucose available then
you can continue to work on a less explosive exercise
almost continuously. This time the pyruvic acid is
turned immediately into carbon dioxide and water
because there is enough oxygen available.
 This aerobic system is important during longer
activities e.g. running/jogging, cycling, swimming
 e.g. marathon, jogging from place to place in rugby
Energy systems used during
exercise
 Although some
sportspeople use one
system more than the
other many depend on 2 or
more when taking part in
sports.
Q – choose a team game and
show where the different
systems are used for
different tasks during a
match
Recovery After Exercise
 After a training session
or playing a game your
body needs to return to a
normal state.
 This is called recovery.
 It takes some time for
your body to recover.
Recovery – Heart Rate
 The heart rate slows
down to its normal
resting rate.
 The fitter you are the
faster this happens.
Recovery – Lactic Acid Removal
 Lactic acid will have been




produced in the muscles
and you will need to get rid
of it.
Oxygen removes lactic acid
from the body.
This is called repaying the
oxygen debt.
The body normally
breathes deeper and faster
to do this.
The process is faster if you
do a cool down
Recovery – Muscle Repair
 Muscles may suffer minor




damage during training.
Exercise may cause
microscopic tears in
muscle fibres.
Your body has to repair
this.
Stiffness and soreness take
time to clear.
Stretching as part of a cool
down helps prevent
stiffness.
Recovery – Replacing Glycogen
 The glycogen stores in the




muscles get used up during
exercise.
The store in the liver may also
get depleted.
It takes time to replace
glycogen.
A starchy snack e.g. a banana,
pasta after exercise will help.
After prolonged exercise such
as marathon running it can
take 48 hours for glycogen
stores to recover.
Recovery – How long does it take?
 This depends on :
 How strenuous the exercise




was
Your fitness. The fitter you
are the faster you recover.
Allow 24-48 hours between
training sessions for recovery
in the early stages of training.
If you train every day, follow a
heavy session one day with a
light session the next.
Even during heavy training,
take one rest day a week.