The AEROBIC system.
AEROBIC FACTS.
The only system to use oxygen.
The slowest system to contribute to
ATP resynthesis, due to complex
chemical reactions.
BUT, it is capable of producing more
ATP than either of the two anaerobic
systems.
AEROBIC FACTS.
Activated at the onset of exercise.
Peak power reached within 1-2min
If exercise intensity remains below 85%
of MAX HR will remain the major energy
provider for extended periods of time
(2hours plus).
See tabel 4.4 pp 101.
How does the system work?


During activity the
aerobic system uses
CHO for fuels. At rest or
very low intensity
activity it utilises fats
(triglycerides) and
CHO.
At rest we burn 1/3
CHO and 2/3 fats.
Aerobic system.

Stage 1:


CHO
CHO is used as the fuel source.
When there is sufficient O2, Glycogen is broken
down into Glucose and Glucose into Pyruvic acid
then energy is made available for ATP
resynthesis.
GLYCOGEN
GLUCOSE
PYRUVIC
ACID
ENERGY
FOR ATP
Aerobic Glycolysis.


The process of breaking down Glucose for
ATP with sufficient O2 is called aerobic
glycolysis.
With enough O2 present during this process
there is no Lactic Acid accumulation.
Aerobic Glycolysis


This process takes
place in the
mitochondria within the
muscle cell.
These “power houses”
produce ATP, which is
then transported to the
myosin cross bridges =
contraction.
Aerobic three stage system.

Stage 1:

CHO and Fats are used to produce energy.
Fats are stored as triglycerides in blood. Glycerol and 3 free fatty acids
(FFA) molecules.
When this is broken down small amounts of energy are released for
ATP used in basic bodily functions and low intensity activities.


GLYCEROL
FFA
FFA
FFA
GLYCEROL+FFA+FFA+FFA
ATP for
ENERGY
Stage 2: Active

CHO broken down in the presence of oxygen.
Glycogen too glucose then pyruvic acid, where
some energy is released in the Krebs cycle along
with CO2.
Activity increases and O2 is provided
=CHO as the preferred fuel (faster than
FFA).
CHO
GLYCOGEN
GLOCOSE
ATP
PYRUVIC
ACID
ATP
Krebs
Cycle
ATP
Stage 3: Very active



After the Krebs cycle we enter the electron transport
system (E.T.C.).
Here huge amounts of ATP are produced as well as
heat, water.
Large amounts of O2 must be available.
ATP
HEAT
HEAT
ATP
ATP
ATP
ETC
Krebs
cycle
ATP
ATP
ATP
HEAT
H20
ATP
H2O
ATP
ATP
H2O
AEROBIC SUMMARY
It requires oxygen which can be provided within 60 sec
(90 % of VO2 max)
It involved more complex chemical reaction than the
other systems.
It prefers CHO. Fats can be used but require much
more O2 to break them down.
It produced non toxic/fatiguing by products and can be
used indefinitely.
It provides 50 times more ATP than the other systems.
It provides significant energy to all activities that are
more than 1-2min in duration