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Intro to Energy Systems - PSE 4U

A look at how our body is supplied with energy during different forms of exercise

Marc Messier

on 12 April 2012

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Transcript of Intro to Energy Systems - PSE 4U

Energy Systems
What system operates during exercise?

This depends on:
the duration of the exercise
how urgently the energy is required
the intensity of the exercise
whether or not oxygen is present
A closer look:
The energy for muscular contractions/movement
is produced either aerobically or anaerobically via
3 energy systems.

These are all activated at the start of exercise & their
contribution is determined by the intensity & duration
of the exercise.

Each system is trying to resynthesis ATP to supply
energy to the body.
The Aerobic System
Anaerobic System
ATP - CP System
Lactic Acid System
The most POWERFUL of the 3 energy systems.
This system requires oxygen.
It is all about complex chemical reactions that help
release energy to our body.
The slowest system to contribute to the
resynthesis of ATP.
Can produce more energy than either of the
anaerobic systems. Up to 50 times as much as both combined.
There is NO toxic/fatiguing by-products released & it
can be used indefinitely.
Its activated at the start of intense exercise.
Peak power is usually reached at 1-2 mins.
The aerobic 'traning zone' is between 70-85% max HR.
As the Lactic Acid system decreases its contribution
this system becomes the major ATP contributor.
Major energy contributor for long distance events & when Max HR remains below 85%.
Gastin & Le Rosigno,l (2001)

It was thought once that the aerobic
energy system didn't actually 'kick in' until at least 2-3 mins
of intense exercise.
However, their research has shown that it contributes up to 55 -65% of
ATP production during an 800m.
Also it was found that that in a max effort lasting 75s, equal energy is derived from the aerobic
& anaerobic systems.
Spencer et al. 1996

As the event duration increases &
maximal effort decreases, the
importance of the anaerobic system
diminishes & the aerobic energy supply
How does it work?
To allow the body to resynthsis ATP to supply
energy for movement the aerobic system has 3 stages.
Breaking down of Fats & Carbs
When fats are broken down, small amounts of
energy are released for basic body functions
& low-intensity activities.
Fats can actually produce more ATP than carbs
but they require more O2 to produce an
equivalent amount of ATP.
Breaking down of Pyruvic Acid
Pyruvic acid is broken down into
carbon dioxide (CO2) & further energy is
released to resynthesis ATP. Also part of the
Krebs Cycle.
Krebs Cycle
A series of chemical reactions occuring in mitochondria that releases energy by removing electrons & hydrogen ions from carbon atoms (oxidisation).
ATP is reformed when we eat, allowing
muscular movements to continue.
When sufficient O2 is supplied, glycogen is
broken down to glucose & pyruvic acid, with
energy then being made available for ATP
This is known as 'Aerobic Glycolysis' & it means
glycogen can be broken down without the formation
of lactic acid.
Aerobic Glycosis
occurs in the mitochondria.
these are aerobic 'powerhouses'
they produce ATP
it is then transported to the myosin crossbridges
this enables muscular contractions/movements of the body.
This is the least complicated of the 3 systems.
It produces MAXIMAL power in the first few seconds of
exercise - 10 to 15secs.
Its the quickest to break down PC to form ATP.
Simple & short chemical reactions.
The more intense the exercise the faster PC is used up.
Used in fast, powerful movements eg. throwing, sprinting, jumping.
A limited amount of PC is stored in the muscles (about 10sec worth).
Once PC has been depleted it can only be replenished when there
is sufficient energy in the body - aerobic pathway or during recovery.
This system is ANAEROBIC so
doesn't depend on O2 being
transported to muscles to release
Involves more complicated & longer chemical reactions.
Is activated at the start of intense exercise.
Peak power is usually reached between 5 & 15 secs.
Produces ATP until fatigue sets in - 2 to 3 minutes.
Needed for extended high-intensity (above 85% max HR) movements eg. 200m sprint, 50m swim.
Paul Gastin & Peter Le Rosignol 2000

Recorded findings that it contributes up to 45% of
ATP production during a 100m sprint.
Previously it was thought it was ALL ATP-PC system.
Breaking down Carbs to glucose & storing it as glycogen for energy
is 'glycolysis'.
This energy helps produce ATP & the lactic acid system does this WITHOUT
O2. So its called 'anaerobic glycolysis'.
Glycogen is not totally broken down as O2 is
not present & a by-product is formed called...

During maximal exercise, the rate of glycolysis can
increase to 100 times the rate at rest
It becomes a stop-gap until sufficient O2
is transported to working muscles for the O2
system to become the major energy contributor.
Full transcript