Download Energy Continuum


The energy systems rarely work in isolation

The body supplies energy continuously
(hence ‘continuum’) as long as activity occurs.

Which is the dominant energy system for:
▪ Marathon?
▪ Shot Put?

It is fairly easy to know the dominant energy
system for the marathon and shot put, but
other sports are not so easy.

So we use the Energy Continuum to show
how the body changes between the 3
systems for activities that exceed the limits of
one or more systems, or for activities that
experience changing levels of intensity.

Important note:
ALL 3 ENERGY SYSTEMS OCCUR
CONTINUOUSLY, BUT THE PROPORTION
OF ENERGY PRODUCED BY EACH SYSTEM
CHANGES AS THE EXERCISE CONTINUES.

The intensity and duration of the activities is
the main determining factor for which system
is predominant.

= point at which a particular energy system is
unable to provide energy
e.g. PC threshold = When no PC left
= approx 10 secs


Onset of Blood Lactate Accumulation
i.e. The point at which the concentration of
lactic acid in the blood rapidly increases.
Normal value for rest or aerobic exercise=
1-2 mmol lactic acid/litre blood
Above 4mmol = OBLA


When this occurs depends on the aerobic
fitness of the performer
Untrained = 50% VO2 Max
Highly Trained = 85% VO2 Max
Why?
their increased ability to remove waste
products and supply oxygen to working
muscles.


Supply of oxygen can determine which
energy system is predominant
Also the various enzymes and food fuels
(this will again depend of
fitness levels)

The way energy is provided for a 1500m race
are very specific –
“The ATP-PC is the predominant system for supplying energy during the
1st 10 seconds, after which the lactic acid system becomes dominant
for the next minute. The Aerobic System takes over for the middle of
the race when the pace settles. There is then a return to the Lactic
Acid system for the final sprint finish.”
 Analyse how the energy is provided for the
following activities (use the same format as given for the 1500m above)
Hockey Game, Marathon, 100m sprint, Trampoline routine

As we know, HR stays elevated after
exercise to help get the body back to its
pre-exercise state = RECOVERY.


We know it from GCSE PE as ‘Oxygen Debt’
but there is actually more to it so we use a
different term:
Oxygen Deficit
At the start of moderate exercise it takes a
while for the aerobic system to provide
energy, so anaerobic processes provide it.
Oxygen Deficit is therefore the extra amount
of oxygen that would be needed to complete
the activity entirely aerobically.

The extra oxygen taken in after exercise (see
graph) is now known as:
E.P.O.C.
(Excess Post-Exercise Oxygen
Consumption)

Note: on the graph HR drops quickly when
exercise stops but this recovery then slows.
i.e. 2 stages to recovery

What happens to the following levels after
strenuous exercise?
PC Stores
Myoglobin
Lactic Acid
Carbon Dioxide
Glycogen
Depleted
All O2 used up
Increased
Increased
Depleted

So after strenuous exercise these all need to
be returned to their pre-exercise levels.
Some are done quickly:
Alactacid Debt (the fast stage)
Some are done slowly:
Lactacid Debt (the slow stage)

PC - elevated metabolism => energy used to
restore PC stores
- takes 3 mins to fully restore PC
(50% restored in 30 secs)
- takes approx 4 litres of Oxygen

Myoglobin
(transports O2 from capillaries to
mitochondria in sarcoplasm)
- stores are emptied during
exercise so the O2 consumed
during EPOC replaces it.
- Takes 1-2 mins to fully replenish
- Takes 0.5 litres of Oxygen (ie the surplus O2
produced by increased HR and ventilation during EPOC)

Lactic Acid - removed in 4 ways during this stage:
- 60% converted to pyruvic acid => krebs cycle
etc etc
- converted to glucose and stored in muscles and
liver
- converted to proteins
- removed via sweating and urine

Takes upto 1 hour to remove all lactic acid

CO2 – elevated after exercise and needs to be
removed.
- 70% dissolved in plasma (carbonic acid)
- chemoreceptors detect increased
CO2/low pH and stimulate CCC and RCC.
Therefore Q and respiratory rate remain
high during recovery to expel CO2
through lungs

Glycogen Stores – only way to replenish is to
ingest carbohydrates.
- usually eat them but some take glucose
solution intravenously (Tour de France Cyclists)
- can take upto 48 hours with high
carbohydrate meal to totally restore
glycogen after a heavy exercise bout.


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
Full recovery of PC takes 3 mins. If doing
speed work – allow full recovery.
Active Cool Down – removal of lactic acid is
quicker. Intensity of cool down depends on
individual but moderate (approx 35%) is best.
Monitor training intensities; then you can
avoid OBLA and maintain quality of training.
Warm Up thoroughly – reduces O2 deficit by
increasing O2 supply to working muscles and
ensure myoglobin stores are full.