To understand the implications the
intensity of exercise has upon the
energy re-synthesis requirements.
To understand the key theories
linked with the energy continuum.
“The relative contribution of each energy
system to ATP re-synthesis determined by the
intensity and duration of exercise”
What does this mean?
Each energy system provides Differing levels
of ATP re-synthesis, the intensity and
duration of exercise determines, which
energy system is most predominant in
providing ATP. Note- they do not work in
Consider the activity and state what percentage of energy will
be provided by each energy system.
Justify your answer!!
Activity % PC % Lactic %
The threshold of any system is the point
at which it cannot provide energy.
The threshold for the PC system is the point it
cannot provide energy for the working
muscles (Usually after 10 seconds).
What about the aerobic threshold, when
is it reached?
Onset of Blood Lactate
“The point at which the concentration
of lactic acid in the blood rapidly
Lactic acid levels:
Normal aerobic work = 1-2mmol of
lactic acid per litre of blood.
OBLA = 4mmol per litre of blood.
When does OBLA occur?
OBLA varies depending on the aerobic fitness of
the performer. In untrained individuals this may
occur at 50% of their Vo2 Max.
In highly trained athletes this may be as high as
85% of their Vo2 max, due to their ability to
dispose of waist products (lactic acid).
Vo2 max = the maximum amount of O2 you
can take into your body and utilise for exercise.
Consider two identical twins both with the
same Vo2 Max, one is trained the other is
not. They both race to the shops, who will
experience OBLA first?
Athletes often use a mix of three energy systems to
re-synthesis ATP during an activity. Explain the term
energy continuum and, using an example from PE,
illustrate when and why an athlete would switch from
one energy system to another. [4 marks].
1 mark = explain.
1 mark = example.
1 mark = when it switches.
1 mark = why it switches.