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
In high intensity exercise longer than 2
seconds ATP is resynthesized using PC
(stored in muscles)
P
C
High energy bond
PC stores are limited
so ATP can only be
resynthesized in this
way for upto 10
seconds

This process involves 2 immediate reactions
which take place within the muscle cell
sarcoplasm.

When PC is broken down energy is released:
P
Energy
C
P
Energy
Energy
C
ADP
Same energy is
then used to
resynthesize ATP
P
ATP
PC => P + C + Energy (Exothermic Reaction)
Enzyme responsible for
the breakdown of PC is
Energy + ADP + P => ATP (Endothermic Reaction)
Creatine Kinase

When energy produced by one reaction is
used in another reaction it is known as a
COUPLED REACTION.

Therefore the resynthesis of ATP using PC is a
COUPLED REACTION

The breakdown of PC is ANAEROBIC.

Which of the following activities use the ATPPC system? (you must be able to justify your choice(s))

Correct Answers:

Why? –
because they all last less than 10 seconds

Wrong Answers:

Why? –
Because they last longer
than 10 seconds

No Oxygen is used and no lactic acid is
formed in this system – therefore it is also
called the Alactic Anaerobic System

The main advantage of the ATP-PC system =
it is a very immediate source of energy

When hard exercise is longer than 10seconds
(beyond ATP-PC threshold) and all PC is used
up, ATP then has to be resynthesized by a
different system – LACTIC ACID SYSTEM

Therefore the point at which we switch from
the ATP-PC System to the Lactic Acid System
is known as the
ALACTIC-LACTIC THRESHOLD

Speed endurance and power athletes use
anaerobic work in order to delay the onset of the
Alactic-Lactic Threshold.

Anaerobic work causes biological adaptations
that allow muscle cell sarcoplasm to contain
more ATP and creatine so ATP-PC system
provides energy for longer at the highest
possible rate.

Some athletes use daily Creatine supplements to
increase the total muscle creatine.

Complete the Homework sheet for next
lesson.