1. Adenosine Tri Phosphate (ATP)

2. ATP Molecular Structure
Molecules
1 Adenosine
and
3 Phosphate

3. Muscular Movement and ATP
1 phosphate molecule breaks off and from this splitting, the energy to move the muscle is released.
The molecule left is
Adenosine Di Phosphate
(1 Adenosine and 2 Phosphates).

4. Muscular Movement and ATP
Stored ATP in the muscle fibres only lasts for 1 or 2 contractions. Therefore ATP must be continually replenished because it can only last for a very short time.
This is the role of the 3 energy systems