The need for ADP reconversion

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Physical Education - The need for ADP reconversion

The need for ADP reconversion

The small amount of ATP in muscle is only sufficient to support a single
explosive muscle contraction. If a performance demands repeated muscle
contractions (i.e. running), then the ADP that is left after the initial
contraction needs to be converted back into ATP so that future contractions
can take place.

ADP reconversion:

Once the ADP and -P molecule have been rejoined (this takes energy to join
the two back together again) back to ATP, the process can begin again with
ATP breaking down to ADP and supplying more energy for muscular
contraction.

So the whole process goes around in a circle, with ATP being broken down
to ADP and energy (for contraction). Then the ADP recombines with energy
from elsewhere to form ATP again, and so the process starts again.

This is all relatively simple and straightforward. ATP breaks down into
ADP and the energy given off goes toward muscle contraction. However the
problem is obvious in the ADP back to ATP bit - where does the energy come
from to recombine the ADP so that it becomes ATP again?

The answer is in the contribution of the three energy systems. Our body
has three different energy systems that it can draw upon in order to supply
this needed energy for ADP reconversion:

* ATP - PC system

* lactic acid system

* aerobic system

All three systems work to some degree all the time. However, one system
provides a greater percentage of the energy, depending on:

* duration of the exercise

* intensity of the exercise

* the athlete's level of fitness

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