The total muscular stores of ATP-PC are very small, limiting the amount of obtainable energy.
In order to accommodate the body's need for an efficient, high-powered ATP-PC energy system, the brunt of the training procedures should fall within the parameters of a high-intensity, short duration, moderate recovery protocol.
For the ATP-PC system, an all-out effort completed under the 30-second intervals is essential, thus an appropriate distance must be determined for each run/drill.
For the ATP-PC system, this is accomplished with a timed work:relief ratio of 1:4 or 1:3.
However, it's the rapid availability rather than the quantity of ATP-PC that makes it so useful.
There is also a shift in emphasis from the LA system to the ATP-PC system, thus preparing the athletes for specific energy needs of their sport.