Final answer:
Intervals aimed at specific improvement of the ATP-CP system should generally last 8-10 seconds.
Step-by-step explanation:
The ATP-CP system is the energy system used by the body for short bursts of high-intensity activity, such as sprinting or weightlifting. It relies on stored ATP (adenosine triphosphate) and creatine phosphate. Intervals aimed at specific improvement of the ATP-CP system should generally last 8-10 seconds, as mentioned in the provided information. This duration allows for the maximum utilization of the ATP-CP system.