Which of the following energy systems lasts the least amount of time?

The ATP-PC system, also known as the phosphagen system, is designed to provide quick bursts of energy for high-intensity activities lasting up to about 10 seconds. This system utilizes adenosine triphosphate (ATP) and phosphocreatine (PCr) stored in the muscles, allowing for rapid energy production without the need for oxygen. It is particularly dominant during short, explosive activities like sprinting or heavy weightlifting, where immediate power is essential.

In contrast, the aerobic system is capable of sustaining energy production for longer durations, often well beyond several minutes, as it involves the use of oxygen to metabolize carbohydrates and fats for sustained energy. The glycolytic system, while also short-term, typically supports activities lasting from about 10 seconds to around 2 minutes, as it relies on glycogen breakdown without oxygen (anaerobic metabolism) but is slower to reach its peak compared to the ATP-PC system. The oxidative system takes much longer to ramp up, providing energy over extended periods, often measured in minutes to hours, by effectively using oxygen.

Thus, when considering the duration of energy provision, the ATP-PC system is the one that operates over the shortest timeframe, making it the correct choice.