Which energy system is activated and burns out after approximately 15 seconds of high-intensity activity?

The ATP/PC system is the correct choice because it is specifically designed to provide energy for short bursts of high-intensity activity lasting around 10 to 15 seconds. This system relies on adenosine triphosphate (ATP) and phosphocreatine (PC) stored in muscle cells. When you engage in activities such as sprinting or heavy lifting, the body quickly uses these stored compounds to produce the immediate energy required for intense effort.

As the activity continues beyond this period, the ATP/PC system depletes its resources, necessitating a switch to other energy systems for sustained energy production. The Glycolytic system, for instance, begins to take over to provide energy for activities lasting from about 30 seconds to a few minutes. In contrast, the Aerobic and Oxidative systems are used for longer durations and moderate intensity activities where oxygen is available to metabolize carbohydrates and fats.

Understanding the duration and function of the ATP/PC system helps in designing training regimens that maximize performance in high-intensity sports or activities where short bursts of effort are required.