What energy system is used for activities lasting several seconds?

The phosphocreatine energy system is the correct choice for activities lasting several seconds. This energy system is primarily utilized during high-intensity, short-duration activities, such as sprinting or high-intensity weightlifting, typically lasting about 10 seconds or less. It relies on the rapid breakdown of phosphocreatine stored in the muscles to regenerate ATP (adenosine triphosphate), which is the immediate energy source for muscle contractions.

This system works anaerobically, meaning it does not require oxygen to produce energy, and it provides a quick but limited supply of energy. Once the phosphocreatine stores are depleted, which occurs rather quickly during intense activities, the body will need to transition to other energy systems for prolonged effort, such as the glycolytic or aerobic systems.

Understanding the specific duration and intensity of activities each energy system supports is key in kinesiology, as it helps guide training and rehabilitation practices to optimize performance and recovery in various physical endeavors.