What type of physical activity would most likely require the use of the ATP-PC energy system?

The ATP-PC energy system, also known as the phosphagen system, is primarily engaged during short bursts of high-intensity activities that last for a duration of about 10 seconds or less. This energy system relies on the stored adenosine triphosphate (ATP) and phosphocreatine (PC) in the muscles, allowing for quick energy release without the need for oxygen. High-intensity interval sprints are characterized by short, explosive effort followed by brief recovery periods, which perfectly aligns with the ATP-PC system's capabilities.

During high-intensity interval sprints, the body predominantly utilizes this system due to the rapid demand for energy, which cannot be sustained for longer durations. The quick, dynamic nature of such sprints means they leverage the immediate energy provided by ATP and phosphocreatine stores before gradually transitioning to other energy systems (like anaerobic glycolysis) as activity continues beyond the immediate energy needs.

In contrast, long-distance running, 1-repetition maximum lifting, and activities like yoga and Pilates primarily utilize other energy systems, including aerobic metabolism, which provides energy over longer durations or at submaximal intensities.