Which energy system predominates during a 15-second sprint?

• A. Glycolytic (anaerobic)
• B. Oxidative (aerobic)
• C. ATP-CP (phosphagen)
• D. All are equally used

Answer: (C)

For a short, maximal effort like a 15-second sprint, the phosphagen (ATP-CP) system provides energy most quickly. It uses stored ATP and phosphocreatine to regenerate ATP without oxygen, delivering rapid bursts of energy needed at the start and through the early part of the sprint. The oxidative system relies on oxygen and slower mitochondrial processes, so it can’t be the main source in such a brief, high-intensity effort. The glycolytic system does contribute energy anaerobically, but at this duration its contribution isn’t the dominant one yet; it becomes more important as the sprint extends beyond roughly 15–20 seconds. So the energy for a 15-second sprint is primarily supplied by the phosphagen system.