Which energy pathway predominates during a 400-meter sprint?

• A. Aerobic respiration.
• B. Creatine phosphate system.
• C. Anaerobic glycolysis.
• D. Oxidative phosphorylation.

Answer: (C)

The key idea is rapid, high-intensity ATP production without relying on oxygen. In a 400-meter sprint, the effort lasts around 40–60 seconds, so the body needs a lot of ATP very quickly. The phosphagen (creatine phosphate) system can power maximal effort for only the first few seconds before its stores are exhausted, so it cannot sustain the entire race. The aerobic (oxidative) system takes longer to ramp up and, at the pace of a sprint, cannot supply ATP fast enough to maintain that power. Anaerobic glycolysis takes over to generate ATP rapidly from glucose without oxygen, providing the bulk of the energy for this event and allowing the sprinter to sustain near-maximal speed throughout most of the race, with some contribution from the other systems at the very start and toward the end.