Which statement best describes the roles of glycolysis and the phosphagen system during aerobic and anaerobic exercise?

• A. The phosphagen system produces more ATP than glycolysis during long-duration exercise.
• B. Both glycolysis and the phosphagen system are only active during prolonged, low-intensity aerobic exercise.
• C. The phosphagen system provides immediate ATP for short, intense activity, while glycolysis supplies ATP during both aerobic and anaerobic exercise, with its end products entering different metabolic pathways depending on oxygen availability.
• D. Glycolysis only functions during aerobic exercise, while the phosphagen system is used exclusively during anaerobic exercise.

Answer: (C)

Verified step by step guidance

1. Understand the phosphagen system: The phosphagen system is a rapid energy system that provides immediate ATP for short bursts of intense activity, such as sprinting or weightlifting. It relies on stored phosphocreatine in muscle cells to regenerate ATP quickly.
2. Understand glycolysis: Glycolysis is a metabolic pathway that breaks down glucose into pyruvate, producing ATP in the process. It can function under both aerobic (with oxygen) and anaerobic (without oxygen) conditions. The end products of glycolysis depend on oxygen availability—pyruvate enters the citric acid cycle during aerobic conditions, while it is converted to lactate during anaerobic conditions.
3. Compare the roles during exercise: The phosphagen system is primarily active during short-duration, high-intensity activities, providing immediate energy. Glycolysis, on the other hand, is active during both aerobic and anaerobic exercise, supplying ATP for sustained activity and adapting its end products based on oxygen availability.
4. Clarify misconceptions: The phosphagen system does not produce more ATP than glycolysis during long-duration exercise; it is designed for short-term energy needs. Glycolysis is not limited to aerobic exercise—it functions in both aerobic and anaerobic conditions.
5. Summarize the correct statement: The phosphagen system provides immediate ATP for short, intense activity, while glycolysis supplies ATP during both aerobic and anaerobic exercise, with its end products entering different metabolic pathways depending on oxygen availability.