An endurance athlete performs repeated high-intensity sprints which deplete muscle glycogen. Why does this depletion impair subsequent sprint performance even if the athlete eats a carbohydrate-rich snack immediately after the sprints?

• A. Because consuming carbohydrates after exercise shifts all available glucose into adipose tissue triglyceride synthesis for energy conservation, rendering none available for muscle glycogen repletion, an overgeneralization that ignores muscle glycogen synthesis capability.
• B. Because muscle glycogen cannot be rapidly replenished and must be restored within muscle cells before it can power high-intensity contractions again, immediate carbohydrate intake requires time for uptake and glycogenesis in muscle.
• C. Because ingested carbohydrates are routed only to the liver and never to skeletal muscle during post-exercise recovery, which is false since muscle can take up glucose postprandially for glycogen synthesis.
• D. Because muscle cells must first convert glycogen back to glucose and then reconvert it to a different polymeric storage molecule unique to muscle before they can contract again, a statement inventing a nonexistent intermediate storage polymer.

Answer: (B)