Which of the following enhances endurance performance by 2-3% when carbohydrate loading is applied?

Carbohydrate loading is a strategic dietary practice commonly employed by athletes to enhance endurance performance. This method focuses on maximizing the glycogen stores in the muscles and liver, which serves as a primary energy source during prolonged physical activities. When carbohydrate intake is significantly increased in the days leading up to an event, it leads to improved muscle glycogen levels.

Elevated muscle glycogen levels enable athletes to sustain higher intensity exercise for a longer duration and delay the onset of fatigue. Research indicates that this practice can enhance performance by approximately 2-3%, making it a valuable strategy for endurance athletes.

While hydration, protein intake, and aerobic capacity play important roles in an athlete’s overall performance, they do not specifically highlight the direct impact of carbohydrate loading on endurance performance in the same way that increased muscle glycogen levels do. Hydration is crucial for maintaining bodily functions and preventing fatigue, higher protein intake supports muscle repair and growth but does not directly relate to immediate energy availability, and improved aerobic capacity indicates an athlete's fitness level rather than the specific benefits gained from carbohydrate loading.