Carbohydrate loading in endurance sports is a strategy used to maximize glycogen stores in muscles before a competition. By increasing carbohydrate intake several days prior to an event, athletes enhance their energy reserves, improving performance and delaying fatigue. This approach is crucial for activities lasting longer than 90 minutes, as it helps sustain energy levels. Proper carbohydrate loading can significantly enhance an athlete's endurance and recovery during prolonged physical exertion.