The primary source of energy for endurance athletes during prolonged activities is typically carbohydrates. Muscles utilize glycogen, stored carbohydrates, as their main energy source for high-intensity and sustained exercise. Adequate carbohydrate intake before, during, and after events is crucial for maintaining energy levels and delaying fatigue. Athletes often consume quick energy sources like gels, bananas, or sports drinks during long workouts to replenish glucose levels and optimize performance. Maintaining glycogen stores is essential for sustaining endurance and improving athletic performance.