During prolonged exercise, ingesting carbohydrates can prevent drops in blood glucose concentration and may help to maintain high rates of carbohydrate oxidation which is needed to maintain high intensity exercise. Glucose is rapidly used at around 60g/hour. The optimal amount of carbohydrate intake is dependent on what your own digestive system can handle.
Carbohydrate, when consumed after exercise, is taken up into glycogen stores. When combined with protein within the first 30 minutes post exercise, carbohydrates are utilised for muscle tissue repair and recovery. The better your fuel and recovery strategy, the better your ability to perform at your next session!