A: Sports drinks are useful for endurance events such as marathons and half marathons. During the event you lose a lot of water and electrolytes through your sweat. A sports drink, at least 40 minutes in, is a great way to top up on hydration, electrolytes and carbohydrate during the event. They are not so useful for shorter events that are less than one hour. For shorter events water is best to ensure good hydration. Practice using sports drinks in your training for the marathon instead of waiting for the event to try them for the first time.