Some athletes preparing for a big event will attempt to carbohydrate load or carbo load. These events include marathons, triathlons, bicycle centuries or longer, and long-distance swimming. The desired outcome is achieving the highest possible level of muscle glycogen just prior to the onset of the competition by coordinating a high carbohydrate intake (over 60 percent) for at least a week prior to competition while at the same time tapering both the intensity and duration of training sessions.
Theoretically, if you start out with more glycogen you should be able to perform longer.
A more common method of carbo-loading would be most beneficial when an event is to last more than an hour. Carbo-loading would not be beneficial for shorter endurance efforts or sports involving only brief efforts (for example, power lifting, velodrome cycling, or most track and field events). However, intermittent sport athletes such as soccer, football, and field and ice hockey playersmight benefit; however, the practice and game schedule would make carbo-loading unrealistic in some cases.