GI is an index which measures post-prandial blood glucose response to carbohydrate containing food. Foods with a GI in the higher range will cause more rapid delivery of the carbohydrate into the bloodstream, and foods with a GL in the lower range, will provide a slower more sustained release of glucose. The GI of a particular food is dependent on a variety of factors, the type of starch as well as the content of fiber, fat and protein in the food.
Low GI - recommended throughout the day leading up to and during practice
The best strategy for athletes is to utilize low GI carbohydrates for pre-exercise to all for sustained energy, and high GI for post-exercise to enhance recovery with quick glycogen uptake in the muscles. However the benefits of using of low GI carbohydrates pre-exercise is questionable if the athlete is able to fuel up during the session, which prolongs energy levels and can also enhance performance.
High GI - recommended after practice and during competitions
High GI carbohydrates are most effective when an athletes has multiple training sessions in one day or a session that is less than 8 hours away. Total quantity of carbohydrates becomes more important if the next training session is more than eight hours away, as the body has adequate time to recover over a longer time period, allowing for sufficient carbohydrate consumption.
GI Food Link
This link gives you reference to Low, Med and High GI foods which athletes can eat pending their training and competition schedule as well as their day(s) of rest. Male and Female athletes may differ. What may also differ in the athletes GI level is the consistent amount of energy expenditure one athlete may have over another athlete.