The effects of high and low glycemic index meals on endurance performance.
The description of carbohydrates as either simple or complex is an insufficient way of classifying them. A metabolically more informative way of describing carbohydrates is the degree to which they raise blood glucose concentrations and this is expressed in terms of glycemic index (GI). Carbohydrates which produce a large increase in blood glucose concentration, in response to a standard amount of carbohydrate (50g), are classified as having a high glycemic index. The metabolic response during exercise is different as a consequence of the glycemic indices of the carbohydrates consumed preceding the exercise, and so the choice of carbohydrate in pre-competition meals could have an effect on performance.