Abstract: Amino acid compositions containing a carbohydrate and any one or more kinds of alanine, proline and glycine as amino acid can suppress a rapid increase in the blood glucose level immediately after ingestion and a decrease in the blood glucose level due to prolonged exercise, and can improve exercise performance. In addition, the present invention provides inhibitors of an increase in the blood glucose level immediately after carbohydrate ingestion, an inhibitor of a decrease in the blood glucose level due to a prolonged exercise, and an exercise performance improver. Therefore, the present invention provides an energy supplement useful for those who exercise (particularly prolonged exercise).