1. The glycemic index (GI) of a food represents the magnitude of the increase in blood glucose that occurs after ingestion of the food. 2. GI tends to be lower for foods that have a high fructose content, exhibit high amylose/amylopectin ratios, are present in relatively large particles, are minimally processed, and are ingested along with fat and protein. 3. Consumption of lower GI foods 30-60 min prior to an endurance exercise bout tends to promote the following effects during exercise: Minimizes the hypoglycemia that occurs at the start of exercise. Increases the concentration of fatty acids in the blood. Increases fat oxidation and reduces reliance on carbohydrate fuel. 4. The GI of a food consumed during exercise is probably less important than at other times because the insulin response to carbohydrate ingestion is suppressed during exercise. 5. Consumption of high GI foods soon after exercise will probably optimally promote the restoration of muscle glycogen. 6. Although manipulation of the GI of ingested foods may alter exercise metabolism, the effect of the GI on exercise performance is controversial and requires additional research. see also: http://www.chinaswim.org.cn/items/youyong/show.php?ID=1001437736
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