The glycemic effect is a measure of the response of blood glucose concentration and insulin to the carbohydrate in a food. It is measured by 1. how quickly and high the blood glucose gets, and 2. how quickly the blood glucose returns to normal.
It is preferential for most athletes to eat food with a low (<60) or medium (60-85) glycemic index before working out, becasue high glycemic (>85) tends to cause a spike and sharp decrease in blood glucose levels. However, there has not been conclusive evidence that eating a sugary snack before exercise diminishes performance.
Here are some examples of the three types of glycemic foods.
High: white bread, angel food cake, doughnut, cornflakes, watermelon, carrots, Rice Crispies
Medium: banana, grapes, sponge cake, All-Bran cereal, pita bread, buckwheat, Special K cereal, linguine
Low: Milk, yogurt, apples, peaches, apricots, lentils, beans, spaghetti
Some of this information was taken from Winning Sports Nutrition by Linda Houtkooper, PhD, RD, FACSM, Jaclyn Maurer Abbot, PhD, RD and Veronica Mullins, MS, RD, CSCS.
Disclaimer: None of the above information can be taken as a substitute for advice from a medical professional, such as a physician.
My third book, Pocket Guide to Fitness, is available on www.louizapatsis.com, http://www.authorhouse.com, www.bn.com and http://www.amazon.com. If you look up my name on those Web sites, you will find my other books The Boy in a Wheelchair and Life, Work and Play: Poems and Short Stories.