Carbohydrates are great foods for athletes. They don't clog your arteries or give you cancer, but carbohydrates don't metabolize at the same rate either.

"If you experience energy lapses during long workouts, experiment with your carbohydrate choices," suggests Kristen J. Reimers, associate director at the International Center for Sports Nutrition in Omaha, Nebraska.

The glycemic index rates the speed at which various carbohydrates are metabolized and their ability to raise blood sugar. Foods that rate high is the list make their energy available after twenty minutes or so, while foods which come in under 35 provide sustained energy. Glucose is the reference point, with an index of 100.

The glycemic response is influenced by the amount of food you eat, its fiber content, fat content or amount of added fat, and the way the food is prepared.

If exercising for longer than an hour or so, load with two grams of low-index carbohydrates per kilogram of body weight. If you eat closer to the workout time, halve the amount. These foods will help to keep your blood sugar level stable through the workout.

Highly glycemic carbs are best just before, during, and after exercise. The sugars from these foods enter the bloodstream quickly to be available to you muscles.

Avoid highly glycemic foods too long before exercise, or pick foods richer in fructose than glusose or the mixture of the two sugars, sucrose. Sugars, and glucose especially, create an insulin reaction when concentrations are boosted without active muscles to eat them up. The result is the carbs that you laboured to scarf down will be bound up in muscle glycogen is your back and arms as well as the legs, rather in your blood ready to be soaked up on the road by the leg muscles you actually use.

Here's how some of everyone's favourite carb-rich foods meet the test:

Sugars
Glucose	100
Honey	73
Table Sugar	65
Starches
Instant Rice	90
Corn Flakes	84
Graham Crackers	74
Cheerios	74
Bagel	72
White Bread	70
Bran Muffin	60
White Rice	56
Oatmeal Cookie	55
Popcorn	55
Brown Rice	55
Spaghetti	41
All-Bran	42
Rye	34
Barley	25
Fruit
Watermelon	72
Raisins	64
Orange Juice	57
Banana	53
Orange	43
Apple Juice	41
Pear	36
Apple	36
Grapefruit	25
Plums	24
Cherries	22
Vegetables
Baked Potato	85
Corn	55
Sweet Potato	54
Chickpeas	33
Green Beans	30
Lentils	29
Kidney Beans	27
Peanuts	15
Dairy
Ice Cream	61
Skim Milk	32
Yogurt	14