Essentials of Nutrition for Sports

The body re-forms a complex carbohydrate for energy storage
called glycogen. Glycogen is the critical fuel for performance in the high aerobic and anaerobic threshold range, and is stored primarily within muscle cells and the liver. Wh

en one exercises for a couple of

hours at high intensity, it is easy to use up these stores.

Since complex carbohydrate is associated with other nutrients

and are critical for glycogen replacement, they form the cornerstone of meal planning.

Maltodextrins

or

glucose polymers

are medium-length chained

carbohydrates, partially broken down from naturally occurring complex carbohydrate. They are often found in energy bars and gels. The contention that they provide a more constant source of energy than simple sugar, one that is easier

to digest than naturally occurring

complex carbohydrate, is only partially true. The discussion of the glycemic index below, explains why.

Fiber

includes indigestible complex carbohydrate. Fiber plays a

role in overall health but has little bearing on athletic performance.

Read about fiber beginning in the free supplement to this book

available at: http://roadbikerider.com/nutritionforsportssupplement.htm

.

Glycemic Index

It used to be thought that simple sugars entered the bloodstream

rapidly but that their effects on energy production were short-lived. It used to be thought that complex sugars provided a steadier release of food energy.

Studies have shown that the rate of release of sugar into the

bloodstream, or glycemic effect, is related to factors other than whether sugars are simple or comp

lex. The rate of digestion of

sugars has more to do with cooking, ripening, and the presence of fiber, fats, and proteins associated with the sugar than it does with the presence of simple sugars. For example, a well-baked potato

releases sugar into the bloodstream almost as rapidly as glucose. The release of simple sugars in whole milk is delayed by the presence of fat. Bananas release sugar more ra

pidly when ripe. Simple sugars

consumed as part of a meal raise blood sugar more slowly than when consumed by themselves.

Pure glucose is assigned a glycemic

index of 100. The rate of

release of sugar into the bloodstream caused by other substances is compared with the release rate of pure glucose.

Sugars that have a glycemic index greater than 80 are considered

to be released quickly. Sugars that have a glycemic index between 40 and 80 are considered to be released moderately. Sugars with a glycemic index below 40 are released slowly.

Sugars that release quickly and help to spare or replace burned

glycogen may be suitable during or after exercise. Sugars that release moderately slowly may be more suitable several hours before or after exercise.

Food

Index

Food

Index

Food

Index

Glucose

100

Bananas

60

Ice

cream

36

Potato, baked

98

Sucrose

60

Milk, whole

34

Carrots, cooked

92

Pasta

50

Milk, fat free

32

Honey

87

Potato chips

50

Beans, kidney

30

Cornflakes

83

Oatmeal

50

Lentils

30

Rice

72

Orange juice

50

Fructose

20

Bread

70

Oranges

43

Carrots, raw

16

Candy bars

65

Beans, baked

40

Beans, soy

15

Raisins

65

Apples

40

Peanuts

10

Table 4. Glycemic index of selected foods.

Nutrition for Sports, Essentials of 46