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CHAPTER 14
CARBOHYDRATES AND TAKING THE TWO-WEEK TEST
Endurance athletes thrive and survive on glucose, which comes from dietary carbohydrates. The body can also obtain glucose from both fat and protein. For most athletes, carbohydrates are the majority macronutrient in their diet, providing the body with energy. Carbohydrate foods include fruits, whole grains, vegetables, brown rice, lentils, beans, and honey; they also provide vitamins, minerals, fiber, water, and many phytonutrients.
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Unfortunately, most of the carbohydrate foods athletes eat are highly processed, such as refined wheat flour—which is made into bread, rolls, bagels, and cereal. Other carb no-nos include white rice, fruit juice, and sugar or sugar-containing products, such as desserts. These foods can be very unhealthy for athletes because they don’t provide the full spectrum of nutrients compared to their natural counterparts, and they can cause increased production of the hormone insulin, which reduces fat burning.
Types of Carbohydrates
All carbohydrates are composed of single sugar molecules that exist in three forms—glucose, fructose, and galactose:
- Complex carbohydrates, also called starches (polysaccharides), contain many single sugars attached together: for example, many glucose molecules held together (glucose + glucose + glucose). These carbs can be found in potatoes, corn, all grains, and beans.
- Double sugars (disaccharides) are made up of two sugars attached to each other. They include sucrose (glucose + fructose), lactose (glucose + galactose), and maltose (glucose + glucose). These are found in table sugar (sucrose), milk sugar (lactose), maple syrup (maltose), and other “malt” sugars, such as maltodextrin.
- Simple sugars (monosaccharides) contain single, unattached sugars. These are found in ripe fruits and vegetables and honey, all of which have various amounts of glucose and fructose.
Unripe fruits and vegetables contain higher amounts of starch and double sugars. During the ripening process, these complex carbs and double sugars are converted to simple sugars, making ripe fruit taste sweeter. As an example, green bananas turn yellow (with black spots) when ripe. Even vegetables are sweeter when ripe: green peppers are unripe and turn red (or yellow) when ripe. Because most of the sugars contained in these plant foods are broken down to simple sugars, no further digestion of these carbohydrates is needed. For some people, eating unripe fruit or vegetables is the reason they get indigestion.
It’s most important to understand this aspect of carbohydrates: Both complex carbs and double sugars require digestion in order to break apart the simple sugars that are attached to each other. This must occur in order for sugar to be absorbed and made available for energy. Complex carbohydrates require the most digestion. Simple sugars don’t require digestion; they are immediately available for absorption.
During the process of digestion, both complex and double-sugar carbohydrates are chemically broken down to their simple sugars (monosaccharide). Digestion occurs primarily in the mouth and small intestine. Once digested, the sugars are absorbed into the blood and are then referred to as “blood sugar.”
Complex carbohydrates and double sugars often don’t completely digest into their simple sugars. This may be due to insufficient chewing of food in order to mix it with the enzymes in saliva, common during the stress of competition or long training. Those incompletely digested carbohydrates can cause significant amounts of intestinal gas, causing discomfort or often pain. We’ve all experienced this type of stress in our intestines during physical activity.
One problem with a high amount of refined carbohydrates in the diet is that they take the place of other healthy foods—fats, proteins, and vegetables. For endurance athletes, this can produce inadequate nutrition as well as reduce fat burning and aerobic function.
Types of Carbohydrates
While many scientists believe that humans have no true requirement for carbohydrates (because fat and protein can be converted to glucose), many people consume refined carbs as a staple of their diet—and in very high amounts. In fact, most athletes consume the majority of their carbohydrates as the refined, processed type.
