The Sport Factory Not all Carbs are Created Equal

Not all Carbs are Created Equal

by Ilana Katz, MS, RD, LD

Carbohydrates, are the building blocks of all plant life. They include fruits, vegetables, grains and starches. Note that �carbs� are expressed in plural, because there are different types, and different carbs are treated differently by our bodies with varying nutritional values. Some carbohydrates are digestible while others are not; some are considered complex, while others are simple; and some carbohydrates contain soluble fiber while others contain insoluble fiber. However, nearly all of the carbohydrates we consume are converted into glucose (blood sugar) with the notable exceptions of fiber and glycerin. The basic carbohydrate for human nutrition is the simple sugar glucose, but our bodies also make a complex carbohydrate called glycogen, which is the storage form of glucose in the muscles and liver.

Some carbs are high in sugar and digest quickly flooding your blood with energy. Others digest slowly and provide a controlled, steady, and even release of energy. Because these differences exist, it is important to think about what specific type of carbs might be best under different circumstances such as training and racing. Athletes require carbohydrates during both high and low intensity work outs, but carbohydrate is more quickly depleted during intense activity. Depletion of carbs results in fatigue and rapid performance decreases. When glucose runs out, the athlete stops, and this is referred to as �hitting the wall�. Athletes must replace carbs at every opportunity in order to avoid this state.

Making the Right Choices at the Right Times

Carbohydates are used pre, during, and post work out in different forms, for different functions. Consuming carbs before activity can top off energy stores and delay fatigue. Consuming carbs during activity helps to maintain blood sugar required to fuel working muscles. Consuming carbs after activity aids in recovery and glycogen replenishment. The types of foods you consume influence the type of carbohydrates available to your system during these times.

Simple carbohydrates also called monosaccharides (sugars) are derived naturally from many foods, and these include glucose, fructose (typically found in fruits and vegetables), galactose (one of the sugars in milk), sucrose (table sugar), lactose (milk sugar), and maltose (grain sugar). Simple carbs provide a quick boost of glucose to the blood stream. These are often used by endurance athletes to sustain glucose levels for greater periods of time. They are readily available and digestible.

Complex carbs, also called polysaccharides, contain many molecules of connected monosaccharides. Polysaccharides can be either digestible (starch, dextrins, and glycogen), or indigestible (cellulose, hemicellulose, pectin, gums, and mucilages). Dietary fiber, a carbohydrate that cannot be digested, is useful in the diet because it may lower fat and cholesterol absorption, improve blood sugar control, and reduce the risk of colon cancer and heart disease. For these reasons complex carbs should comprise most of your diet outside of training and to replenish glycogen stores. For an athlete complex carbs are essential for performance.

An athlete's ability to store glycogen is determined by conditioning, hydration and the availability of an enzyme (glycogen synthetase) to form glycogen from glucose. This enzyme's availability can be strengthened by recovering with correct nutrition from intense workouts. This enzyme is elevated after exercise. It is elevated highest within 30 minutes post-exercise, but remains above normal levels even 24 hours later. For this reason, it is vital that an adequate amount of complex carbohydrates is taken in as soon after workouts as possible. (Adding a small amount of protein to a high carbohydrate meal or snack will not only enhance glycogen storage capacity, but it will also aid in muscle recovery.)

Some sports nutrition products use glucose polymers, a type of artificially formed polysaccharide. These are chains of glucose molecules that are easily separated in the digestive system, providing a boost of glucose efficiently for an athlete.

Using the Glycemic Index for Performance

Measuring the impact of various carbohydrates on blood sugar is a complex process that takes into account how much and how quickly the sugar gets into the bloodstream. The Glycemic Index (GI) is a measuring system giving a numerical rating to each carbohydrate. The GI can be useful for athletes looking for sustained energy and optimal recovery. The GI thus further categorizes carbs into "High Glycemic" and "Low Glycemic" foods. Low Glycemic carbs are recommended for sustained energy levels (slower absorption, lowered insulin response) such as fructose (fruit sugar), whole wheat pasta, galactose (milk sugar), brown rice, sweet potato, oats, bran products and most vegetables (except carrots, corn and root vegetables).

Low GI carbs are good for pre work out meals or snacks. Consuming low GI cards prevent premature lowering of blood sugar levels and thus avoid fatigue. High GI carbs, such as refined sugar (candy), honey, white rice/pasta, bread, and most processed foods are absorbed quickly. High GI carbs are good during training, and after training they benefit recovery. During high intensity training your body may have difficulty processing Low GI carbs, so simple sugars provide a quick and ready source of energy. Consuming high GI carbs within the first 15 minutes to 2 hours after training aids in replenishing depleted glycogen levels in the muscles most completely.

Conclusion

Athletes should rely heavily on carbohydrates for fuel, not all carbs are good for all occasions. The key is that glucose is the main source of fuel for muscular activity, and the higher the exercise intensity, the greater the reliance on glucose a fuel. Not only does the type of carbohydrate influence performance, but the concentration of carbohydrates is also worth considering. Sports nutrition products are specifically designed to provide both simple and slow releasing carbs in optimal concentrations to prevent gastrointestinal distress (cramps). Having carbohydrate-containing beverages during exercise is thus a good practice.

And remember, if the body is not supplied with enough energy in the form of carbohydrates, it will burn protein for the fuel it requires; a much slower process. This will take protein away from its normal functioning of building and repairing muscle tissue; thus, supplying the body with an appropriate amount of carbohydrates will prevent the unnecessary breakdown of protein (muscle).

Ilana Katz has a masters degree in dietetics with an emphasis in sports nutrition. Her work has ranged from elite to recreational athletes. She specializes in body composition and weight management specific to individual goals and needs.

Ilana, herself participates in many endurance and team events in order to relate personally to her clientele. Ilana consults at various athletic centres around Atlanta and is the founder of the nutrition program IndiFITualize.

Published in: Nutrition News