What are Carbohydrates?
Carbohydrates are one of the main types of nutrients. They are the most important source of energy for your body. Your digestive system changes carbohydrates into glucose (blood sugar). Your body uses this sugar for energy for your cells, tissues and organs. It stores any extra sugar in your liver and muscles for when it is needed.
Carbohydrates are called simple or complex, depending on their chemical structure. Simple carbohydrates include sugars found naturally in foods such as fruits, vegetables, milk, and milk products. They also include sugars added during food processing and refining. Complex carbohydrates include whole grain breads and cereals, starchy vegetables and legumes. Many of the complex carbohydrates are good sources of fiber.
Why Carbohydrate Supplements are Necessary?
Building up and maintaining glycogen stores during training requires a carbohydrate-rich diet. When adequate carbohydrate is not consumed on a daily basis between training sessions, the pre-exercise muscle glycogen content gradually declines and training or competitive performance may be impaired. Daily restoration of the body’s carbohydrate reserves should be a priority for athletes involved in intense training.
“Some athletes train so heavily that they have difficulty eating enough food to obtain the amount of carbohydrate needed for optimum performance. Athletes who have this problem can consider a commercial high-carbohydrate supplement. Most products are 18 to 24% carbohydrate and contain glucose polymers (maltodextrins) to reduce the solution’s osmolality and potential for gastrointestinal distress.”
“High carbohydrate supplements do not replace regular food, but are designed to supply supplemental calories and carbohydrate when needed. If the athlete has no difficulty eating enough food, these products are unnecessary.”
“High carbohydrate supplements can be consumed before or after exercise (eg, with meals or in between meals). Though ultra-endurance athletes may also utilize them during exercise, they are too concentrated in carbohydrate to double for use as a fluid replacement beverage.”
“Carbohydrate feedings maintain blood glucose levels at a time when muscle glycogen stores are diminished. Thus, carbohydrate oxidation (and therefore ATP production) can continue at a high rate and endurance is enhanced.”
Carbohydrate Supplementation Effects on Training
“There is a growing body of evidence suggesting that the performance of resistance-training exercises can elicit a significant glycogenolytic effect that potentially could result in performance decrements. These decrements may result in less than optimal physiological adaptations to training.”
“Currently some scientific evidence suggests that carbohydrate supplementation prior to and during high-volume resistance training results in the maintenance of muscle glycogen concentration, which potentially could result in the maintenance or increase of performance during a training bout.”
“Some researchers suggest that ingesting carbohydrate supplements prior to and during resistance training may improve resistance-training performance. Additionally, the ingestion of carbohydrates following resistance exercise enhances the resynthesis of muscle glycogen, which may result in a faster time of recovery from resistance training, thus possibly allowing for a greater training volume.”
How much to take?
It is suggested that athletes who train heavily consume 7 to 10 g of carbohydrate/kg/day (8). The typical American diet supplies about 4 to 5 g of carbohydrate/kg/day. An intake of 6 to 7 gm of carbohydrate/kg/day is sufficient when the athlete exercises hard (>70% of VO2max) for about an hour per day. An intake of 8 to 10 g of carbohydrate/ kg/day is recommended when the athlete exercises hard for several hours or more per day.
Some athletes may need to reduce fat intake to below 30% of total calories to obtain 8 to 10 g of carbohydrate/kg/day. Sugar intake may be increased to meet the increased carbohydrate requirement, but the majority of the carbohydrate should come from complex carbohydrates. They are more nutrient-dense and, compared to sugary foods, provide more B vitamins necessary for energy metabolism as well as more fiber and iron. Sugar, however, contributes to tooth decay and many products that are high in sugar are also high in fat.
Carbohydrate is the preferred fuel for most sports. Since the depletion of endogenous carbohydrate stores (muscle and liver glycogen and blood glucose) impairs athletic performance, athletes should strive to optimize their carbohydrate stores before, during, and after exercise.
Athletes should consume 7 to 10 g of carbohydrate/kg/day to replenish muscle and liver glycogen following training sessions or competitive events. One to four hours prior to exercise, athletes should consume 1 to 4 g of carbohydrate/kg to “top off” muscle and liver glycogen stores. During exercise lasting an hour or longer, athletes should consume 30 to 60 g of carbohydrate per hour to maintain blood glucose levels and carbohydrate oxidation. To optimize glycogen repletion following exercise lasting 90 minutes or longer, athletes should consume 1.5 g of carbohydrate/kg within 30 minutes, followed by an additional 1.5 g of carbohydrate/kg feeding two hours later.
“A carbohydrate is a biological molecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water); in other words, with the empirical formula Cm(H2O)n (where m could be different from n). Some exceptions exist; for example, deoxyribose, a sugar component of DNA, has the empirical formula C5H10O4. Carbohydrates are technically hydrates of carbon; structurally it is more accurate to view them as polyhydroxy aldehydes and ketones.”