The carbohydrates or sugars compounds are generally formed by carbon, oxygen and hydrogen and unlike the proteins rarely contain nitrogen in their composition. These are substances that preferentially use our body as an energy source.
Given the number of units they contain, carbohydrates are classified into four groups:
1. Monosaccharides: is the simplest carbohydrate. As indicated by the prefix mono-- consist solely of a single unit, such as glucose and fructose.
2. Disaccharides: As the prefix di-, these carbohydrates are made up of two units. The best known is sucrose or table sugar, which is the union of glucose and fructose. Lactose is another disaccharide that consists of glucose and galactose.
3. Oligosaccharides: They are made of short and medium chain mono-(3 chains of 15-20 units). This group includes the maltodextrins, glucose chains of varying length with an average of ten units of glucose from the hydrolysis or breakdown of starch.
4. Polysaccharides: These are carbohydrates that are composed of very long chains of monosaccharides. They differ in turn two main groups depending on whether or not energy is used by the body:
- Used as a source of energy: We emphasize the starch of vegetable origin, which is formed by long chains of glucose and glycogen of animal origin.
- Not usable as a source of energy: The most important polysaccharides are integrated into what is called dietary fiber or dietary fiber.
Carbohydrates and Sport
Sports nutrition experts point out that carbohydrates should be the 60-70% of energy intake in the diet of the athlete.
First question arises, what is the ideal carbohydrate to the athlete should consume throughout the day. We must understand that none of the above carbohydrates met all the characteristics to make it ideal carbohydrate exclusively to the sport.
It is obvious that we cannot feed an athlete with only glucose or fructose throughout the day. Similarly, it would be impractical and ineffective for example, a cyclist is fed with rice or potatoes while making a march of 4 hours by bike.
Therefore, each type has specific characteristics in digestion, gastric emptying, rate of absorption, metabolism in the body that makes perfect use in a particular time of the athlete's daily nutrition.
Foods rich in Carbohydrates
As we have seen, one of the ways you can classify carbohydrates is the basis of the number of units they contain. In this way, we can divide them into monosaccharides, disaccharides, oligosaccharides and polysaccharides.
Another way to classify food is based on the glycemic index which is the ability of a food to vary more or less the concentration of blood glucose and therefore, to stimulate the secretion of insulin.
The glycemic index is taken in reference to glucose which has an index of 100. If a food is capable of increasing the amount of glucose in the blood is said to be high-glycemic index and change occurs only if blood glucose is said to be low glycemic index.
Classification of foods according to their Glycemic Index
Foods with high GI:
- Glucose 100
- Rice 91
- Carrots 90
- Cereals 84
- Potatoes 83
- Honey 73
- Bread 70
Foods with moderate GI:
- Sugar 59
- Banana 56
- Grapes 52
- Peas 50
- Chocolate 49
- Oat Cereal 48
- Spaghetti 41
Foods with low glycemic index:
- Orange 40
- Peach 35
- Cauliflower 33
- Apple 30
- Lentils 29
- Whole milk 25
- Fructose 23
Importance of Energy Reserves of Glycogen
Studies in which doctors began to link the carbohydrate with the energy capacity began over sixty years ago. This initial work showed that those athletes who follow a diet rich in carbohydrates for three days before a test, had a much greater resilience that their colleagues who had followed a diet richer in protein and fat. They were therefore the first evidence indicating the importance of carbohydrates in sports.
Thirty years later, appears the explanation for the early doctors to which we referred earlier. Through a biopsy, samples were obtained from the muscle of the athlete before, during and after a resistance test. The results clearly show that the athlete fatigue is directly related to low levels of muscle glycogen . Recall that glycogen is a carbohydrate long chain composed of glucose units and is the way the body stores glucose for energy.
So, today is well aware that those athletes who are capable of storing higher levels of muscle glycogen are also those with greater resilience. In consequence, as dietary advice, the athlete must take care to store as much energy as possible as glycogen in the body.
Logically, the first question we must pose is how to maximize the level of energy storage in muscle glucose. There are basically two aspects that determine the level of muscle glycogen and therefore the capacity of the athlete are:
- The level of training
As dietary advice, we can just influence the level of training of the athletes. The analysis of muscle biopsy, show that people who practice sports frequently have higher levels of muscle glycogen that sedentary people.
Addition to the degree of training, diet plays another key role to achieve high levels of muscle glycogen. For example, there are numerous medical studies showing that if days before a competition, there is a diet rich in carbohydrates, this increases the capacity of resistance athlete.