Carbohydrates

According to the so-called law of isodynamics, the three energy-providing nutrients carbohydrates, fats and proteins can theoretically substitute for each other in energy production.

The isodyname quantities are:

• 1 g fat = 2.27 g carbohydrates = 2.27 g protein
• 1 g carbohydrates = 1 g protein = 0.44 g fats

The proportion of nutrients of the daily food energy recommended by the DGE should be as follows:

• Carbohydrates: 55-60 % energy (kcal%)
• Fats: 25-30 % Energy (kcal%)
• Proteins: 10-15 % Energy (kcal%)

In fact, however, these ratios do not correspond at all with our present civilized diet. Thus, the existing poor carbohydrate-fat ratio, in which 40% of food energy is supplied by fats but only 40% by carbohydrates, has an unfavorable effect on health, well-being and body weight. In recent years, the consumption of valuable complex carbohydrates (in cereals, potatoes, vegetables) has decreased, while the intake of simple sugars ("empty calories") and fats has increased considerably. In this context lies also the problem of high overweight (obesity), which is a risk factor for the development of various diseases such as cardiovascular diseases, diseases of the musculoskeletal system and the psyche, diabetes, etc.

Carbohydrates

Carbohydrates are considered the most important source of energy for all physical and mental performance. A distinction is made in dietary carbohydrates between monosaccharides (single sugars), disaccharides (double sugars), oligosaccharides (made up of 3-10 monosaccharides) and polysaccharides (multiple sugars).

Examples:

Simple sugars (monosaccharides)

• Dextrose, also dextrose or glucose
• Mannose, an epimer of glucose
• Fructose, also fruit sugar
• Galactose, also mucilage sugar
• Ribose, part of ribonucleic acid (RNA)
• Deoxyribose, part of deoxyribonucleic acid (DNA)

Dual sugars (disaccharides)

• Sucrose, also beet sugar or cane sugar (glucose + fructose)
• Lactose, also milk sugar (glucose + galactose)
• Lactulose, a synthetically modified milk sugar
• Maltose, also malt sugar (glucose + glucose)
• Trehalose

Multiple sugars (polysaccharides)

• Strength
• Cellulose
• Glycogen

The basic building block glucose is the only form of carbohydrate that can be used for energy production. Therefore, the complex carbohydrates must first be broken down or converted into the basic building block glucose. This is done by enzymes (amylases) in the mouth and stomach such as ptyalin. Carbohydrates (glucose building blocks) can provide energy for muscle contractions up to four times (anaerobic) or twice (aerobic) faster than fats, which always require oxygen to burn. Second, glucose, a monosaccharide, is the sole source of energy for the brain and nervous system. Therefore, in its absence, glucose must be synthesized from amino acids by gluconeogenesis (new glucose formation).

If no amino acids are available from the diet (there is no immediate protein store), muscle protein is broken down (anticatabolic effect). Amino acids are released from the muscle proteins and released into the blood for the formation of glucose. In the meantime, this is also known among strength athletes. In order to keep this anticatabolic effect low and to conserve protein reserves, athletes must eat a diet rich in carbohydrates.

Carbohydrates in food

Simple sugars such as glucose, fructose and galactose are mainly found in fruit and honey. Important dietary disaccharides are milk sugar (lactose), maltose (found in beer, for example), and cane or beet sugar (sucrose), which is contained in commercially available household sugar. Complex polysaccharides are found in the form of starch, especially in potatoes, rice and cereals.

Glycemic Index (GI)

The glycemic index (GI) indicates the blood sugar-increasing effect of certain carbohydrates or carbohydrate-containing foods in numbers. The reference value here is glucose (dextrose), which has a glycemic index of 100. Not only the carbohydrate content of a food is decisive for the rise in blood sugar, but also its composition. For example, pure glucose is absorbed quickly and directly into the blood, and blood glucose levels rise rapidly. Foods containing more complex carbohydrates (primarily starch) paired with fiber are digested much more slowly, and the carbohydrates are continuously absorbed into the blood.

No blood sugar spikes occur. The WHO has recommended the glycemic index for the selection of carbohydrates as part of a healthy diet. Foods with a low GI are to be preferred. These do not raise blood sugar abruptly and the pancreas does not have to constantly overproduce insulin, the body's hormone that serves to lower blood sugar levels. The organ is not equipped for a constant high sugar load, so that a decline in its ability to function and eventually manifest diabetes mellitus can be the result.

Which carbohydrates are recommended for athletes?

Simple carbohydrates (mono- and disaccacharides) such as glucose, household sugar (sucrose) and fructose (fruit sugar) are "empty calorie carriers", i.e. they provide no vitamins and minerals apart from calories. are recommended. In terms of blood sugar levels, The complex carbohydrate carriers, e.g. bananas, cereal products, potatoes, fruits, vegetables and legumes, have the advantage that they are not broken down into glucose as quickly and therefore do not lead to a high rise in blood sugar levels as quickly. The simple carbohydrates (sugar, fructose, glucose), due to their rapid absorption into the blood, cause a rapid and high rise in blood sugar, which results in a large release of insulin. Insulin causes a glucose influx into the muscle cells for energy utilization or a build-up of energy reserves in the form of glycogen or, when these are filled, fat. This causes the blood glucose level to drop so quickly that hypoglycemia may occur. This is reflected in a feeling of hunger.

In sports medicine studies it has been proven that the increase of carbohydrates during loads over 45 minutes is useful. It has been shown that carbohydrates can be digested even during the most strenuous exertion and passed through the blood to the muscle cells. This allows one to conserve glycogen reserves and sustain loads longer. The banana is an excellent carbohydrate donor because it has a favorable mixture of complex and simple (fast) carbohydrates. Its low glucose content enters the blood immediately, while the abundant starch enters slowly, while the fructose, which is also present, enters quickly but is slowly converted into glucose (dextrose) over the course of the following hour. Thus, one gets an immediate, slight, but constantly increased blood sugar level at a favorable level for a long-lasting effect at high performance. Therefore, the banana is a popular break food not only in tennis.

Misuse

Insufficient carbohydrate intake can be compensated to some extent by dietary fats. If both carbohydrates and fats are lacking as energy suppliers, protein is broken down instead of the normal energy sources. Prolonged deficiencies can thus lead to the breakdown of muscle, for example. Sufficient carbohydrate intake, on the other hand, has a protein-saving effect. Excessive carbohydrate intake, on the other hand, when the normal storage form is exhausted, i.e. the glycogen reserves are filled up, is converted into body fat in the long term and stored in the adipose tissue. Weight gain is the result.

Importance of glycogen stores

The human body has limited stores of carbohydrates and therefore must constantly replenish its stores through food, otherwise premature fatigue and inadequate recovery after exercise may result. Glycogen stores are normally between 300-400g, with 1/3 being liver glycogen (60-100g) to regulate blood glucose levels and 2/3 being muscle glycogen. A normal mixed diet can store an average of 1.5g of glycogen per 100g of muscle mass in muscle, while this can increase to 2.0g/100g of muscle mass on a high carbohydrate diet. Training can significantly increase the ability to store glycogen in the muscles.

Increasing muscle glycogen stores through "carbo-loading". Athletes can increase muscle glycogen stores up to 2.5 g per 100 g of muscle mass.

Supercompensation of muscle glycogen stores:

If glycogen stores are almost completely depleted after intense physical exertion, they can be increased above the initial level during the regeneration phase if the diet is suitably rich in carbohydrates (60-80% of total energy intake). The first phase, when carbohydrates are stored most rapidly in the muscles, extends over the first 10 hours. This finding shows how important it is to consume sufficient carbohydrates within the first hours after the end of exercise. However, the prerequisite is always that they are emptied beforehand by an appropriately intense endurance load.