Carbohydrates make the basic energy fuel for humans, whether we like it or not. Many myths have been associated with the ingredient. Nowadays we know it can be a two-edged sword but once used correctly, it will bring positive results.
Carbohydrate free diets and fat burning
Any sportsperson doing silhouette sports or disciplines with weight limits, has at least once followed a low-carbohydrate or very low-carbohydrate diet, in a more or less conscious way. It is true that such a diet leads to a relatively quick reduction of weight but this is not the only effect. Scientists have analysed the impact of low-carbohydrate diet on the body of people doing sports. The following two results were particularly interesting.
The results of the first study were published in the "Journal of Applied Physiology” and they state that strength training at a glycogen deficit causes a disorder of the expression of genes responsible for muscle hypertrophy. In another study, conducted in 2005, scientists from the Human Performance Lab in Indiana discovered that a diet deprived of carbohydrates weakens the expression of the gene encoding the muscle protein (AKT). AKT, or protein kinase B, is an essential molecule involved in the cellular signalling pathways. This factor is also able to induce the protein synthesis pathways and that is why it is a key signalling protein in cellular pathways leading to the hypertrophy of skeletal muscles and general growth of the tissues. After examining sections of tissues, the scientists discovered that the reduced concentration of glycogen in the muscles reduced the expression of genes responsible for muscle hypertrophy. Results revealing that the resting level of the expression of genes involved in the hypertrophy of the muscles (encoding myogenin and IGF-1) was lower than in the ones deprived of glycogen were even more worrying. The conclusions from the experiment were as follows: weight training at a simultaneous deficiency of glycogen in the muscles does not stimulate the activity of the genes engaged in the processes contributing to muscle growth. Diets containing small and moderate quantities of carbohydrates work out better than a low-carbohydrate ketogenic diet, if we want to remove the fatty tissue and maintain the anabolic condition. In the light of the results of the quoted study we have to realise that a low level of carbohydrates impairs regeneration of the muscles and prevents their mass increase.
If you pay peanuts, you get monkeys – types and structure of carbohydrates
Normally, carbohydrates are classified as simple (mono- or disaccharides) or complex (polysaccharides), depending on the number of components – simple sugars – in a carbohydrate molecule. Their structure, however, tells very little about the impact they have on our body and the level of sugar in the blood. They are more often categorised with GI and GL parameters.
The glycemic index is the measure of how the body reacts to food containing carbohydrates. To make a precise measurement, each source of nutrition is compared with the standard – normally glucose – and tested at equivalent quantities of carbohydrates (the glycemic index of glucose is 100).
Food with a high GI causes a high increase in the sugar level in the blood, when the GI value exceeds 70. Examples of such food include processed starch products, e.g. potatoes, corn flakes, white bread, white rice and products containing sugar, e.g. cakes, sweets and sweetened beverages, as well as low-quality Carbo type of supplements.
Foodstuffs with a low glycemic index do not exceed the value of 55 and cause a slower and lower increase in the sugar level in the blood. Such products include bean, lentils, wholemeal bread, muesli, some fruit and some dairy products. Products with a medium GI include porridge, some kinds of rice and sweet potatoes , whose glycemic index has a medium value between 55 and 70.
Protein-rich food such as meat, fish, poultry and eggs, as well as food rich in fat, e.g. plant oils, butter, margarine and avocado contain minor amounts of carbohydrates or do not contain them at all, therefore they have no GI value. However, adding these products to your meal – both fats and proteins, as well as foodstuffs with a low glycemic index – can reduce the total GI value of the meal. Ripening of fruit, cooking and other thermal processing have a negative impact on the GI – as a result of the processes, the GI value goes up.
Although the glycemic index (GI) points to the glucose release rate, the glycemic load (GL) reflects the abundance of the consumed portion (carbohydrates per serving), i.e. both the quality and quantity of carbohydrates.
The main problem related to the GI is that it does not take into account the size of the portion, and thus makes a false negative impression about the specific food. Watermelon, for instance, with a glycemic index of 72, is classified as having a high GI, so it would be forbidden for a person concerned about maintaining a slim figure, following a low GI diet. However, a medium-sized piece of the fruit (weighing ca. 120 g) provides only 6 g of carbohydrates, which is a quantity insufficient to increase the level of sugar in the blood. You would have to eat 720 g of watermelon to collect 50 g.
Another drawback is the fact that some food with a high content of fat has a low GI, which provides a wrong, seemingly beneficial impression on the particular foodstuff. Potato chips, for instance, have a lower GI (54) than roast potatoes (85). It is easy to overeat with them, since they are rich in fat (saturated fatty acids) and have a high calorific density. They are not stodgy, though.
Glucose - the basis of human metabolism
Metabolism of carbohydrates is mainly related to glucose, which is the only source of energy for the brain and spinal cord. It is an energy substrate for the muscles, liver, heart, kidneys and intestines, and its reserves are stored in the liver and muscles in the form of glycogen. The serum transports the consumed carbohydrates in a form of glucose to the liver, where the following processes are carried out:
• transformation of carbohydrates into fats,
• storing sugars in the form of glycogen,
• glucose release to the blood serum to transport it to tissues such as muscles.
Glycogen is a form of storing glucose in the liver and muscles. Long-lasting training effort conditions its initial level in the muscle cell. Its content depends on the kind of diet. A diet rich in carbohydrates, as compared to a protein-fat diet and normal and mixed diets, predisposes the body to the longest operation of the muscles. Glycogen reserves in the body are limited and amount to 300 g in people not doing any sport, whereas they can even reach the level of 600 g in sportspeople. Carbohydrate reserves depend on: intensity of effort, load duration, kind of training as well as the quality and quantity of the supplied sugar.
Functions of carbohydrates in the body
In the introduction, we quoted an analysis of a study confirming the impact of a high-carbohydrate diet on building muscle mass, supplying the working muscles and supporting their recovery after an effort. However, it is not the only tissue using the fuel. Both the brain and the heart also need a constant supply of carbohydrates (in the form of glucose circulating in the blood) to function properly.
Carbohydrates from food are transformed into glycogen, which is deposited in the muscles – exactly in the same way as we fuel up the car before a journey, our muscles have to be filled with glycogen before training. The more active we are, the more of these compounds we need. Persons doing exercise every day for 2 hours need ca. 4-7 g of carbohydrates per each kilogram of their body weight, or ca. 50–60% of the total calorie supply. It certainly depends on the sport you do and your somatotype, but the general rule is that the more muscles are involved in the effort at a time, the more carbohydrates are necessary for a properly quick regeneration of glycogen. With the above in mind, crossfit, swimming, MMA or long-distance running will be characterised by higher consumption of carbohydrates than bodybuilding, although there are some exceptions to the rule. Intensely training sportspeople, doing exercise for more than 4 hours a day, may need up to 10 g of carbohydrates per kilogram of their body weight.
When it comes to the physiology of the body, it is worth mentioning glycogen supercompensation, which is the basis of the beneficial impact of physical exercise on the body. The phenomenon was particularly well recognised, described and widely used in sports training but it can be well used to explain a number of processes occurring in the human body during any kind of effort and rest. It also allows for a rational planning of the effort and is based on exhausting the energy reserves during exercise. Struggling to restore the balance, the body replenishes the previous reserves (compensation) at rest. If the effort was so high that the reserves were exhausted, not only does the body compensate for the losses it suffered, but it also stores some spare reserves. This makes it possible to perform at a slightly higher level next time compared to the previous cycle. Thus, the body behaves similarly to some cautious housewives, who in a situation when a product from their pantry is used very quickly, besides trying to restore the previous condition, make a surplus to avoid such an unpleasant future surprise when they run out of it in a critical situation. Proper supercompensation processes make the basis of success in every sports discipline.
Digestion of carbohydrates
The process of enzymatic decomposition of carbohydrates begins in the oral cavity. By chewing, the food is comminuted and mixed with saliva generated in salivary glands. Saliva contains an enzyme called ptyalin, which decomposes some bonds in complex carbohydrates. It transforms amylose to maltose and maltotriose, and amylopectin to maltose, maltotriose and dextrins. Ptyalin can only act within the oral cavity and the oesophagus. Its efficiency is impeded in the acidic environment of the stomach. The salivary glands also secrete amylase, which also hydrolyses complex carbohydrates. Similarly to ptyalin, it is deactivated in the acidic environment of the stomach.
The subsequent stages of digestion initiated in the oral cavity take place in the intestines under the influence of amylase, an enzyme secreted by the pancreas. When food gets from the stomach to the duodenum, the alimentary hormone – cholecystokinin – is secreted by the cells lining its walls. It stimulates the pancreas to produce pancreatic juice, composed of e.g. pancreatic amylase. It is an enzyme which further decomposes carbohydrates to quite simple forms called oligosaccharides. They can be absorbed directly into the blood to a minor extent. However, the majority of them are subject to further decomposition to single molecules, i.e. simple sugars, which are used directly as a source of energy.
The last stage of carbohydrate digestion takes place on the surface of cells covering the small intestine, i.e. the brush border. Oligosaccharidase (lactase, maltase, saccharose and isomaltase) and disaccharidase enzymes are secreted there and break carbohydrates down into the basic simple sugar used by the human body – glucose.
Hormone balance and absorption of carbohydrates
Only some carbohydrates are absorbed by passive transport without any participation of the body hormones. It happens for instance when you drink isotonic drinks containing up to 6% of carbohydrates during your workout. When glucose builds up in the blood (elevated concentration after a meal), transport regulated by insulin and glucagon is activated. Insulin is a hormone produced by beta cells of the pancreas. Thanks to an increased production of insulin and its impact on the effector cells (myocytes, adipocytes and hepatocytes) glucose penetration into the cells interior is boosted, which reduces its level in the blood. When the situation is reverse (low level of sugar in the blood), glucagon (hormone produced by alpha cells of the pancreas) gets to the liver through the portal vein and is almost completely absorbed there, whereas only a small amount gets to the general circulation. When you are hungry, glucagon secretion goes up, which contributes to maintaining the proper concentration of glucose in the blood and is extremely important for maintaining proper functioning of the brain. Glucose and insulin are the essential regulators of carbohydrates transformation in the body. One should remember that insulin is the basic factor determining why carbohydrates can be called a two-edged sword. Its excess secretion will after some time lead to a gradual immunity of the body to the hormone, resulting in type 2 diabetes.
Carbohydrates and post-workout recuperation
The human body has only a small reserve of carbohydrates (glycogen), which is used up quickly during effort, causing a loss of effort tolerance. What is more, muscle catabolism increases since amino acids released from the proteins are transformed into glucose (glucose-alanine cycle). That is why we have to replenish carbohydrates during effort to maintain high physical efficiency and always directly after training – to increase the carbohydrate reserve (glycogen supercompensation). In a period close to the effort, use only carbohydrates with a varied structure, preferably in a liquid form, i.e. containing mono-, oligo- and polysaccharides (TREC MAX CARB, VITARGO ELECTRO-ENERGY). Such carbohydrate compositions can only be found in supplements, however. They guarantee quick replenishment of energy, efficient limitation of protein decomposition and significant over-replenishment of glycogen reserves.
Supplementation with carbohydrates
Not everything comes down to the glycemic index of the particular kind of carbohydrates and to whether they are simple or complex. There are also other biological factors influencing metabolism, and scientists had to make great efforts to understand their action. The rate at which carbohydrates leave the stomach is another issue important for each sportsperson. The more dynamic the process is, the faster they get to the bowels, where they are digested and absorbed. It leads to a faster increase in the glucose and insulin levels and the subsequent process of storing glycogen and the body undertaking post-workout anti-catabolic action (not to mention that is not recommended to do physical exercise on a full stomach). Research was conducted in 2000 comparing the speed of Vitargo, carbohydrates acquired from corn starch and a mixture of maltodextrin and glucose leaving the stomach. It turned out that in the case of Vitargo the process was much more dynamic, which partly explains why the product replenishes the used reserves of glycogen so fast (over 80% more efficiently). For endurance athletes and people doing physical exercise several times a day, Vitargo makes an obvious choice both before and after the training. But what about those who focus only on building dry muscle mass and strength, doing traditional exercise, where the workout session takes place once a day and lasts for an hour or less? The latest studies also indicate that it is legitimate to take Vitargo also in this case ¬– consumed after weight training, it replenishes the energetic reserves of the body 63% more rapidly, taking maximum advantage of the "anabolic window". This accelerates the process of muscle mass regeneration and extension . It is actually a paradox: why do complex carbohydrates from Vitargo (amylopectin isolated as a result of multi-stage starch purification) leave the stomach and are absorbed faster than pure glucose? In fact, owing to an extremely high molecular weight, the osmolality of the product is very low, as opposed to glucose. To put in in simple terms, the parameter determines how long it takes for a particular kind of carbohydrates to be neutralised in the stomach acids. The most important point is what budget we have. If we are looking for the cheapest source of carbohydrates before or after training, let's choose maltodextrin or dextrose. If, however, we want to use carbohydrates that seem most effective, the results of research suggest that we should take Vitargo. If we are ready to pay more for a good protein supplement than for cheap, low quality plant proteins, why not focus on the best carbohydrates in our supplementation, accelerating muscle growth and regeneration at the same time?
• Ketogenic diets work well when you quickly want to lose fatty tissue, but they can also cause muscle loss.
• Ketogenic diets increase muscle acidity (reduce the pH), which can accelerate proteolysis in the muscle tissue.
• Training under glycogen deficiency reduces expression of genes responsible for the hypertrophy of muscles.
• Your trim when doing weight training is limited by a low level of glycogen.
• A low level of glycogen activates the AMPK. This is a molecular ingredient of a functional signal transduction pathway, which makes it possible for the skeleton muscle cells to react to the accessibility of nutritive ingredients. Interestingly enough, atrophy related to age and a reduced growth possibility are features typical of quickly contracting skeleton muscles. After a biopsy of muscle tissues, it turns out that the level of AMPK increases with age in the tissue at rest. Furthermore, an increased activity of AMPK is related to the atrophy of quickly contracting muscles.