Carbohydrate english version.... This article to remind readers of the target (professional and lay) who, despite currently we tend to favor the raising of the protein in the diet at the expense of the carbohydrate, the latter (represented by the sum of simple carbohydrates and complex) FUNDAMENTAL importance in human nutrition and in particular in support of sport performance. Carbohydrates or carbs are nutritious calories made up of carbon, hydrogen and oxygen; Importance of Carboidratisi divided into mono, oligo-and polysaccharides in proportion to the number of molecules (bound by a hydrogen bond) of which they are made. IN A BALANCED SYSTEM COVERING THE CARBOHYDRATES 55-60% OF FOOD RATION, they have the function to KEEP glucose homeostasis (glucose concentration in the blood) and are used especially during the intense work, especially in physical exercise. Oxidized, carbohydrates provide an average of 4.1 kcal / g REPRESENT THE HOME ENERGY SUBSTRATE OF CENTRAL NERVOUS SYSTEM; In addition, carbohydrates are part of nucleic acids (ribose and deoxyribose) and certain enzymes and vitamins. Because of its importance in the maintenance of blood glucose, glucose (simple carbohydrate) is stored as glycogen (complex carbohydrate); the latter is present in muscles (about 70%), liver (about 30%) and in the kidneys (approximately 2%). Once depleted glycogen stores, the rate of re-synthesis of reserves is estimated to be 5% to 7% of the time; In addition, ENERGY SYSTEM USING A BALANCED, COMPLETE MUSCLE ASSOCIATED WITH REST, for a total recovery takes at least 20 hours. The blood glucose, the value of which fluctuates in physiological conditions between 3.3 and 7.8 mmol / l (60-140 mg / 100 ml), can be defined as a reflection of the balance between production and utilization. In the fasting state the liver and kidney glucose continuously enter into the bloodstream to prevent your blood sugar drops below the 3.3 to 5 mmol / l. After taking the meal, glucose is absorbed from the gut into the blood poured by increasing the blood sugar up to 130/140 mg / dl; consequently, the secretion of INSULIN (hormone BASIC ENTRY OF GLUCOSE IN ALL THE FABRIC WITH THE EXCEPTION OF THE NERVOUS) increases, and ENCOURAGES glycogen resynthesis. Conversely, when in conditions of prolonged fasting blood glucose falls below normal values, the body responds by lowering the production of insulin in order to maintain the blood glucose and to ensure the proper functioning of the central nervous system. In a similar situation, the cells that need energy production can use the lipid substrate through the B-oxidation of fatty acids, but to do this in an optimal manner is always necessary a small amount of carbohydrates; if after a few days of fasting blood glucose is insufficient to support the central nervous system, would increase as a result the risk of neuroglycopenia (condition that causes SEIZURES, COMA AND DEATH). In addition to promoting glycogen synthesis, insulin tends to turn off glycogenolysis, favoring the lowering of blood sugar. It is of vital importance for the regulation of energy metabolism as IS THE ONLY TO HORMONE hypoglycemic effect, while glucagon, adrenaline, cortisol and somatotropin (hormones or regulators against controinsulari) stimulate the degradation of reserves with hyperglycaemic effect. Hyperglycemia = stimulation of insulin secretion and inhibition of the release of hormones against regulators Hypoglycemia = inhibition of insulin secretion and stimulation of the release of hormones against regulators It still wrong to consider the regulation of blood glucose as an isolated process, as it APPEAR CLOSELY RELATED TO THE METABOLISM OF FAT AND PROTEIN; the whole is mediated by hormonal mechanisms extremely sophisticated able to ensure an optimal quantity of metabolic energy to the cells of the organism. In prolonged fasting, or after LARGE VOLUMES OF EXERCISE, glycogen stores are exhausted and the energy can only be provided by the oxidation of fatty acids and gluconeogenesis from alanine (converted to pyruvate and inserted into the Krebs cycle ) resulting from the catabolism of muscle protein. Addition to the latter, albeit to a lesser extent, contribute to the production of glucose, glycerol, lactate, and other amino acids (such as aspartate, valine and isoleucine that are convertible into intermediates of the Krebs cycle). A neoglucogenesis too active promotes the overproduction of ketone bodies by the liver; under conditions of hypoglycemia, the latter representing MAJOR SOURCE ENRGETICA for extrahepatic tissues, but because of their acidity, PH MAY AFFECT THE BLOOD AND PROMOTE THE APPEARANCE OF SIDE EFFECTS INDUCED BY keto-acidemia. Curiosity Many practitioners of physical culture and some nutrition experts assess the Glucidi as non-essential elements, as their physiological homeostasis is partly guaranteed by the process of gluconeogenesis. However, observing the cycle of energy production and evaluating the intensity of metabolic activation in the sport of endurance, it is appropriate to specify that: In the Krebs cycle, a key step in cell respiration capable of producing NADH and FADH2 (that will come later in the respiratory chain), the starting substrate Acetyl-Coenzyme A (derived from glycolysis of glucose and B-oxidation of fatty acids) NEED an immediate CONDENSATION with oxaloacetate by citrate synthase. Oxaloacetate is the molecule of departure and arrival of the Krebs cycle, and can be obtained from the demolition of asparagine and aspartic acid (non-essential amino acid) BUT in a much more rapid and efficient conversion of the PYRUVATE by pyruvate carboxylase. Whereas the pyruvate is a molecule resulting from the glycolysis of carbohydrates (macronutrients introduced with food in a rapid and selective), while the amino acid asparagine is present in limited amounts in foods (and its ex-novo synthesis is however not a process of rapid use), I think we can say that in cellular respiration and in particular in the energy metabolism of carbohydrates endurance sports play a crucial to say the least. Glycemic Index The metabolism of carbohydrates can be expressed in terms of glycemic index (GI); This index highlights the differential impact of carbohydrates on blood glucose and sullinsulinemia. In particular, the IG is equal to the ratio between the glycemic response of a particular food and the reference value, multiplied by 100 The reference food can be white bread or glucose and the dose of carbohydrate is considered equal to 50 grams. The IG is useful to define the quality of the food pre-race meal (which must have a low metabolic rate), and the IMMEDIATE (within one hour) post-race (which on the contrary, will be characterized by the rate of digestion , absorption and metabolism of insulin ALSO INDEPENDENT very high). Studies performed on athletes who practice moderate and prolonged activity have shown that carbohydrate intake during exercise NOT positively influences physical activity in terms of metabolism and performance (although it is not mentioned the potential for saving and restoring the muscle glycogen); therefore seems more logical choice to consume meals with high amounts of carbohydrates low GI before the provision.
Posted on: Mon, 06 Oct 2014 21:37:57 +0000
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