In healthy individual skeletal muscles represent 45 % of the total mass and spend most of energy for movement. The body’s energy is produced primarely in the aerobic and also in anaerobic way. There are three major energy mechanisms that provide energy and restore ATP reserves: by the hydrolysis of creatine phosphate, anaerobic glycolysis of glucose and oxidative phosphorylation of fats, carbohydrates and proteins. The energy resources for physical activity are muscle glycogen, blood glucose, free fatty acids, triglycerides and amino acids. Several factors influence the source and the way of energy use during workout; intensity and duration of training, level of training and of metabolic characteristics of an individual. Carbohydrates are the primary and fastest source of energy. They are stored in the body as muscle glycogen and liver glycogen, and are also found as free glucose in the blood. Muscle glycogen is the primary source of energy, while the liver glycogen maintains a normal blood sugar level for optimum training and so that undisturbed functioning of central nervous system. The nutritional regeneration after exercise is very important as it restores the energy, nutrition and fluid balance and enable tissue regeneration and training adaptation. The time that is needed for regeneration depends upon: the exhaustion of glycogen stores, extent of muscle damage, amount and time of carbohydrate consumption and level of training. Studies have shown that glycogen restoration approximately takes place in three stages. In general, the first 2 hours of the recovery is the fastest, over the next 4 hours it slows down and after this period, restoration slows down to a normal speed. The key factors in restoring muscle glycogen stores are the amount, time and type of carbohydrate intake, the frequency of meals, and in certain situation also the combination of proteins and carbohydrate consumption.
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