Important studies on the use of proteins have shown that exercise metabolizes some amino acids faster than others.
For over 30 years the effects of the use of branched chain amino acids have been studied and it is highlighted how their use maximizes the sports performance of athletes. Research conducted from 1970 to 1990 has shown that demanding physical activity uses a large amount of non-essential amino acids. (alanine and glutamine) in a higher percentage than all the others. The level of these two amino acids decreases during physical activity, therefore the remaining pool of amino acids present in the muscle and blood must make up for their production.
Branched chain amino acids
Until a few years ago it was believed that proteins were not used for energy purposes during physical exercise, provided that the caloric supply in carbohydrates and fats was adequate. The three branched chain amino acids (BCAAs), leucine, isoleucine and valine , constitute a third of muscle proteins (actin, myosin and titin) and are more involved in the process of resynthesis of alanine, during sports. There are three branched chain amino acids: valine, isoleucine and leucine. Like all other amino acids, B.C.A.A. (from the English branched chain amino acid) have a plastic function, moreover, thanks to their aliphatic portion they can be catabolized to produce energy and glucose (see glucose-alanine cycle, glucogenic amino acids, hepatic neoglucogenesis). liver but, after being absorbed in the small intestine, they are carried by the blood and subsequently captured directly by the muscles, where they can be used to repair damaged protein structures (anabolism) or for energy purposes. With their action they are also able to reduce the production of lactic acid, the central fatigue syndrome and to preserve the immune defenses (thanks to the stimulation on the resynthesis of glutamine).
Branched-chain amino acid metabolism
Today it is scientifically proven that the oxidation of amino acids for energy purposes occurs already in the early stages of exercise and acquires more and more importance with its persistence and intensification. The use of BCAAs for energy purposes is linked to the energy reserves of the exercise. body, the more these (adipocytes, hepatic glycogen and muscle glycogen) are reduced and the greater will be the oxidation of the carbonaceous structure of amino acids and the production of glucose through hepatic neoglucogenesis. The endurance muscle activity, if particularly prolonged over time. , is characterized by the reduction of protein synthesis due to the lack of amino acids that occurs following their use as an energy source. This degradation also continues in the first recovery phase to replenish damaged muscle fibers. Branched chain amino acids also play an essential role in protein synthesis and are therefore also indicated in anaerobic or power sports as they are functional to the growth of muscle mass. Scientists have succeeded in demonstrating that of the 3 branched amino acids, leucine is the one that plays the main role and is therefore the amino acid used by far the most compared to all those existing in the body. The rate of degradation of leucine is high during l "endurance exercise (aerobic) but also during anaerobic exercise (sprint, weights, etc.).
The Prog. Vernon Young of MIT, considered a world authority in the field of proteins, measured exactly how much leucine can be consumed during physical activity, for example by measuring subjects who had cycled on a bicycle ergometer at 55% of VO2Max, they found that the oxidation of leucine was increased by 240%, although the effort required by the experiment was moderate. Consequently, with the high consumption of leucine, similar results can be found in the use of isoleucine and valine. The possible causes of branched-chain amino acid catabolism during exercise are 3:
• Increased use of free BCAAs in the blood
• Reduced commitment of BCAAs in muscle protein synthesis
• Depletion of muscle proteins.
Integration with branched chain amino acids "
