Edited by Jacopo Zuffi, courtesy of La Palestra magazine
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 amino acids have been studied and it is evident that their use maximizes the athletes' sporting performance. Research conducted from 1970 to 1990 showed 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 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 exercise, provided that the caloric supply in carbohydrates and fats was adequate. The three branched chain amino acids (BCAAs), leucine, isoleucine and valine, constitute one third of the muscle proteins (actin, myosin and titin) and are more involved in the process of resynthesis of alanine, during sports practice. There are three branched chain amino acids: valine, isoleucine and leucine. Like all other amino acids, BCAAs (from the English branched chain amino acid) have a plastic function, and thanks to their aliphatic portion they can be catabolized to produce energy and glucose (see glucose-alanine cycle, glucogenic amino acids, hepatic neoglucogenesis). The branched amino acids must not be metabolized by the liver but, after being absorbed in the small intestine, they are conveyed by the blood and subsequently picked up 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 stimulus on glutamine resynthesis).
Metabolism of branched chain amino acids
Today it has been scientifically demonstrated that the oxidation of amino acids for energy purposes occurs already in the early stages of the exercise and acquires more and more importance with the continuation and intensification of the same. The use of BCAAs for energy purposes is linked to the body's energy reserves, the more these (adipocytes, liver glycogen and muscle glycogen) are reduced and the greater the oxidation of the carbonaceous structure of the amino acids and the production of glucose through neoglucogenesis liver. 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 is also prolonged in the first recovery phase to supply the damaged muscle fibers. The branched 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 absolute most used amino acid compared to all those existing in the body. The breakdown rate of leucine is high during resistance exercise (aerobic) but also during the anaerobic exercise (tripping, 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 cycle ergometer sl 55% of VO 2 Max, found that the leucine oxidation was increased by 240%, despite the effort required by the experiment was moderate. Consequently, due to the high consumption of leucine, similar results are found in the use of isoleucine and valine. There are 3 possible causes of catabolism of branched chain amino acids:
• Increased use of free BCAAs in the blood
• Reduced BCAA commitment in muscle protein synthesis
• Exhaustion of muscle proteins.
Integration with branched chain amino acids »
