It is known that protein supplementation during strength training increases hypertrophic gains. The complementary protein intake builds, repairs and makes positive the nitrogen balance. The key amino acid is leucine, and ingested proteins with a high leucine content would be more conducive to initiating protein synthesis. In a way, the quality of proteins would therefore have an impact on muscle mass.
There is evidence that taking protein, in addition to diet during a training program increases hypertrophy. But other research has been done to try to define the mode of action of the proteins with regard to the dose, the moment of setting and the quality of these proteins . The meta-analyzes focused on the muscle hypertrophy measured after training and supplementation and not on the gain in strength and on the quality of the proteins that really weighs in the balance.
The muscle hypertrophy that occurs after training is the result of several processes causing changes in the content and activity of the cells. Exercise sensitizes the muscle to the accumulation of blood amino acids. Exercise therefore acts in synergy with the synthesis of muscle proteins (MPS) that occurs with proteins. The muscle fibers thus benefit from this addition of proteins to increase their size, provided that they combine a higher intake with the usual consumption, and a training of musculation and this whatever the age. The time of taking, before or after training, also does not seem essential to influence the strength or hypertrophy,
What is absolutely necessary to trigger the famous synthesis of proteins are the essential amino acids (the famous BCAA, leucine, isoleucine, valine) and it is known that among them leucine alone is the signaling molecule capable of putting En route the process by being the foundation of muscle building. As evidence for the need for another, the leucine threshold is higher in the elderly to induce protein synthesis and therefore a higher dosage (both leucine and protein) at rest or In combination with exercise. The best result was observed with whey proteins, the most naturally leucine-rich.
Other studies have shown the superiority of whey protein , with a high leucine content, for its effect on muscle mass increase (on average + 2.24 kg), in studies combining whey and bodybuilding, which classifies Whey in first position for its effect on body composition as part of a muscle gain as part of a weight loss or weight maintenance regimen . Whey is more supportive of hypertrophy than carbohydrates (which are meant to provide energy, not amino acids) and other proteins, although this difference is not very marked, as the gain in strength Occurs with all forms of protein.
However, the quality of proteins remains important, as is the leucine content, as whey drinkers gain more muscle . If one considers rice protein, it would take twice as much as whey to cause the same effects. The comparison of whey protein and pea protein was not conclusive because the doses were insufficient in both cases to cause this famous synthesis of proteins. As for the other types of proteins, mixed they gave responses quite similar to the whey, because of their extended amino acids, or enriched with some BCAA.