Muscle protein synthesis (MPS) is the biological process by which the body builds new proteins to repair and build muscle tissue. It involves using amino acids to repair existing muscle proteins or create new ones. MPS is crucial for muscle growth, repair, and maintenance of muscle mass, influencing overall health and physical performance. Resistance training creates small tears in muscle fibers, which the body then repairs by synthesizing new proteins, leading to increased muscle strength and size.
MPS and muscle protein breakdown (MPB) constantly occur, and the balance between these processes determines muscle mass. When MPS exceeds MPB, muscle mass increases; when MPB exceeds MPS, muscle mass decreases. Factors influencing MPS include nutrition, exercise (especially resistance training), rest, and genetics. Consuming enough protein, especially essential amino acids like leucine, is crucial for maximizing MPS. The timing of protein intake, particularly after exercise, can also enhance MPS.
Aging can lead to a blunted MPS response to protein intake, contributing to the loss of muscle mass. However, physical activity, especially resistance training, can increase the sensitivity of muscle tissue to protein and help compensate for this anabolic resistance. Researchers have also identified a protein, ZAK-beta, that plays a fundamental role in building muscles, with potential implications for treating muscle disorders and age-related muscle loss. Vegan or animal-based protein sources seem to have no impact on muscle building.
