What is the Origin of Muscle Protein Synthesis Rate?

This term is foundational to muscle physiology, derived from molecular biology studies tracking amino acid incorporation into myofibrillar proteins. The rate refers to the velocity of this anabolic process, typically measured in fractional synthesis rate per unit time. It is intrinsically linked to the action of anabolic hormones like testosterone and IGF-1.

What is the Mechanism of Muscle Protein Synthesis Rate?

The central mechanism involves the mTOR (mammalian Target of Rapamycin) signaling pathway, which acts as the master regulator of MPS. Growth factors, including IGF-1, and essential amino acids, particularly leucine, bind to upstream components, activating mTORC1. This activation then phosphorylates downstream targets like 4E-BP1 and S6K, which ultimately enhance the translational machinery responsible for polypeptide chain elongation.

Muscle Protein Synthesis Rate

Meaning

Muscle Protein Synthesis Rate (MPS) is the biochemical measurement reflecting the speed at which muscle tissue creates new structural proteins, a key determinant of muscle mass maintenance and hypertrophy. This rate must exceed the Muscle Protein Breakdown Rate (MPBR) for net positive adaptation to occur following stimuli like resistance training or adequate amino acid provision. Clinical assessment helps determine the efficacy of anabolic interventions. Tracking MPS is essential for optimizing body composition goals.