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Muscle Protein Synthesis Threshold

Meaning

The Muscle Protein Synthesis Threshold, often referred to as the leucine threshold, is the minimum concentration of circulating amino acids, particularly the branched-chain amino acid leucine, required to maximally stimulate the anabolic process of muscle protein synthesis (MPS) in skeletal muscle tissue. This physiological benchmark is crucial for initiating muscle repair, growth, and maintenance, making it a central focus in preventing age-related sarcopenia and promoting musculoskeletal health. Failure to consistently reach this threshold, especially in older adults, leads to a net catabolic state and gradual loss of functional muscle mass. Clinical nutritional planning must ensure that this threshold is met at strategic times.