Glossary

MPS (Muscle Protein Synthesis)

Protein Metabolism Muscle Building Biochemistry

MPS stands for the synthesis of muscle protein. Together with MPB (Muscle Protein Breakdown) it defines the net protein balance: MPS > MPB → gain, MPB > MPS → loss. The term is descriptive, not prescriptive.

Notice

This page provides context and guardrails. It is not individual medical, nutrition, or training advice. Suitability and tolerance are individual; for pre-existing conditions, pregnancy/lactation, or medication, consult qualified professionals before making changes.

Concept and Context

Quick insight MPS describes the formation of new muscle proteins from amino acids. It is stimulated by resistance training and the intake of essential amino acids (especially leucine). Net outcome emerges only in relation to MPB.

  • MPS > MPB: tendency toward net muscle gain.
  • MPB > MPS: tendency toward net loss.
  • Drivers (examples): mechanical tension, protein intake, energy & sleep status.

Measurement and Evidence

Direct MPS measurements in studies use tracer methods and are not available in daily practice. In coaching contexts, MPS is therefore assessed indirectly via performance trends, circumferences and body composition. Time “windows” are approximations and context-dependent.

MPS as a process metric does not replace program design around MEV, SRA and recovery.

Influencing Factors and Practical Ranges

  • Protein per meal (range): practical literature often discusses ~25–40 g high-quality protein or roughly ~0.3–0.5 g/kg — suitability is individual.
  • Leucine threshold: commonly cited ~2–3 g leucine per meal; see Leucine Threshold.
  • Postprandial duration: elevated MPS for ~3–5 h after protein intake; varies with source, dose and status.
  • Training effect: resistance training elevates MPS for hours up to >1 day depending on stimulus, muscle and training status.
  • System factors: energy availability, sleep quality, stress and activity (NEAT) modulate amplitude and duration.

Framework values are orientation — not a recommendation.

Relation to Other Terms

MPB describes protein breakdown. The Leucine Threshold addresses meal amino-acid signaling. MEV, RIR and RPE structure training stimulus. MPS is a process metric — not a meal plan or training prescription.

MYTH #1

“Hardgainers must eat 6 meals a day”

False. The number of meals is secondary – what matters are total daily calories and protein distribution. Most hardgainers do perfectly fine with 3–4 meals plus shakes, as long as they reach their lean surplus and spread their protein evenly throughout the day. Learn more in the full article: Myth #1.

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Ideal as a home base when you want to put creatine, protein, the leucine threshold, MPS, and liquid calories into context – with direct links to Myth-Busting #10 and clear hardgainer priorities.

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Notice

Descriptive information for orientation — not a treatment, diet or training prescription. Individual differences and possible contraindications apply.

© Hardgainer Performance Nutrition® • Glossary • Updated: Nov 20, 2025