Muscle Protein Synthesis Calculator
Calculate the optimal timing and protein dose to maximize Muscle Protein Synthesis (MPS) for your specific workout and body weight.
Frequently Asked Questions — Muscle Protein Synthesis Calculator
How long does muscle protein synthesis last after a workout?+
MPS remains elevated for approximately 24-48 hours after a resistance training session. This is the full "anabolic window." The commonly cited 30-minute window is mostly relevant for fasted trainees who need to halt muscle protein breakdown immediately after training. For non-fasted individuals, the urgency is much lower — missing a 30-minute post-workout meal will NOT significantly impair muscle growth if total daily protein is adequate.
What is the difference between muscle protein synthesis (MPS) and muscle protein breakdown (MPB)?+
MPS (Muscle Protein Synthesis) = the rate at which the body builds new muscle tissue. MPB (Muscle Protein Breakdown) = the rate of muscle protein degradation. Net Muscle Protein Balance (NMPB) = MPS minus MPB. Muscle is gained when MPS > MPB (positive protein balance). Exercise independently raises both MPS and MPB — protein intake tips the balance toward MPS. This is why protein timing and dose matter, but daily protein total matters most.
Does protein source affect MPS rates?+
Yes, significantly. Protein sources ranked by MPS stimulation: (1) Whey protein isolate — highest leucine content (10-11%), fastest absorption, greatest MPS stimulus. (2) Whole eggs — better than egg whites alone due to fat aiding nutrient absorption. (3) Casein — slower but more sustained release. (4) Soy protein — comparable to whey for many outcomes. (5) Plant proteins (pea, rice blend) — effective when combined (rice+pea) to provide complete amino acid profile.
How does leucine trigger muscle protein synthesis?+
Leucine is the key amino acid that directly activates the mTOR (mechanistic Target of Rapamycin) signaling pathway — the master switch for muscle building. The leucine threshold for maximizing MPS is approximately 2-3g per meal. This is met by: 25-30g of whey protein, 30-35g of chicken, or 3-4 whole eggs. Below the leucine threshold, MPS response is sub-optimal regardless of meal protein content.