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Leucine Threshold Calculator

Calculate your optimal leucine intake for maximum muscle protein synthesis (MPS)

🎯 2.5g minimum threshold💪 Personalized for your body🧬 Science-backed formula

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Understanding the Leucine Threshold

What is the Leucine Threshold?

The leucine threshold is the minimum amount of leucine (2.5-3g) needed to trigger muscle protein synthesis (MPS). Below this threshold, your muscles won't get the signal to grow, regardless of total protein intake.

Key Study: Moore et al. (2009) - Critical role of leucine in MPS activation

Why 2.5g Matters

Research shows that 2.5g of leucine acts as a metabolic trigger, activating the mTOR pathway responsible for muscle growth. This dose maximally stimulates protein synthesis regardless of total protein amount.

Key Study: Churchward-Venne et al. (2012) - Leucine supplementation of protein

Age and Anabolic Resistance

After age 40, muscles become less sensitive to amino acid signals (anabolic resistance). Older adults may need 25-40% more leucine per meal to achieve the same MPS response as younger individuals.

Key Study: Burd et al. (2013) - Greater stimulation required in elderly

Timing and Distribution

Spreading leucine intake across 4-5 meals optimizes 24-hour MPS. Each meal should hit the threshold - pulse feeding (3×3g) beats continuous feeding (9×1g).

Key Study: Areta et al. (2013) - Timing of protein ingestion

Our Calculation Formula

Base Requirement: 39 mg leucine per kg body weight (Phillips & Van Loon, 2011)
Training Adjustment: +33% for intense training, +49% for athletes
Goal Adjustment: +20% for muscle building, +15% for cutting
Age Adjustment: +10% after 40, +25% after 60 (anabolic resistance)
Minimum Threshold: 2.5g per meal (Moore et al., 2009)
Maximum Effective: 4.0g per meal (diminishing returns beyond this)

Scientific References

Areta, J.L., et al. (2013). Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis. J Physiol, 591(9), 2319-31.
Burd, N.A., et al. (2013). Greater stimulation of myofibrillar protein synthesis with ingestion of whey protein isolate v. micellar casein at rest and after resistance exercise in elderly men. Br J Nutr, 108(6), 958-62.
Churchward-Venne, T.A., et al. (2012). Leucine supplementation of a low-protein mixed macronutrient beverage enhances myofibrillar protein synthesis in young men: a double-blind, randomized trial. Am J Clin Nutr, 96(6), 1454-64.
Moore, D.R., et al. (2009). Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men. Am J Clin Nutr, 89(1), 161-8.
Pasiakos, S.M., et al. (2013). Leucine-enriched essential amino acid supplementation during moderate steady state exercise enhances postexercise muscle protein synthesis. Am J Clin Nutr, 97(5), 1090-7.
Phillips, S.M. & Van Loon, L.J. (2011). Dietary protein for athletes: from requirements to optimum adaptation. J Sports Sci, 29(S1), S29-38.

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