The Study
Co-ingestion of protein and leucine stimulates muscle protein synthesis rates to the same extent in young and elderly lean men.
This study showed that when healthy young and old men ate protein and leucine after light exercise, their muscles started building faster than when they ate just carbs. But it doesn't prove this makes them stronger or bigger over time — just what happened right after eating.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
When older people eat protein and leucine with carbs after moving around, their muscles start building new protein just like young people’s do.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 554 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — this means older adults can rebuild muscle as well as young adults if they get enough leucine with their protein, which challenges the idea that aging always causes muscle resistance to protein.
- 2Young men: muscle growth rate went from 0.060% to 0.082% per hour.
- 3Elderly men: from 0.043% to 0.072% per hour.
- 4Carbs alone made muscles break down protein.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
The American journal of clinical nutrition
Year
2006
Authors
R. Koopman, L. Verdijk, R. Manders, A. Gijsen, M. Gorselink, E. Pijpers, A. Wagenmakers, L. V. van Loon
Related Content
Claims (5)
Consuming 20 grams of protein and 3.5 grams of free leucine with carbohydrates after daily physical activity increases muscle protein synthesis rates by 35% in healthy young men and by 67% in healthy elderly men over six hours, with no statistically significant difference between the two age groups.
When young and elderly men consume protein and leucine together with carbohydrates after simulated daily activities, their bodies retain more protein than they break down.
When healthy older men consume protein and leucine together, their muscles build new protein at a rate similar to that of healthy young men, as long as enough leucine is provided.
When healthy young and elderly men consume only carbohydrates after physical activity, their bodies break down more muscle protein than they build.
Healthy young men have higher rates of protein synthesis and breakdown throughout the body compared to healthy elderly men.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.