Research

Hormonal

Post-exercise ingestion of carbohydrate combined with protein and free leucine significantly increases mixed muscle fractional synthetic rate and whole-body net protein balance compared to carbohydrate alone.

After resistance training, consume a drink containing carbohydrates and protein within the recovery window. Adding extra leucine (or using a whey protein source, which is naturally high in leucine) alongside carbohydrates maximizes muscle protein synthesis and shifts your body into a net positive protein balance, whereas carbohydrates alone are insufficient to stop muscle breakdown.

GoodSupportsHIGH confidence
We conclude that coingestion of protein and leucine stimulates muscle protein synthesis and optimizes whole body protein balance compared with the intake of carbohydrate only.
René Koopman et al. · American Journal of Physiology-Endocrinology and Metabolism · 2004

Why this rating

Randomized, double-blind, controlled trial with stable isotope tracing (gold standard for synthesis measurement), though sample size is small (n=8).

Source

Combined ingestion of protein and free leucine with carbohydrate increases postexercise muscle protein synthesis in vivo in male subjects

René Koopman et al. · American Journal of Physiology-Endocrinology and Metabolism · 2004

DOI 10.1152/ajpendo.00413.2004

rct · n=8Cited 313×
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DOI resolved against Crossref · corpus check 2026-06-10

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