Muscle protein synthesis (MPS) is the anabolic process that repairs and grows muscle fibres after resistance training. MPS is stimulated by two primary factors: mechanical loading from exercise (particularly resistance training) and amino acid availability (particularly leucine). Protein intake of 20-40g per meal maximally stimulates MPS; spreading protein evenly across 3-4 meals per day produces greater total MPS than eating the same total in 1-2 meals. MPS remains elevated for 24-48 hours after resistance exercise. Anabolic window research shows meal timing is less critical than once believed — total daily protein matters most.
Key points
- Stimulated by resistance training + protein
- Leucine is the key trigger amino acid
- 20-40g per meal maximally stimulates MPS
- Elevated for 24-48h after resistance training