The temporal pattern of blood amino acid elevations, such as a rapid spike versus a slow release, does not necessarily determine muscle protein synthesis rates, because total amino acid availability, represented by the area under the curve, may be similar across different patterns and blood concentrations do not consistently correlate with muscle protein synthesis.

Study: Protein Type, Protein Dose, and Age Modulate Dietary Protein Digestion and Phenylalanine Absorption Kinetics and Plasma Phenylalanine Availability in Humans

The study shows that how fast or slow amino acids enter the blood depends on the type of protein, but the total amount that gets in matters more—supporting the idea that timing isn’t everything.

Study: Ingestion of Free Amino Acids Compared with an Equivalent Amount of Intact Protein Results in More Rapid Amino Acid Absorption and Greater Postprandial Plasma Amino Acid Availability Without Affecting Muscle Protein Synthesis Rates in Young Adults in a Double-Blind Randomized Trial

The study found that even though free amino acids caused a faster spike in blood levels compared to whole protein, both led to the same amount of muscle building, supporting the idea that how fast levels rise isn’t the most important factor.

Study: Influence of protein source (cricket, pea, whey) on amino acid bioavailability and activation of the mTORC1 signaling pathway after resistance exercise in healthy young males

Even though whey protein caused a bigger spike in amino acids in the blood, it didn’t lead to more muscle growth signals than pea or cricket protein. This supports the idea that how fast amino acids rise isn’t the only thing that matters for building muscle.