Ingestion of essential
and their presence in the blood is a potent stimulus to increase muscle protein synthesis.
Some researchers have hypothesized that there is a limit to how much protein synthesis can be elevated even when essential
remain elevated. To provide further evidence of this effect, researchers from the United Kingdom measured the time course of increased muscle protein synthesis after the ingestion of 45 grams of whey protein isolate. Blood levels of essential amino acids, particularly leucine, peaked after 60 min and remained elevated 3 hours after ingestion of the
drink. Rates of
synthesis lagged slightly behind the increase in blood leucine peaking at about 90 min after ingestion to levels that were three-fold higher than pre-whey ingestion. After this peak, rates of protein synthesis rapidly returned to baseline despite continued availability of
inside the muscle. The results clearly show that a bolus of whey protein results in a marked but transient increase in protein synthesis. The decline in protein synthesis in the face of increased plasma and muscle levels of leucine and other essential amino acids suggests that there may be a limit to the increase in
muscle protein synthesis
possible with a single meal of protein. The results lead one to speculate that pulsing protein in repeated doses is a better strategy than using a single bolus, although future research is required to confirm if this is more effective.
- Atherton PJ, Etheridge T, Watt PW, Wilkinson D, Selby A, Rankin D, Smith K, Rennie MJ. Muscle full effect after oral protein: time-dependent concordance and discordance between human muscle protein synthesis and mTORC1 signaling. Am JClin Nutr. 2010 Nov;92(5):1080-8.