Rapid aminoacidemia enhances muscle protein synthesis

Rapid aminoacidemia enhances myofibrillar protein synthesis and anabolic intramuscular signaling responses after resistance exercise

Background: Ingestion of whey or casein yields divergent patterns of aminoacidemia that influence whole-body and skeletal muscle myofibrillar protein synthesis (MPS) after exercise. Direct comparisons of the effects of contrasting absorption rates exhibited by these proteins are confounded by their differing amino acid contents.

Objective: Our objective was to determine the effect of divergent aminoacidemia by manipulating ingestion patterns of whey protein alone on MPS and anabolic signaling after resistance exercise.

Design: In separate trials, 8 healthy men consumed whey protein either as a single bolus (BOLUS; 25-g dose) or as repeated, small, “pulsed” drinks (PULSE; ten 2.5-g drinks every 20 min) to mimic a more slowly digested protein. MPS and phosphorylation of signaling proteins involved in protein synthesis were measured at rest and after resistance exercise.

Results: BOLUS increased blood essential amino acid (EAA) concentrations above those of PULSE (162% compared with 53%, P < 0.001) 60 min after exercise, whereas PULSE resulted in a smaller but sustained increase in aminoacidemia that remained elevated above BOLUS amounts later (180–220 min after exercise, P < 0.05). Despite an identical net area under the EAA curve, MPS was elevated to a greater extent after BOLUS than after PULSE early (1–3 h: 95% compared with 42%) and later (3–5 h: 193% compared with 121%) (both P < 0.05). There were greater changes in the phosphorylation of the Akt–mammalian target of rapamycin pathway after BOLUS than after PULSE.

Conclusions: Rapid aminoacidemia in the postexercise period enhances MPS and anabolic signaling to a greater extent than an identical amount of protein fed in small pulses that mimic a more slowly digested protein. A pronounced peak aminoacidemia after exercise enhances protein synthesis.

Tl;dr: drink a whey-protein shake immediately after your workout for the best increase in muscle-protein synthesis.


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Anonymous says April 5, 2013

In the past Art DeVany and others have claimed that food/protein intake immediately after exertion shuts down a growth hormone surge that normally happens. The claim was you should wait an hour or two after training to eat.

Mangan says April 6, 2013

Interesting, I’d like to see a scientific reference for that. Absent protein intake, exercise just breaks down muscle, is my understanding.

Bill says April 6, 2013

Hi Mangan,
I would never argue against the use of protein supplements for exercisers, but I WOULD argue about timing – imo all of the logic seems to favor PRE-exercise nutrition as opposed to drinking a “whey-protein shake immediately AFTER your workout” – eg, http://caloriesproper.com/?p=2055. What are your thoughts on the issue?
all best, Bill

Mangan says April 6, 2013

I gotta say that most of the research I’ve read favors protein post-workout. Pre is of course good too, but post is better. There are lots of papers out there on this.

Toddy Cat says May 3, 2013

Art DeVany has also argued that steroid abuse was not a problem in baseball in the 1990’s. I’ve learned a lot from Art, but he does have some rather odd opinions.

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