West DW, Burd NA, Coffey VG, Baker SK, Burke LM, Hawley JA, Moore DR, Stellingwerff T, Phillips SM. Rapid aminoacidemia enhances myofibrillar protein synthesis and anabolic intramuscular signaling responses after resistance exercise. Am J Clin Nutr. 2011 Sep;94(3):795-803.

Abstract

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.

This trial was registered at clinicaltrials.gov as NCT01319513.

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Some believe that by ingesting small amounts of whey protein or pulsing protein after we train you will get much growth than just one big protein shake after we train. This intermittent feeding, in theory mimics a more slowly digested protein. This technique is very popular among athletes who believe in intermittent fasting.

Researchers from McMaster University in Canada have discovered that strength athletes benefit more from ingesting the whey in one large portion than in several small ones. In their study 8 healthy men trained their quadriceps with 8 sets of 10 reps on a leg extension machine. Immediaely after training half of the subjects were given 1 shake that contained 25g of whey protein (BOLUS) and the other half were given smaller shakes of 2.5g of whey every 20 minutes (PULSE). Blood was measured in the subjects for 320 minutes (~5.5 hours)

The design for this experiment is shown in the graph below.

Figure1:


Throughout the 320 minutes that the researchers monitored the subjects' blood . They found the same amounts of essential amino acids [Figure 2] and leucine [figure 3] in both the 25g group and the 10 X 2.5g group.

Figure 2:


Figure 3:


Over the 5 hour period of time one can easily observe that the 25g group [BOLUS] had a peak in the essential amino acid and leucine concentration an hour after intake. In the 10 X 2.5 g group [PULSE] seems to be no peak as seen in Figure 4.

Figure 4:


The excessive amount of essential amino acids and leucine seemed to also stimulate the production of muscle fibre protein [Myofibrillar FSR] discovered from samples of muscle tissue from the subjects as seem below.

Figure 5:


So what does this tell us? Obviously pulsing stimulates myofibrillar FSR (muscle gowth) however when it comes to good, better or best it seems that a 1 time feeding of whey protein is best. During that 1st hour post exercise it is probably a good idea that the body gets as much EAA and leucine as possible to maximally stimulate myofibrillar protein synthesis. The rapid rise in extracellular essential amino acid concentrations, or possibly of leucine alone, that occurred after BOLUS appears to underpin the greater signal activation and protein synthetic response that are observed after an acute bout of resistance exercise. I would personally like to see a comparison of 25g to maybe 50g immediately after training. I have a feeling slightly more might even stimulate myofibrillar protein synthesis even further. Anyway, this is a very interesting study.