After a workout muscles recover and grow faster the more amino acids they can absorb from the blood. That’s why so many strength athletes drink a shake with whey or another easily absorbed protein after working out. Sports scientists at McMaster University in Canada have discovered that strength athletes benefit more from ingesting the whey in one large portion than in several small ones.
There are indications that proteins have a strong anabolic effect in elderly people if you administer them in concentrated form: to start with you deny your body protein for a number of hours and then you give it a couple of dozen grams at once. We’ve written about this here, here and here.
Research on protein pulse feeding is popular among athletes who believe in intermittent fasting. Logical, as an increased anabolic effect from a concentrated administration of protein meshes seamlessly with the idea of intermittent fasting.
The Canadians make no comment about intermittent fasting or protein pulsing. Their article is more fundamental.
The researchers got male students to train their upper leg with 8 sets of 10 reps on a leg extension machine and then gave the students proteins. Half of the students were immediately given a giant-size shake containing 25 g whey [BOLUS], the other half were given a mini-shake every 20 minutes containing 2.5 g whey [PULSE]. [A little confusing as we just talked about protein pulses: our apologies.]
The set up for the experiment is shown below.
Throughout the 320 minutes that the researchers monitored the students’ blood they found the same amounts of essential amino acids [below left] and leucine [below right] in both the 25 g group and the 10 X 2.5 g group.
But over time there’s a clear difference: in the 25 g group [BOLUS] you can see that there was a peak in the essential amino acid and leucine concentration an hour after intake. In the 10 X 2.5 g group [PULSE] there’s no peak.
The excessive amount of essential amino acids and leucine stimulates the production of muscle fibre protein [Myofibrillar FSR] the Canadians discovered when they studied samples of muscle tissue from the subjects.
“In conclusion, we report that BOLUS after resistance exercise is more effective in stimulating myofibrillar protein synthesis than is PULSE”, the researchers conclude. “The greater myofibrillar protein synthesis response after BOLUS was associated with greater acute phosphorylation of anabolic signaling proteins that regulate translation initiation. 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.”
Rapid aminoacidemia enhances myofibrillar protein synthesis and anabolic intramuscular signaling responses after resistance exercise.
West DW, Burd NA, Coffey VG, Baker SK, Burke LM, Hawley JA, Moore DR, Stellingwerff T, Phillips SM.
Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Canada.
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.
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.
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.
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.
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.
PMID: 21795443 [PubMed - indexed for MEDLINE]