Post Workout Science: Bolus of Protein or Spread it Out?
by: Robbie Durand
I remember as a young teenager setting my alarm clock on my watch for 3-hour interval alarms. Every time the alarm went off, I immediately slugged a BCAA mixture, because back in the day, that’s what I was told. All the top trainers and bodybuilders told me that I had to eat every three hours for optimal protein synthesis. It made sense to think that keeping protein elevated every few hours would create a more anabolic environment. Well, according to the newest research in the Journal of Nutrition, my theory of drinking a protein shake every 3 hours to create a more anabolic environment was flawed.
Muscle protein synthesis is stimulated by a meal and is sustained for at least two hours, but then declines toward normal levels, which occurs in conjunction with the changes in circulating insulin and aminos.
Researchers from McMaster University in Hamilton, Ontario, reported recently that men who consumed whey protein after exercise, either by consuming the entire drink rapidly or consuming it spaced every 20 minutes over a 200-minute feeding period, had dramatically different results despite consuming the same amount.
Muscle biopsies taken from the subjects found that muscle protein synthesis was elevated to a greater extent after rapidly consuming a large single dose of whey protein than after consuming it in smaller portions over a longer period.
There were greater changes in anabolic signaling pathways for muscle hypertrophy (growth) after rapid rather than slow consumption. So it makes sense after your workout to slug your protein drink as opposed to sipping it like a glass of wine.
In a previous study in the Journal of Nutrition, researchers examined how taking constant or intermittent feeding pulses of amino acids would alter protein kinetics. The researchers found that although both continuous and intermittent feeding stimulated muscle protein synthesis, the greatest increase in muscle protein synthesis occurred in the intermittently fed group. So they reported that there is a ceiling effect when it comes to protein synthesis and the constant bombardment of amino acids is not going to further enhance protein synthesis once a maximal level is achieved.
Researchers recently performed another study demonstrating that a one bolus of amino acid is just as effective as spacing or sipping amino acid intake over short periods. In the study, 16 young healthy men were assigned to drink either a 15 g mixed-EAA drink, either as a single dose (“Bolus”) or in 4 fractions at 45-min intervals (“Spread”). At the end of the study, the bolus feeding or single dose achieved rapid increases in insulin levels and amino acids into the bloodstream, whereas spread feeding achieved attenuated insulin responses, gradual low-amplitude aminoacidemia. Despite these differences, identical anabolic responses were observed. With both spread and bolus feeding strategies, a latency of at least 90 minutes was observed before an upswing in muscle protein synthesis was evident. Similarly with both feeding strategies, muscle protein synthesis returned to fasting rates by 180 minutes despite elevated circulating EAAs. The researchers suggested, “Despite distinct plasma and muscle profiles, Bolus feeding provided no anabolic advantage over spread feeding (or vice versa); these findings are in keeping with our hypothesis of there being an intrinsic muscle-full state in young men at rest.” Basically, when I was younger, I did not have to slam a protein shake as clearly based on the studies, one bolus of amino acids had the same effect as sipping smaller doses every 45 minutes. So whether you sip on a protein shake or you just want to chug it down all at once, it does not really matter, as long as you realize that there is no benefit to either method.
So don’t be afraid to go for 2-3 hours without becoming paranoid that you are going to go into a catabolic state, you’re not.
Gazzaneo MC, Suryawan A, Orellana RA, Torrazza RM, El-Kadi SW, Wilson FA, Kimball SR, Srivastava N, Nguyen HV, Fiorotto ML, Davis TA. Intermittent bolus feeding has a greater stimulatory effect on protein synthesis in skeletal muscle than continuous feeding in neonatal pigs. J Nutr. 2011 Dec;141(12):2152-8.
Mitchell, William Kyle et al. “A Dose- rather than Delivery Profile–Dependent Mechanism Regulates the ‘‘Muscle-Full’’ Effect in Response to Oral Essential Amino Acid Intake in Young Men.”J. Nutr. February 1, 2015