In the never-ending debate of gorging vs. grazing—well, sort of—an intriguing study published in the American Journal of Clinical Nutrition may well turn heads when it comes to the frequent-feeding mantra. For instance, we know that whey is a “fast” protein whereas casein is a “slow” one. If you want a bolus of protein in your body fast, whey is the way to go. If you want that slow trickle of amino acids, then the night-time protein casein is for you.
A French lab more than a decade ago suggested that a “slow” protein may be more anabolic in the long run. Let’s see what happened in a recent experiment.
A group of eggheads looked at the effect of divergent aminoacidemia by manipulating intake patterns of whey protein alone on muscle protein synthesis and anabolic signaling after resistance exercise. In separate experiments, eight healthy men took whey protein either as a single 25-gram bolus or as repeated, small, “pulsed” drinks every 20 minutes to mimic a more slowly digested protein. The anabolic response was measured at rest and after they lifted weights.
The single feeding increased blood essential amino acid concentrations above those of the pulse dosage (162 percent vs. 53 percent) 60 minutes postexercise. On the other hand, pulse doses resulted in a smaller but sustained increase in aminoacidemia that remained elevated above single-dose amounts later, 180 to 220 minutes postexercise. Okay, that makes sense, but what does it mean?
The bottom line on all those findings: Muscle protein synthesis was elevated to a greater extent after the single dose than after the smaller doses: 95 percent vs. 42 percent at one to three hours and 193 percent vs. 121 percent at three to five hours. Translation: Even though the total amount of essential amino acids that flooded the system was the same for both dosage types, the net anabolic effect was still greater with the single feeding.
So for the most anabolic response, the postexercise period is best served with one big dose of protein—in this case whey.1 A reasonable way to accomplish that would be to get a threshold amount of protein and amino acids to optimize the anabolic response. I’d suggest a 20-to-40-gram dose of protein postexercise. If you’re larger than a sumo wrestler, take in even more.
Editor’s note: Jose Antonio, Ph.D., is the CEO of the International Society of Sports Nutrition (www.TheISSN.org); also check out his Web site, www.TheWeekendWorkout.com.
1 West, D.W., et al. (2011). Rapid aminoacidemia enhances myofibrillar protein synthesis and anabolic intramuscular signaling responses after resistance exercise. Am J Clin Nutr. 94(3): 795-803.