You have likely heard of protein spiking that is used by unscrupulous supplement companies to artificially elevate protein levels in protein powders. Well, recent evidence suggests that modest spiking of protein powder with the branched chain amino acid (BCAA) leucine can maximize protein synthesis after endurance exercise.
In a recent study published in Medicine and Science in Sports and Exercise, researchers sought to determine if a low dose of leucine mixed with a postworkout whey protein/carbohydrate blend would boost protein synthesis after a bout of interval training. In a nutshell, they found that taking 5g of leucine with 23g of whey protein isolate in a postworkout shake maximized protein synthesis.
This is not surprising, since leucine is the primary BCAA involved in turning on anabolism, but it does show that you easily can get more from your protein shakes. It cannot be overstated that we do not recommend using products that add amino acids simply to boost protein scores. As such, we recommend buying blended or pure protein powders (i.e., with no added amino acids), then simply add 5g of free form leucine to your postworkout shake to maximize anabolism.