The complex human machine seeks to protect its self by breaking down components of muscle fibers for fuel during intense exercise such as weight training or sporting activity. This procedure naturally results in an increased blood level of free fatty acids, which is a homeostatic regulating signal the brain to stop breaking down muscle.
Now, when taken before training high doses of the branched chain family along with some very specific other amino acids, plays an elaborate trick by flooding the blood with free fatty acids to prevent muscle break down long before it is supposed to begin. As a result an alternative fuel source is available for use (FFA) and muscle fibers you have worked hard to earn are spared that function.
We do know that glutamine is heavily leached from muscle during exercise. It may be likely that FFA's preexisting within the muscles beforehand will be readily used to stimulate growth and repair, slow that process and put you a big step ahead of the game by thwarting muscle break down and further stimulating anabolism.
Both branched chain amino acids and glutamine are proven to reduce muscle breakdown during training by stimulating an anabolic state throughout the workout. Once more, BCAA's can even raise insulin to that acceptable level I talked about earlier in the absence of easily stored energy. The BCAA group can act in cooperation with glutamine as a surprisingly efficient intrinsic muscular fuel source.
So, a state of anabolism and elevated protein synthesis (muscle growth) can be promoted by the right combination of the BCAA group and glutamine (I use the PRD product GlutaCene and NitroMine in my research) when taken before a workout. Such usage can be timed perfectly to arrive at the functioning cell just as the workout winds down and ends. This alternative super fuel is used by muscles and can spare valuable stored energy in the form of glycogen. Now that 'spared' glycogen can be used down the stretch of your competition or even your workout if it is unusually long and hard, when you need it most.