BCAA Fit rule is a high-quality blend of branched essential amino acids for effective muscle mass gain. Leucine, isoleucine and valine are the purest elements of protein and the most important components necessary for the construction of muscle tissue, and the ratio of 2:1:1 provides the most effective action of these substances. How to take BCAA One serving of 5g. mixed with a small amount of liquid. On training days, one portion is taken 20-30 minutes before the start and the second portion after the end of the workout.