Branched-chain amino acids (BCAA) are essential amino acids (specifically, valine, leucine and isoleucine). They are essential, meaning we must get them in our diet because our bodies do not produce them. Branched chain amino acids have various functions related to energy production during and after exercise so they are needed in adequate amounts, but not excessive.
BCAA are often used to prevent fatigue and improve concentration. But the most relevant to you, perhaps, is the common practice of taking BCAAs to improve exercise performance and reduce muscle breakdown. While the first use has a fair amount of sceptics, the second is widely accepted in the medical world.
In today's martial art world, it seems the type of arts that get the most attention are the sports schools like MMA (Mixed Martial Arts), Tae Kwon Do and JuJitsu schools. I have found that although many of these schools have students (and instructors) that are technically and athletically quite good, it saddens me to see some of them have lost the essence of the martial way. I realize this isn't all martial arts schools, but I have seen a trend that has lead many martial artists away from the true meaning of karate do.
The Martial Way, also called Budo, means "knowledge as a way to improve ones life and the life of others." Budo is a way of living and a way of dying.