Branched-chain amino acids
Branched-chain amino acids, or BCAAs, include the amino acids leucine, isoleucine, and valine. They've gotten a lot of press in recent years, and for good reason. Kendall states, "It's well-known that BCAAs, especially leucine, help to regulate protein metabolism by promoting protein synthesis and suppressing protein breakdown. This can help to speed up the recovery process of muscles damaged during resistance training."
In other words, a BCAA supplement could help you recover more quickly while reducing the experience of delayed onset muscle soreness, helping you feel a little bit better the next time you hit the gym. Even better, you might find your BCAA supplement helps you increase workout intensity and endurance capacity. It all gets pretty technical, but Kendall explains, "Since BCAAs and tryptophan (another amino acid) compete for the same protein carrier, increasing BCAA concentrations can reduce the amount of tryptophan crossing the blood-brain barrier (BBB), reducing the amount of serotonin produced, potentially delaying fatigue."