GLOSSARY

Valine is an essential branched-chain amino acid classed as glucogenic. This describes its carbon skeleton, not a guaranteed endurance effect from supplementation.

Leucine, isoleucine and valine form the three branched-chain amino acids and are all essential for humans. BCAA abbreviates that group rather than naming a fourth amino acid. Many protein foods contain them, so adequate food protein itself contributes to their intake without automatically requiring a separate branded product.

After nitrogen removal or transfer, an amino acid's carbon skeleton can enter energy, glucose-producing or ketogenic pathways. This differs from dietary essentiality. Glucogenic does not mean immediate, complete conversion of every gram eaten into blood glucose; bodily demand and metabolic conditions determine actual flux through these pathways.

Initial branched-chain amino acid processing occurs substantially in tissues such as muscle, and oxidation can change during exercise. This is not the main fuel pathway for every session and does not automatically require extra BCAAs. An amino acid used for energy also need not have come from newly broken-down muscle protein.