Proposed mechanism of action(s)

BCAAs are essential amino acids metabolised primarily within the skeletal muscle and they play an important role in both cellular energy homeostasis² and in the regulation of muscle protein synthesis.³ Theoretically, by supporting energy metabolism and by stimulating muscle protein synthesis it is suggested that BCAA/ leucine may support muscle growth. Furthermore, there is some evidence that BCAA/leucine supplementation may assist in the recovery from muscle damaging exercise via similar mechanisms to those described above.

Finally, BCAA supplementation may provide substrate to working muscle under glycogen depleted conditions and due to BCAA competition for transport into the brain with tryptophan, BCAA supplementation may limit tryptophan entry into the brain. Theoretically this would reduce serotonin production in the brain and limit the onset of fatigue.⁴