Tryptophan (TRP) is an essential amino acid. Metabolites of TRP have been identified as important mediators in immune regulation and function of the central nervous system. Inflammation strongly stimulates to the breakdown of TRP into Kynurenine (KYN), representing the initial step of the KYN pathway. Recently, exercise interventions have been able to demonstrate a modification of the KYN pathway plausibly by altering inflammation. However, modifications differ between acute and chronic exercise interventions. As such, this review examines the current studies that have investigated the effect of an acute (single bout) or chronic (training) exercise intervention on levels of TRP and KYN in both healthy and diseased populations.