It's no exaggeration Vigorous exercise definitively improves mental health Here's how: 1) Exercise increases an enzyme on skeletal muscle known as kynurenine aminotransferase 2) This increases the conversion of kynurenine into kynurenic acid 3) This reduces the amount of kynurenine available to then be transformed into other harmful metabolites, such as quinolinic acid (a neurotoxin that plays a role in depression) | FoundMyFitness