Exercise increases tryptophan's entry into the brain by alleviating competition with branched-chain amino acids, thereby increasing serotonin production.

“Additionally, exercise helps promote the brain transport of tryptophan, serotonin's precursor, into the brain, further supporting your mental well-being and cognitive functions.”

“exercise causes BCAAs to be taken up into muscle & this alleviates competition & allows tryptophan to get into brain.”

“when you exercise Branch chain amino acids like Lucine and isol luuc get taken up into your muscle and they eleviate the competition between tryptophan and Branchin amino acids which usually occurs in the brain so so tryptophan gets in your brain more when you're exercising”