Board Thread:Versus Debates/@comment-26104757-20160511101338/@comment-3965545-20160512233859

Itachi is only proven for a fact to have low Stamina while he was deathly ill. Which according to the most recent explanations he had acquired after awakening the MS, he started taking medicine for it after Joining the Akatsuki which means he was at least 15 when got got sick. He has been sick and taking Medicine since then. So his stamina would most likely be much higher otherwise.