Chess grandmasters need incredible amounts of brain power, and also extreme physical endurance, to take on their rivals. Major tournaments can run six hours a day, ten to twelve days in a row. Players might burn up to 6,000 calories and lose two pounds a day during these grueling matches. Today’s chess world champions might train with two hours a day of running, swimming, or tennis, plus a strict diet. In a respin of one of our most popular episodes, ESPN’s Aishwarya Kumar joins Mina Kimes to break down how top chess players meld mind and body.