Chess grandmasters need incredible amounts of brain power, but also extreme physical endurance. Major tournaments can run for six hours a day, 10 to 12 days in a row. Players might burn up to 6,000 calories and lose two pounds a day during these grueling matches. To prepare, today's chess world champions endure physical training that would tire out any pro athlete: hours a day of running, swimming or playing tennis while maintaining a strict diet. ESPN's Aishwarya Kumar joins Mina Kimes to break down how top chess players meld mind and body training in more sophisticated and extreme ways, all to best their fierce rivals.