The necessity of physical fitness to create peak mental performance has been a well-known fact in esports. Useful to see the documented effects of pushing yourself cognitively within the chess world.

The 1984 World Chess Championship was called off after five months and 48 games because defending champion Anatoly Karpov had lost 22 pounds. “He looked like death,” grandmaster and commentator Maurice Ashley recalls.

https://www.espn.com/espn/story/_/id/27593253/why-grandmasters-magnus-carlsen-fabiano-caruana-lose-weight-playing-chess