https://www.stlpr.org/2020-12-03/on-chess-settling-the-debates-is-chess-a-sport chess
While tournaments don’t contain the same physical action as what is displayed on a football field, it is a fallacy to believe that chess players don’t require both mental and physical exertion. There may not be a more demanding game for mental acuity, but being in good physical shape is also a prerequisite for the world’s most competitive players. For these world-class chess players, training their bodies for peak performance is key to staying on top of the rigorous mental demands of the game. Chess grandmaster Levon Aronian has been quoted saying: “The best way to manage the stress is to be in good physical shape. At this moment I have lots of chess knowledge and, therefore, apart from chess, I need to have physical strength.”
Again heart rate is physical exertion it is a muscle
That's what stress is a physical reaction it isn't just emotional lol