In Roosevelt: The Story of a Friendship, Owen Wister describes Theodore Roosevelt in 1881, at work on a book:
He finished his Naval History of the War of 1812 mostly standing on one leg at the bookcases in his New York house, the other leg crossed behind, toe touching the floor, heedless of dinner engagements and the flight of time. A slide drew out from the bookcase. On this he had open the leading authorities on navigation, of which he knew nothing. He knew that when a ship’s course was one way, with the wind another, the ship had to sail at angles, and this was called tacking or beating. By exhaustive study and drawing of models, he pertinaciously got it all right, whatever of it came into the naval engagements he was writing about.
His wife used to look in at his oblivious back, and exclaim in a plaintive drawl: “We’re dining out in twenty minutes, and Teedy’s drawing little ships!”
Doing research and writing while standing sounds pretty tough, but I guess that’s what made TR the man he was.