Which trackball? Logitech Marble Mouse works great for me because it puts my hand in a position that most resembles a hand-shake (relative to other mice and trackballs.) I noticed immediate benefits and thought "Hey trackballs are great!" but then I started using a Mac at work and the scrolling there is not so great so I bought a Kensington Expert Mouse for the fancy scroll ring. Just awful. Wrists flat on the desk, hands bent up toward the ceiling. Worse than a mouse. Not all trackballs are great.