"Using a mouse, keyboard or gamepad make my arm tired, so I can't use them in a continual manner. The only device I can use for an extended period of time is a joystick. It's posing problems when I'm test-playing something in progress." - Masahiro Sakurai
Sakurai says that his RSI is so bad that it's at, "the point where it's starting to restrict my work and lifestyle." Sakurai plans on switching to a trackball to get his work done.