The manual two-choice reaction task was performed by using a computer connected with two joysticks, fixed in front of the ergometer handlebars. Two empty squares (6 × 6 cm) were horizontally lined up on the center of the screen, adjusted to the subject's eye-level, drawn in yellow on blue.
When one of the squares became filled with red, the subjects were asked to respond as quickly and accurately as possible by tilting the appropriate joystick. A warning signal appeared 1200 msec after the preceding response.