The invention relates to a structure of rocker arms with optical sensing control for an exercise apparatus. The rocker arm of an exercise apparatus includes a handgrip. At least an optical sensor in accordance with the invention is positioned within a finger groove of the handgrip. The finger groove is so constructed that its form corresponds to the finger pad of the finger of an operator. Meanwhile, the finger groove is provided with an aperture in which the optical sensing element is hidden. The optical sensing element is connected to a console of the exercise apparatus through a conducting wire for setting different functions (exercise speed, slope or resistance) by means of effective detection signals. Therefore, the exercise apparatus is operable by means that a finger of both hands is slightly moved at fixed point during the exercise session.