A treadmill exerciser involving an upwardly and rearwardly sloping treadmill having a plurality of steps which are activated by the weight of a person "walking" up them. The tread portion and the riser portion of each step are connected at both ends by hinges to each other and to endless chains which permit the steps to move or fold around end sprockets as the steps move from an upper inclined course of the chains to a lower inclined return course, and vice versa. A speed control mechanism, driven by one of the chains, employs a gyroscopic flywheel which cooperates with a non-rotatable but axially slidable brake drum to provide even, continuous step movement and a controlled start-up. The flywheel drives a plastic cylinder composed of plastic fingers which fly out, under centrifugal force, into contact with the inner surface of the brake drum thus preventing further increased speed for the user. With the brake drum in one axial position, the plastic fingers become partially disengaged allowing for rapid step speed; when the brake drum is moved to an opposite axial position, step movement is halted. The brake drum can be adjusted to positions between the above two axial positions to provide a controlled speed of movement compatible with the interests or needs of the operator. A control panel, mounted between the top of the tubular handrail shafts, provides operating, goal-setting, and health related information.