This pedal exerciser allows normal walking and running in place on pedals (16, 17) reciprocal back and forth by returning the pedal from varying strides to a forward step-down position in response to user's end of stride action of stepping down on the forward pedal and lifting the other foot at the rear. A return force is applied to a pedal only during its return stroke, avoiding the high force opposing user's stride of elastic return devices. This enables high return forces to return the pedals at high stride rates and long strides without high user stride effort, making possible pedal exercisers allowing normal, varying walk-run strides as on powered treadmills but without a motor drive. Mechanical and pneumatic versions are described, manual and motorized, providing cushioned step-down with automatic stride length, speed variation and stopping responding to user's foot force.