A motorized machine for passively applying a tapping force to the bottoms of a user's feet includes a motor, a pedal rocking mechanism, at least one pedal and at least one bumper configured so as to cooperate to, during operation of the motor, cause the bottom portion of the at least one pedal to tap against the at least one bumper so as to provide pulsatile acceleration to the bottom of the user's foot. The pulsatile acceleration has a force sufficient to increase pulsatile shear stress to the endothelium, of sufficient magnitude to cause the release of beneficial mediators.