MRI-compatible stepper exercise device. The subject extends and then flexes alternating knees in a dynamic stepping motion as shown in (A) and (B). The resistance is controlled by weights on the lever. Subjects step to the beat of a metronome, and the workload is calculated with readings from an optical displacement sensor on the levers and the frequency of the motion. The device allows comparison of parameters in the same scan plane under rest and stress conditions, as shown in (C).