The University of Wyoming's Biomechanics Laboratory is examining the link between the energetics and mechanics of both human and animal locomotion. The group is currently investigating how the relative duration of muscular activity (i.e. duty factor) influences the time course of performance loss resulting from the impairment in muscle force production that occurs as the duration of an all-out effort extends from seconds to minutes. In order to conduct one of their experimental protocols, this group requires human subjects to precisely and repeatedly match prescribed contractile and relaxation periods during knee-extension exercise. To provide subjects with visual feedback with respect to their adherence to the assigned contractile durations and limb velocities, a custom instrumentation array panel was developed consisting of two arrays of high-visibility light emitting diodes. One array provides the experimental subject with the selected, or target, rate of position change while the complementary array provides an indication of the actual rate of displacement achieved by the subject.