Abstract
An exercise ergometer that employs two flywheels for inertial resistance was created to abate ankle extensor mass and strength losses incurred with space flight. Unlike other flywheel- and inertia-based devices, the ergometer imparts muscle-lengthening resistance so that the ankle extensors may perform concentric and eccentric muscle actions within a single exercise repetition. Due to the unique manner the ergometer operates and the need to quantify workout data for the development of in-flight exercise protocols, instrumentation of the device is an important concern. After calculation of the flywheels' moment of inertia, a motor with a small rotary shaft and rubber wheel at its terminal end was mounted on the ergometer so that it stayed in contact with, and rotated concurrently with, a single flywheel. Voltage samples produced from changes in flywheel velocity were recorded on-line at 100 MHz. Exercise performance was assessed in healthy college-age subjects (n=34) across two workouts spaced one week apart. Workouts entailed two sets of ten seated calf press repetitions as subjects were instructed to exert maximal voluntary effort. Multiple test-retest measures revealed the inertial resistance ergometer, instrumented as described herein, elicits reproducible intra- and inter-workout performance data.