Affiliations: [a] Exercise & Sports Science Program, The University
of Tulsa, Tulsa, OK 74104, USA | [b] Department Physics, Massachusetts Institute of
Technology, Boston, MA 02139, USA | [c] Department Physics & Engineering Physics, The
University of Tulsa, Tulsa, OK 74104, USA
Note: [] Address for correspondence: John F. Caruso, Ph.D., 312 Chapman
Hall, 600 S. College Avenue, The University of Tulsa, Tulsa, OK 74104, USA.
Tel.: +1 918 631 2924; Fax: +1 918 631 2068; E-mail: john-caruso@utulsa.edu
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.
