Affiliations: [a] Exercise and Sports Science Program, The University of Tulsa, Tulsa, OK, USA | [b] The University of Oklahoma College of Medicine, Tulsa, OK, USA | [c] Department of Chemistry and Biochemistry, The University of Tulsa, Tulsa, OK, USA
Correspondence:
[*]
Corresponding author: John Caruso, 800 S. Tucker Drive, Tulsa, OK 74104, USA. Tel.: +1 918 631 2924; Fax: +1 918 631 2068; E-mail:[email protected]
Abstract:
BACKGROUND: To limit physiological changes incurred with space
flight, exercise hardware should impart sufficient mechanical loads with
minimal energy costs. OBJECTIVE: Assess net energy costs from exercise done on
flywheel-based hardware. METHODS: Subjects (17 men, 19 women) performed the following leg
press workouts in a randomized sequence: two sets of concentric-only (CO2)
actions, two sets with both concentric and eccentric (CE2) activity, and
four sets of concentric-only (CO4) actions. Workouts entailed 8-repetition
sets with 90-second rest periods. O2 was measured before, during and
after workouts to calculate net energy costs. Total work (TW) was derived
from flywheel rotation rates as follows: TW = (1/2)(J)(ω 2)
whereby J = rotation inertia and ω = angular velocity. TW and net
energy costs were assessed with 2(gender) × 3(workout) ANOVAs with repeated
measures for workout. RESULTS: TW had significant differences by gender (men > women) and
workout (CE2, CO4 > CO2). Net energy costs also yielded significant
differences by gender (men > women) and workout (CO4 > CE2, CO2). CONCLUSIONS: For the CE2 workout ∼ 50% of the TW occurred
through muscle lengthening. Eccentric actions should be part of workouts
done on this hardware, as they impart large mechanical loads with little net
energy cost.
