A combined individualized cycling exercise and artificial gravity training protocol as a spaceflight deconditioning countermeasure

Orthostatic intolerance (OI) remains a post-flight challenge for astronauts. As part of the ESA/CNES BRACE bed rest study, we tested, in ambulatory participants, a combined individualized cycling exercise and artificial gravity (AG) training procedure as a multi-system OI countermeasure. The training limits of cycling intensity and AG exposure were based on individual V̇O2peak and presyncopal AG level. In a randomized crossover design, heart rate (HR) and blood pressure responses were assessed during cycling with or without AG exposure. Our results demonstrated cardiovascular stimuli (i.e., higher HR and blood pressure) during cycling with AG exposure. Greater maximum HR responses were observed in men with AG exposure. This novel individualized exercise and orthostatic training protocol was successful in providing each participant with equally strenuous cardiovascular stimuli close to their tolerance limits regardless of individual and sex differences.