Led by Dr. Adrien Robin and Dr. Ana Diaz-Artiles and supported by a postdoctoral grand from the Translational Research Institute for Space Health (TRISH), this project examines how graded gravitational stress (from head-down to head-up tilt) shapes cardiovascular and ocular function in healthy adults. In a crossover design, participants (men and women) complete two deconditioning protocols: (1) 48 hours of head-down bed rest and (2) a drug-induced hypovolemia (using diuretic). During each session we systematically vary body angle and continuously measure hemodynamics, fluid transfert, and vascular/ocular indices. Our goal is to define sex-specific dose–response curves to gravity and identify mechanisms of deconditioning. Findings will inform astronaut health risk models and enable individualized countermeasures such as optimized exercise, fluid loading, and compression garments. The work also translates to Earth, supporting better management of syncope, safer perioperative positioning (e.g. Trendelenburg position), and more effective rehabilitation strategies for older or bedridden patients.
