Daily use of countermeasures to prevent headward fluid shifts throughout 30 days of strict head-down tilt bed rest

We demonstrate that daily use of lower body negative pressure or venoconstrictive thigh cuffs following aerobic exercise is well tolerated throughout 30 days of exposure to the spaceflight analog strict head-down tilt bed rest. Both countermeasures reduced SV and internal jugular vein cross-sectional area, indicators of the venous fluid shift, but to a lesser degree than the upright posture.