Cardiovascular DeconditioningHead-Down TiltBed RestHeadPostureDown SyndromeHead and Neck NeoplasmsHead MovementsSyncope, VasovagalFemur HeadSperm HeadSyncopeRotationFemur Head NecrosisHead Injuries, ClosedCraniocerebral TraumaSupine PositionOtolithic MembraneGravity SensingGravitationVestibule, LabyrinthOrientationPelvisDizzinessAccelerationOrthostatic IntoleranceHeart RateWeightlessness SimulationCarcinoma, Squamous CellEye MovementsSemicircular CanalsHead Protective DevicesPelvic BonesTime FactorsPostural Orthostatic Tachycardia SyndromeModels, BiologicalAutonomic Nervous SystemHumeral HeadNeck MusclesBlood PressureVestibular DiseasesTorsion AbnormalityPediculusReproducibility of ResultsVestibular Function Tests