PostureSupine PositionTilt-Table TestGravitationFaceHypotension, OrthostaticOrientationGravity SensingDizzinessPatient PositioningHead-Down TiltPostural BalancePerceptual DistortionHeart RateProne PositionRotationSyncope, VasovagalPostural Orthostatic Tachycardia SyndromeOtolithic MembraneProprioceptionPattern Recognition, VisualSupinationSyncopeBlood PressureBiomechanical PhenomenaHead MovementsOrthostatic IntoleranceAstronautsBaroreflexSpace FlightWeightlessnessLegHemodynamicsExercise TestCardiac OutputPhysical ExertionVisual PerceptionVestibule, LabyrinthHyoid BoneNeck MusclesLower Body Negative PressureAdaptation, PhysiologicalMovementRecognition (Psychology)Blood VolumeForm PerceptionQuipazineFootEsophagusBed RestExercisePulmonary Gas ExchangePhotic StimulationEsophageal pH MonitoringAortic BodiesReninTorsoAldosteroneTachycardiaValsalva ManeuverWeight-BearingHypovolemiaGastroesophageal RefluxSympathetic Nervous SystemMidodrineRegional Blood FlowReflex, Vestibulo-OcularPlasma VolumeSemicircular CanalsGeneralization, StimulusNystagmus, PhysiologicRespiratory MechanicsAnalysis of VarianceAutonomic Nervous SystemWeightlessness SimulationVascular ResistanceReference ValuesOxygen ConsumptionMuscle, SkeletalPressureCardiovascular Physiological PhenomenaElectromyographySensation DisordersCarotid SinusTongueGaitFurosemideFigural AftereffectIschiumMassagePsychophysicsAccelerationAnkleBicyclingSyndromeTechnetium Tc 99m Sulfur ColloidTime FactorsPerceptual MaskingLocomotionWheelchairs