Tilt-Table TestDizzinessSupine PositionPostureSyncope, VasovagalBaroreflexSyncopeHypotension, OrthostaticSympathetic Nervous SystemHeart RateBlood PressureHemodynamicsGravitationGravity SensingFaceOrientationRotationOtolithic MembranePatient PositioningPostural Orthostatic Tachycardia SyndromeOrthostatic IntoleranceHead MovementsVestibule, LabyrinthHead-Down TiltPostural BalancePerceptual DistortionProne PositionProprioceptionWeightlessness SimulationSupinationSpace FlightBiomechanical PhenomenaPattern Recognition, VisualHeadAstronautsAutonomic Nervous SystemWeightlessnessLegSemicircular CanalsCardiac OutputAdaptation, PhysiologicalNeck MusclesValsalva ManeuverLower Body Negative PressureVisual PerceptionFigural AftereffectAccelerationMovementMidodrineForm PerceptionSpinal CurvaturesPelvisPhotic StimulationExercise TestPhysical ExertionTachycardiaRegional Blood FlowVascular ResistanceNystagmus, PhysiologicCarotid SinusHyoid BoneEye MovementsPsychophysicsExerciseRecognition (Psychology)Plasma VolumeIschiumEsophagusPulmonary Gas ExchangeReninSpace PerceptionBlood VolumeWeight-BearingMassageAnalysis of VarianceQuipazineCardiovascular Physiological PhenomenaPelvic BonesReference ValuesTime FactorsFootAldosteroneBed RestMuscle, SkeletalCardiovascular DeconditioningRespiratory MechanicsEsophageal pH MonitoringSpineWheelchairsAortic BodiesElectromyographyTorsoAutonomic Nervous System DiseasesGaitSensation DisordersBlood Flow VelocityHypovolemiaGastroesophageal RefluxElectrocardiographyReflex, Vestibulo-Ocular