RestBed RestPhysical ExertionExerciseExercise TestHead-Down TiltWeightlessness SimulationAdrenal Rest TumorHeart RateWeightlessness CountermeasuresMuscle, SkeletalOxygen ConsumptionTime FactorsBlood PressureCardiovascular DeconditioningHemodynamicsTomography, Emission-Computed, Single-PhotonTechnetium Tc 99m SestamibiRegional Blood FlowCoronary CirculationHeartSpace FlightLegPhysical EnduranceCardiac OutputRepressor ProteinsMyocardial Perfusion ImagingBicyclingPulmonary Gas ExchangeDobutamineMuscle ContractionSupine PositionStroke VolumeRespirationBlood Flow VelocityGravity, AlteredDipyridamoleLower Body Negative PressureOxygenThallium RadioisotopesLactic AcidGated Blood-Pool ImagingWeightlessnessEchocardiography, StressHyperemiaPostureOrthostatic IntoleranceElectrocardiographyVentricular Function, LeftVascular ResistanceSympathetic Nervous SystemCarbon DioxidePhysical Conditioning, AnimalExercise ToleranceAnalysis of VarianceElectromyographyNitrogen RadioisotopesReference ValuesOrganotechnetium CompoundsMagnetic Resonance ImagingCoronary DiseaseEnergy MetabolismIsometric ContractionBaroreflexTomography, Emission-ComputedTreatment OutcomeReproducibility of ResultsEchocardiographyForearmRadiopharmaceuticalsAutonomic Nervous SystemWeight LiftingEpinephrineVentricular Dysfunction, LeftVasodilator AgentsAdaptation, PhysiologicalRubidium RadioisotopesProspective StudiesElectric StimulationRespiratory MechanicsBrainSensitivity and SpecificityPhosphocreatineMyocardial IschemiaFollow-Up StudiesMovementIschemiaNorepinephrineRadionuclide VentriculographyMuscle FatigueValsalva ManeuverRunningAdenosineGlycogenMusclesAngina PectorisHeart VentriclesNeuronsPlasma VolumePredictive Value of Tests