Heart RateExercise TestRestPhysical ExertionHeartOxygen ConsumptionExerciseBlood PressureAdrenergic beta-AntagonistsHemodynamicsElectrocardiography, AmbulatoryElectrocardiographyPropanolaminesExercise ToleranceTime FactorsHeart FailureBed RestHeart Rate, FetalAngina PectorisVagus NerveDouble-Blind MethodAutonomic Nervous SystemHeart DiseasesProspective StudiesHypertensionHeart TransplantationHeart Defects, CongenitalSympathetic Nervous SystemBaroreflexFetal HeartRespirationMyocardial ContractionStroke VolumeCardiac OutputMyocardiumHeart AtriaVentricular Function, LeftDogsHeart Function TestsHeart BlockPropranololMyocardial IschemiaHeart ValvesCoronary DiseaseRegional Blood FlowMuscle, SkeletalCardiovascular Physiological PhenomenaParasympathetic Nervous SystemTelemetryTreatment OutcomeNorepinephrineEchocardiographyCardiotonic AgentsBradycardiaTachycardiaOxygenBlood Flow VelocityFollow-Up StudiesCoronary CirculationPostureCardiovascular SystemAtropineEpinephrineReference ValuesMetoprololPressoreceptorsPhysical EnduranceMyocardial InfarctionSupine PositionVentricular Dysfunction, LeftSystoleReflexRisk FactorsCardiac Pacing, ArtificialSinoatrial Node