Heart RateHeartExercise TestExercise TherapyExerciseExercise TolerancePhysical ExertionOxygen ConsumptionHeart FailureBlood PressureHeart Rate, FetalPhysical EnduranceAutonomic Nervous SystemHemodynamicsHeart DiseasesMuscle, SkeletalRestHeart TransplantationTime FactorsHeart Defects, CongenitalElectrocardiographySympathetic Nervous SystemBicyclingFetal HeartBaroreflexPhysical FitnessAdrenergic beta-AntagonistsRespirationElectrocardiography, AmbulatoryCardiovascular Physiological PhenomenaCardiac OutputStroke VolumeRunningAnaerobic ThresholdMyocardial ContractionLactic AcidHeart Function TestsPulmonary Gas ExchangeHeart AtriaMyocardiumRegional Blood FlowCoronary DiseaseHeart BlockVentricular Function, LeftPropranololDogsResistance TrainingHeart ValvesParasympathetic Nervous SystemTelemetryMuscle Stretching ExercisesEnergy MetabolismNorepinephrineOxygenBradycardiaTreatment OutcomeCardiovascular SystemPhysical Education and TrainingEchocardiographyProspective StudiesAnalysis of VarianceDouble-Blind MethodPropanolaminesEpinephrineCross-Over StudiesBody TemperatureAdaptation, PhysiologicalLegPostureReference ValuesTachycardiaBreathing ExercisesReflexPressoreceptorsAtropineRisk FactorsCardiotonic AgentsCardiac Output, LowSupine PositionFollow-Up StudiesMyocardial InfarctionMyocardial IschemiaBody WeightMetoprololVentricular Dysfunction, LeftCatecholaminesSportsSystoleChronic DiseaseSinoatrial NodeCarbon DioxideRats, WistarRats, Sprague-DawleyDiastoleBlood Flow VelocityRespiratory MechanicsGlycogenAgingAutonomic Nervous System DiseasesWalking