Athletic PerformanceExercise ToleranceExercise TestSportsPerformance-Enhancing SubstancesDoping in SportsAthletesPhysical EnduranceSports MedicineSerotoninExerciseFlatfootRunningAnabolic AgentsExercise TherapyOxygen ConsumptionFootballMuscle, SkeletalPhysical ExertionDietary SupplementsBicyclingAnaerobic ThresholdSerotonin Plasma Membrane Transport ProteinsReceptors, SerotoninReceptor, Serotonin, 5-HT2ATask Performance and AnalysisReceptor, Serotonin, 5-HT1ASerotonin Uptake InhibitorsMuscle FatiguePsychomotor PerformanceLactic AcidSerotonin AntagonistsPhysical Conditioning, AnimalHeart RateDyspneaPulmonary Gas ExchangeLung Diseases, ObstructiveTime FactorsReceptor, Serotonin, 5-HT2CSerotonin AgentsReceptor, Serotonin, 5-HT2BReceptors, Serotonin, 5-HT2Breathing ExercisesReceptor, Serotonin, 5-HT1BSerotonin Receptor AgonistsPhysical FitnessCarnosineDouble-Blind MethodPhysical Education and TrainingRespiratory Function TestsAnalysis of VarianceAltitudeEnergy MetabolismWalkingMuscle StrengthReceptors, Serotonin, 5-HT1Pulmonary VentilationRespiratory MusclesCross-Over StudiesSerotonin SyndromeRestSerotonin 5-HT2 Receptor AntagonistsIntermittent ClaudicationOxygenFatigueInspiratory CapacityReproducibility of ResultsAdaptation, PhysiologicalSwimmingFontan ProcedureMuscle ContractionHemodynamicsCardiovascular Physiological PhenomenaPulmonary Disease, Chronic ObstructiveGlycogenRespirationReceptors, Serotonin, 5-HT3Dietary CarbohydratesBody WeightHeart FailureSerotonin 5-HT2 Receptor AgonistsLactatesForced Expiratory VolumeQuadriceps MusclePlasma VolumeCardiac OutputSingle-Blind MethodTryptophan HydroxylaseTreatment OutcomeDehydrationLegCitrate (si)-SynthaseBody Temperature RegulationSerotonin 5-HT1 Receptor AgonistsCarbon DioxideNeuropsychological TestsReceptors, Serotonin, 5-HT4CognitionSensitivity and SpecificityStroke Volume