Isometric ContractionMuscle ContractionPhysical EnduranceMuscle, SkeletalMuscle FatigueMusclesElectromyographyMuscle, SmoothMuscle Fibers, SkeletalIsotonic ContractionTorqueElectric StimulationMyocardial ContractionUterine ContractionElbowMuscle, Smooth, VascularMuscle RelaxationRecruitment, NeurophysiologicalMotor NeuronsMuscle StrengthMuscle ProteinsCalciumKneePhysical ExertionBiomechanical PhenomenaSarcomeresQuadriceps MuscleTime FactorsMyosinsPapillary MusclesExerciseMusculoskeletal Physiological PhenomenaVasoconstrictionPsoas MusclesMuscle SpindlesRabbitsMyofibrilsVolitionGuinea PigsMuscle Fibers, Fast-TwitchTracheaPotassium ChlorideOxygen ConsumptionMyographyStress, MechanicalLegMuscle DevelopmentRunningPhosphocreatineRats, WistarRana temporariaHindlimbDose-Response Relationship, DrugMuscle Fibers, Slow-TwitchPhenylephrineThighAcetylcholineMyosin Light ChainsMuscle WeaknessPhysical Conditioning, AnimalAdenosine TriphosphateRats, Sprague-DawleyAdaptation, PhysiologicalElasticityTendonsModels, BiologicalAnkle JointVasoconstrictor AgentsAction PotentialsCatsMuscle Strength DynamometerNorepinephrineMitochondria, MuscleAnuraEvoked Potentials, MotorEnergy MetabolismHand StrengthActinsMasseter MuscleReflex, StretchAorta, ThoracicHeart RateRespiratory MusclesMovementMyocytes, Smooth MuscleDogsPeristalsisReflexAnalysis of VarianceHandFingersMotor CortexArmRana esculentaPhysical Education and TrainingNeck MusclesAgingMuscle DenervationWeight-BearingForearm