Isometric ContractionMuscle ContractionMuscle FatigueMuscle, SkeletalElectromyographyElectric StimulationIsotonic ContractionTorqueMyocardial ContractionUterine ContractionElbowRecruitment, NeurophysiologicalMusclesMuscle, SmoothMuscle Fibers, SkeletalMotor NeuronsKneeMuscle StrengthMuscle RelaxationSarcomeresBiomechanical PhenomenaCalciumMusculoskeletal Physiological PhenomenaVasoconstrictionPhysical EnduranceMyosinsTime FactorsVolitionPapillary MusclesPsoas MusclesQuadriceps MusclePhysical ExertionMuscle, Smooth, VascularRana temporariaGuinea PigsMyographyPotassium ChlorideRabbitsPhenylephrineStress, MechanicalPhosphocreatineAnkle JointMuscle SpindlesMyofibrilsDose-Response Relationship, DrugElasticityVasoconstrictor AgentsThighAcetylcholineTracheaAction PotentialsNorepinephrineRana esculentaEvoked Potentials, MotorLegAdenosine TriphosphateAnuraAorta, ThoracicTendonsFingersMyosin Light ChainsRats, WistarMuscle Strength DynamometerCatsHandForearmReflex, StretchHand StrengthMotor CortexExerciseElbow JointModels, BiologicalThumbArmRats, Sprague-DawleyKnee JointMovementWeight-BearingFemoral NerveDogsHindlimbGastrointestinal MotilityNeural ConductionReflexAnalysis of VarianceMasseter MuscleHeart RateMuscle TonusFeedback, SensoryBupranololActinsUrinary BladderAdaptation, PhysiologicalEnergy MetabolismPeristalsisTranscranial Magnetic StimulationIsoproterenolHeartBlood PressureAtropine