Muscle FatigueFatigueMuscle, SkeletalMusclesMuscle ContractionCell HypoxiaIsometric ContractionChest PainElectromyographyMuscle ProteinsFatigue Syndrome, ChronicMuscle Fibers, SkeletalMyocardiumAnoxiaMental FatigueHeartMyocytes, CardiacQuadriceps MuscleRespiratory MusclesMuscle, SmoothPhysical EnduranceAbdominal MusclesMuscle, Smooth, VascularPapillary MusclesMuscle DevelopmentTime FactorsMyocardial ContractionElectric StimulationBackTorqueExerciseCalciumMuscle RelaxationMuscle WeaknessCardiac OutputMuscle StrengthNeck MusclesDiaphragmPhysical ExertionOxygenMuscle Fibers, Fast-TwitchMyofibrilsIntercostal MusclesMuscle Fibers, Slow-TwitchSarcomeresOxygen ConsumptionChest TubesMuscular DiseasesHypoxia, BrainHeart VentriclesSarcoplasmic ReticulumArrhythmias, CardiacLactic AcidBiomechanical PhenomenaRabbitsElbowMitochondria, MuscleMuscle DenervationExercise ToleranceMyocytes, Smooth MuscleExercise TestCardiac Surgical ProceduresCells, CulturedTroponin CRats, WistarRats, Sprague-DawleyTroponinFetal HypoxiaCardiomegalyMuscle CellsRadiography, ThoracicTroponin IDeath, Sudden, CardiacAdaptation, PhysiologicalInhalationRespirationBicyclingPhosphocreatineThoracic WallOculomotor MusclesAction PotentialsDogsFemoral NerveRNA, MessengerAnalysis of VarianceElectric Stimulation TherapyCardiac MyosinsGlycogenHypoxia-Inducible Factor 1, alpha SubunitMyosin Heavy ChainsMotor NeuronsMuscle, StriatedAdenosine TriphosphateRunningMuscle SpindlesSarcolemmaLumbosacral RegionCardiomyopathiesHeart RateEnergy Metabolism