Muscle FatigueFatigueMuscle, SkeletalMusclesMuscle ContractionCell HypoxiaIsometric ContractionMuscle ProteinsElectromyographyFatigue Syndrome, ChronicMuscle Fibers, SkeletalMyocardiumMental FatigueAnoxiaHeartMyocytes, CardiacPhysical EnduranceQuadriceps MuscleMuscle, SmoothRespiratory MusclesExerciseAbdominal MusclesMuscle, Smooth, VascularPapillary MusclesTime FactorsMuscle DevelopmentMyocardial ContractionPhysical ExertionElectric StimulationTorqueBackCalciumMuscle StrengthMuscle WeaknessMuscle RelaxationNeck MusclesCardiac OutputDiaphragmOxygenMuscle Fibers, Fast-TwitchMyofibrilsMuscle Fibers, Slow-TwitchSarcomeresIntercostal MusclesOxygen ConsumptionMuscular DiseasesHypoxia, BrainVaccines, EdibleSarcoplasmic ReticulumLactic AcidPhysical FitnessHeart VentriclesMotor ActivityArrhythmias, CardiacRabbitsElbowExercise ToleranceMitochondria, MuscleMuscle DenervationExercise TestMyocytes, Smooth MuscleCells, CulturedRats, WistarRats, Sprague-DawleyTroponin CCardiac Surgical ProceduresAdaptation, PhysiologicalFetal HypoxiaMuscle CellsBicyclingCardiomegalyTroponinDeath, Sudden, CardiacAnalysis of VarianceEnergy MetabolismTroponin IPhosphocreatineRunningRNA, MessengerRespirationAction PotentialsInhalationOculomotor MusclesFemoral NerveElectric Stimulation TherapyModels, BiologicalDogsGlycogenMyosin Heavy ChainsCardiac MyosinsHypoxia-Inducible Factor 1, alpha SubunitMotor NeuronsAgingAdenosine TriphosphateMuscle, StriatedHeart RateLegSarcolemmaMuscle SpindlesLumbosacral Region