Myosin Type IIIMyosinsMuscle, SkeletalMyosin Type IVFetal HeartMusclesMyosin SubfragmentsMuscle Fibers, SkeletalMyosin Heavy ChainsEchocardiography, Four-DimensionalMuscle ProteinsMyosin Type IMyosin Type IIUltrasonography, PrenatalMyosin Light ChainsNonmuscle Myosin Type IIBMyocytes, CardiacRabbitsMuscle ContractionNonmuscle Myosin Type IIAMyosin Type VActinsMuscle, SmoothHeartHeart Defects, CongenitalMyocardiumCardiac OutputMitochondria, MuscleAdenosine TriphosphatasesMuscle DevelopmentActomyosinMuscle Fibers, Fast-TwitchChickensMuscle Fibers, Slow-TwitchCa(2+) Mg(2+)-ATPaseExercisePregnancyFetal DiseasesGestational AgeFetoscopyMagnetocardiographyGlycogenCardiac VolumeAdenosine TriphosphateCardiac MyosinsKineticsCardiac Surgical ProceduresCalciumGizzardMolecular Sequence DataFetoscopesHeart Rate, FetalSatellite Cells, Skeletal MuscleMuscle, Smooth, VascularRhabdomyomaTime FactorsMyofibrilsNaphthalenesulfonatesMuscle FatigueMuscle CellsQuadriceps MuscleArrhythmias, CardiacAmino Acid SequenceTropomyosinMuscular DiseasesPeptide FragmentsHeart VentriclesPregnancy Trimester, SecondRNA, MessengerIsometric ContractionMuscular AtrophyCardiomegalyMyocardial ContractionDeath, Sudden, CardiacAdenosine DiphosphateCells, CulturedPhysical ExertionEchocardiography, Three-DimensionalOxygen ConsumptionPhysical EnduranceInsulinPhosphocreatineMuscle DenervationFetusEchocardiographyPhosphorylationDithionitrobenzoic AcidBase SequenceProtein BindingGlucoseLegCitrate (si)-SynthaseMyoblastsGene Expression RegulationSignal TransductionElectrophoresis, Polyacrylamide GelCardiomyopathiesCollagen Type IIISarcolemmaLactic Acid