Hindlimb SuspensionMuscular AtrophyHindlimbMuscle, SkeletalAtrophyMuscle Fibers, Slow-TwitchMuscle Fibers, Fast-TwitchMuscle ProteinsMuscle Fibers, SkeletalMusclesMyosin Heavy ChainsMuscle ContractionWeight-BearingWeightlessness SimulationMuscle DenervationSuspensionsOrgan SizeMuscular Disorders, AtrophicSKP Cullin F-Box Protein LigasesRats, WistarRats, Sprague-DawleyMuscle DevelopmentImmobilizationAdaptation, PhysiologicalMyostatinMuscle FatigueTime FactorsBody WeightMuscle, SmoothIsometric ContractionElectromyographyRNA, MessengerMitochondria, MuscleH-ReflexMuscle, Smooth, VascularMuscular Atrophy, SpinalMotor NeuronsMuscle WeaknessMuscle SpindlesElectric StimulationSatellite Cells, Skeletal MuscleMyofibrilsPhysical Conditioning, AnimalOptic AtrophyMuscular DiseasesCachexiaGlycogenWeightlessnessSpace FlightCats