Quadriceps MuscleTendonsTendon InjuriesPatellar LigamentPatellaRuptureKneeKnee JointThighKnee InjuriesPatellofemoral Pain SyndromeMuscle, SkeletalMuscle StrengthMusclesAchilles TendonMuscle WeaknessMuscle FatigueTorqueIsometric ContractionRupture, SpontaneousMuscle ContractionFemoral NerveMuscle Strength DynamometerElectromyographyBiomechanical PhenomenaAnterior Cruciate LigamentElectric Stimulation TherapyMuscle Fibers, SkeletalMuscle ProteinsLegExerciseMuscular AtrophyMuscular DiseasesTendon TransferRange of Motion, ArticularMuscle, SmoothRespiratory MusclesOsteoarthritis, KneePhysical EnduranceWeight-BearingMuscle Fibers, Slow-TwitchTendinopathyElectric StimulationPatellofemoral JointJoggingWeight LiftingArtificial OrgansMuscle, Smooth, VascularImmobilizationJoint InstabilityMitochondria, MuscleGaitOxygen ConsumptionMuscle DevelopmentPhysical ExertionExercise TherapyBicyclingMyostatinArthroplasty, Replacement, KneeExercise TestRecovery of FunctionMuscle Fibers, Fast-TwitchPulmonary Disease, Chronic ObstructiveTime FactorsMotor NeuronsMuscle SpindlesAbdominal MusclesAdaptation, PhysiologicalPhysical Conditioning, HumanLactic AcidFemurH-ReflexMuscle DenervationAnalysis of VarianceBiopsyHypertrophyMusculoskeletal Physiological PhenomenaParaplegiaPain MeasurementLigamentsPainReflex, StretchGlycogenMuscle RelaxationMotor ActivityOrgan SizeRegional Blood FlowMyocytes, Smooth MuscleOculomotor MusclesAgingHindlimbAthletic InjuriesStress, MechanicalProprioceptionHydrarthrosisNeck MusclesMovementAnterior Cruciate Ligament ReconstructionTreatment OutcomeMagnetic Resonance Imaging