FatigueMuscle FatigueFatigue Syndrome, ChronicMental FatigueSeverity of Illness IndexCost of IllnessCritical IllnessQuestionnairesQuality of LifeIllness BehaviorMental DisordersChronic DiseaseMuscle ContractionMuscle, SkeletalIsometric ContractionDepressionTime FactorsSleep DisordersFibromyalgiaTreatment OutcomePhysical EnduranceSick RoleNeoplasmsPainElectromyographyProspective StudiesAsthenopiaCross-Sectional StudiesRisk FactorsUnited StatesExercisePrevalenceAdaptation, PsychologicalTorqueStress, PsychologicalFeverHealth StatusComorbidityInfluenza, HumanPsychiatric Status Rating ScalesAttitude to HealthAnxietyNeurastheniaPsychometricsSurvivorsRespiratory Tract InfectionsPersian Gulf SyndromeDiaphragmFoodborne DiseasesDepressive DisorderActivities of Daily LivingPhysical ExertionAnalysis of VarianceLongitudinal StudiesMuscle StrengthFollow-Up StudiesCase-Control StudiesMentally Ill PersonsCohort StudiesAcute DiseaseElectric StimulationWork Schedule TolerancePostpoliomyelitis SyndromePopulation SurveillanceSleepStereotypingPsychotic DisordersGastrointestinal DiseasesRespiratory Tract DiseasesMultiple SclerosisPain MeasurementOccupational DiseasesInfant, NewbornDiarrheaQuadriceps MuscleAge FactorsBipolar DisorderExercise TherapyPilot ProjectsAffectRetrospective StudiesReproducibility of ResultsRegression AnalysisSelf CareSocioeconomic FactorsMaterials TestingAbsenteeismFractures, StressHealth SurveysDisorders of Excessive SomnolenceHospitalizationCognitive TherapyDouble-Blind MethodEmploymentKneeEnvironmental IllnessHealth Status IndicatorsSex FactorsIncidenceMood Disorders