Mobility LimitationSocial ParticipationMuscle StrengthTennesseeWalkingDisabled PersonsMuscle Strength DynamometerActivities of Daily LivingAgingLongitudinal StudiesDisability EvaluationLower ExtremityHealthGeriatric AssessmentGaitHand StrengthMotor ActivityPostural BalancePennsylvaniaAge FactorsCross-Sectional StudiesHealth StatusTestosteroneRisk FactorsOdds RatioUnited StatesProspective StudiesProportional Hazards ModelsQuestionnairesObesityElectrophoretic Mobility Shift AssaySocial Mobility