简介：Naturaladultagingisassociatedwithmanyfunctionalimpairmentsofthehumanneuromuscularsystem.Oneofthemoreobservablealterationsisthelossofcontractilemusclemass,termedsarcopenia.Thelossofmusclemassoccursprimarilyduetoaprogressivelossofviablemotorunits,andaccompanyingatrophyofremainingmusclefibers.Notonlydoesthelossofmusclemasscontributetoimpairedfunctioninoldage,butalterationsinfibertypeandmyosinheavychainisoformexpressionalsocontributetoweaker,slower,andlesspowerfulcontractingmuscles.Thisreviewwillfocusonmotorunitlossassociatedwithnaturaladultaging,age-relatedfatigability,andtheage-relateddifferencesinstrengthacrosscontractilemuscleactions.

简介：<正>Background:Short-legwalkingbootsareacommoninterventionforacuteandchroniclowerextremityinjury.Fewstudieshaveexaminedtheneuromuscularadaptationsassociatedwithshort-legwalkingbootsandnopreviousstudyhasinvestigatedtimingcharacteristicsofmuscleactivationduringgait.Thepurposeofthecurrentstudywastoexaminethetimingandamplitudesofmuscleactivationoftheextrinsicanklemusculatureduringwalkingintwotypesofshort-legwalkingboots.Methods:Elevenhealthyyoungadultsperformedfivelevelwalkingtrialsataself-selectedpaceineachofthreeconditions:normalwalking.GaitWalkerandEqualizershort-legwalkingboots.Groundreactionforceswerecollectedfromaforceplatformwhilesurfaceelectromyography(EMG)wascollectedfromthetibialisanterior,peroneuslongusandmedialgastrocnemius.EMGsignalswererectifiedandsmoothedusingtherootmeansquaredwitha20-mssmoothingwindowandwerenormalizedtothelargestmeanofthenormalwalkingtrials.Arepeatedmeasuresanalysisofvariancewasusedtoassesstheeffectofshort-legwalkingbootsontheonset,durationandamplitudeofmuscleactivation.Results:Short-legwalkingbootsweregenerallyassociatedwithearlieronsetsofmuscleactivationandlongerdurationsofmuscleactivation.However,therewasnoreductioninEMGamplitude.Conclusion:Thefindingsofthisstudyshowthattheinducedalterationsinmuscleactivationpatternsmaylimittheshort-legwalkingboots.