Objective:Thissystematicreviewaimedtocriticallyanalyzetheliteraturetodeterminehowhigh-intensityintermittenttraining(HIIT)affectsrecreationalendurancerunnersintheshort-andlong-term.Methods:ElectronicdatabasesweresearchedforliteraturedatingfromJanuary2000toOctober2015.Thesearchwasconductedusingthekeywords'high-intensityintermittenttraining'or'high-intensityintervalexercise'or'intervalrunning'or'sprintintervaltraining'and'endurancerunners'or'longdistancerunners'.Asystematicapproachwasusedtoevaluatethe783articlesidentifiedforinitialreview.StudieswereincludediftheyinvestigatedHIITinrecreationalendurancerunners.ThemethodologicalqualityofthestudieswasevaluatedusingthePhysiotherapyEvidenceDatabase(PEDro)scale(forinterventionstudies)andthemodifiedDownsandBlackQualityIndex(forcross-sectionalstudies).Results:Twenty-threestudiesmettheinclusionarycriteriaforreview.Theresultsarepresentedin2parts:cross-sectional(n=15)andinterventionstudies(n=8).Inthe15cross-sectionalstudiesselected,endurancerunnersperformedatleast1HIITprotocol,andtheacuteimpactonphysiological,neuromuscular,metabolicand/orbiomechanicalvariableswasassessed.Interventionstudieslastedaminimumof4weeks,with10weeksbeingthelongestinterventionperiod,andincluded2to4HIITsessionsperweek.MostofthesestudiescombinedHIITsessionswithcontinuousrun(CR)sessions;2studies’subjectsperformedHIITexclusively.Conclusion:HIIT-basedrunningplans(2to3HIITsessionsperweek,combiningHIITandCRruns)showathleticperformanceimprovementsinendurancerunnersbyimprovingmaximaloxygenuptakeandrunningeconomyalongwithmuscularandmetabolicadaptations.Tomaximizetheadaptationstotraining,bothHIITandCRmustbepartoftrainingprogramsforendurancerunners.
