Purpose:Thepurposeofthisstudywastoinvestigatetheeffectofvariableintensitiesonasimplememoryrecognitiontaskduringexercise.Methods:Twentyactiveparticipantstookpartininitialtesting,afamiliarizationtrialandthenfour60mincyclinginterventionsinarandomizedorder.Interventionsconsistedofnoexercise（control）,constantexerciseat90%ventilatorythreshold（constant）and2trialsthatinitiallymimickedtheconstanttrial,butthenincludedperiodsofhigh(90%VO2peak)andlowintensities(50%VO2peak).Cardiorespiratorymeasuresandcapillarybloodsamplesweretakenthroughout.Ashorttablet-basedcognitivetaskwascompletedpriortoandduring（50and55minintoexercise）eachintervention.Results:Theexerciseconditionsfacilitatedresponsetime（p=0.009）,althoughtheextentofthiseffectwasnotasstronginthevariableexerciseconditions（p=0.011–0.089）.Highintensityexerciseperiodsresultedinsomecognitiveregressionbacktowardscontroltrialperformance.Elevationsincardiorespiratorymeasuresandperiodsofhypocapniacouldnotexplainchangesincognitiveperformance.Conclusion:Changesincognitiveperformancewithvariationsinexerciseintensityarelikelytohaveimplicationsforsportandoccupationalsettings.Thetimingofcognitiveteststoexerciseintensitychangesaswellasuseofshortcognitiveassessmentswillbeimportantforfuturework.
