考点17阅读理解之说明文(2020•全国卷I,C)Racewalkingsharesmanyfitnessbenefitswithrunning,researchshows,whilemostlikelycontributingtofewerinjuries
Itdoes,however,haveitsownproblem
Racewalkersareconditionedathletes
ThelongesttrackandfieldeventattheSummerOlympicsisthe50-kilometerracewalk,whichisaboutfivemileslongerthanthemarathon
Butthesport’srulesrequirethataracewalker’skneesstaystraightthroughmostofthelegswingandonefootremainincontact(接触)withthegroundatalltimes
It’sthisstrangeformthatmakesracewalkingsuchanattractiveactivity,however,saysJaclynNorberg,anassistantprofessorofexercisescienceatSalemStateUniversityinSalem,Mass
Likerunning,racewalkingisphysicallydemanding,shesays,Accordingtomostcalculations,racewalkersmovingatapaceofsixmilesperhourwouldburnabout800calories(卡路里)perhour,whichisapproximatelytwiceasma