ISSN: 1524-4539 
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doi: 10.1161/CIRCULATIONAHA.107.185649
2007, 116:1081-1093: originally published online August 1, 2007
Circulation 
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PhysicalActivityandPublicHealth
UpdatedRecommendationforAdultsFromtheAmericanCollegeof
SportsMedicineandtheAmericanHeartAssociation
WilliamL.Haskell,PhD,FAHA;I-MinLee,MD,ScD;RussellR.Pate,PhD,FAHA;
KennethE.Powell,MD,MPH;StevenN.Blair,PED,FACSM,FAHA;
BarryA.Franklin,PhD,FAHA;CarolineA.Macera,PhD,FACSM;
GregoryW.Heath,DSc,MPH,FAHA;PaulD.Thompson,MD;AdrianBauman,PhD,MD
Summary—In1995theAmericanCollegeofSportsMedicineandtheCentersforDiseaseControlandPreventionpublished
nationalguidelinesonPhysicalActivityandPublicHealth.TheCommitteeonExerciseandCardiacRehabilitationofthe
AmericanHeartAssociationendorsedandsupportedtheserecommendations.Thepurposeofthepresentreportistoupdate
andclarifythe1995recommendationsonthetypesandamountsofphysicalactivityneededbyhealthyadultstoimproveand
maintainhealth.Developmentofthisdocumentwasbyanexpertpanelofscientists,includingphysicians,epidemiologists,
exercisescientists,andpublichealthspecialists.Thispanelreviewedadvancesinpertinentphysiologic,epidemiologic,and
clinicalscientificdata,includingprimaryresearcharticlesandreviewspublishedsincetheoriginalrecommendationwas
issuedin1995.Issuesconsideredbythepanelincludednewscientificevidencerelatingphysicalactivitytohealth,physical
activityrecommendationsbyvariousorganizationsintheinterim,andcommunicationsissues.Keypointsrelatedtoupdating
the physicalactivityrecommendationwereoutlinedandwritinggroupswereformed.Adraftmanuscriptwas preparedand
circulatedforreviewtotheexpertpanelaswellastooutsideexperts.Commentswereintegratedintothefinalrecommendation.
PrimaryRecommendation—Topromoteandmaintainhealth,allhealthyadultsaged18to65yrneedmoderate-intensityaerobic
(endurance)physicalactivityforaminimumof30minonfivedayseachweekorvigorous-intensityaerobicphysicalactivityfor
aminimumof20minonthreedayseachweek.[I(A)]Combinationsofmoderate-andvigorous-intensityactivitycanbeperformed
tomeetthisrecommendation.[IIa(B)]Forexample,apersoncanmeettherecommendationbywalkingbrisklyfor30mintwice
duringtheweekandthenjoggingfor20minontwootherdays.Moderate-intensityaerobicactivity,whichisgenerallyequivalent
toabriskwalkandnoticeablyacceleratestheheartrate,canbeaccumulatedtowardthe30-minminimumbyperformingbouts
eachlasting10ormoreminutes.[I(B)]Vigorous-intensityactivityisexemplifiedbyjogging,andcausesrapidbreathingand
asubstantialincreaseinheartrate.Inaddition, everyadultshouldperformactivitiesthatmaintainorincreasemuscular
strengthandenduranceaminimumoftwodayseachweek.[IIa(A)]Becauseofthedose-responserelationbetweenphysical
activityandhealth,personswhowishtofurtherimprovetheirpersonalfitness,reducetheirriskforchronicdiseasesand
disabilitiesorpreventunhealthyweightgainmaybenefitbyexceedingtheminimumrecommendedamountsofphysical
activity.[I(A)](Circulation.2007;116:1081-1093.)
KeyWords:benefits
risks
physicalactivitydose
physicalactivityintensity
I
n1995theCentersforDiseaseControlandPrevention(CDC)
andtheAmericanCollegeofSportsMedicine(ACSM)issueda
publichealthrecommendationthat‘‘EveryUSadultshouldaccu-
mulate30minutesormoreofmoderate-intensityphysicalactivity
onmost,preferablyall,daysoftheweek’’(49).Thepurposeofthe
recommendationwastoprovidea‘‘clear,concise,publichealth
message’’ that would “encourage increased participation in
physicalactivity”byalargelysedentaryUSpopulation.
ThisdocumentwasapprovedbytheAmericanCollegeofSportsMedicineonJanuary5,2007,andtheAmericanHeartAssociationScienceAdvisory
andCoordinatingCommitteeonMarch24,2007.
Whenthisdocumentiscited,theAmericanCollegeofSportsMedicineandtheAmericanHeartAssociationwouldappreciatethefollowingcitation
format:HaskellWL,LeeI-M,PateRP,PowellKE,BlairSN,FranklinBA,MaceraCA,HeathGW,ThompsonPD,BaumanA.Physicalactivityand
publichealth:updatedrecommendationforadultsfromtheAmericanCollegeofSportsMedicineandtheAmericanHeartAssociation.Circulation.
2007;116:1081–1093.
ThisarticlehasbeencopublishedintheAugust2007issueofMedicine&ScienceinSports&Exercise(MedSciSportsExer.2007;39:1423–1434).
Copies:ThisdocumentisavailableontheWorldWideWebsitesoftheAmericanCollegeofSportsMedicine(www.acsm.org)andtheAmericanHeart
Association(www.americanheart.org).Asinglereprintisavailablebycalling800-242-8721(USonly)orwritingtheAmericanHeartAssociation,Public
Information,7272GreenvilleAve,Dallas,TX75231-4596.AskforreprintNo.71-0417.Topurchaseadditionalreprints,call843-216-2533ore-mail
kelle.ramsay@wolterskluwer.com.
Permissions: Multiplecopies,modification,alteration, enhancement, and/or distribution of this document arenot permitted d without t the express
permission oftheAmerican n CollegeofSports Medicine e ortheAmerican n Heart Association. . Instructions for obtaining g permission n are located d at
http://www.americanheart.org/presenter.jhtml?identifier=4431.Alinktothe“PermissionRequestForm”appearsontherightsideofthepage.
©2007bytheAmericanCollegeofSportsMedicineandtheAmericanHeartAssociation,Inc.
Circulationisavailableathttp://circ.ahajournals.org
DOI:10.1161/CIRCULATIONAHA.107.185649
1081
ACSM/AHARecommendations
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Morethan10yearshavepassedsincethisrecommenda-
tion was s issued. New science e has added d to o our under-
standingof the biologicalmechanisms s by y which physical
activity provides s health h benefits and the physical activity
profile (type, , intensity, , amount) ) that t is s associated d with
enhanced health and quality y of f life. . The intent of f the
original recommendation, however, has s not t been fully
realized. Physical inactivity y remains s a pressing g public
healthissue.Technologyandeconomic incentives tendto
discourage activity, technology by reducing the energy
needed for activities of daily living, and economics by
payingmoreforsedentarythanactivework.
Inaddition,therearepeoplewhohavenotaccepted,and
otherswhohavemisinterpreted,theoriginalrecommenda-
tion.Somepeoplecontinuetobelievethatonlyvigorous-
intensity activitywill improvehealthwhile others s believe
thatthelightactivities oftheirdailylivesaresufficientto
promote health h (53). Compounding these e challenges,
physicalactivityrecommendations havebeenpublishedin
theinterimthatcouldbeinterpretedtobeinconflictwith
the1995recommendation(4,26,57,71).
Favorable trenddata from 1990to2004in the United
States basedontheCDCBehavioralRisk k FactorSurveil-
lanceSystemindicatethatovertimefewermenandwomen
reportednoleisure-timephysicalactivity(13).Thepreva-
lence of f leisure-time physical inactivity remained fairly
constantthrough 1996,butmore recentlyhas s declined d in
bothgenders(Fig.1).In200523.7%ofadultsreportedno
leisure-timeactivity(14).
However, there e remains a a broad range of f evidence to
underscore concern that US adults s are e still not active
enough. For example, , data a from m 2005 5 indicate e that less
than half (49.1%) ) of U.S. adults s met t the e CDC/ACSM
physical activity recommendation (12). Men were more
likely to meet the recommendation (50.7%) thanwomen
(47.9%).Formenandwomen combined,youngerpeople
weremorelikelytobe active thanolderpeople,withthe
prevalence of those meeting the recommendation n declin-
ing from 59.6% amongthose 18–24 yrof age to 39.0%
among those 65 years and older (Fig. 2). White, non-
Hispanics (51.1%) were most t likely to o meet t the e recom-
mendation followed by ‘‘other’’ racial or ethnic groups
(46.3%), Hispanics, (44.0%) and African-Americans
(41.8%). Persons with a a college degree were e the most
likely to meet t the e recommendation (53.2%) ) followed by
thosewithsomecollegeeducation(50.2%),ahighschool
education(45.9%), and less than highschool (37.8%).
Disease outcomes s inversely related to regular physical
activityinprospective observational studiesincludecardi-
ovascular disease, , thromboembolic stroke, hypertension,
type2diabetesmellitus,osteoporosis,obesity,coloncancer,
breast cancer, anxiety and depression (33). Scientific
evidencecontinuestoaccumulate,withmorerecentefforts
focused on the nature of the relation between physical
activityandhealth,ratherthantryingtodetermineifsucha
relation exists (33). This additional evidence e includes
compelling new data on women (21,39,40), and more
conclusiveevidenceonstroke(77),somecancers(69),and
cognitivefunction(78,83).Theprimarylimitationofmuch
of the e data linking physical activity to morbidity and
mortalityduetochronicdiseasesisthatformanyconditions
few randomized trials of adequate e design have been
conducted.However,this situationisnotallthat different
fromdataregardingtherelationbetweensomeotherhealth-
related behaviors s and d clinical outcomes,suchas s cigarette
smokingorsaturatedfatintakeandcoronaryheartdisease
(CHD). No o adequately y designed randomized controlled
study in the e general l population has shown that stopping
smoking or decreasing saturated fat or r trans-fatty y acid
FIGURE2—Prevalence ofU.S.menandwomen meetingtheCDC/
ACSMphysicalactivityrecommendationsbyage,2005.
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intakesignificantlydecreasesCHDmortalityyetgettingthe
publictostopsmokingorreducetheirintakeofsaturatedfat
ortrans-fattyacidsaremajorcomponentsofnationalpublic
healthcampaigns(50).
Thepurposeofthis reportistoupdatethe 1995CDC/
ACSM recommendation. . The intent is s toprovide amore
comprehensiveandexplicitpublichealthrecommendation
for adults based upon n available e evidence of the e health
benefitsofphysicalactivity.
Expert panel process. InFebruary2003,an expert
panel was convened and charged with reviewing and
updating the original CDC/ACSM recommendation for
physicalactivityandpublichealth(49).Thispanel,which
consistedofphysicians,epidemiologists,exercisescientists
and public health experts, , reviewed d scientific advances
sincethepublicationoftheoriginalrecommendation,newly
issued recommendations provided by other organizations
andcommunicationsissuessuchasclarityandconsistency.
Forscientific input,thepanelinitiallyreliedheavilyon
published evidence from m a a meeting held in 2000 0 jointly
sponsoredbyCDCandHealthCanadaonDose-Response
Aspects of f Physical Activity and d Health h (33). . The con-
clusion and consensus statement from this meeting were
based on n systematic c reviews of the e literature. Panel
membersalsoconductedextensivesearchesoftheliterature
onphysicalactivityandhealthto2006.
In addition n to scientific c updates, , the expert t panel
consideredissuesandadvancesinunderstandingroles and
strategies in n communication of health messages s in the
update and clarification ofthe prior recommendations.A
second CDC-HealthCanada workshopon communicating
physicalactivitymessageswasheldin2001andidentified
severalkeystrategiesforimprovingthecommunicationof
physicalactivityrecommendations(59).A differentexpert
panel developed a recommendation forolder adults s as a
companion recommendation to that presented in n this
article (47). . Manuscripts describing the e recommendation
foradults generally y and forolder adults s as a companion
were circulated for comments, revised, and d edited d for
consistency before review and d approval l by ACSM and
the American Heart t Association (AHA). . For r current
physical activity y guidelines directed at school-age youth
thereaderisreferredtotherecentpublicationbyStrongand
colleagues(65).
UPDATEDRECOMMENDATIONSTATEMENT
Thisrecommendation applies s tohealthyadultsbetween
18and65yrofage,andtopersonsinthisagerangewith
chronic conditions not related to physical activity (e.g.,
hearing impairment). . During pregnancy and the post-
partumperiodadditionalprecautionsmaybeneeded:these
issues have been n considered d by y other r expert committees
(3,7). The e present t preventive recommendation specifies
how adults, , byengaginginregularphysical activity, can
promote and maintain health,and reduce risk ofchronic
diseaseandprematuremortality.Acompanionrecommen-
dation (47) ) builds on the information in this paper but
specificallyapplies toadultsaged65andover,andadults
aged50–64withchronicconditionsorphysicalfunctional
limitations (e.g.,arthritis),that affectmovementabilityor
physicalfitness. Thefollowing recommendationreflectsa
review of f evidence published since the issuance of the
CDC/ACSM recommendation in 1995 and considers s key
issues not fully y clarifiedin the original recommendation.
Classification of f recommendations (COR) and d level of
evidence (LOE) ) are expressed in n American College of
Cardiology/AmericanHeartAssociation (ACC/AHA) for-
matasdefinedinTable1andtheMethodologyManualfor
ACC/AHAGuidelineWritingCommittees(2).
AerobicActivity.Topromote andmaintainhealth,all
healthy adults s aged 18–65 yr r need d moderate-intensity
aerobic physical activity for a minimum of 30 min on
fivedayseachweekorvigorous-intensityaerobic activity
for a minimum m of f 20 min on three days each week. [I
(A)] Also, , combinations s of moderate- and vigorous-
intensity activity can n be performed d to meet this
recommendation. [IIa (B)] For r example, , a a person n can
meetthe recommendation bywalking briskly for30 min
twice during the week and d then jogging for 20 min n on
twootherdays.Moderate-intensityaerobicactivity,which
is generally equivalent to a brisk walk and noticeably
accelerates the heart rate,can n be accumulatedtowardthe
30-min minimum frombouts s lasting10ormoreminutes.
TABLE 1.ACC/AHAapproachtoassigningtheclassificationofrecommendationsandlevelofevidence.
Classificationsofrecommendation (COR)I,II,andIIIareusedtosummarizeindications(suggestedphrasesforwritingrecommendations)
ClassI:Conditionsforwhichthereisevidenceand/orgeneralagreementthatagivenprocedureortreatmentisusefulandeffective(should;isrecommended;isindicated;
isuseful.effective,beneficial)
ClassII:Conditionsforwhichthereisconflictingevidenceand/oradivergenceofopinionabouttheusefulness/efficacyofaprocedureortreatment
IIa:Weightofevidence/opinionisinfavorofusefulness/efficacy(isreasonable;canbeuseful,effectiveorbeneficial;isprobablyrecommended orindicated)
IIb:Usefulness/efficacyislesswellestablishedbyevidence/opinion(may/mightbeconsidered,may/mightbereasonable,usefulness/effectivenessisunknown,
unclear/uncertainornotwellestablished)
ClassIII:Conditionsforwhichthereisevidenceand/orgeneralagreementthattheprocedure/treatmentisnotuseful/effectiveandinsomecasesmaybeharmful
(isnotrecommended;isnotindicated;should not;isnotuseful/effective,beneficial;maybeharmful)
Levelsofevidence(LOE)forindividualclassassignments
A:Dataderivedfrommultiplerandomizedclinicaltrials
B:Dataderivedfromasinglerandomizedtrialorfromnonrandomizedstudies
C:Consensusopinionofexperts
Fordetailsaboutthisclassificationsystemseereference(2).
Haskelletal
PhysicalActivityandPublicHealth
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[I (B)] ] Vigorous-intensity activity y is exemplified d by
jogging, and causes rapid d breathing and a a substantial
increase in heart t rate. . This recommended amount of
aerobicactivityis inadditiontoroutineactivitiesofdaily
living of light intensity (e.g., self f care, , cooking, casual
walking or shopping) ) or lasting g less s than n 10 min n in
duration (e.g., walking around home or office, walking
from the parking lot).
Muscle-Strengthening Activity. To promote and
maintain good health and physical independence, adults
will benefit t from m performing g activities that t maintain n or
increasemuscularstrengthandenduranceforaminimumof
twodayseachweek.[IIa(A)]Itisrecommendedthat8–10
exercisesbeperformedontwoormorenonconsecutivedays
each week using the majormuscle groups. Tomaximize
strengthdevelopment,aresistance(weight)shouldbeused
thatallows 8–12repetitions ofeach h exercise resulting in
volitionalfatigue.Muscle-strengtheningactivitiesincludea
progressive weight-training program, weight bearing
calisthenics,stairclimbing,andsimilarresistanceexercises
thatusethemajormusclegroups.
Benefits of f Greater r Amounts of f Activity.
Participationinaerobicandmuscle-strengtheningphysical
activitiesaboveminimumrecommendedamountsprovides
additional health benefits s and results in n higher r levels of
physicalfitness.[I(A)]Manyadults,includingthosewho
wishtoimprovetheirpersonalfitnessorfurtherreducetheir
riskforprematurechronic healthconditions andmortality
related tophysicalinactivity,shouldexceedtheminimum
recommended amounts of f physical activity (33). In
addition,tofurtherpromote andmaintain skeletal health,
adults will l benefit by engaging in extra weight-bearing
activityandhigher-impactactivitysuchasstair-climbingor
jogging,as tolerated.[IIa (B)] ] To help preventunhealthy
weight gain, some adults s will l need to exceed minimum
recommendedamountsofphysicalactivitytoapointthatis
individually effective in n achieving energy balance, while
considering theirfood intake andother factors s that affect
bodyweight.[IIa(B)]
CLARIFICATIONSTOTHE1995
RECOMMENDATION
Although fundamentally unchanged from the e 1995
recommendation,theupdatedrecommendationisimproved
in several l ways. . First, , the recommended d frequency for
moderate-intensityphysicalactivityhasbeenclarified.The
1995documentsimplyspecified‘‘most,preferablyalldays
perweek’’as therecommendedfrequency y while the new
recommendation identifies five days per week as s the
recommendedminimum.
Second, vigorous-intensity y physical l activity y has been
explicitly incorporated d into o the e recommendation. To
acknowledge both the e preferences of f some adults for
vigorous-intensity physical activity and the substantial
science base e related d to participation in such activity (4),
the recommendation n has been n clarified d to encourage
participation in eithermoderate- and/or vigorous-intensity
physical activity. Vigorous-intensity physical activity was
implicitinthe1995recommendation.Itisnowexplicitlyan
integralpartofthephysicalactivityrecommendation.
Third, the updatedrecommendation now specifies that
moderate-andvigorous-intensityactivitiesarecomplemen-
taryintheproductionofhealthbenefitsandthatavarietyof
activities can be e combined to meet t the e recommendation.
This combining g of activities is based on the amount
(intensity   duration) of activity y performed d during the
weekandusestheconceptofMETs(metabolicequivalents)
toassignanintensityvaluetoaspecificactivity(SeeTable1
andsectionregardingActivityDosebelow).
Fourth,theupdated recommendationnow w clearlystates
thattherecommendedamountofaerobicactivity(whether
ofmoderate-orvigorous-intensity)isinadditiontoroutine
activitiesofdailylivingwhichareoflightintensity,suchas
selfcare,casualwalkingorgroceryshopping,orlessthan
10 min n of f duration n such h as walking g to the parking lot
ortakingoutthetrash.Few activitiesincontemporarylife
areconductedroutinelyatamoderateintensityforatleast
10 min in duration. However, moderate- or vigorous-
intensity activities s performedas apart ofdaily y life (e.g.,
briskwalking towork, gardening with shovel, carpentry)
performed in bouts of 10 min or more e can n be counted
towards the recommendation.Although h implied,this s con-
cept was s not t effectively communicated d in n the original
recommendation.
Fifth,thenewrecommendationemphasizestheimportant
fact that t physical l activity above the recommended mini-
mum amount t provides s even n greater health h benefits. The
pointofmaximumbenefitformosthealthbenefitshasnot
beenestablishedbutlikelyvarieswithgeneticendowment,
age,sex,healthstatus,bodycompositionandotherfactors.
Exceeding the minimum recommendation further reduces
theriskofinactivity-relatedchronicdisease.Althoughthe
dose-response relation was s acknowledged in the e 1995
recommendation,thisfactisnowexplicit.
Sixth,althoughtheoriginal recommendationintroduced
theconceptofaccumulatingshortboutsofphysicalactivity
towardthe30-mingoal,therewasconfusionregardinghow
shorttheseepisodescouldbe.Forconsistencyandclarity,
the minimum length of f these e short bouts is clarified as
being10min.
Seventh,muscle-strengtheningactivitieshavenow been
incorporated into the e physical activity y recommendation.
Althoughthe1995recommendationmentionedtheimpor-
tanceofmuscularstrengthandendurance,itstoppedshort
of making g specific declarations s in this s area. Available
evidencenow allows theintegrationofmusclestrengthen-
ingactivitiesintothecorerecommendation.
Finally,minorwordingchanges intherecommendation
havebeenmadetoenhanceclarityincommunications.For
example,theterm‘‘aerobic’’orendurancehasbeenadded
toclarifythetypeofphysicalactivitybeingrecommended
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andtodifferentiateitfrommuscle-strengtheningexercises,
whicharenowpartofthecorerecommendation.
Activity Dose. The term dose e is s used d frequently in
descriptionsofphysicalactivity,butitcanbeinterpretedin
severalways—asthetotalamountofphysicalactivity(i.e.,
total energy expended) or as s the intensity, duration, or
frequency of activity. Although many studies s have
includedameasureofthetotalamountofphysicalactivity
(which may be e used d to o characterize participants as
‘‘active,’’‘‘moderatelyactive,’’or‘‘inactive’’forexample),
relatively few observational studies s have included d details
on the kinds of activity carried out t or r the e duration and
frequency of f each bout of f activity y (36,37). In brief,the
total amount of physical activity is s a a function of its
intensity, duration and frequency. Accordingly, vigorous
intensity activities (those having 9 9 6.0 0 metabolic
equivalents orMETs)carriedout fora particularduration
and frequency generate e greater r energy expenditure than
moderate-intensityactivities(3.0to6.0METs)ofthesame
durationandfrequency.
Since the 1995 recommendation, several large-scale
prospective observational studies, enrolling thousands s to
tens ofthousands s ofpersons, have e clearly documented a
dose-responserelationbetweenphysicalactivityandriskof
cardiovasculardiseaseandprematuremortalityinmenand
women,andinethnicallydiverseparticipants(38,40,48,55,
67,84).These studies include the CollegeAlumni Health
Study(48),theHealthProfessionals’Follow-upStudy(67),
the Nurses’ Health Study (41), the Women’s s Health
Initiative (40), and the Women’s Health Study (37). All
observed significantly y lower r levels of risk with h greater
amounts of f physical l activity. . Readers s should note e that
the physical l activityassessed d inthese studies s was inten-
tional; (i.e., , it was in addition n to the usual l activities s of
dailyliving).
Very few w studies s have e been conducted to examine the
effects of f intensity, , duration, or r frequency y of physical
activity independent of their contribution to the total
amountofphysicalactivity.Basedonrecentdata,thereis
someindicationthatvigorous-intensityactivitiesmayhave
greater benefit for reducing g cardiovascular r disease e and
prematuremortalitythanmoderate-intensityphysicalactiv-
ity, which is s independent t of f their contribution to energy
expenditure(35,61,66).Inaddition,theresultsofasingle
observationalstudysuggest that durationofactivitybouts
doesnotinfluenceriskafteraccountingforthetotalamount
ofenergyexpended(36).
Significantly lower r risks s of f coronary y heart disease or
cardiovasculardiseasehavebeenassociatedwithaslittleas
2.6–5.0 METIhIwk
j1
of walking g (approximately 45–75
minutesperweekofbriskwalking)intheWomen’sHealth
Initiative(40),60–90minIwk
j1
ofwalkingintheWomen’s
Health Study (38), and 3.9–9.9 METIhIwk
j1
of walking
(approximately 60–150 minIwk
j1
at a briskpace) inthe
Nurses’HealthStudy(39).Withhigher‘‘doses’’ofphysical
activity, risks s for r cardiovascular disease have been lower
buttheexactmagnitudeoftheadditionalreductioninrisk
remainsuncertain.
Thus, a body of f evidence e has grown n since e the 1995
recommendation that reaffirms s a dose-response relation
betweenphysicalactivityandhealthbenefits,inparticular
theloweringofriskofcardiovasculardiseaseandpremature
mortality.Thatsignificantlylowerriskshavebeenobserved
withas little as 45–150minIwk
j1
ofbrisk walkingrein-
forces theoriginal1995recommendationforQ30minId
j1
ofmoderate-intensityactivityonmostdays.Also,itiswell
documented that physical activity of longer duration or
higher intensity is s associated with additional risk k decre-
ments, but t the exact t shape of f the e dose-response curve
remainsunclearandmayvarydependingonhealthoutcome
ofinterest and the baseline physical activity level of the
populationbeingevaluated.
The 1995 recommendation advocatedthe accumulation
of physical l activity in ‘‘intermittent bouts s of physical
activity,as shortas8–10min,totaling30minormore.’’
Sincepublicationoftheoriginal recommendation, experi-
mentalresearchhasbeenconductedevaluatingtheeffects
of increasing physical l activity y in short t bouts on n chronic
disease risk factors. As s a a risk factor, these e variables are
typicallyinthecausalpathwayofthediseaseprocessand
byalteringthese riskfactorsinafavorabledirection,itis
assumedthatincreasesinphysical activitywilleventually
reduceriskofadverseclinicaloutcomes.
Althoughexistingresearchaddressingthe accumulation
issue of physical activity in short bouts s is s less s than
complete,asummaryoftheexperimentalfindingssuggests
that moderate-intensity y physical l activity in n shorter bouts
(usually lasting g 10 0 min) ) that t is s accumulated toward the
30-minminimumcanbeaseffectiveassingle,longerbouts
inaffectingchronicdiseaserisk factors.Cardiorespiratory
fitness (17,28,44,46), , lipid/lipoprotein n profiles (17,46),
bloodpressure(44),fastingplasmainsulin(17),postpran-
diallipidemia(45)andweightcontrol(28)allappeartobe
affected beneficially y with h intermittent t bouts of f physical
activity.Inseveralstudiestheeffectsofaccumulatedshort
bouts are e similar to those seenwith continuous s bouts of
physicalactivitylastingQ30min.
A question raised frequently about t physical l activity
dose is how various s amounts s of moderate-and vigorous-
intensity aerobic activity y that t individually are e below the
recommended thresholds s might be combined d to meet the
intentoftheserecommendations.Forexample,cantwoor
three bouts s of moderate-intensity physical l activity be
combined with h two bouts s of f vigorous-intensity y physical
activity to o meet t recommendations? Existing scientific
literature does notallowa direct answertothis question.
However,thedataarestronglysuggestive:thereisalarge
body of f evidence e from observational studies showing
that higher levels of energy expended—which in a free-
living population likely derives from m a combination of
moderate-andvigorous-intensityactivities—areassociated
with numerous health benefits (25,36,37,39,40,55,67,78).
Haskelletal
PhysicalActivityandPublicHealth
1085
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http://circ.ahajournals.org/
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The health benefits ofvarious combinations ofmoderate-
and vigorous-intensity activity have not t been n sufficiently
examined in n observational l studies s nor investigated d using
randomized controlled d trials. . However, based on n health
outcome data fromobservationalstudies andanextensive
database on the energy costs of f various activities, the
followingapproachis recommendedfordeterminingwhat
combinationsofmoderate-andvigorous-intensityactivities
meetthedoserecommendation.
A shorthand d method for estimatingenergy expenditure
duringphysicalactivityistheMETormetabolicequivalent
(1).OneMETrepresents an n individual’s s energy y expendi-
turewhilesittingquietly.Anadultwalkingat3mphona
flat,hardsurfaceisexpendingabout 3.3METs andwhile
jogging/runningonasimilarsurfaceat5mph(12minper
milepace)isexpendingapproximately8METs(seeTable2
for the e MET values of f selected d activities). Thus, if a
manorwomenwalked at3 mph (moderate-intensity) for
30 min they y would d accumulate e 99 9 METImin n of f activity
(3.3 MET 30min= 99METImin), but iftheyjogged
at5mphfor20mintheywouldaccumulate160METImin
(8MET20min=160METImin).So,ifamanorwomen
wastomeettheminimummoderateintensityrecommenda-
tionbywalkingfor30minat3mphon5daysoftheweek,
theywouldaccumulateabout495METImin(995),orto
meet theminimum vigorous-intensityrecommendationby
joggingat5mphfor20minon3daystheywouldaccumu-
lateabout480METImin(1603).Also,theycouldmeet
therecommendationbywalkingat3.0mphfor30minon
2 days (3.3 MET   60 0 min = 198 METImin) ) and d then
joggingat5mphfor20min on2otherdays s (8MET
40min=320 METImin) for a total during the week k of
about518METImin(320+198).
UsingMETs as anindicatorofactivityintensityallows
generally healthy y adults to accumulate e credit for the
various moderate or r vigorous s intensity y activities they
performduringtheweek.Whencombiningmoderateand
vigorous intensityactivitytomeetthecurrent recommen-
dation,theminimumgoalshouldbeintherangeof450to
750 METIminIwk
j1
.Thesevalues are basedontheMET
range of f 3 3 to 6 6 for moderate-intensity activity y and
150 minIwk
j1
(3   150 0 = = 450 and 5 5   150 0 = = 750).
Individuals should start t at t the e lower end of f this s range
whenbeginninganactivityprogramandprogresstowards
thehigherendastheybecomemorefit.ListedinTable2
aretheMETvaluesforavarietyofphysicalactivitiesthat
are of light, , moderate e or vigorous s intensity. For a
comprehensive listing of f MET T values see tabulation by
Ainsworthandcolleagues (1) ) orthefollowing g Web site:
http://prevention.sph.sc.edu/tools/compendium.htm. It is
recognizedthatactualMETvalues can n vary fromperson
topersondependingonavarietyoffactors(e.g.,howthey
performtheactivity,skilllevel,bodycomposition),butthe
valuesprovidedinthecompendiumaresufficientlyaccurate
TABLE 2.METequivalentsofcommonphysicalactivitiesclassifiedaslight,moderateorvigorousintensity.
LightG3.0METs
Moderate3.0– 6.0METs
Vigorous96.0METs
Walking
Walking
Walking,jogging &running
Walkingslowlyaroundhome,
storeoroffice=2.0*
Walking3.0 mph=3.3*
Walkingatveryverybriskpace(4.5mph)=6.3*
Walkingatverybriskpace(4 mph)=5.0*
Walking/hikingatmoderatepaceandgradewithnoor
lightpack(G10lb)=7.0
Hikingatsteepgradesandpack10–42lb=7.5–9.0
Jogging at5mph=8.0*
Jogging at6mph=10.0*
Runningat7mph=11.5*
Household &occupation
Sitting—usingcomputerworkatdeskusing
lighthandtools=1.5
Cleaning—heavy:washingwindows,car,
cleangarage=3.0
Shovelingsand,coal,etc.=7.0
Standingperforming lightworksuchas
makingbed,washingdishes,ironing,
preparingfoodorstoreclerk=2.0–2.5
Sweepingfloorsorcarpet,vacuuming,
mopping=3.0–3.5
Carryingheavyloadssuch asbricks= 7.5
Carpentry—general=3.6
Heavyfarmingsuchasbailinghay=8.0
Carrying &stackingwood=5.5
Shoveling,diggingditches=8.5
Mowinglawn —walkpowermower=5.5
Leisuretime&sports
Arts&crafts,playing cards=1.5
Badminton —recreational=4.5
Basketballgame=8.0
Billiards=2.5
Basketball—shootingaround=4.5
Bicycling—onflat:moderateeffort(12–14mph)=8.0;
fast(14–16mph)=10
Boating—power=2.5
Bicycling—onflat:lighteffort(10–12mph)=6.0
Skiingcrosscountry—slow(2.5mph=7.0;
fast(5.0–7.9 mph)= 9.0
Croquet=2.5
Dancing —ballroomslow= 3.0;
ballroomfast=4.5
Soccer—casual=7.0;competitive= 10.0
Darts=2.5
Fishingfromriverbank&walking =4.0
Swimming —moderate/hard =8–11†
Fishing—sitting= 2.5
Golf—walkingpullingclubs=4.3
Tennissingles=8.0
Playingmostmusicalinstruments=2.0–2.5
Sailingboat, wind surfing=3.0
Volleyball—competitiveatgymorbeach=8.0
Swimmingleisurely=6.0†
Tabletennis=4.0
Tennisdoubles=5.0
Volleyball—noncompetitive=3.0–4.0
Ainsworth,etal.2000(1).*Onflat,hardsurface.†METvaluescanvarysubstantiallyfrompersontoperson duringswimmingasaresultofdifferentstrokesandskilllevels.
1086
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forgenerallyhealthyadultsage18–65yrforthepurposes
ofthisrecommendation.
In summary, 30 0 min n of f moderate-intensity y physical
activity 5dIwk
j1
or20minofvigorous-intensityphysical
activityon 3dIwk
j1
,or acombinationofmoderate- and
vigorous-intensity activity in the range of 450 to 750
METIminIwk
j1
is the minimal amountof f activityrecom-
mended to achieve substantial health h benefits s over and
abovethe routinelight-intensity activities s ofdaily living.
ThisactivitycanbeaccumulatedinQ10-minbouts.Larger
amounts of physical l activity, including more e activity y at
higherintensities,provideadditionalhealthbenefitsbutthe
nature of f the relationship p (amount t versus benefit) likely
variesbyhealthoutcome.Moregenerally,theshapeofthe
dose-response curves, the possible points of maximal
benefit,andthepossiblebenefitsfromactivityboutsshorter
than10minremainunclear.Moreover,furtherinvestigation
is requiredtodetermine howmenandwomenmight best
combineboutsofmoderate-andvigorous-intensityphysical
activitytoobtain desiredbenefits s and d the relativeimpor-
tance of f various components of physical l activity y (e.g.,
intensity, frequency, , energy expenditure) in n achieving
specificoutcomes.
Muscular Strength and d Endurance. . Evidence
supporting the health benefits of f activities s that increase
muscular strength and endurance in n non-elderly
populations has s accumulated rapidly in recent t years
(10,52). For r example, mechanical loading on skeletal
tissue by resistance exercise can effectively stimulate e an
increaseinboneformationinyoungadultsandslowbone
loss in middle e age e (75).Presumably, , this s canresultina
lowerriskofosteoporosis,osteopeniaandbonefracture.In
addition, recent t observational studies s have e suggested an
inverseassociationbetweenriskofall-causemortalityand
various components of muscular strength h or r endurance
(18,32). Although h the specific mechanisms for these
associations are not known, , one may be e the e ability of
muscular strengthening activities s to o promote the
developmentandmaintenanceofmetabolicallyactivelean
muscle mass, which h is s particularly important t for
enhancingglucosemetabolism (27).Resistancetrainingat
leasttwiceperweekprovidesasafeandeffectivemethodto
improving muscular strength and endurance by 25% to
100%ormore(52).Itisrecommendedthat8–10exercises
be performed on two or more e nonconsecutive e days s each
weekusingthemajormuscles.Aresistance(weight)should
be used that results in substantial l fatigue after r 8–12
repetitions of each h exercise. . The e emerging g evidence on
musculoskeletal health h benefits s (30,52) ) and the e potential
population-wide effects of f promoting g skeletal health
supporttheneedfora publichealth recommendationthat
includesresistanceexercise.
Obesity, Gaining, , and d Losing g Weight. . Rapidly
increasingratesofobesityreflectalackofenergybalance
as large numbers of people are consistently expending
fewer calories than they consume. Unfortunately, few
reliable dataareavailable on the relative contributions to
this obesity epidemic c by energy y intake e and energy
expenditure,although bothaswellas s individual variation
areimportant.Whilemore informationis gatheredonthe
varied causes s of f obesity, it seems vitally important t for
publichealtheffortstoaddressbothenergyexpenditureand
energyintake.
It is s reasonable e to assume that persons s with relatively
highdailyenergyexpenditureswouldbelesslikelytogain
weight over r time, compared with h those e who have e low
energyexpenditures.Sofar,datatosupportthishypothesis
arenotparticularlycompelling(57),butsomeobservational
data indicate thatmen whoreport at least 45–60min of
activityonmostdaysgainlessweightthanlessactivemen
(16). Furthermore, the specific types s and d amounts of
activityrequiredtopreventweightgaininthemajorityof
people have e not t been well established d using prospective
studydesigns,anditisclearthattheycannotbeprecisely
setwithout consideringindividual factors suchas energy
intakeandgenetics.Thus,currentlyitisbesttoassumethat
the specific amount of f physical l activity that will help
preventunhealthyweightgainisafunctionthatdiffersfrom
individual to individual,butthat in generalmore activity
increasestheprobabilityofsuccess(62).
The only discretionary y component t of f daily y energy
expenditure is s physical l activity, , and the replacement of
typicallysedentaryroutinesbyvariouskindsofactivityis
a common approach h to o increasing g energy expenditure.
For example, walking or r bicycling g instead of driving g a
carforshort trips would expendadditionalcalories while
traveling the same distance. Still, despite e the e intuitive
appeal of the e idea that physical activity y helps in losing
weight,it appears to produce onlymodest increments s of
weight loss s beyond those e achieved by dietary measures
and its effects no doubt vary among g people e (64). . A
review ofstudies where exerciseorphysicalactivitywas
the sole intervention or r was added d to caloric restriction
foundonlymodestweightlossresultingfromexercise(57).
However,these studies were relativelyshorttermandthe
effectofphysicalactivityonweightlossoverthelongterm
remainsunclear.
Severalobservationalstudieshavebeenconductedonthe
roleofphysicalactivityinpreventingweightregainafteran
initialsizableweightloss(34,41,58,76,82).Thedesignsand
methods of f these studies s have varied, , but all focused on
peoplewhohadlost30–50lb(13.6–22.7kg)andhadnot
regained after r several years. Studies using self-report t of
physicalactivityandenergyexpenditureassessedbydoubly
labeled water techniques (58,76) generally support the
notion that 60–90 min of moderate-intensity physical
activity/daymaybenecessaryforweightmaintenanceafter
suchlargeweightlosses.
In 2005 5 the US S Departments of Health and d Human
ServicesandAgriculturepublishedDietaryGuidelines for
Americans 2005 (71) in which recommendations s were
included regarding the e profiles of f activity that would
Haskelletal
PhysicalActivityandPublicHealth
1087
by guest on September 4, 2011
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contribute to 1) ) the protection n against t selected chronic
diseases(Q30minofmoderateintensityexerciseon most
days), 2) ) prevention n of unhealthy weight t gain (approxi-
mately60minofmoderate-to vigorous-intensityactivity
onmostdays),and3)tosustainweightlossinadultswho
have lost t substantial body weight t (participate in n at least
60–90minofmoderate-intensityactivitydaily).SeeTable3
for a summary y of f these e recommendations. . These weight
gainpreventionguidelinescomefromtheInstituteofMedi-
cineReportpublishedin2002(26)andaresimilartothose
publishedintheInternationalAssociationfortheStudyof
Obesity report in n 2003 3 (‘‘it seems likely that moderate
intensity activity y of approximately 45 to 60 minutes per
dayIisrequiredtopreventthetransitiontooverweightor
obesity’’ and d ‘‘prevention of f weight regain n in formally
obese individuals requires 60–90 minutes of moderate
intensity orlesseramounts s ofvigorousintensityactivity’’
(57),page101]).TheDHHSguidelinesareconsistentwith
the priorCDC/ACSM guidelines s (49) ) and this update in
that a minimum of 30 minId
j1
of moderate-intensity on
5 dIwk
j1
provides meaningful protection n against various
chronicdiseases,thatgreaterbenefitisachievedbyactivity
of greater duration and/or intensity, and that t resistance
exercise should be performed to enhance skeletal muscle
strengthandendurance.
Attempting to maintain a healthy weight is influenced
bya complexset ofcultural,psychosocial and biological
factorsmakingitisdifficulttoaccuratelyidentifywhatthe
primary cause of obesity is for any individual. One can
argue that t people e become e obese because they consume
more calories thanthey expend,but this does not tellus
why the imbalance exists or r the best t way to o correct t it.
Meaningfulphysical activityguidelines fortheprevention
of unhealthy weight gain n or r obesity will l need d to o be
effectively integrated with calorie e intake e guidelines. . For
most adults in the US S today, consumption of calories is
unimpeded while expenditure of calories s via physical
activity is difficult; thus s it is unlikely y that without t some
selfrestrictionofcalorieintakeorexpandedopportunities
and greater encouragement for physical activity many
peoplewillbecomeorcontinuetobeoverweightorobese.
Development ofsuchintegrated ‘‘calorie balance’’guide-
lines andspecific strategies onhow w to effectively imple-
mentthem shouldbea high priorityforphysical activity
and nutrition professionals.In the meantime,because of
the documented obesity-independent benefits of regular
physicalactivity(25,37,40),adultsregardlessofbodysize
or shape e should be encouraged d to o meet the moderate-
intensity,minimumof30minId
j1
on5dIwk
j1
guideline.
For individuals s who o achieve this s level of activity, but
remainoverweight,anincreaseintheirphysicalactivityisa
reasonablecomponentofanystrategytoloseweight.
ADDITIONALISSUES
Risk of f Physical l Activity. Physically y active e adults
tend to experience a higherincidence ofleisure-time and
sportrelatedinjuriesthantheirlessactivecounterparts(15).
However, it appears that t healthy adults who meet the
presentrecommendationsbyperformingmoderate-intensity
activitieshaveanoverallmusculoskeletalinjuryratethatis
notmuch differentthan inactive adults s (11).More active
menandwomenhaveahigherinjuryrateduringsportand
leisure-time activity while inactive adults report t more
injuries during nonsport t and nonleisure e time. . A possible
reason for this s lower r injury incidence e during g non-leisure
time is the increased fitness levels (endurance, strength,
balance)ofthemoreactiveadults(23).
Risk of f musculoskeletal injuries s increases as the
intensityandamount ofthe activityincreases andcanbe
as high h as 55% among men and d women n involved in
joggingprograms (51)andU.S.Armybasictraining(29).
Thus, while physical l activity above the minimal recom-
mendations results inadditionalhealthbenefits, , the asso-
ciated musculoskeletal health risks s are increased d as s well,
possibly negating some of the e added d benefit. This dose-
injuryrelationforspecificactivitiesisunknownandlikely
differs byactivityandindividualanatomicandbehavioral
characteristics(24).
As with h musculoskeletal l injuries, , the risk k of f sudden
cardiac arrest or myocardial infarction is s very low w in
generallyhealthyadultsduringmoderate-intensityactivities
(74,79). However, risk of cardiovascular r complications
increases transiently during vigorous s physical exertion,
especially for persons who o have latent or r documented
coronaryarterydiseaseandarehabituallysedentary(9).For
example, Siscovick and associates (60) ) reported d that the
relative risk of cardiac arrest during vigorous exercise
(jogging)comparedwiththatatallothertimesoftheday,
was56timesgreateramongmenwhoexerciseinfrequently
and only y 5 5 times greater r among g men n who exercise
TABLE 3.PhysicalactivityrecommendationsincludedintheDietaryGuidelinesforAmericans2005(USDepartmentofHealthandHuman Services,2005).
Engageinregularphysicalactivityandreducesedentaryactivitiestopromotehealth,psychologicalwell-being,andahealthybodyweight.
Toreducetheriskofchronicdiseaseinadulthood:Engageinatleast30minofmoderate-intensityphysicalactivity,aboveusualactivityatworkorhome,
onmostdaysoftheweek.
Formostpeople,greaterhealthbenefitscanbeobtainedbyengaginginphysicalactivityofmorevigorousintensityorlongerduration.
Tohelpmanagebodyweightandpreventgradual,unhealthybodyweightgaininadulthood:Engageinapproximately60minofmoderate-tovigorous-intensityactivityon
mostdaysoftheweekwhilenotexceedingcaloricintakerequirements.
Tosustainweightlossinadulthood:Participateinatleast60–90 minofdailymoderate-intensityphysicalactivitywhilenotexceedingcaloricintakerequirements.Some
peoplemayneedtoconsultwithahealthcareproviderbeforeparticipating inthislevelofactivity.
Achievephysicalfitnessbyincludingcardiovascularconditioning,stretchingexercisesforflexibility,andresistanceexercisesorcalisthenicsformusclestrengthandendurance.
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frequently.Despitethetransientincreasesintheincidence
of sudden death and acute myocardial infarction n during
vigorous intensity exercise, , (20,43,60,81), , it t should be
noted that, compared to their sedentary counterparts and
thosewithlowaerobicfitness,physicallyactiveoraerobi-
callyfitindividualshavea25%to50%loweroverallriskof
developingcardiovasculardisease(54,70,80).
Screening/Clearance.Thereiscontroversyregarding
theutilityofmedicalscreeningproceduressuchasexercise
testingpriortoinitiatingvigorous exerciseprograms.The
ACSM recommends s symptom-limited d exercise testing
beforevigorousexercise(960%V
˙
O
2max
)isundertakenby
menQ 45 5 yrandwomen Q Q 55yr,thosewith2 2 ormore
major cardiac risk factors, persons with any signs or
symptomsofcoronaryarterydisease,orthosewithknown
cardiac,pulmonary,ormetabolicdisease(6).However,few
systematically collected data a are e available e to o substantiate
this recommendation. . Guidelines developed by the AHA
and the American College ofCardiology underscore this
lackofdata (19). Also, areport in 2003 fromthe AHA
indicatedthatexercisetestingisnotnecessaryforallpeople
beginning a a moderate e intensity physical activity program
(68). Moreover, guidelines from m the U.S. . Preventive
Services Task Force e discount the use of exercise test
screeningforheartdiseaseinlow-risk,asymptomaticadults
(73).Theserecommendationsandtheextremelylowrateof
cardiovascular complications in asymptomatic persons
while performing moderate-intensity y activity y (74,79), , the
poorpredictive value ofexercise testingforacutecardiac
events(42),thehighcostsofmassexercisetesting,andthe
uncertainties associated with interpreting abnormal
electrocardiographicorcardiac imaging results inpersons
with a low w pretest risk of f coronary y artery y disease (63),
indicate that it is impractical to use exercise e testing g to
prevent serious cardiovascularevents inallasymptomatic
persons who exercise, especially y during g activities of
moderateintensity.
Asymptomatic menand womenwhoplantobe physi-
cally active at t the e minimum levels s ofmoderate-intensity
activity set t forth in the e present recommendation do not
need to consult t with h a physician or health care provider
priortobeginningunless theyhavespecificmedicalques-
tions. Symptomatic persons s or r those with anycardiovas-
culardisease,diabetes,otheractivechronicdisease,orany
medicalconcern,shouldconsultaphysicianorhealthcare
providerprior to any substantive increase inphysical ac-
tivity,particularlyvigorous-intensityactivity(68).
Promoting Physical Activity. Individually adapted
behaviorchangeiscritical tofacilitateaphysicallyactive
lifestyle (31), , but t the process involves s a a multitude of
complex variables, including g personal, , programmatic,
social,environmentalandrelatedfactors.Toachievelong-
termchangesinhealth-relatedbehaviors,theseandmedical
factorsmustbeaddressedcollectively(56).Allhealthcare
professionals should d broaden n their advice to o patients
beyond the traditional l prescriptive program based d on
medicalclearanceandsupervisionbyinitiallyencouraging
themtoaccumulatemoderate-intensityphysicalactivityas
specifiedinthepresentrecommendation.Awiderangeof
activities should be e identified that meet each person’s
interests, needs, schedule and environment, , take e into
considerationfamily, work and social commitments,with
options for inclement weather r and d travel. Excellent
materials forthe education n and counseling of clients are
availableformtheNationalInstitutesofHealth(72),ACSM
(5),andAHA(8).As informationhasincreasedaboutthe
rolethatenvironmental influences play y in n promoting or
inhibiting physical activity even among the most
motivated persons s (31,56), future efforts to promote
physical activity must considerhow people interact with
their environment t (22). . For all l health professionals, , the
challenge is s to leverage e their professional credibility to
enroll increasing numbers s of participants in physical
activity programs s that are designed d to overcome barriers
to long-term adherence, using g effective e behavioral
management and environmental change strategies, so that
many more individuals will realize the e benefits provided
byaphysicallyactivelifestyle.
CONCLUSION
Frequent physical activity is animportant behavior for
individualandpopulationhealth.SeeTable4.Topromote
andmaintainhealth,allhealthyadults need d to engagein
TABLE 4.Physicalactivityrecommendationsforhealthyadultsaged18–65yr—2007.
1.Topromoteandmaintaingoodhealth, adultsaged18–65yrshouldmaintainaphysicallyactivelifestyle.I(A)
2.Theyshouldperformmoderate-intensityaerobic(endurance)physicalactivityforaminimumof30minonfivedayseachweekorvigorous-intensityaerobicactivityfora
minimumof20minon threedayseachweek.I(A)
3.Combinationsofmoderate-andvigorous-intensityactivitycanbeperformedtomeetthisrecommendation.Forexample,apersoncanmeettherecommendationbywalking
brisklyfor30mintwiceduringtheweekandthen joggingfor20minontwo otherdays.IIa(B)
4.Thesemoderate-orvigorousintensityactivitiesareinadditiontothelightintensityactivitiesfrequentlyperformedduringdailylife(e.g.,selfcare,washingdishes,usinglight
toolsatadesk)oractivitiesofveryshortduration(e.g.,taking outtrash,walkingto parking lotatstoreoroffice).
5.Moderate-intensityaerobicactivity,whichisgenerallyequivalenttoabriskwalkandnoticeablyacceleratestheheartrate,canbeaccumulatedtowardthe30-minminimum
byperformingboutseachlasting 10ormoreminutes.I(B)
6.Vigorous-intensityactivityisexemplifiedbyjogging,andcausesrapidbreathing andasubstantialincreaseinheartrate.
7.Inaddition,atleasttwiceeachweekadultswillbenefitbyperformingactivitiesusingthemajormusclesofthebodythatmaintain orincreasemuscularstrengthand
endurance.IIa(A)
8.Becauseofthedose-responserelationbetweenphysicalactivityandhealth,personswhowishtofurtherimprovetheirpersonalfitness,reducetheirriskforchronicdiseases
anddisabilities,orpreventunhealthyweightgainwilllikelybenefitbyexceedingtheminimumrecommendedamountofphysicalactivity.I(A)
Haskelletal
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