Quantity and Quality of Exercise for Developing and Maintaining...

26 Pages·2011·0.37 MB·English

SPECIAL COMMUNICATIONS
Quantity and Quality of
Exercise for Developing
and Maintaining
Cardiorespiratory,
Musculoskeletal, and
Neuromotor Fitness in
Apparently Healthy
Adults: Guidance for
Prescribing Exercise
POSITIONSTAND
This pronouncement was written for the American College of
Sports Medicine by Carol Ewing Garber, Ph.D., FACSM, (Chair);
BryanBlissmer,Ph.D.;MichaelR.Deschenes,Ph.D.,FACSM;Barry
A.Franklin,Ph.D.,FACSM;MichaelJ.Lamonte,Ph.D.,FACSM;I-Min
Lee, M.D.,Sc.D.,FACSM; DavidC. Nieman,Ph.D.,FACSM; and
DavidP.Swain,Ph.D.,FACSM.
SUMMARY
ThepurposeofthisPositionStandistoprovideguidancetoprofessionals canbenefitfromengaginginamountsofexerciselessthanrecommended.
who counsel and prescribe individualized exercise to apparently healthy Inadditiontoexercisingregularly,therearehealthbenefitsinconcurrently
adultsofallages.Theserecommendationsalsomayapplytoadultswith reducingtotaltimeengagedinsedentarypursuitsandalsobyinterspersing
certain chronic diseases or disabilities, when appropriately evaluated and frequent,shortboutsofstandingandphysicalactivitybetweenperiodsof
advised by a health professional. This document supersedes the 1998 sedentaryactivity,eveninphysicallyactiveadults.Behaviorallybasedex-
AmericanCollegeofSportsMedicine(ACSM)PositionStand,‘‘TheRec- erciseinterventions,theuseofbehaviorchangestrategies,supervisionbyan
ommended Quantity and Quality of Exercise for Developing and Main- experiencedfitnessinstructor,andexercisethatispleasantandenjoyable
tainingCardiorespiratoryandMuscularFitness,andFlexibilityinHealthy canimproveadoptionandadherencetoprescribedexerciseprograms.Ed-
Adults.’’ The scientific evidence demonstrating the beneficial effects of ucating adults about and screening for signs and symptoms of CHD and
exerciseisindisputable,andthebenefitsofexercisefaroutweightherisksin gradualprogressionofexerciseintensityandvolumemayreducetherisks
mostadults.Aprogramofregularexercisethatincludescardiorespiratory, of exercise.Consultationswithamedicalprofessionalanddiagnosticex-
resistance, flexibility, and neuromotor exercise training beyond activities ercise testing for CHD are useful when clinically indicated but are not
ofdailylivingtoimproveandmaintainphysicalfitnessandhealthises- recommended for universal screening to enhance the safety of exercise.
sentialformostadults.TheACSMrecommendsthatmostadultsengage KeyWords:PracticeGuidelines,Prescription,PhysicalActivity,Physical
inmoderate-intensitycardiorespiratoryexercisetrainingforQ30minIdj1on Fitness,Health,AerobicExercise,ResistanceExercise,FlexibilityExercise,
Q5dIwkj1foratotalofQ150minIwkj1,vigorous-intensitycardiorespira- NeuromotorExercise,FunctionalFitness
toryexercisetrainingforQ20minIdj1onQ3dIwkj1(Q75minIwkj1),ora
combinationofmoderate-andvigorous-intensityexercisetoachieveatotal
energyexpenditureofQ500–1000METIminIwkj1.On2–3dIwkj1,adults INTRODUCTION
should also perform resistance exercises for each of the major muscle
Manyrecommendationsforexerciseandphysicalactivity
groups,andneuromotorexerciseinvolvingbalance,agility,andcoordina-
byprofessionalorganizationsandgovernmentagencieshave
tion.Crucialtomaintainingjointrangeofmovement,completingaseries
been published since the sui generis publications of the
offlexibilityexercisesforeachthemajormuscle–tendongroups(atotalof
60 s per exercise) on Q2 dIwkj1 is recommended. The exercise program AmericanCollegeofSportsMedicine(ACSM)(10,11).The
shouldbemodifiedaccordingtoanindividual’shabitualphysicalactivity, number of recommendations has escalated after the release
physicalfunction,healthstatus,exerciseresponses,andstatedgoals.Adults of the 1995 Centers for Disease Control and Prevention
whoareunableorunwillingtomeettheexercisetargetsoutlinedherestill (CDC)/ACSMpublichealthrecommendations(280)andthe
1996USSurgeonGeneral’sReport(371),andtheostensibly
contradictory recommendations between these documents
0195-9131/11/4307-1334/0
MEDICINE&SCIENCEINSPORTS&EXERCISE have led to confusion among health professionals, fitness
(cid:1)
Copyright(cid:2)2011bytheAmericanCollegeofSportsMedicine professionals, and the public (32,155). The more recent
DOI:10.1249/MSS.0b013e318213fefb recommendationsoftheAmericanHeartAssociation(AHA)
1334
and the ACSM (155,264) and the 2008 Physical Activity rating system of the National Heart Lung and Blood Institute S
Guidelines for Americans (370) have helped clarify public (263)showninTable3.Observationalstudiesofphysicalac- P
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health recommendations for physical activity, and these tivity and, to a lesser extent, physical fitness are the primary C
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are now are incorporated into the current edition of the sourcesofdatasupportingthebenefitsofexerciseinreducing A
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ACSM’s Guidelines for Exercise Testing and Prescription therisksofmortalityandmorbidity,andthesestudiesprovided
C
(14). The purpose of this Position Stand is to provide scien- guidanceontherecommendedpatternsandvolumesofexercise O
tific evidence-based recommendations to health and fitness togainhealthandfitnessbenefits.Randomizedclinicaltrialsof M
professionals in the development of individualized exercise exercise training and meta-analyses contributed evidence for M
prescriptions for apparentlyhealthy adultsofall ages. When thecausaleffects(effectivenessandefficacy)ofexercisetrain- U
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appropriately evaluated and advised by a healthprofessional ing(frequency,intensity,duration,mode,pattern,volume)for
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(e.g., physician, clinical exercise physiologist, nurse), these improvingphysicalfitnessandbiomarkersofchronicdisease. A
recommendations may also apply to persons with certain ThefocusoftherecommendationsinthisPositionStandis T
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chronic diseases or disabilities, with modifications required on exercise, which connotes intentional physical activity for
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according toanindividual’shabitualphysicalactivity, phys- improving health and fitness. The terms physical activity and
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ical function, health status, exercise response, and stated physical fitness are used when these terms more precisely re-
goals.TheadvicepresentedinthisPositionStandisintended flectthenatureofthescientificevidencethatsupportstheex-
principally for adults whose goal is to improve physical fit- ercise recommendations. The data supporting the benefits of
nessandhealth;adultathletesengagingincompetitivesports exercisehavebeenderivedprimarilyfromobservationalstud-
and advanced training regimens can benefit from more ad- ies that have evaluated physical activity, or less commonly,
vanced training techniques (13,212,254,255). The evidence physical fitness (rather than exercise), while the randomized
statements and summary exercise recommendations derived clinicaltrialscentermostlyonexercise.Exercise,physicalac-
fromthescientificreviewarefoundinTables1and2. tivity, and physical fitness are closely related constructs, but
This document updates the scientific evidence published theyhavedistinctmeanings.Table4presentsthedefinitionsof
since the 1998 Position Stand (12). Epidemiological studies, these and other common terms used in this Position Stand.
randomized and nonrandomized clinical trials, meta-analyses, All terms used in this document conform with the definitions
evidence-based guidelines, consensus statements, and scien- foundinthePhysicalActivityGuidelinesAdvisoryCommittee
tific reviews published from 1998 to 2010 were identified Report(372)andtheclassificationsofcardiovasculardiseases
throughbibliographicsearchesusingcommoncomputersearch (CVD)oftheAHA(229).
engines (e.g., PubMed, Medline, Google Scholar, IndexCat,
PsychArticles, and CINAHL). References cited in the 2008
WHAT ARE THE HEALTH BENEFITS OF
PhysicalActivityGuidelinesAdvisoryCommitteeReport(372),
PHYSICAL ACTIVITY AND EXERCISE IN
theAHA/ACSMpublichealthstatements(155,264),andarti-
ADULTS?
clebibliographieswerealsoreviewedbythewritinggroup.
Interpretationoftheavailablescientificevidencewasmade Regularphysicalactivityandexerciseareassociatedwith
byconsensusofthewritinggroupmembersusingtheevidence numerous physical and mental health benefits in men and
TABLE1.Summaryofthegeneralevidencerelevanttotheexerciseprescription.
EvidenceStatement EvidenceCategory
Healthbenefits Engaginginregularexerciseandreducingsedentarybehaviorisvitalforthehealthofadults. A
Reversibilityoftrainingeffects Training-inducedadaptationsarereversedtovaryingdegreesovertimeuponcessationof A
aprogramofregularexercise.
Heterogeneityofresponse Thereisconsiderablevariabilityinindividualresponsestoastandarddoseofexercise. A
Exerciseregimen Cardiorespiratoryandresistanceexercisetrainingisrecommendedtoimprovephysicalfitnessandhealth. A
Flexibilityexercisesimproveandmaintainandjointrangeofmovement A
Neuromotorexercisesandmultifacetedactivities(suchastaijiandyoga)canimproveormaintain B
physicalfunction,andreducefallsinolderpersonsatriskforfalling.
Neuromotorexercisesmaybenefitmiddleagedandyoungeradults D
Exerciseadoptionandmaintenance Theory-basedexerciseinterventionscanbeeffectiveinimprovingadoptionandshort-termadherencetoexercise. B
Moderate-intensityexerciseandexercisethatisenjoyablecanenhancetheaffectiveresponsestoexercise, B
andmayimproveexerciseadherence
Supervisionbyanexperiencedhealthandfitnessprofessionalandenhanceexerciseadherence C
Risksofexercise ExerciseisassociatedwithanincreasedriskofmusculoskeletalinjuryandadverseCHDevents. B
Thebenefitsofexercisefaroutweightherisksinmostadults. C
Warm-up,cooldown,flexibilityexercise,andgradualprogressionofexercisevolumeandintensitymay C
reducetheriskofCVDeventsandmusculoskeletalinjuryduringexercise.
ConsultationwithaphysiciananddiagnosticexercisetestingforCHDmayreducerisksofexerciseif C
medicallyindicated,butarenotrecommendedonaroutinebasis.
Consultationwithawell-trainedfitnessprofessionalmayreducerisksinnoviceexercisersandinpersonswith D
chronicdiseasesandconditions
Preexercisescreening ScreeningforandeducatingabouttheforewarningsignsorsymptomsofCVDeventsmayreducethe C
risksofseriousuntowardevents.
Tableevidencecategories:A,randomizedcontrolledtrials(richbodyofdata);B,randomizedcontrolled(limitedbodyofdata);C,nonrandomizedtrials,observationalstudies;D,panel
consensusjudgment.FromtheNationalHeartLungandBloodInstitute(263).
QUANTITYANDQUALITYOFEXERCISE Medicine&ScienceinSports&Exercised 1335
S TABLE2.Evidencestatementsandsummaryofrecommendationsfortheindividualizedexerciseprescription.
N
Evidence-BasedRecommendation EvidenceCategory
O
Cardiorespiratory(‘‘aerobic’’)exercise
I
T Frequency Q5dIwkj1ofmoderateexercise,orQ3dIwkj1ofvigorousexercise,oracombinationof A
CA moderateandvigorousexerciseonQ3–5dIwkj1isrecommended.
Intensity Moderateand/orvigorousintensityisrecommendedformostadults. A
I
N Light-tomoderate-intensityexercisemaybebeneficialindeconditionedpersons. B
U Time 30–60minIdj1(150minIwkj1)ofpurposefulmoderateexercise,or20–60minIdj1(75minIwkj1)ofvigorous A
M exercise,oracombinationofmoderateandvigorousexerciseperdayisrecommendedformostadults.
M G20minIdj1(G150minIwkj1)ofexercisecanbebeneficial,especiallyinpreviouslysedentarypersons. B
Type Regular,purposefulexercisethatinvolvesmajormusclegroupsandiscontinuousandrhythmicinnature A
O
isrecommended.
C Volume AtargetvolumeofQ500–1000METIminIwkj1isrecommended. C
L IncreasingpedometerstepcountsbyQ2000stepsperdaytoreachadailystepcountQ7000steps B
A perdayisbeneficial.
CI Exercisingbelowthesevolumesmaystillbebeneficialforpersonsunableorunwillingtoreachthisamount C
E ofexercise.
P Pattern Exercisemaybeperformedinone(continuous)sessionperdayorinmultiplesessionsofQ10mintoaccumulate A
S thedesireddurationandvolumeofexerciseperday.
ExerciseboutsofG10minmayyieldfavorableadaptationsinverydeconditionedindividuals. B
Intervaltrainingcanbeeffectiveinadults. B
Progression Agradualprogressionofexercisevolumebyadjustingexerciseduration,frequency,and/orintensityisreasonable B
untilthedesiredexercisegoal(maintenance)isattained.
ThisapproachmayenhanceadherenceandreducerisksofmusculoskeletalinjuryandadverseCHDevents. D
Resistanceexercise
Frequency Eachmajormusclegroupshouldbetrainedon2–3dIwkj1. A
Intensity 60%–70%ofthe1RM(moderatetohardintensity)fornovicetointermediateexerciserstoimprovestrength. A
Q80%ofthe1RM(hardtoveryhardintensity)forexperiencedstrengthtrainerstoimprovestrength. A
40%–50%ofthe1RM(verylighttolightintensity)forolderpersonsbeginningexercisetoimprovestrength. A
40%–50%ofthe1RM(verylighttolightintensity)maybebeneficialforimprovingstrengthinsedentarypersons D
beginningaresistancetrainingprogram.
G50%ofthe1RM(lighttomoderateintensity)toimprovemuscularendurance. A
20%–50%ofthe1RMinolderadultstoimprovepower. B
Time Nospecificdurationoftraininghasbeenidentifiedforeffectiveness.
Type Resistanceexercisesinvolvingeachmajormusclegrouparerecommended. A
Avarietyofexerciseequipmentand/orbodyweightcanbeusedtoperformtheseexercises. A
Repetitions 8–12repetitionsisrecommendedtoimprovestrengthandpowerinmostadults. A
10–15repetitionsiseffectiveinimprovingstrengthinmiddleagedandolderpersonsstartingexercise A
15–20repetitionsarerecommendedtoimprovemuscularendurance A
Sets Twotofoursetsaretherecommendedformostadultstoimprovestrengthandpower. A
Asinglesetofresistanceexercisecanbeeffectiveespeciallyamongolderandnoviceexercisers. A
e2setsareeffectiveinimprovingmuscularendurance. A
Pattern Restintervalsof2–3minbetweeneachsetofrepetitionsareeffective. B
ArestofQ48hbetweensessionsforanysinglemusclegroupisrecommended. A
Progression Agradualprogressionofgreaterresistance,and/ormorerepetitionsperset,and/orincreasingfrequencyisrecommended. A
Flexibilityexercise
Frequency Q2–3dIwkj1iseffectiveinimprovingjointrangeofmotion,withthegreatestgainsoccurringwithdailyexercise. B
Intensity Stretchtothepointoffeelingtightnessorslightdiscomfort. C
Time Holdingastaticstretchfor10–30sisrecommendedformostadults. C
Inolderpersons,holdingastretchfor30–60smayconfergreaterbenefit. C
ForPNFstretching,a3-to6-scontractionat20%–75%maximumvoluntarycontractionfollowedbya B
10-to30-sassistedstretchisdesirable.
Type Aseriesofflexibilityexercisesforeachofthemajormuscle–tendonunitsisrecommended. B
Staticflexibility(activeorpassive),dynamicflexibility,ballisticflexibility,andPNFareeacheffective. B
Volume Areasonabletargetistoperform60softotalstretchingtimeforeachflexibilityexercise. B
Pattern Repetitionofeachflexibilityexercisetwotofourtimesisrecommended- B
Flexibilityexerciseismosteffectivewhenthemuscleiswarmedthroughlighttomoderateaerobicactivityor A
passivelythroughexternalmethodssuchasmoistheatpacksorhotbaths.
Progression Methodsforoptimalprogressionareunknown.
Neuromotorexercisetraining
Frequency Q2–3dIwkj1isrecommended. B
Intensity Aneffectiveintensityofneuromotorexercisehasnotbeendetermined.
Time Q20–30minIdj1maybeneeded. B
Type Exercisesinvolvingmotorskills(e.g.,balance,agility,coordination,andgait),proprioceptiveexercise B
training,andmultifacetedactivities(e.g.,taijiandyoga)arerecommendedforolderpersonsto
improveandmaintainphysicalfunctionandreducefallsinthoseatriskforfalling.
Theeffectivenessofneuromuscularexercisetraininginyoungerandmiddle-agedpersonshasnotbeen D
established,butthereisprobablebenefit.
Volume Theoptimalvolume(e.g.,numberofrepetitions,intensity)isnotknown.
Pattern Theoptimalpatternofperformingneuromotorexerciseisnotknown.
Progression Methodsforoptimalprogressionarenotknown.
Tableevidencecategories:A,randomizedcontrolledtrials(richbodyofdata);B,randomizedcontrolledtrials(limitedbodyofdata);C,nonrandomizedtrials,observationalstudies;
D,panelconsensusjudgment.FromtheNationalHeartLungandBloodInstitute(263).
1336 OfficialJournaloftheAmericanCollegeofSportsMedicine http://www.acsm-msse.org
TABLE3.Evidencecategories. S
P
EvidenceCategory SourcesofEvidence Definition
E
A Randomizedcontrolledtrials Evidenceisfromendpointsofwell-designedRCT(ortrialsthatdepartonlyminimallyfromrandomization)that C
(RCT;richbodyofdata) provideaconsistentpatternoffindingsinthepopulationforwhichtherecommendationismade.CategoryA IA
thereforerequiressubstantialnumbersofstudiesinvolvingsubstantialnumbersofparticipants. L
B Randomizedcontrolledtrials EvidenceisfromendpointsofinterventionstudiesthatincludeonlyalimitednumberofRCT,posthocor
C
(limitedbodyofdata) subgroupanalysisofRCT,ormeta-analysisofRCT.Ingeneral,CategoryBpertainswhenfewrandomizedtrials O
exist,theyaresmallinsize,andthetrialresultsaresomewhatinconsistent,orthetrialswereundertaken
M
inapopulationthatdiffersfromthetargetpopulationoftherecommendation.
C Nonrandomizedtrials, Evidenceisfromoutcomesofuncontrolledornonrandomizedtrialsorfromobservationalstudies. M
observationalstudies U
D Panelconsensusjudgment Expertjudgmentisbasedonthepanel’ssynthesisofevidencefromexperimentalresearchdescribedinthe N
literatureand/orderivedfromtheconsensusofpanelmembersbasedonclinicalexperienceorknowledge I
C
thatdoesnotmeettheabove-listedcriteria.Thiscategoryisusedonlyincaseswheretheprovisionofsome
A
guidancewasdeemedvaluablebutanadequatelycompellingclinicalliteratureaddressingthesubjectofthe
T
recommendationwasdeemedinsufficienttojustifyplacementinoneoftheothercategories(AthroughC). I
O
EvidencecategoriesreprintedwithpermissionfromtheNationalHeartLungandBloodInstitute(263). N
S
women. All-cause mortality is delayed by regularly engag- WHAT ARE THE HEALTH BENEFITS OF
ing in physical activity; this is also the case when an indi- PHYSICAL FITNESS?
vidual increases physical activity by changing from a
Eachcomponentofphysicalfitness(i.e.,cardiorespiratory
sedentary lifestyle or a lifestyle with insufficient levels of
fitness,muscularstrengthandendurance(muscularfitness),
physicalactivitytoonethatachievesrecommendedphysical
body composition, flexibility, and neuromotor fitness) con-
activitylevels(372).Exerciseandphysicalactivitydecrease
ceivablyinfluencessomeaspectofhealth.Quantitativedata
the risk of developing CHD, stroke, type 2 diabetes, and on the relationships between fitness and health are avail-
someformsofcancer(e.g.,colonandbreastcancers)(372). able for only some fitness components, with the most data
Exercise and physical activity lower blood pressure; im-
available on body composition and cardiorespiratory fit-
prove lipoprotein profile, C-reactiveprotein, and other CHD
ness. In the domain of body composition, overall and ab-
biomarkers;enhanceinsulinsensitivity,andplayanimportant
dominal obesity are associated with increased risk of
roleinweightmanagement(372). Of particular relevance to
adverse health outcomes (12,37,92,301), whereas greater
older adults, exercise preserves bone mass and reduces the
fat-free mass is associated with a lower risk of all-cause
riskoffalling(264).Preventionofandimprovementinmild
mortality (37,160). Higher levels of cardiorespiratory and
tomoderatedepressivedisorders and anxietycan occurwith muscular fitness are each associated with lower risks for
exercise (35,155,244,250,305,337,398). A physically active poorer health (24,42,75,117,128,189,265,292,339).
lifestyle enhances feelings of ‘‘energy’’ (294), well-being
Relationships between cardiorespiratory fitness, biologi-
(25,406),qualityoflife(81,139,302),andcognitivefunction
calriskfactors,andclinicalhealthoutcomestendtoparallel
(203,318,333)andisassociatedwithalowerriskofcognitive
those for physical activity: apparently healthy middle-aged
declineanddementia(210,281,387,405).
and older adults with greater cardiorespiratory fitness at
TABLE4.Definitionofkeyterms.
Activecommuting Travelingtoorfromworkorschoolbyameansinvolvingphysicalactivity,suchaswalking,ridingabicycle(324).
Biomarkers Aspecificbiochemicalindicatorofabiologicalprocess,event,orcondition(i.e.,disease,aging,etc.)(251).
Cardiometabolic FactorsassociatedwithincreasedriskofCVDandmetabolicabnormalitiesincludingobesity,insulinresistance,
glucoseintolerance,andtype2diabetesmellitus.
Physicalactivity ‘‘Anybodilymovementproducedbyskeletalmusclesthatresultsinenergyexpenditure’’(64)aboveresting(basal)levels(371).
Physicalactivitybroadlyencompassesexercise,sports,andphysicalactivitiesdoneaspartofdailyliving,occupation,leisure,
andactivetransportation.
Exercise ‘‘Physicalactivitythatisplanned,structured,andrepetitiveand[that]hasasafinalorintermediateobjectivetheimprovementor
maintenanceofphysicalfitness’’(64).
Physicalfitness ‘‘Theabilitytocarryoutdailytaskswithvigorandalertness,withoutunduefatigueandwithampleenergytoenjoy[leisure]pursuitsandto
meetunforeseenemergencies’’(64).Physicalfitnessisoperationalizedas‘‘[asetof]measurablehealthandskill-relatedattributes’’that
includecardiorespiratoryfitness,muscularstrengthandendurance,bodycompositionandflexibility,balance,agility,reactiontime
andpower(1985).
Physicalfunction Thecapacityofanindividualtocarryoutthephysicalactivitiesofdailyliving.Physicalfunctionreflectsmotorfunctionandcontrol,physical
fitness,andhabitualphysicalactivity(54,176)andisanindependentpredictoroffunctionalindependence(130),disability(126),morbidity,
andmortality(125).
Energyexpenditure Thetotalamountofenergy(gross)expendedduringexercise,includingtherestingenergyexpenditure(restingenergyexpenditure+exercise
energyexpenditure).EnergyexpendituremaybearticulatedinMETs,kilocaloriesorkilojoules(342).
MET Anindexofenergyexpenditure.‘‘[AMETis]theratiooftherateofenergyexpendedduringanactivitytotherateofenergyexpended
atrestI.[One]METistherateofenergyexpenditurewhilesittingatrestIbyconvention,[1METisequalto]anoxygenuptake
of3.5[mLIkgj1Iminj1]’’(370).
MET-minutes Anindexofenergyexpenditurethatquantifiesthetotalamountofphysicalactivityperformedinastandardizedmanneracrossindividualsand
typesofactivities(370).CalculatedastheproductofthenumberofMETsassociatedwithoneormorephysicalactivitiesandthenumber
ofminutestheactivitieswereperformed(i.e.,METs(cid:1)minutes).Usuallystandardizedperweekorperday.
Example:jogging(atÈ7METs)for30minon3dIwkj1:7METs(cid:1)30min(cid:1)threetimesperweek=630METIminIwkj1.
Sedentarybehavior Activitythatinvolveslittleornomovementorphysicalactivity,havinganenergyexpenditureofabout1–1.5METs.Examplesaresitting,
watchingtelevision,playingvideogames,andusingacomputer(276).
QUANTITYANDQUALITYOFEXERCISE Medicine&ScienceinSports&Exercised 1337
S baseline, and those who improve fitness over time have a (214,237,320,353). This observation is congruent with the
N lower risk of all-cause and CVD mortality and morbidity findings from the DREW trial (76) among sedentary, over-
O
(41,213,339,340).Adecreasedriskofclinicaleventsisalso weightpostmenopausalwomen,which showedthatone-half
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A associated with greater cardiorespiratory fitness in individ- the currently recommended volume of physical activity was
C uals withpreexisting disease (75,213,247,262,338). sufficienttosignificantlyimprovecardiorespiratoryfitness.
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N
The minimum level of cardiorespiratory fitness required The available data support a dose–response relationship
U
forhealthbenefitmaybedifferentformenandwomenand between physical activity and health outcomes, so it is rea-
M
M for older and younger adults. This is because the distribu- sonable to state with respect to exercise, ‘‘some is good;
O tionofcardiorespiratoryfitnessisdifferentbetweenhealthy more is better.’’ However, the shape of the dose–response
C men and women (14) and a nonlinear decline in cardiore- curve is less clear, and it is probable that the shape of the
L spiratory fitness, which occurs with advancing age when curve may differ depending on the health outcome of inter-
A
I not accompanied by a program of regular exercise (118). est and the baseline level of physical activity of the indi-
C
E Sex- and age-specific norms for cardiorespiratory fitness vidual (155).
P
in apparently healthy adults are available in the ACSM Howcanstudiesofphysicalfitnesshelptoclarify
S
Guidelines for Exercise Testing and Prescription(14). the question of ‘‘How much physical activity is
needed?’’ The physical activity dose required to achieve a
specific health benefit may be further clarified by equating
HOW MUCH PHYSICAL ACTIVITY IS
specific amounts of physical activity to the levels of cardio-
NEEDED TO IMPROVE HEALTH AND
respiratoryfitnesssufficienttoconferhealthbenefits.Forin-
CARDIORESPIRATORY FITNESS?
stance,astudyofapparentlyhealthymiddle-agedadults(335)
Whatvolumeofphysicalactivityisneeded?Several showed that all-cause and CVD mortality rates were ap-
studies have supported a dose–response relationship be- proximately 60% lower in persons with moderate compared
tween chronic physical activity levels and health outcomes with low cardiorespiratory fitness, estimated from time to
(155,372),suchthatgreater benefit isassociatedwithhigher fatigue on a treadmill test. The adults of moderate fitness in
amounts of physical activity. Data regarding the specific thisstudyreportedaweeklyenergyexpenditureinmoderate-
quantityandqualityofphysicalactivityfortheattainmentof intensity physical activity, such as brisk walking on level
thehealthbenefitsarelessclear.Epidemiologicstudieshave ground, of È8–9 METIhIwkj1. Therefore, a level of cardio-
estimated the volume of physical activity needed to achieve respiratory fitness associated with substantial health benefit
specifichealthbenefits,typicallyexpressedaskilocaloriesper seemstobeattainablethroughadoseofexerciseorphysical
week(kcalIwkj1),MET-minutesperweek(METIminIwkj1), activitycompatiblewiththerecommendationsinthisPosition
or MET-hours per week (METIhIwkj1). Large prospective Standandothercurrentpublications(14,155,264,370).
cohort studies of diverse populations (216,237,320,353)
clearly show that an energy expenditure of approximately
WHAT IS THE EFFECT OF EXERCISE
1000 kcalIwkj1 of moderate-intensity physical activity (or
TRAINING ON CARDIORESPIRATORY
about 150 minIwkj1) isassociated withlower rates ofCVD
FITNESS AND CARDIOVASCULAR AND
andprematuremortality.Thisisequivalenttoanintensityof
METABOLIC DISEASE (CARDIOMETABOLIC)
about3–5.9METs(forpeopleweighingÈ68–91kg)and10
RISK FACTORS?
METIhIwkj1.TenMET-hoursperweekcanalsobeachieved
withQ20minIdj1ofvigorous-intensity(QÈ6METs)physical What is the role of exercise intensity in modify-
activityperformedQ3dIwkj1orforatotalofÈ75minIwkj1. ing the responses to exercise? Either moderate- or
Previous investigations have suggested that there may be a vigorous-intensity exercise, or both, can be undertaken to
dose–response relationship between energy expenditure and meet current exercise recommendations, provided the crite-
depression, but additional study is needed to confirm this rion for total volume of energy expended is satisfied. What
possibility(25,101). islessclearisthis:forthesamevolumeofenergyexpended,
In the general population, this 1000 kcalIwkj1 volume of is vigorous-intensity exercise associated with additional
physical activity is accumulated through a combination of risk reduction? The data are unclear because most epidemi-
physicalactivitiesand exerciseofvarying intensities.There- ologic studies examining chronic disease outcomes and
fore, the 2008 Physical Activity Guidelines for Americans randomizedclinicaltrialsofexercisetraininghavenottaken
(370), the 2007 AHA/ACSM recommendations (155,264), into account the total volume of energy expended (323).
and the ACSM guidelines (14) allow for a combination of Thatis,inmoststudieswherebenefitisfoundforvigorous-
moderate- and vigorous-intensity activities to expend the compared with moderate-intensity exercise, there is also a
requisite weekly energy expenditure. An intriguing observa- greater volume of exercise in the vigorous-intensity condi-
tionfromseveralstudiesisthatsignificantriskreductionsfor tion. Thus, it is unclear whether the added benefit is due to
CVDdiseaseandprematuremortalitybegintobeobservedat the vigorous-intensity per se or whether the results simply
volumes below these recommended targets, starting at about reflect the additional benefit due to the higher volume of
one-halfoftherecommendedvolume(i.e.,È500kcalIwkj1) energy expended. Nevertheless, there are some reports that
1338 OfficialJournaloftheAmericanCollegeofSportsMedicine http://www.acsm-msse.org
support that vigorous-intensity exercise is associated with factors. Two comprehensive reviews by Durstine et al. S
greater risk reductions for CVD and all-cause mortality (102,103)foundlittleevidenceforanintensitythresholdfor P
E
comparedwithmoderate-intensityactivityofsimilarenergy changes in HDL cholesterol, LDL cholesterol, or trigly- C
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expended (155). cerides, although most studies did not control for exercise A
L
Exercise intensity is an important determinant of the volume, frequency, and/or duration and were conducted at
C
physiological responses to exercise training (12,14,120). intensitiesQ40%V˙O2max.Similarmethodologicallimitations O
Earlier randomized trials did not control for total exercise pertain to studies evaluating blood pressure, glucose intol- M
volume, so the independent contributions of volume and erance, and insulin resistance (6,284,361). Several studies M
intensity were unclear, but more recent studies have sup- suggest that exercise intensity does not influence the mag- U
N
ported the greater benefits of vigorous versus moderate nitudeoflossofbodyweightorfatstores(99,266),butthese
I
C
exercise. DiPietro et al. (97) found significant improve- data are also confounded by variability in exercise volume A
ments in glucose utilization in sedentary older men and and other factors. Corroborating evidence is provided by a T
I
O
women who engaged in vigorous (80% maximal oxygen study of sedentary subjects who walked at a self-selected
N
uptake (V˙O2max)) exercise but not in those who performed pacewithfixedvolume(10,000stepsperdayon3dIwkj1) S
moderate (65%V˙O ) exercise, although all subjects and improved lipoprotein profiles and expression of genes
2max
expended 300 kcalIdj1 on 4 dIwkj1. A comprehensive re- involved in reverse lipid transport, without accompanying
view by Swain (343) concluded that there were greater changes in body weight and total body fat (56). Further, a
improvements in V˙O with vigorous-intensity exercise studyof16pairsofsame-sextwinswithdiscordantphysical
2max
training compared with moderate-intensity exercise, when activitypatternsfoundthatgreatervolumesofexercisewere
the volume of exercise is held constant. Additional studies associatedwithlowertotal,visceral,liver,andintramuscular
support these conclusions (19,97,161,269,313,383). body fat, with the active twin having on average 50% less
Is there a threshold intensity of exercise needed visceral fat and 25% less subcutaneous abdominal fat com-
to improve cardiorespiratory fitness and to reduce pared with theinactivetwin (221).
cardiometabolic risk? According to the overload prin- The short-term effects of exercise on mental health, par-
ciple of training, exercise below a minimum intensity, or ticularlydepression,maybeafunctionofexerciseintensity,
threshold,willnotchallengethebodysufficientlytoresultin although a specific threshold has not been identified. There
increased V˙O and improvements in other physiological aresomedatatosuggestthatthegreatestbenefitisconferred
2max
parameters (12,14). Evidence for a minimum threshold of through moderate- to vigorous-intensity activity consistent
intensityforbenefitissupportedinmanystudies,butnotall, with the recommendations presented in this Position Stand
andthelackofconsistentfindingsseemstoberelatedtothe (i.e., QÈ17.5 kcalIkgj1Iwkj1; È1400 kcalIwkj1) (101).
initial state of fitness and/or conditioning of the subjects Does the pattern of exercise training make
(12,345).SwainandFranklin(345)reviewed18clinicaltrials a difference? Current recommendations advise that
that measured V˙O before and after exercise training in moderate-intensity physical activity may be accumulated
2max
37traininggroupsandfoundthatsubjectswithmeanbaseline in bouts of Q10 min each to attain the daily goal of
V˙O values of 40–51 mLIkgj1Iminj1 (È11–14 METs) Q30 minIdj1 (14,155,264,370). The data supporting a dis-
2max
seemedtorequireanintensityofatleast45%oxygenuptake continuous exercise pattern come primarily from random-
reserve (V˙O R) to increase V˙O , but no apparent thresh- ized clinical trials examining short versus long bouts of
2 2max
old was found for subjects with mean baseline V˙O physicalactivityinrelationtochangesincardiorespiratory
2max
G40 mLIkgj1Iminj1 (G11 METs), although È30%V˙O R fitness, blood pressure, and studies of active commuting
2
wasthelowestintensitystudied.Supportingthesefindings, (141,151).Acomprehensivereview(260)concludedthatthe
a comprehensive review of exercise training in runners evidence comparing the effectiveness of long versus short
determinedthat‘‘nearmaximal’’(i.e.,95%–100%V˙O ) bouts of exercise for improving body composition, lipopro-
2max
training intensities were needed to improve V˙O in teins,ormentalhealthismeagerandinconclusive.Onlyone
2max
well-trained athletes, while 70%–80%V˙O seemed to study, in men, examined short (e15 min)versus long bouts
2max
provideasufficientstimulusinmoderatelytrainedathletes of physical activity in relation to chronic disease outcomes,
(254). Thus, a threshold of exercise intensity may vary andthefindingssuggestitisthevolumeofenergyexpended
dependingonfitnesslevel,anditmaybedifficulttoprecisely that is important rather than the duration of the exercise
defineanexactthresholdtoimprovecardiorespiratoryfitness (215). Durations of exercise G10 min may result in fitness
(40,196,214). Additional randomized controlled trials and and health benefits, particularly in sedentary individuals
meta-analyses are neededtoexplore the threshold phenome- (215); however, the data are sparse and inconclusive.
non in populations of varying fitness levels and exercise A different accumulation issue relates to a pattern of
trainingregimensbecauseoftheinteractiveeffectsofexercise physical activity sometimes called a ‘‘weekend warrior’’
volume, intensity, duration, and frequency and individual pattern,wherealargetotalvolumeofphysicalactivitymay
variabilityofresponse. be accumulated over fewer days of the week than is rec-
There areeven fewer data available on theexistence of a ommended. There are few studies evaluating this exercise
threshold to favorably modify other cardiometabolic risk pattern, but existing evidence supports the possibility of
QUANTITYANDQUALITYOFEXERCISE Medicine&ScienceinSports&Exercised 1339
S benefit, althoughthe risks are unknown. A study of men in- bouts of physical activity or standing, attenuation of these
N dicatedthattheweekendwarriorpatternwasassociatedwith adverse biological effects can occur (157). This evidence
O
lower rates of premature mortality, compared with being suggests it is not enough to consider whether an individual
I
T
A sedentary, but only among men without cardiovascular risk engagesinadequatephysicalactivitytoattainhealthbenefits
C factors(217).Theseresultssuggestthepossibilitythatphys- but also that health and fitness professionals should be
I
N
icalactivitymightbeneededonaregularbasistoimprovethe concernedabouttheamountoftimeclientsspendinactivities
U
risk profile of men with risk factors. A randomized study suchastelevisionwatchingandsittingatadesk.
M
M (253) showed that previously untrained middle-aged partic-
O ipants who accumulated endurance training on consecutive
WHAT IS THE EFFECT OF EXERCISE
C weekend days attained similar improvements in cardiorespi-
TRAINING ON CARDIORESPIRATORY
L ratory fitness compared with those who completed similar
A FITNESS AND CARDIOVASCULAR AND
I mode,volume(È1400kcalIwkj1),andintensity(90%ofthe
C METABOLIC DISEASE (CARDIOMETABOLIC)
E ventilatory threshold) of training but in a pattern consistent
SP withcurrentrecommendations(30minIdj1at5dIwkj1). RISK FACTORS?
Another pattern of exercise involves varying the exercise Studies substantiating the previous Position Stand (12),
intensity within a single bout of exercise, termed interval the AHA/ACSM statements (155,264), the 2008 Physical
training. With interval training, the exercise intensity is var- Activity Guidelines for Americans (370), and ACSM’s
iedatfixedintervalsduringasingleexercisebout,whichcan Guidelines for Exercise Testing and Prescription (14)
increase the total volume and/or average exercise intensity clearlydemonstrate thatexerciseoftheintensity, duration,
performed.Amethodcommonlyusedinathletes,short-term and frequency recommended here results in improvements
(e3months)intervaltraininghasresultedinsimilarorgreater in cardiorespiratory fitness (i.e., V˙O ). Moreover, a
2max
improvements in cardiorespiratory fitness and cardio- plateau in the training effect occurs, whereby additional
metabolic biomarkers such as blood lipoproteins, glucose, increasesinexercisevolumeresultinlittleornoadditional
interleukin-6, and tumor necrosis factor >, and muscle fatty improvements in V˙O (12).
2max
acid transport compared with single-intensity exercise in Cardiorespiratoryexercisereducesseveralcardiometabolic
healthyadults(77,89,142,161,261,351,388)andpersonswith diseaseriskfactors,althoughthemagnitudeofeffectismod-
metabolic, cardiac, or pulmonary disease (28,104,144,313, est, varies according to individual and exercise program
383,399). However, a study of healthy untrained men (268) characteristics,andachangeinonecardiometabolicriskfactor
found thatinterval running exercisewas moreeffective than apparently occurs independently of a change in another
sustainedrunningofsimilartotalduration(È150minIwkj1) (271,361,395). Favorable improvements in hypertension,
in improving cardiorespiratory fitness and blood glucose glucose intolerance, insulin resistance, dyslipidemia, and in-
concentrations but less effective in improving resting HR, flammatory markers have been reported in middle-aged and
bodycomposition,andtotalcholesterol/HDLratio.Itisclear older persons exercising within the volumes and quality
from these results that additional studies of interval training of exercise recommended here, even during weight regain
are needed to more fully elucidate the effects, particularly (47,102,103,184,260,284,288,310,328,357,358,361,
with respect to varying interval characteristics (e.g., exercise 376,385). The benefits of exercise on cardiometabolic risk
intensity,workintervalduration,restintervalduration)andin factors are acute (lasting hours to days) and chronic, high-
diversepopulations.Nonetheless,thesestudiesshowpromise lighting the value of regular exercise participation on most
for the use of interval training in adults, but the long-term days of the week (360,388,389). Exercise without dietary
effects and the safety of interval training remain to be eval- modification has a modest effect (È2%–6%) on short-term
uated, although no adverse effects have been reported in the (e6 months) weight loss (99), but favorable changes in as-
literaturetodate. sociatedcardiometabolicriskfactors(e.g.,visceralabdominal
A fourth activity pattern that has important implications fat, total body fat, and biomarkers) can occur even in the
forhealthissedentarybehavior,whichisanattributedistinct absence of concomitant weight reduction (96,150,195,
fromphysicalactivity(276).Sittingandlowlevelsofenergy 288,361), albeit weight loss enhances these improvements
expenditurearehallmarks ofsedentarybehaviorand encom- (102,103,256,361).Someriskfactorchanges,suchasreduc-
passactivitiessuchastelevisionwatching,computeruse,and tion of LDL and the attenuation of decline in HDL accom-
sitting in a car or at a desk (276). Spending long periods of panying reduced dietary intake of saturated fat, occur only
timeinsedentarypursuitsisassociatedwithelevatedrisksof whenexerciseiscombinedwithweightloss(102,103,361).
CHD mortality (384) and depression (354), increased waist Whatistheeffectofvaryingexercisevolumeson
circumference,elevatedbloodpressure,depressedlipoprotein the health and fitness of adults? Although epidemio-
lipaseactivity,andworsenedchronicdiseasebiomarkerssuch logical evidence demonstrates a dose–response association
as blood glucose, insulin, and lipoproteins (158,159,276, between the volume of exercise and health outcomes, ran-
364,390). Sedentariness is detrimental even among in indi- domized clinical trials (RCT) are needed to demonstrate
vidualswhomeetcurrentphysicalactivityrecommendations causal biological effects. Until recently, few data from
(158,276). When sedentary activities are broken up by short RCT were available comparing the effects of different
1340 OfficialJournaloftheAmericanCollegeofSportsMedicine http://www.acsm-msse.org
fixed exercise volumes on fitness and biomarkers of dis- S
eesroaearfcndsitedesh.noeetmCarhriveyzuoce,roldcumohmtvmoeeetesrewnaxdleae.eitrgd(c7hias6wt,e)eofeevikvroxlaleyuoldumbeaenetiseesnedrtgoetpynfhose5eistx0tyemp%ffeee,n(nc5d1ot0i0pto%u0afru%Ve˙vsO,aa(lr4o2y,mrwina81xog,)5ma0ene%xindn- ResistanceExercise RelativeIntensity %1RM 30G30–49 50–69 70–84 Q85 (48). PECIALCO
12kcalIkgj1Iwkj1, respectively; orapproximately330,840, yr) 370).ertion M
aap6rtsnthoeencremcaotrdepootvdvoeisme1eonnrsmds0limtutoh0itebmnaesh0nelnseatefldstkoeoeeotcvrfihdxneaferhleleweItcirwohegxcaeefherkiesdfvrejrkeiciroeto1lintslysf,rrueuieaetmvsrlisnetsn(opse1esimlisnps8urosaega)mf,tcwylovettebhiraaov.vyuesfleAefutsleflesmoiymc.ptb)sntero.tsteesuhreslAeadiersmsvitde(edlri4seoadno%fiw,acsninrae–iyaanin–8tnsgirr%vdbeoerseepne)pmoesgeoop-rveonhctonicdsasdneeuleuesfrrsgenaroetsgelcffidefetziteomshecatideass-tt AbsoluteIntensity(MET)byAge YoungMiddle-agedQ(20–39yr)(40–64yr)Older(65 2.42.01.6GGG2.4–4.72.0–3.91.6–3.1 4.8–7.14.0–5.93.2–4.7 7.2–10.16.0–8.44.8–6.7 QQQ10.28.56.8 DepartmentofHealthandHumanServices(uptakereserve;RPE,ratingsofperceivedex MUNICATIONS
Sn
HOW ARE EXERCISE INTENSITY AND Uge
VOMLoUstMepEidEemSiTolIoMgiAcTanEdDm?any laboratory studies provid- AbsoluteIntensity METs 2G2.0–2.9 3.0to5.9 6.0–8.7 Q8.8 7),andthe˙VOR,oxy2
ing evidence of the beneficial effects of exercise have clas- (34ake;
ssto(afcwcepcatii%svorV˙hennkieciinaosotfeilcftneOetdddlctrVuydnnniTa˙ea6iiisaeiuemsgbsddat2ntvpOihldrieaiM(eRtbIhiiMisovihiymaelttnq2dai.stui’in,yetrte,tEm,goounnsueEhiyer.snwlsntdeTdae,aeeHmoiTuexejnacw,lsxyehstfnt,xsdRarrhate.e1xei(ialeas,leax)leedrly4exRmTient,lccnaxtihao,rseeydmaohe,i5ncdbaaecmeerxsbnen8iydctrvnereaaesyispucsied%i,veolcrseo1setiofreenbiicrcshcticeiglnt7Mrxutadietueiloaaacysynti3ocaelneptebnpnreeeseoEe)rnrgidrnc(stanc.csnsxneee3eTiooodcsioistFtnfiesdsnfsr2ixleinmirmsicirtgtuorilse3ncypdttycnyoeepraitremea)sigieextv)ecgtfoenps.-yitode.rretertloiiifstlsmxMyiuosmnnslitEyinvoitoohattnrghnhm(yehulianoienmn(e4—myndaenacepeda,aso,sgwisghp.ts5eeavtiurguaamea(nulera8obisk1.ecrcarbcoadcrs,,rrreaes,atae7eoet1lufukoeiodxsevurpmda3vem7r(lairdllitdipannnem,icyu3mlhgmoi2topeidrtgaoty)eosiodLo6fareu(.nevrssar1alerp4aIetmerMgchoeedcmeerht7brer)sasruotaednei.olmtp3soetlimaetrahswseoniode)airtaHmtureewrp.esrjel,tisntsgaiulave,oRetuacTts1ityvhssrtoeertotareuuihhsiotoemsefmnrgwodoetcredpr(dmyeoeoeexa%hnrleehLsmnaesmrxmpereceoteotbIfwaHeaniefhimxiinoafrmuesaboosmsntegeoRnrcau—lssririderaulyrnlnaasd)bolmyicaki,lsutptnjttstolaisoaiiibeeuuffrsrdinndnnsx1noernooxiereetii))gggnydyees--r---r-f-:,, relativeandabsoluteexerciseintensityforcardiorespiratoryenduranceandresistanceexercise. CardiorespiratoryEnduranceExercise ˙)RelativetoIntensity(%VO2max)MaximalExerciseCapacityinMETsRelativeIntensity PerceivedExertion20METs10METs5METs˙˙˙˙R%VO(Ratingon6–20RPEScale)%VO%VO%VOmax2max2max2max2max 5737Verylight(RPE9)343744GGGGGG–6337–45Verylight–fairlylight34–4237–4544–51(RPE9–11)–7646–63Fairlylighttosomewhat43–6146–6352–67hard(RPE12–13)–9564–90Somewhathardtovery62–9064–9068–91hard(RPE14–17)QQQQQQ9691Veryhard(RPE18)919192 SportsMedicine(14),Howley(173),SwainandFranklin(344),SwainandLeutholtz(346),Swainetal.˙˙ximalHR;HRR,HRreserve;VO,maximaloxygenuptake;%VO,percentofmaximaloxygenupt2max2max
improvements in cardiorespiratory fitness when used for nsity: %H G57 64 77 Q geofofma
epinxrteeTesrnaccsbriisiltbeeyin5pugrsseehisnxocgewrripcsrietsitloheanetfi,voaerpthpaeanrnnocidxneidmaicbvaasitndeoulcubaltleaes(s1rmie2fcie)co.tahmtoimodnsenocdfoemedxmewrochnieslnye ofexerciseinte %HRRor˙R%VO2 30G30–39 40–59 60–89 Q90 AmericanColleHR,percentmax
umndthseeeaeottetduhrdsmoleidynirsn;ivitpnehorgdefarceuetmfxsiocieenerraeg.cs,iusaNirteneocomiatnhnsetetennurnotdstmiioebteyfsethaiehossxadsevn.ureemIcctieesciedsossmatphirnrpiaultatyedroneeensdniqettuyatmiolvlesaktilohmeefoenupdtltthotiaone-f TABLE5.Classification Intensity VerylightLight Moderate Vigorous Near–maximaltomaximal TableadaptedfromtheHR,maximalHR;%max
QUANTITYANDQUALITYOFEXERCISE Medicine&ScienceinSports&Exercised 1341
S mindthattherelationshipsamongactualenergyexpenditure, engaged in a new program of physical activity meeting
N HRR,V˙O R,%HR ,and%V˙O canvaryconsiderably current exercise recommendations averaged about 7000
O 2 max 2max
depending on exercisetestprotocol, exercisemode, exercise steps per day (187). Two meta-analyses of pedometer use
I
T
A intensity, resting HR, fitness level, age, body composition, showed that participants in randomized clinical trials in-
C and other factors (57,90,185,277,289,315,336). The HRR or creasedtheirdailystepsonaveragebyabout2000stepsper
I
N V˙O R methods may be preferable for exercise prescription day,equaltowalkingapproximately1mileIdj1,andfewof
U 2
because exercise intensity can be underestimated or over- the most sedentary subjects achieved the goal of 10,000
M
M estimated when using %HRmax and %V˙O2max methods steps per day (51,193). In participants with elevated blood
O (52,57,231,287,342,346). However, the advantage of the pressure, an increase of 2000 steps per day was associ-
C HRRorV˙O Rmethodshasnotbeensupportedbyallstudies ated with a modest decrease in systolic blood pressure
2
L (90,277). The accuracy of the %HR and HRR methods (È4 mm Hg), independent of changes in body mass index,
A max
I may be influenced by the method used to estimate maximal suggestingthatfewerthan10,000stepsperdaymayprovide
C
E HR.Specializedregressionequationsforestimatingmaximal health benefits. Recent work to determine step count cut
P
HR (133,147,352,407) are purported to be superior to the points corresponding to moderate-intensity walking dem-
S
commonlyusedequationof220j agefortheestimationof onstrated that 100 steps per minute is a very rough approx-
maximal HR because influences associated with aging imationofmoderate-intensityexercise(242).Becauseofthe
andpossiblegenderdifferences(133,147,156,352).Although substantial errors of prediction using either step counts or
these equations are promising, further study in diverse pop- thisalgorithmtoestimateenergyexpenditure(204,242,368),
ulationscomposed of men and women isneeded before one it may be prudent to use both steps per minute combined
or more can be recommended for universal application. Di- with currently recommended durations of exercise for exer-
rect measurements of HR and oxygen uptake are recom- cise prescription (e.g., 100 steps per minute for 30 min per
mended for individualized exercise prescription for greater session)(242,368).
accuracy, but when not feasible, estimation of exercise in-
tensityisacceptable.
MET-minutes per week and kilocalories per minute per
WHAT ARE THE BENEFITS OF IMPROVING
week have been used for estimating exercise volume in re-
MUSCULAR FITNESS?
search, but these quantifications are seldom used for exer-
ciseprescriptionforindividuals.Yet,thesemaybeusefulin The health benefits of enhancing muscular fitness have
approximatingthegrossenergyexpenditureofanindividual becomewellestablishedduringthepastdecade(392).Higher
because of the proliferating evidence supporting the impor- levels of muscular strength are associated with significantly
tant role of exercise volume in realizing health and fitness better cardiometabolic risk factor profiles (188,189), lower
outcomes. The METs per minute and kilocalories per week riskof all-cause mortality (117,128,265), fewer CVD events
forawidearrayofphysicalactivitiescanbeestimatedusing (128,353), lower risk of developing functional limitations
previously published tables(4,5). (54,235), and nonfatal disease (189). At present, there are
insufficientprospectivedataonthedose–responsecharacter-
istics between muscular fitness and health outcomes or the
existenceofathresholdforbenefittorecommendaminimal
CAN STEPS PER DAY BE USED TO
levelofhealth-relatedmuscularstrength,power,orendurance
PRESCRIBE EXERCISE?
(31). Apart from greater strength, there is an impressive
Pedometers are popular and effective for promoting array of changes in health-related biomarkers that can be
physical activity (366) and modest weight loss (308), but derived from regular participation in resistance training,
they provide an inexact index of exercise volume (26,368). includingimprovementsinbodycomposition(177,178,328),
They are limited in that the ‘‘quality’’ (e.g., speed, grade, blood glucose levels (66,67,207,327,328), insulin sensitivity
duration) of steps often cannot be determined. A goal (55,199), and blood pressure in persons with prehyper-
of 10,000 steps per day is often cited, but even fewer steps tension or stage 1 hypertension (80,328). Accordingly, re-
may meet contemporary exercise recommendations (367). sistance training may prove to be effective to prevent and
Forexample,recentdatafrom‘‘AmericaontheMove’’(27) treat the ‘‘metabolic syndrome’’ (234).
showed those individuals who reported ‘‘exercising strenu- Importantly, exercise that promotes muscle strength and
ously’’on3dIwkj1(durationofexercisenotascertained),a mass also effectively increases bone mass (bone mineral
level that probably meets current recommendations, accu- densityandcontent)andbonestrengthofthespecificbones
mulated a mean of 5486 T 231 SEM steps per day. People stressed(201,233,341)andmayserveasavaluablemeasure
reporting 4 dIwkj1 of ‘‘strenuous exercise’’ accumulated toprevent,slow—orevenreverse—thelossofbonemassin
6200T220stepsperday,and7891T540stepsperdaywere people with osteoporosis (201,233,341). Because muscle
reportedbythose ‘‘exercisingstrenuously’’on6–7dIwkj1. weakness has been identified as a risk factor for the devel-
In a randomized trial evaluating different doses of physical opment of osteoarthritis, resistance training may reduce the
activity on fitness levels, initially sedentary women who chance of developing musculoskeletal disorder (331). In
1342 OfficialJournaloftheAmericanCollegeofSportsMedicine http://www.acsm-msse.org
persons with osteoarthritis, resistance training can reduce How many sets of exercises are needed? Most S
pain anddisability (39,252). individuals respond favorably (e.g., hypertrophy and P
E
The mental health benefits associated with resistance strengthgains)totwotofoursetsofresistanceexercisesper C
I
training have received less attention than cardiorespiratory musclegroup(13,386),butevenasinglesetofexercisemay A
L
exercise. Preliminary work suggests that resistance train- significantly improve muscle strength and size, particularly
C
ing may prevent and improve depression and anxiety in novice exercisers (12,13). The target number of sets per O
(65,271,282), increase ‘‘energy’’ levels, and decrease fa- muscle group can be achieved with a single exercise or by M
tigue (294). However, these results are inconclusive and using a combination of more than one exercise movement M
requirefurtherstudy. (e.g., two sets of shoulder press and two sets of lateral U
N
raises).
I
C
What duration of rest intervals between sets and
A
intensity is appropriate to improve muscular fit- T
HOW CAN EXERCISE IMPROVE AND I
O
ness? For a general fitness program, rest intervals of
MAINTAIN MUSCULAR FITNESS? N
2–3 min are most effective for achieving the desired in-
S
Muscular fitness is composed of the functional parame- creases in muscle strength and hypertrophy (13). Robust
ters of strength, endurance, and power, and each improves gains in both hypertrophy and strength result from using a
consequenttoanappropriatelydesignedresistancetraining resistance equivalent to 60%–80% of the individual’s one-
regimen. As the trained muscles strengthen and enlarge repetition maximal (1RM) effort (386). For novice through
(hypertrophy), the resistance must be progressively in- intermediate strength trainers, a load of 60%–70% of the
creased if additional gains are to be accrued. To optimize 1RMisrecommended(i.e.,moderatetohardintensity),while
the efficacy of resistance training, the program variables experienced exercisers may work at Q80% of the 1RM
(frequency, intensity, volume, rest intervals) are best tai- (i.e.,hardtoveryhardintensity)(13).Theselectedresistance
loredtotheindividual’sgoals(13). shouldpermitthecompletionof8–12repetitionsperset—or
The focus here is on program design for adults seeking thenumberneededtoinducemusclefatiguebutnotexhaus-
general or overall muscular fitness with associated health tion. For people who wish to focus on improving muscular
benefits.Individualswhodesiretoengageinmoreadvanced endurance, a lower intensity (i.e., G50% of 1RM; light to
orextensiveresistancetrainingregimensaimedatachieving moderate intensity) can be used to complete 15–25 repeti-
maximal muscular strength and hypertrophy are referred to tionsperset,withthenumberofsetsnottoexceedtwo(59).
therelevant ACSM Position Stand (13). Table5showstherelativeintensitiesforresistancetraining.
What types of exercises improve muscular fit- How often should resistance training be per-
ness? Many types of resistance training equipment can ef- formed? Meta-analysesshowthatoptimalgainsinmuscle
fectivelybeusedtoimprovemuscularfitness,includingfree functionandsizecanoccurwithtrainingtwotothreetimes
weights, machines with stacked weights or pneumatic resis- per week (285,306,386). This can be effectively achieved
tance, and even resistance bands. A resistance training pro- with‘‘wholebody’’trainingsessionscompletedtwotothree
gram emphasizing dynamic exercises involving concentric times a week or by using a ‘‘split-body’’ routine where se-
(shortening) and eccentric (lengthening) muscle actions that lectedmusclegroupsaretrained duringonesessionandthe
recruit multiple muscle groups (multijoint exercises) is remainingmusclegroups inthenext. Arestperiodof48to
recommended,includingexercisestargetingthemajormuscle 72 h between sessions is needed to optimally promote the
groups of the chest, shoulders, back, hips, legs, trunk, and cellular/molecular adaptations that stimulate muscle hyper-
arms(13).Single-jointexercises thatisolatefunctionallyim- trophy andthe associated gains in strength (36).
portant muscle groups such as the abdominals, lumbar Are there differences in resistance training
extensors(lowerback),calfmuscles,hamstrings,quadriceps, recommendations according to individual char-
biceps, etc., should also be included. To prevent muscular acteristics? The resistance training recommendations de-
imbalances, training opposing muscle groups (antagonists), scribed hereareappropriateformenand womenofvirtually
such as the quadriceps and hamstrings, as well as the all ages (1,386). Older, very deconditioned, or frail indivi-
abdominalsandlumbarextensors,isimportant. dualsinitiatingaresistancetrainingregimen,maybeginwith
The exercises should be executed using correct form and lower resistance, perhaps 40%–50% of 1RM (i.e., very light
technique, including performing the repetitions deliberately tolightintensity),alongwithagreaternumberofrepetitions
and in a controlled manner, moving through the full range (i.e., 10–20) (110). After achieving an acceptable level of
ofmotionofthejoint,andusingproperbreathingtechniques muscular conditioning, older and frail persons can increase
(i.e., exhalation during the concentric phase and inhalation the resistance and perform the exercises as detailed above
duringtheeccentricphase;avoidingtheValsalvamaneuver) (110). Because some studies indicate that the risk of acci-
(13). Training that exclusively features eccentric contrac- dental falls and resultant bone fractures is more closely re-
tions should bediscouraged because severe muscle damage latedtoadeclineinmuscularpowerthanstrength,ithasbeen
and soreness as well as serious complications such as rhab- suggestedthatresistancetrainingfortheolderpersonshould
domyolisis can ensue (78). emphasize the development of power (46,71). Research has
QUANTITYANDQUALITYOFEXERCISE Medicine&ScienceinSports&Exercised 1343