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 Copyright © 2011 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. 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 E health recommendations for physical activity, and these tivity and, to a lesser extent, physical fitness are the primary C I are now are incorporated into the current edition of the sourcesofdatasupportingthebenefitsofexerciseinreducing A L 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 N appropriately evaluated and advised by a healthprofessional ing(frequency,intensity,duration,mode,pattern,volume)for I C (e.g., physician, clinical exercise physiologist, nurse), these improvingphysicalfitnessandbiomarkersofchronicdisease. A recommendations may also apply to persons with certain ThefocusoftherecommendationsinthisPositionStandis T I O chronic diseases or disabilities, with modifications required on exercise, which connotes intentional physical activity for N according toanindividual’shabitualphysicalactivity, phys- improving health and fitness. The terms physical activity and S 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 Copyright © 2011 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. 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 Copyright © 2011 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. 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 Copyright © 2011 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. 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 I T 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. I 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 Copyright © 2011 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. 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 I 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 Copyright © 2011 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. 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 Copyright © 2011 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. 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 Copyright © 2011 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. 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 Copyright © 2011 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. 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 Copyright © 2011 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.