Regular physical activity is associated with a wide range of health benefits.1 Unfortunately, only about 20% of adults and high school aged youth meet the current federal guidelines for both aerobic and muscle-strengthening physical activity.2 In 2016, the US Department of Health and Human Services convened the 2018 Physical Activity Guidelines Advisory Committee (PAGAC) to review and summarize the current scientific evidence regarding the relationship between physical activity and health. The committee’s report serves as the basis for the Physical Activity Guidelines for Americans, 2nd Edition,3 which updates the 2008 Physical Activity Guidelines for Americans.4 The 2008 PAGAC Scientific Report5 provided a fundamental starting point for allowing the 2018 Committee to examine more broadly the wide-ranging benefits of physical activity to health, as well as the types, volumes, and intensities of physical activity that are associated with those benefits.
New findings since the 2008 PAGAC Scientific Report5 substantially expand the list of health benefits that are attributable to physical activity. Moreover, the 2018 Scientific Report provides more specific knowledge about how to achieve those health benefits and demonstrates that physical activity promotion at the population level can be accomplished using a variety of strategies. This article summarizes the process and major findings of the 2018 PAGAG Scientific Report,1 with emphasis on topics not previously addressed in 2008. The full report is available at https://health.gov/paguidelines/second-edition/report.aspx.
Methods
Scope of Review
The committee established 9 subcommittees based on current public health priorities and areas with new information since the 2008 PAGAC Scientific Report: (1) aging, (2) brain health, (3) cancer primary prevention, (4) cardiometabolic health and prevention of weight gain, (5) exposure, (6) individuals with chronic conditions, (7) promoting regular physical activity, (8) sedentary behavior, and (9) youth, as well as a pregnancy working group. Through a series of discussions and ranking procedures, the committee identified 38 questions and 104 subquestions to be addressed by the subcommittees (Supplementary Table S1 [available online]). Questions were selected for their public health relevance, potential to inform public policies and programs, maturity of the relevant science, and applicability to the general US population. Methodological details regarding question development, analytical frameworks, inclusion and exclusion criteria, and search strategies are available in the 2018 Scientific Report,6 the supplementary material to the report,7 and a peer-reviewed article.8
Data Sources and Searches
The review of the literature was assisted by a consulting services company through a contract with US Department of Health and Human Services. Three bibliographic databases (PubMed®, CINAHL, and Cochrane Library) were used for all searches, which included only studies of human subjects published in English in peer-reviewed journals or high-quality reports. The inclusion dates varied among questions (Supplementary Table S1 [available online]), most often depending on whether a similar question had been addressed by the 2008 PAGAC Report.5 All searches began with a search for systematic reviews, meta-analyses, pooled analyses, and high-quality reports such as the 2008 PAGAC Report. For a few questions, the committee expanded the search to include original research articles because the search for systematic reviews: (1) was insufficient to address the question at hand (excessive weight gain, children <6 y, progression of osteoarthritis, relation of step counts and bout duration to health outcomes), (2) had captured experimental studies but not observational studies (fall-related injuries among older people), or (3) had not captured recently published original research known to be important (sedentary behavior). If the committee became aware of a relevant article that was not captured by the search, the search methods were examined to determine why the article had been missed, and if appropriate, the search was revised and repeated.
Study Selection, Evidence Extraction, and Synthesis
All titles and abstracts were reviewed by 2 subcommittee members. Discrepancies were resolved by discussion or by a third reviewer. Potentially relevant articles based on title and abstract underwent full-text review by 2 subcommittee members. Articles that remained after title, abstract, and full-text review were examined in detail by 2 or more subcommittee members. Although procedures varied among subcommittees, subcommittee members generally extracted the most pertinent information into “working tables” (see, eg, https://health.gov/paguidelines/second-edition/report/supplementary_material/pdf/Supplementary_Table_S-F2-1.pdf). Using standard procedures, the consulting service staff prepared extractions, which included the citation, search dates for systematic reviews, the abstract, and information about the exposure and the outcome. Information from these tables and from the ad hoc tables prepared by subcommittee members provided the foundation for committee discussions and conclusions.
Strength of Evidence Assessment
For every question and subquestion, each subcommittee presented a draft of its conclusions based on the available evidence to the full committee. This draft included information on the strength of the evidence supporting that conclusion and a summary of the underlying evidence. Evidence was graded as strong, moderate, limited, or not assignable based on a modification of the Assessment of Multiple Systematic Reviews (AMSTARExBP) for systematic reviews, meta-analyses, and pooled analyses6,9,10; the US Department of Agriculture Nutrition Evidence Library Bias Assessment Tool for original research11,12; a tool created for the 2018 PAGAC for reports6; and committee-developed procedures for grading the evidence based on 5 criteria: applicability, generalizability, risk of bias/study limitations, quantity and consistency, and magnitude and precision of effect (Supplementary Table S2 [available online]). The committee discussed, modified if appropriate, and gave final approval for all conclusions and strength of evidence assessments in public meetings.
Results
A total of 20,838 titles, 4,913 abstracts, and 2,139 full-text articles were evaluated; 837 unique articles met the criteria for inclusion. The number of included articles per question ranged from 2 to 96, with a median of 15 articles (Supplementary Table S1 [available online]). Operational definitions and methods for measuring physical activity varied considerably among the included articles. For the general adult population, self-reported leisure-time aerobic activity of moderate to vigorous intensity was the most prevalent domain reported in the available literature. Other domains (eg, occupational, transportation, household activity) were inconsistently available. Studies of device-measured physical activity (eg, accelerometer, pedometer) were uncommon, except for studies that examined the role of step counts, bout duration, and high-intensity interval training on health outcomes. For children <6 years of age, most studies utilized device-measured physical activity and included light-, moderate-, and vigorous-intensity activity. For older adults, most intervention studies used combinations of different types of activity (eg, aerobic, muscle strengthening, balance training), which tended to be of light to moderate intensity. Sedentary behavior was operationalized as time spent sitting, time spent watching television, or counts below a specified value on an accelerometer.
The Health Benefits of Physical Activity
The scientific evidence accumulated since the 2008 Scientific Report markedly expands the list of documented health benefits accruing to more physically active individuals. The most recent literature now includes evidence of (1) reduced risk of cancer of the bladder, endometrium, esophagus, kidney, lung, and stomach; (2) reduced risk of dementia; (3) reduced risk of excessive weight gain in children, adults, and pregnant women; (4) reduced risk of gestational diabetes and postpartum depression; and (5) reduced risk of fall-related injuries in older people. In addition, there is evidence that physical activity is associated with (1) improved quality of life, (2) improved sleep; (3) reduced feelings of anxiety and depression in healthy people and in people with existing clinical syndromes, and (4) improved cognitive function across the life span. Regular physical activity improves bone health and weight status in children 3 to <6 years and physical function among older people regardless of frailty or existing chronic disease (Table 1).1 For individuals with 1 of 15 prevalent and diverse chronic conditions examined (eg, breast cancer, osteoarthritis, Parkinson’s disease) 1 or more preventive health benefits were reported for those who were more physically active (Table 2).13–15 In the paragraphs below, we summarize findings from 2 topic areas (brain health and weight gain) not previously addressed in the 2008 Scientific Report.
Physical Activity–Related Health Benefits for the General Population Documented by the 2008 and 2018 Physical Activity Guidelines Advisory Committees
Children and youth | ||
3 to <6 y of agea | Improved bone health and weight status | |
6–17 y of age | Improved cognitive function Improved cardiorespiratory and muscular fitness Improved bone health Improved cardiovascular risk factor status Improved weight status or adiposity Fewer symptoms of depression | |
Adults, all ages | ||
All-cause mortality | Lower risk | |
Cardiometabolic conditions | Lower risk of cardiovascular disease and cardiovascular disease mortality (including heart disease and stroke) Lower risk of hypertension Lower risk of type 2 diabetes | |
Cancer | Lower risk of bladder, breast, colon, endometrium, esophagus, kidney, stomach, and lung cancers | |
Brain health | Reduced risk of dementia Improved cognitive function Improved cognitive function following acute bouts of aerobic activity Improved quality of lifeImproved sleep Reduced feelings of anxiety and depression in healthy people and in people with existing clinical syndromes Reduced risk of depression | |
Weight status | Reduced risk of excessive weight gain An additive effect on weight loss when combined with moderate dietary restriction Weight loss and the prevention of weight regain when a sufficient dose of moderate-to-vigorous physical activity is attained | |
Older adults | ||
Falls | Reduced risk of falls Reduced risk of fall-related injuries | |
Physical function | Improved physical function in older adults with and without frailty | |
Women who are pregnant or postpartum | ||
During pregnancy | Reduced risk of excessive weight gain Reduced risk of gestational diabetes No risk to fetus from moderate-intensity physical activity | |
During postpartum | Reduced risk of postpartum depression |
Note: Benefits in bold are those added in 2018; benefits in regular font are those noted in the 2008 Scientific Report.5 Only outcomes with strong or moderate evidence of effect are included in the table.
aInsufficient information available for children 0 to <3 years.
Physical Activity–Related Health Benefits for Individuals with a Chronic Condition Documented by the 2008 and 2018 Physical Activity Guidelines Advisory Committees
Individuals with preexisting medical conditions | |
---|---|
Breast cancera | Reduced risk of all-cause and breast cancer mortality |
Colorectal cancera | Reduced risk of all-cause and colorectal cancer mortality |
Prostate cancera | Reduced risk of prostate cancer mortality |
Osteoarthritisb | Decreased pain Improved function and quality of life |
Hypertensionb | Reduced risk of progression of cardiovascular disease Reduced risk of increased blood pressure over time |
Type 2 diabetesb | Reduced risk of cardiovascular mortality Reduced progression of disease indicators: hemoglobin A1c, blood pressure, blood lipids, and body mass index |
Recent hip fracturec | Improved walking, balance, and activities of daily living |
Frailtyc | Improved walking, balance, and activities of daily living |
Strokec,d | Improved walking, physical fitness, functional independence Improved cognition |
Spinal cord injuryb | Improved physical fitness Improved walking and wheel chair skills |
Dementiad | Improved cognition |
Multiple sclerosisb,d | Improved walking Improved strength and physical fitness |
Parkinson’s diseasec,d | Improved walking, balance, activities of daily living, and cognition |
Schizophreniad | Improved quality of life and cognition |
Attention deficit hyperactivity disorderd | Improved cognition |
Note: Benefits in bold are those added in 2018; benefits in normal font are those noted in the 2008 Scientific Report.5 Only outcomes with strong or moderate evidence of effect are included in the table. Outcomes assessed varied by chronic condition.
aMortality and disease progression outcomes. bMortality, development of new chronic condition, quality of life, physical function, and progression of disease. cPhysical function only. dCognition.
Brain Health
Brain health, an area of recent and rapid development, is positively affected by single bouts, as well as by regularly performed moderate- to vigorous-intensity physical activity (MVPA). In addition to reducing the risk of dementia, physical activity improves several components of cognition, including executive function (ie, the organization of everyday activities, planning for the future, and self-regulation of impulsive and sensation-seeking behaviors), memory, processing speed, attention, and academic performance. These performance improvements are supported by evidence from neuroimaging techniques demonstrating parallel changes in brain structure and function.16–20 The beneficial effects are observed across a variety of physical activities, including aerobic and strength training activity, and are reported in both healthy populations and in populations exhibiting cognitive deficits due to conditions such as schizophrenia, stroke, Parkinson’s disease, and Alzheimer’s disease. Improvements in cognitive performance are observed for up to an hour after a single bout of physical activity, with more sustained improvements observed with regular participation.13 MVPA also improves other aspects of brain health, such as symptoms of depression and anxiety among individuals with and without clinical depression or anxiety and perceived quality of life.13 In addition, both a single bout and regularly performed MVPA improve sleep quality, reduce sleep onset latency, increase time in deep sleep, improve sleep efficiency (the percentage of time actually sleeping), and reduce daytime sleepiness.13 Moreover, it does not seem to matter whether the activity is performed more than 8 hours, 3 to 8 hours, or less than 3 hours before bedtime.21
Prevention of Weight Gain
Excessive weight gain is less common among children and adults (including pregnant women) who are more physically active,22–24 with greater amounts of physical activity associated with a lower risk of significant weight gain or development of obesity (Figure 1).25 For people with overweight or obesity, the relative risk reduction in all-cause mortality, cardiovascular disease incidence and mortality, and incidence of type 2 diabetes is similar to that experienced by people with normal body weight.1
Characteristics of Physical Activity Associated With Benefits
The Dose–Response Relationship Between Physical Activity and Health
All reviews reported an inverse relationship between self-reported MVPA and all-cause mortality, cardiovascular disease mortality and incidence, and incidence of type 2 diabetes; analyses comparing 3 or more physical activity exposure categories consistently reported an inverse, curvilinear dose–response relationship (Figure 2).1,22,26–29 The response curves demonstrate that when the least active individuals add even small amounts of activity to their daily routine, (1) there is no threshold that must be exceeded before benefits begin to accrue (ie, the reduction in risk begins with the addition of any amount of MVPA), (2) the slope of risk decline is steepest for the least active individuals, and (3) the reduction in risk continues across the full range of commonly achieved volumes, although the slope diminishes with increasing levels of MVPA.
Sedentary Behavior
There is a direct relationship between sedentary behavior and all-cause and cardiovascular disease mortality, incidence of cardiovascular disease, and type 2 diabetes, as well as the incidence of endometrial, colon, and lung cancers.30 The dose–response curves illustrate a direct relationship between both total sitting time and television viewing time and all-cause mortality (Figure 3).
Interaction Between Sitting Time and MVPA
Mortality risk is higher for longer versus shorter sitting times; however, this risk difference diminishes as the amount of MVPA increases—especially among those reporting the greatest volume of MVPA (Figure 4).31 Compared with the referent group (most MVPA [top quartile] and lowest sitting time [<4 h/d]), individuals with the least MVPA (bottom quartile) and most sitting time (>8 h/d) have the highest risk of all-cause mortality (1.59, 95% confidence interval 1.52–1.66). By contrast, individuals who are in the bottom quartile of MVPA but who report the least sitting time (<4 h/d) are at elevated risk (1.27, 95% confidence interval 1.22–1.30), but only about half that of those who sit the most. For individuals reporting the greatest volume of MVPA (an estimated 35–38 metabolic equivalent-h/wk), the excess risk of mortality for different strata of sitting essentially disappears.
Sedentary time, light physical activity, and MVPA interact within a finite, 24-hour day. A heat map developed by the 2018 PAGAC committee depicts the risk of all-cause mortality associated with various combinations of sitting time (in hours) and MVPA (in minutes) (Figure 5). The heat map was derived from regression techniques to interpolate the hazard ratios between 4 levels of sitting time and 4 levels of MVPA based on a harmonized meta-analysis of Ekelund et al.31 We have assumed that for any given level of MVPA, the time spent sitting and the time spent in light-intensity activity (eg, walking about, light housework) are reciprocal. High sitting time is associated with low light-intensity time and low sitting time is associated with high light-intensity activity. As indicated by the heat map: (1) at low levels of MVPA, replacing sitting time with light-intensity activity reduces risk of premature mortality, (2) MVPA is necessary to achieve the greatest risk reduction, (3) for an equivalent reduction in risk, increasing MVPA requires appreciably less time per day than increasing light-intensity activity, and (4) at the highest levels of MVPA (an estimated 35–38 metabolic equivalent-h/wk), the time spent sitting has a negligible effect on mortality risk.
Bout Length of MVPA
Recent research using device-measured physical activity and assessing a variety of cardiometabolic health indicators indicates that bouts of MVPA of any length (ie, time duration) contribute to the health benefits associated with the accumulated total volume of physical activity.32–46 Of 40 comparisons within 14 studies, 78% (31 comparisons) indicated that bouts <10 minutes long were as good or better than bouts ≥10 minutes.1 An additional 10% (4 comparisons) reported that bouts <10 minutes long were associated with risk reduction but did not make a direct comparison with bouts ≥10 minutes.
Strategies for Promoting Physical Activity
Numerous intervention strategies, delivered through diverse communication channels and aimed at multiple population sectors and demographic subgroups, have been effective in increasing physical activity (Table 3).47 They include interventions aimed at individuals, interventions delivered in community settings, and programs delivered through a range of information and communication technology channels; elements of the built environment are also associated with increased physical activity. Although a number of interventions have small effect sizes (ie, d in the range of 0.2–0.4),47 some, such as telephone-assisted advice and support and mobile phone interventions, have produced effect sizes in the medium range or stronger (ie, d ≥ 0.5).48,49 Some sedentary behavior worksite interventions that targeted physical changes to work stations (eg, sit–stand workstations) have also had medium to large effect sizes (ie, d ≥ 0.5).50
Selected Types of Interventions Shown to Increase Physical Activity or Reduce Sedentary Behavior
Social ecological level | Type of physical activity intervention |
---|---|
Individual | Interventions targeting youth, particularly if families are incorporated |
Behavior theory-based interventions aimed at adults and older adults | |
Peer-led behavioral self-management interventions for older adults and individuals with chronic disease | |
Community | Community-wide interventions including intensive contact with a majority of targeted population |
School-based interventions that aim to increase physical activity during physical education classes | |
Multicomponent school-based interventions aimed at increasing student physical activity throughout the school day | |
Communication environment | Wearable activity monitors in combination with goal setting and other behavioral strategies |
Telephone-assisted interventions in the general adult population including older adults | |
Internet-delivered interventions that include educational components | |
Computer-tailored print interventions in the general adult population | |
Mobile phone programs that include text messaging for adults | |
Smartphone applications for children and adolescents | |
Physical environment and policy | Point-of-decision prompts to use stairs versus escalators or elevators |
Built environment infrastructure and elements to enable active transport and support recreational physical activity among children and adults | |
Access to parks and outdoor or indoor recreational facilities for children and adults | |
Interventions to reduce sedentary behavior | |
---|---|
Community | School-based interventions that aim to reduce television viewing and other screen time behaviors through counseling, parental involvement, tailored feedback, and use of screen allowance devices at home |
Worksite interventions targeting sedentary behavior including physical changes to workstations |
Discussion
This study provides an overview of the process used to develop the 2018 PAGAC Scientific Report and highlights topic areas not addressed in the 2008 Report (eg, brain health, prevention of weight gain, sedentary behavior, aspects of physical activity dose, new strategies for promoting physical activity). The benefits of physical activity include a reduced risk of many of the most common, severe, and expensive health outcomes (eg, heart disease, stroke, hypertension, dementia, type 2 diabetes, cancer, depression, and fall-related injuries in older adults). Benefits and risk reductions were observed across the entire age spectrum. People with established chronic conditions also receive preventive health benefits (eg, reduced risk for other conditions, improved physical function). In addition to the range of health benefits listed in Tables 1 and 2, more physically active people of all ages enjoy greater physical function, enabling them to conduct their daily lives with more energy and without undue fatigue.1 Indeed, the array of physical, mental, and functional health benefits conferred by regular physical activity establish it as both a “best buy in public health”51 and a worthy prescription tool for clinicians.
For the past 10 years, the federally recommended guidelines for physical activity have been 150 to 300 minutes per week of moderate-intensity activity, 75 to 150 minutes per week of vigorous-intensity activity, or an equivalent mixture of both. Those people performing this recommended volume of activity or more achieve substantial health benefits.1,5 Less well appreciated, however, is that the 30% to 50% of US adults52 who perform little or no MVPA can achieve some valuable health benefits by performing MVPA in amounts below the target range or by substituting light-intensity physical activity for sitting time. The interactions observed among sedentary time, light-intensity physical activity, and MVPA over the course of the day provide additional flexibility in the ways that physical activity behaviors can be modified to reduce the risk of all-cause mortality and other chronic conditions. This added flexibility in achieving federal guidelines for physical activity may be a good way for some people to begin increasing the overall volume of their weekly physical activity.5
The curvilinear, inverse dose–response relationship between physical activity and health was previously described in 2008 only for all-cause mortality.5 The most recent 2018 PAGAC Scientific Report now provides evidence of similarly shaped curves for cardiovascular mortality and incidence, as well as for the incidence of type 2 diabetes.22,29 There is insufficient information to depict dose–response curves for other health benefits at this time. It seems likely that the dose–response curves will be similarly shaped, although the maximal reductions in risk may be greater or lesser and may be reached at greater or lesser volumes of activity.
The social ecological model has been used as a framework for conceptualizing, studying, and implementing interventions to improve health behaviors, including physical activity. This model posits that health behaviors are influenced not only by person-level characteristics but also a broad range of social, community, and societal factors as well. Physical activity interventions, operating at all levels of the social ecological model, have been tested and found to be effective in increasing physical activity.47 In recent literature, many of the successful approaches have been directed toward individuals via specific channels, such as telephone-based advice and support, text messaging, smartphone apps, and other forms of electronic communication. The explosion of physical activity-relevant information and novel communication technologies provides an unprecedented opportunity to expand the reach, the tailored “touch,” and the sustained impact of interventions to those who could benefit most. In addition, a large amount of evidence indicates that activity-friendly physical and social environments are associated with more physically active lifestyles across age groups, settings (school, workplace), and different forms of activity (recreation, active transport). Because effect sizes for specific interventions have been modest, it is likely that multiple strategies operating at all levels of the social ecological model will be needed to shift the population’s current physical activity behaviors to healthier levels. Thus, interventions that produce only modest change by themselves may contribute importantly to larger cumulative efforts.53
Conclusion
In sum, findings from the 2018 Scientific Report underscore the public health impact of increasing population levels of regular physical activity and provide a firm foundation for the development of federal physical activity guidelines for the general US population. The list of health benefits attributable to greater amounts of physical activity continues to grow longer and applies to all segments of the US population. The public health burden associated with insufficient physical activity is substantial. Many of the most common causes of death, most prevalent chronic conditions, and most expensive medical conditions in the United States are favorably influenced by regular participation in physical activity (Table 4).54–57 Thus, even small increases in regular MVPA, especially if made by the least physically active individuals, would appreciably reduce the burden and cost of disease in the United States. More difficult to quantify are the physical activity benefits associated with improved cognition, better perceived quality of life, fewer symptoms of depression and anxiety, enhanced quality of sleep, and improved physical function across the full life span. Yet, these are the benefits that affect everyone on a daily basis and contribute not only to greater life satisfaction but also to enhanced productivity and fewer visits to health care providers.55,58
Leading Causes of Death, Most Prevalent Chronic Conditions, and Most Expensive Medical Conditions for Which Greater Participation in Physical Activity Would Be Expected to Reduce Incidence, Prevalence, and Expense Indicated by Shading and Bold Type
Ten leading causes of death54 | Ten most prevalent chronic conditions55 | Ten most expensive medical conditions56 |
---|---|---|
Heart disease | Hypertension | Heart conditions |
Cancer | Hyperlipidemia | Trauma disordersa |
Chronic lung diseases | Upper respiratory conditionsb | Cancer |
Unintentional injuriesa | Arthritis | Mental disorders |
Stroke | Mood disorders | Asthma/COPD |
Alzheimer’s disease | Diabetes | Hypertension |
Diabetes | Anxiety disorders | Type 2 diabetes |
Influenza and pneumonia | Asthma | Arthritis |
Kidney disease | Coronary artery disease | Back problems |
Suicide | Thyroid disorders | Healthy childbirth |
Note: Conditions in bold and shaded cells are favorably influenced by greater participation in regular physical activity.
aIncludes falls. bIncludes allergies and sinusitis.
Acknowledgments
The authors would like to thank the following who served as Consultants to the committee: Matthew P. Buman, PhD (Arizona State University); David E. Conroy, PhD (The Pennsylvania State University, University Park, PA); Kelly Evenson, PhD (University of North Carolina-Chapel Hill, Chapel Hill, NC); Christine M. Friedenreich, PhD (University of Calgary, Alberta, Canada); William L. Haskell, PhD (Stanford University, Stanford, CA); Virginia Byers Kraus, MD, PhD (Duke University School of Medicine, Durham, NC); Melissa A. Napolitano, PhD (The George Washington University, Washington, DC); Steven J. Petruzzello, PhD (University of Illinois at Urbana-Champaign, Urbana, IL); and Ronald J. Sigal, MD (University of Calgary, Alberta, Canada). Outside experts to the committee: Katherine Brooke-Wavell, PhD (Loughborough University, Loughborough, UK); Alison N. Cernich, PhD (Eunice Kennedy-Shriver National Institute for Child Health and Human Development, Bethesda, MD); Lisa Chasan-Tabor, ScD (University of Massachusetts, Amherst, MA); Tim Church, MD, PhD (ACAP Health Consulting); Janet E. Fulton, PhD (Centers for Disease Control and Prevention, Atlanta, GA); William L. Haskell, PhD (Stanford University, Stanford, CA); Wendy M. Kohrt, PhD (University of Colorado Denver, Aurora, CO); Heather McKay, PhD (University of British Columbia, Vancouver, BC); Richard P. Troiano, PhD (National Institutes of Health, Bethesda, MD); Jonathan Tobias, MD, PhD (University of Bristol, Bristol, UK); and Pedro F. Saint-Maurice, PhD (National Cancer Institute, Bethesda, MD). Co-Executive secretaries for the committee: Richard D. Olson, MD (Division of Preventive Science, Office of Disease Prevention and Health Promotion); Katrina L. Piercy, PhD (Physical Activity and Nutrition Advisor, Office of Disease Prevention and Health Promotion); Rachel M. Ballard, MD (Office of Disease Prevention, National Institutes of Health); Janet E. Fulton, PhD (Physical Activity and Health Branch, Division of Nutrition, Physical Activity, and Obesity, Centers for Disease Control and Prevention); Deborah A. Galuska, PhD (Associate Director for Science, Division of Nutrition, Physical Activity, and Obesity, Centers for Disease Control and Prevention); Shellie Y. Pfohl, MS (through September, 2016, President’s Council on Fitness, Sports, & Nutrition); Richard P. Troiano, PhD (Division of Cancer Control and Population Sciences, National Cancer Institute, National Institutes of Health). Lead management staff for HHS: Stephanie M. George, PhD (Office of Disease Prevention, National Institutes of Health); Alison Vaux-Bjerke, MPH (Office of Disease Prevention and Health Promotion). Management support staff for HHS: Emily Bhutiani, MS (National Cancer Institute, National Institutes of Health through June 2017); Eric Hyde, MPH (Division of Nutrition, Physical Activity, and Obesity, Centers for Disease Control and Prevention); Kate Olscamp, MPH (President’s Council on Fitness, Sports & Nutrition); Sarah Prowitt, MPH (Office of Disease Prevention and Health Promotion); Julia Quam, MSPH (Office of Disease Prevention and Health Promotion); Kyle Sprow, MPH (National Cancer Institute, National Institutes of Health). Data assistance staff for HHS: Susan A. Carlson, PhD (Division of Nutrition, Physical Activity, and Obesity, Centers for Disease Control and Prevention); Geoffrey Whitfield, PhD (Division of Nutrition, Physical Activity, and Obesity, Centers for Disease Control and Prevention). Technical writer/editor: Anne Brown Rodgers, HHS Consultant. ICF literature review staff, leadership team: Bonny Bloodgood, MA; Audie Atienza, PhD; Sondra Dietz, MA; Isabela Lucas, PhD; Mary Schwarz, Bethany Tennant, PhD; Andrea Torres, PhD; and ICF librarians, abstractors, and additional support staff. Technical assistance to subcommittees: Tim Hughes and Susanne DeSantis (The George Washington University); Jamie Cohen, Katherine Collins, George Grove Jr, and Chelsea Stillman, PhD (University of Pittsburgh); David Bartlett, PhD (Duke University); Andrew Hua, PhD (University of Illinois at Urbana-Champaign); Benjamin Chrisinger, PhD, and Darlyne Esparza (Stanford University); Janna Borden and Michaela Schenkelberg (University of South Carolina); and Jessica Goyette-Blankenship (Purdue University). The committee’s work was supported by the
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