Physical Activity Guidelines Advisory Committee Research Articles

Effectiveness of exercise on pain intensity and physical function in patients with knee and hip osteoarthritis: an umbrella and mapping review with meta-meta-analysis

Purpose The aim of this review was to provide a qualitative and quantitative overview of the effects of exercise on pain, physical function, and quality of life for patients with knee and hip osteoarthritis. Materials and methods This study was an umbrella and mapping review with meta-meta-analysis. Meta-analyses of randomized controlled trials were included. The methodological quality and risk of bias were evaluated using the Modified Quality Assessment Scale for Systematic Reviews and the Risk of Bias in Systematic Reviews tool. The quality of evidence was evaluated using the Physical Activity Guidelines Advisory Committee Grading Criteria. Results 41 meta-analyses were included, 43.9% of the studies had adequate methodological quality, and 56.1% of the studies had a low risk of bias. Moderate evidence was found that exercise decreases pain intensity (33 meta-analyses; SMD = −0.49; 95% CI −0.56 to −0.42), improves function (19 meta-analyses; SMD = −0.50; 95% CI −0.58 to −0.41), strength (6 meta-analyses; SMD = −0.57; 95% CI −0.70 to −0.44) and quality of life (SMD = −0.36; 95% CI −0.46 to −0.27) for patients with hip and knee osteoarthritis. Conclusion Exercise is an effective intervention to decrease pain intensity and improve function in patients with hip and knee osteoarthritis. (PROSPERO, CRD42020221987)

Evaluating the Science to Inform the Physical Activity Guidelines for Americans Midcourse Report

Abstract
 The Physical Activity Guidelines for Americans (Guidelines) advises older adults to be as active as possible. Yet, despite the well documented benefits of physical activity just 12.8% of those ages 65 and older meet the Guidelines. To address this, the U.S. Department of Health and Human Services (HHS) developed a Midcourse Report focused on effective strategies to improve older adult physical activity behaviors. The first step in this process was a systematic literature review.
 A literature review team was contracted to examine the evidence on key settings and effective behavioral intervention strategies, as well as effective policy, systems, and environmental (PSE) approaches, to improve physical activity among older adults. The PSE search employed an equity-centered framework adapted to researching PSE approaches for improving physical activity outcomes in older adults.
 Sixteen thousand eight hundred and eighty-three titles and abstracts were screened, and 734 full articles were reviewed for inclusion. Of those, 64 original research articles were included for the final review to answer two questions, one (plus 5 sub-questions) focused on Settings/Strategies literature (46 studies) and one (plus 2 sub-questions) focused on PSE literature (18 studies).
 The literature review process identified key settings and evidence-based strategies to support older adults in becoming more physically active, and provides a foundation for the Physical Activity Guidelines for Americans Midcourse Report: Implementation Strategies for Older Adults. More research is needed to address how factors related to equity and psychosocial constructs influence physical activity behaviors among older adults. 
  
 Key Words
 Physical activity, policy, older adults, systematic review, Policy-Systems-Environment, aerobic physical activity, muscle strengthening physical activity
  
  
 Introduction
 The Physical Activity Guidelines for Americans (Guidelines) (U.S. Department of Health and Human Services (HHS), 2018) serves as the benchmark and primary, authoritative voice of the federal government for providing science-based guidance on physical activity, fitness, and health for Americans. The most recent edition, released in 2018, provides evidence-based recommendations for Americans ages 3 and older to safely get the physical activity they need to stay healthy (HHS, 2018). In 2013, five years after the release of the first edition of the Guidelines, HHS released a midcourse report (Physical Activity Guidelines for Americans Midcourse Report Subcommittee of the President’s Council on Fitness, Sports & Nutrition (PAG Midcourse Subcommittee), 2013). This report focused on strategies to increase physical activity among youth and focused on five key areas where youth live, learn, and play – preschool and childcare centers, schools, family and home, community (built environment), and primary care medical settings (PAG Midcourse, 2013). The next midcourse report focused on older adults (ages 65 and older).
 The benefits of regular physical activity occur throughout life and are essential for healthy aging. Research suggests it is never too late to start being physically active. Despite the many benefits of physical activity, only 12.8% of adults over age 65 meet the aerobic and muscle-strengthening Guidelines (HHS Office of Disease Prevention and Health Promotion (ODPHP), 2022). This rate may be influenced by several factors, as barriers to physical activity differ from individual to individual and are influenced by socioeconomic, cultural, built environment, and other community factors.
 The Guidelines contains quantitative recommendations for older adults but does not include implementation strategies. Therefore, a literature review was conducted to identify successful interventions to promote increased physical activity and adherence to the key guidelines for older adults and summarized in the Physical Activity and Older Adults Systematic Literature Review (ICF Next, 2023). The Physical Activity Guidelines for Americans Midcourse Report: Implementation Strategies for Older Adults (Midcourse Report) (HHS, 2023) serves to further the breadth of the Guidelines to facilitate the implementation of proven programs and other strategies that can increase levels of physical activity among older adults. This paper outlines the literature review methodology to support the Midcourse Report.
 Methods: Literature Review
 In 2022, HHS contracted with a Literature Review Team to review the evidence on effective strategies to increase physical activity among older adults. This work was supported by the President’s Council on Sports, Fitness & Nutrition (PCSFN) Science Board (Science Board), made up of 11 experts in physical activity and older adult populations.  
 The Literature Review Team used a methodology supported by best practices for systematic literature reviews developed by the United States Department of Agriculture’s (USDA) Nutrition Evidence Systematic Review (NESR) (USDA NESR Branch, 2023), the Agency for Healthcare Research and Quality (AHRQ) (AHRQ, 2014), the Cochrane Collaboration (Higgins et al., 2022), and the Health and Medicine Division of the National Academies of Sciences, Engineering, and Medicine standards to review, evaluate, and synthesize published, peer-reviewed physical activity research (Institute of Medicine (US) Committee on Standards for Systematic Reviews of Comparative Effectiveness Research, 2011). This review process was largely guided by the approach taken to review the literature for the 2018 Physical Activity Guidelines Advisory Committee Scientific Report (2018 Physical Activity Guidelines Advisory Committee, 2018; Torres et al., 2018). Paralleling the 2018 process, this protocol-driven review approach was undertaken to maximize transparency, minimize bias, and ensure the review conducted was timely, relevant, and high quality. There are two major distinctions between this review and that conducted by the 2018 Physical Activity Guidelines Advisory Committee: 1) the decision to review original articles instead of using a “review of reviews” approach; and 2) to focus on research with physical activity outcomes as opposed to health outcomes.
 All work completed by the Literature Review Team was under the direction and review of ODPHP, on behalf of the National Institutes of Health (NIH), the Centers for Disease Control and Prevention, and the PCSFN. The Literature Review Team coordinated the literature review process, developed an abstraction tool and accompanying abstraction and triage guides, and implemented training and quality control protocols. Several groups supported the literature review work:
 
 Librarians reviewed search strategies and provided guidance as needed.
 The Triage Team conducted title and abstract triage of articles identified through the literature searches.
 The Abstraction Team engaged in rigorous training before abstracting data from included articles. A portion of this group also assessed risk of bias on a subset of the included articles.
 The Science Board identified, aggregated, organized, and analyzed the scientific literature.
 
 A six-step process was used to examine the literature:
 
 Step 1: Develop systematic review questions
 Step 2: Develop systematic review strategy
 Step 3: Search, screen, and select evidence to review for each question
 Step 4: Abstract data and assess the risk of bias of the research
 Step 5: Describe the evidence
 Step 6: Complete evidence portfolios and draft Scientific Report
 
 Step 1: Developing Systematic Review Questions
 Following the cadence of previous editions of the Physical Activity Guidelines for Americans with an interim Midcourse Report, HHS initiated the process to review the scientific literature focused on effective approaches to promote physical activity among older adults. ODPHP outlined a need to examine intervention strategies and key settings that are effective in promoting movement and achievement of the key guidelines for physical activity for older adults. Additional factors of interest for the literature review included how engagement in physical activity interventions may influence mental health, well-being, social connection, and other related social and emotional factors; as well as how interventions implemented as policy, systems, and environmental approaches to change the context influence physical activity in older adult populations.
 Solidifying Systematic Review Questions. The Literature Review Team developed research questions focused on the previously specified topics. The research questions and corresponding sub-questions are as follows:
 Question 1: What are effective intervention strategies to increase physical activity among older adults?
 
 Does the mode of delivery (e.g., virtual, in person, phone) impact the effectiveness of interventions?
 Does the setting impact the effectiveness of the interventions?
 What barriers exist to engaging or participating in the intervention? What are the retention, attrition, and/or attendance rates?
 Do personal characteristics (e.g., ability, age, sex, race/ethnicity, socioeconomic status) or chronic health conditions influence participation?
 Do interventions assess changes in participant mental health, quality of life, well-being, resilience, or social connection and isolation?
 
 Question 2: What are effective policy, systems, and environmental (PSE) strategies to increase physical activity among older adults?
 
 Is there a dose-response relation between the scope and reach of the PSE strategy and “success”?
 Does the “success” of the PSE strategy vary by geographical location or by sociodemographic subgroup?
 
 Step 2: Develop Systematic Review Strategy
 Develop Analytical Frameworks. Analytical frameworks were developed for each research question. Analytical frameworks are graphic representations used to lay the groundwork and initial parameters for each search. The frameworks served as a guide to define key variables, inform the inclusion and exclusion criteria, and develop the literature review strategy. These frameworks were created using the PICO method (population, intervention, comparison, and outcomes) (Higgins et al., 2022) and were modeled on the approach used for the 2018 Physical Activity Guidelines Advisory Committee Scientific Report (2018 Physical Activity Guidelines Advisory Committee, 2018; Torres et al., 2018). The frameworks were constructed during weekly meetings (see supplementary materials).
 Develop Inclusion and Exclusion Criteria. The Literature Review Team created inclusion and exclusion criteria for each research question. The template used to draft inclusion and exclusion criteria was modeled off the approach used for the 2018 Physical Activity Guidelines Advisory Committee Scientific Report (2018 Physical Activity Guidelines Advisory Committee, 2018), and adapted to meet the needs of this particular review. These templates were used to determine whether studies were eligible to be selected for each respective systematic literature review and whether studies would provide data to support the focal research questions. To promote consistency and relevance, and to account for scope parameters, each template included similar sections (Tables 1 and 2).
 Table 1. Inclusion and Exclusion Criteria for Question 1: What are effective intervention strategies to increase physical activity among older adults?
 
 
 
 
 Include
 
 
 
 
 Published in English Language
 
 
 
 
 English Language Publication
 
 
 
 
 Peer-Reviewed Literature
 
 
 
 
 Published From 2012 to 2022
 
 
 
 
 Original Research
 
 
 
 
 Human Participants
 
 
 
 
 Intervention Study (Comparison Required)
 
 
 
 
 Must Measure Physical Activity Outcome
 
 
 
 
 Older Adults (minimum or mean age of 65 years or older)
 
 
 
 
 Designs Include Randomized Controlled Trials, Non-Randomized Controlled Trials, and Quasi-Experimental Studies
 
 
 
 
 Exclude
 
 
 
 
 Studies of Older Adults in Long-Term, Memory, or Hospice Facilities
 
 
 
 
 Studies of Disease-Specific Therapeutic Exercise Delivered in Health/Medical Facility
 
 
 
 
 Table 2. Inclusion and Exclusion Criteria for Question 2: What are effective policy, systems, and environmental (PSE) strategies to increase physical activity among older adults?
 
 
 
 
 Include
 
 
 
 
 Published in English Language
 
 
 
 
 Peer-Reviewed Literature
 
 
 
 
 Published from 2012-2022
 
 
 
 
 Original Research
 
 
 
 
 Human Participants
 
 
 
 
 Study Conducted in the United States
 
 
 
 
 Intervention Study (PSE Intervention)
 
 
 
 
 Must Measure Physical Activity Outcome
 
 
 
 
 Older Adults, Middle Age (50+ years) and Older
 
 
 
 
 Designs Include Non-Randomized Controlled Trials, Prospective Cohort, Retrospective Cohort, Case-Control, Cross-Sectional, Before and After, Geospatial, Environmental, and Surveillance
 
 
 
 
 Exclude
 
 
 
 
 Studies of Older Adults in Long-Term, Memory, or Hospice Facilities
 
 
 
 
 Studies of Disease-Specific Therapeutic Exercise Delivered in Health/Medical Facility
 
 
 
 
 Develop Search Strategy. A search strategy was created to identify peer-reviewed original research for each systematic review conducted. Each search strategy included search terms, Boolean logic to join terms, databases used, and key limits relevant to the inclusion criteria (e.g., research type, date of publication, language, study population, and filters specific to databases). The three databases included in each review were PubMed, CINHAL, and PsychINFO. These databases were selected due to the subject matter of articles included within each database.
 The Literature Review Team developed sets of search terms most relevant to each review. These sets included terms capturing a broad range of articles based on older adult population, intervention study design, comparison approach, and physical activity outcomes. Once these search terms were drafted, library representatives from the literature review contractor and the NIH Library reviewed the search strategies and provided suggestions for updates. Throughout the search strategy development process, draft searches were run to assess the number of articles included in the search and if the collected articles represented the nature of the research questions. In response to these outputs, modifications were made to the search strategies as needed. The final search strategies were shared with the Science Board for review and affirmation. 
 Step 3: Search, Screen, and Select Evidence to Review
 The searching and screening process was completed to collect a thorough body of original research needed to support each systematic review. Specifically, a primary search was completed within the original literature, and a supplemental search of existing meta-analyses and systematic literature reviews was conducted to support this process. A review of the original research was completed using the previously developed search strategies. Once results were generated, duplicates were removed, and results were triaged based on title and abstract.
 Triage Training. Once the search strategy was implemented, each title/abstract underwent two rounds of review by members of the triage team. Members of the triage team were provided with thorough training and required to complete a certification process to ensure consistency between reviews prior to initiating triage. This training involved a comprehensive instructional presentation that was supported by a triage training manual that included detailed instructions, definitions, reporting instructions, response options, and example titles/abstracts. In addition to the formal training, members of the leadership team met one-on-one with triagers on an as-needed basis to promote consistency and accuracy. Prior to initiating the triage process, all potential triagers were required to complete a certification process on a subset of abstracts. Triagers who did not display a high level of consistency with the group on the practice assignment were not authorized to participate in the formal abstraction process.
 Title and Abstract Triage. Triagers were instructed to first review titles to assess eligibility and then move to abstracts if the article appeared to be potentially relevant. Triagers were instructed to then include or exclude articles based on information provided within the abstract. If articles were removed from consideration at the abstract review stage, triagers were required to provide a reason. These reasons differed based on the search, but often included reasons such as ineligible age of participants, no physical activity outcome included, and/or no physical activity component of intervention reported. When conflicts existed in decisions made by screeners, discrepancies were resolved by a member of the triage team. The lists of included and excluded articles were shared with members of the Science Board.
 Additional Supplemental Search Activities. Additional search activities were undertaken to further fortify the pool of articles collected through the initial search of the original literature. First, using the pre-established search terms, a systematic search was undertaken to identify relevant meta-analyses and systematic literature reviews that could potentially include original research articles relevant to the focal inclusion criteria. In tandem with this, a snowball approach (Wohlin, 2014) was also used to locate any additional meta-analyses and systematic literature reviews that could be deemed relevant. Reference pages and results tables from each of these meta-analyses and systematic literature reviews were hand-reviewed to identify original research articles that should be included within the review. These selected articles were reviewed in full-text and added to the pool if they fit the specified inclusion criteria.
 Science Board members were encouraged to share additional articles that fit inclusion criteria with the Literature Review Team. These articles were identified through the Science Board’s expertise and familiarity with the subject matter. If an article was identified that met the inclusion criteria, it was reviewed in full text and abstracted by the Abstraction Team.
 Full Text Review. Full text review for the list of included articles was conducted by members of the Literature Review Team. Two reviewers assessed each full-length article based on the inclusion criteria to determine whether it should be included or excluded from the final pool for review. Further, any articles that were identified as potentially ineligible during the abstraction process were added to the list of excluded articles.
 Step 4: Abstract Data and Assess Risk of Bias
 The abstraction process was used to collect and summarize key characteristics of each study that supported the systematic literature review purpose. The goal of abstraction was to (a) document key elements of each study for ease of review, and (b) use this information to present trends across the full body of evidence.
 Abstraction Training. Abstractors were onboarded, trained, and certified to complete all abstraction activities. Abstraction candidates participated in a thorough and rigorous multi-phased process prior to initiating abstraction. This training involved a multi-hour instructional session. This session was supported by an abstractor training manual that included detailed instructions, definitions, reporting instructions, response options, example abstraction questions, and thoroughly annotated version of articles used in the training. In addition to the formal training, members of the Literature Review Team met with and/or delivered written feedback to the abstractors to ensure consistency and promote recalibration when needed. Prior to initiating the abstraction process, all potential abstractors were required to complete abstraction on practice articles. Abstractors who did not display a high level of consistency with the group during the practice sessions did not participate in the formal abstraction process.
 Abstraction Process Explanation and Quality Control. Abstractors worked in pairs to independently review articles, abstract articles, and document findings. Abstractors were provided with random assignments of articles from members of the Literature Review Team. When discrepancies in abstraction were identified by the Literature Review Team, abstractors were asked to review and discuss these discrepancies. When discrepancies could not be settled among abstractors, members of the Literature Review Team reviewed the situation/materials and provided input and clarification to settle on a decision. The Literature Review Team conducted quality control and independently conducted a third round of abstraction for 20% of all articles included in each respective review. This quality control process was completed to ensure accuracy, clarity, and consistency in abstraction.
 Data Documentation. An online database was created, and abstractors entered their data into this system using forms created by the Literature Review Team. All pairings of abstractors independently read and reviewed articles, abstracted key information, and entered it into the online database. After discrepancy resolution and quality control procedures were completed, the abstracted data was edited as needed and used to populate article evidence summary tables and inform trend tables demonstrating overarching themes in the data.
 Assessing Risk of Bias. Articles were assessed for internal validity, using either the ROBINS-I (Sterne et al., 2016) or ROBINS-E tool (ROBINS-E Development Group, 2022). These tools assess risk of bias in studies that compare the health effects of exposures or interventions across a range of study types (e.g., RCT’s, observational, etc.). These tools are tailored by study design and pose different sets of questions based on whether a study is a randomized controlled trial (RCT), non-randomized controlled trial, or an observational study. The risk of bias assessment for each study was completed by two reviewers (from either the Abstraction Team or the Science Board). When discrepancies arose, the reviewers discussed and resolved discrepancies. 
 Additionally, the Policy, Systems, and Environments review used an equity-centered framework relevant to the research evidence and adapted to researching policy, systems, and environmental approaches for improving physical activity outcomes in older adults (Venkateswaran et al., 2023). The diversity-equity-inclusion frame was applied to studies assessed for risk of bias using ROBINS-E across relevant domains of bias (ROBINS-E Development Group, 2022) (i.e., confounding, selection of participants into the study, classification of exposures, departures from intended exposures, missing data, measurement of outcomes, and selection of reported results, aligned with PICO model).
 Step 5: Describe the Evidence                                            
 Evidence Portfolios. To facilitate the analysis of the evidence, the Literature Review Team prepared evidence portfolios for each question (see supplementary materials). The evidence portfolios documented the full process followed for both reviews, including the sources of evidence, conclusions, evidence grades, description of evidence, populations analyzed, individual evidence summary tables, risk of bias and quality assessment charts, search strategies, literature trees, references, and rationales for exclusion of articles during full-text triage.
 Step 6: Complete Evidence Portfolios and Draft Scientific Report
 Science Board members reviewed and deliberated on the body of evidence to develop conclusion statements that supported each of the research questions. Conclusion statements were tightly associated with the evidence, focused on general agreement among the studies around the independent variables and outcomes, and acknowledged areas of disagreement or limitations, where they existed. The conclusion statements reflected only the evidence reviewed and not information Science Board members might have known from another source.
 Along with the evidence portfolios, a rubric was developed to guide the assessment and grading of the strength of the evidence supporting each conclusion statement (Table 3). The rubric was adapted from the 2018 Physical Activity Guidelines Advisory Committee (2018 Physical Activity Guidelines Advisory Committee, 2018) and the 2020 Dietary Guidelines Advisory Committee (2020 Dietary Guidelines Advisory Committee, 2020). Grading the strength of the evidence was based on applicability of the populations, exposures, and outcomes studied; generalizability to the population of interest; risk of bias and study limitations; quantity and consistency of findings across studies; and magnitude and precision of effect.
 Table 3. Physical Activity and Older Adults Systematic Literature Review Grading Criteria
 
 
 
 
 Grade 
 
 
 Definition 
 
 
 
 
 Strong 
 
 
 The conclusion statement is based on a strong body of evidence as assessed by risk of bias, consistency, directness, precision, and generalizability. The level of certainty in the conclusion is strong, such that if new evidence emerges, modifications to the conclusion are unlikely to be required. 
 
 
 
 
 Moderate 
 
 
 The conclusion statement is based on a moderate body of evidence as assessed by risk of bias, consistency, directness, precision, and generalizability. The level of certainty in the conclusion is moderate, such that if new evidence emerges, modifications to the conclusion may be required. 
 
 
 
 
 Limited 
 
 
 The conclusion statement is based on a limited body of evidence as assessed by risk of bias, consistency, directness, precision, and generalizability. The level of certainty in the conclusion is limited, such that if new evidence emerges, modifications to the conclusion are likely to be required. 
 
 
 
 
 Grade Not Assignable 
 
 
 A conclusion statement cannot be drawn due to either a lack of evidence or evidence that has severe limitations related to risk of bias, consistency, directness, precision, and/or generalizability. 
 
 
 
 
 Results
 The Physical Activity and Older Adults Systematic Literature Review (ICF Next, 2023) used a rigorous and systematic methodology. The methodology allowed the Literature Review Team to search, screen, select, abstract, assess the risk of bias, and include considerations of equity in original research related to effective strategies to get older adults moving; and grade the evidence from insufficient to strong. Over nine months, two literature searches were conducted, resulting in 16,883 titles and abstracts screened, and 734 full articles reviewed for inclusion. Of those, 64 original research articles were included for the final review to answer two questions, one focused on Settings and Strategies literature (46 studies) with five sub-questions and one focused on Policy, Systems, and Environments literature (18 studies) with two sub-questions (Figures 1 and 2). The process is documented for each research question in an evidence portfolio (see supplementary materials).
 Figure 1. Literature Tree Diagram for Question 1: What are effective intervention strategies to increase physical activity among older adults?
 Figure 2. Literature Tree Diagram for Question 2: What are effective policy, systems, and environmental (PSE) strategies to increase physical activity among older adults?
  
 Discussion
 The Physical Activity and Older Adults Systematic Literature Review (ICF Next, 2023) evaluated the current scientific literature on strategies to increase physical activity among older adults to inform the Physical Activity Guidelines for Americans Midcourse Report: Implementation Strategies for Older Adults (HHS, 2023). Several strategies emerged across a variety of settings; the most commonly researched were home, health care, and community. Several limitations to the Physical Activity and Older Adults Systematic Literature Review (ICF Next, 2023) and opportunities to strengthen the research base on physical activity interventions for older adults should be noted.
 While the literature review looked at original research articles rather than systematic reviews or meta-analyses, most included studies did not measure, analyze, or disaggregate findings based on important individual or group characteristics. For the  Settings and Strategies question, the team  attempted to determine if the personal characteristics (e.g., ability, age, sex, race/ethnicity, socioeconomic status) influence physical activity participation, but there was insufficient evidence to yield any analysis. For the Policy, Systems, and Environments question, equity considerations were applied, particularly concepts of diversity, inclusion, and access to study samples and intervention contexts to determine inequalities in physical activity outcomes. The samples did not reflect diverse populations and therefore an inability to grade the evidence or provide specific analysis for different subsets of older adults. For example, of the 18 included studies, only three studies examined specific racial/ethnic minority populations; two studies reported findings relative to disability-mobility limitations; and one study reported findings relative to health (multiple sclerosis status). Only two studies compared exposure to urban versus rural community geographies. Most studies of policy, systems, and environmental interventions employed cross-sectional design, examining residential neighborhoods (exposure context) in relation to physical activity outcomes, typically self-reported.
 Because of the importance of social connection and mental well-being, especially for older adults who are socially isolated or live alone, the review made efforts to examine these concepts in relation to physical activity outcomes and interventions. Unfortunately, most published studies of interventions for improving physical activity in older adults did not include social or mental well-being outcomes, such as social cohesion, quality of life, resilience, or mental health status.
 Lastly, few studies employed longitudinal designs, assessed long-term maintenance of outcomes, or investigated strategies to improve retention or prevent drop out in interventions to increase physical activity among the diversity of older adults, so physical activity maintenance, population and subpopulation effect remain uncertain.
 The Physical Activity and Older Adults Systematic Literature Review (ICF Next, 2023) provides a foundation suggesting what strategies work and in which settings to support physical activity in older adults. Several limitations to the literature review can be used as areas to strengthen future research to ensure more diverse populations are recruited, studied, analyzed, and outcomes documented in the scientific literature.
  
 Conclusion
 The Systematic Review (ICF Next, 2023) and Midcourse Report (HHS, 2023) are useful for physical activity researchers; policy makers; exercise and health professionals; clinicians; gerontologists; built environment professionals; local, state, territorial, and Tribal leaders; and others working with older adults. These reports are necessary as a guide to apply evidence-based strategies to support older adults to be more physically activity and to expand the future evidence base to translate Guidelines into practice. 
 Author Contributions
 Conceptualization: A.V.B. and K.L.P.; Data Curation: D.H.J.; Formal Analysis: D.H.J.; Funding Acquisition: A.V.B. and K.L.P.; Investigation: D.H.J.; Methodology: A.V.B., D.H.J., and K.L.P.; Project Administration: A.V.B. and K.L.P.; Resources: A.V.B. and K.L.P.; Supervision: A.V.B. and K.L.P.; Validation: D.H.J.; Writing – Original Draft: A.V.B., D.H.J., and K.L.P.; Writing – Review & Editing: A.V.B. and K.L.P.
 Acknowledgments
 The authors are grateful to the 2022 President’s Council on Sports, Fitness & Nutrition Science Board for their work on the literature review: Barbara J. Nicklas (Science Board Chair), Susan W. Buchholz, David E. Conroy, Cheryl Der Ananian, Loretta DiPietro, Mark Fenton, Deborah H. John, NiCole R. Keith, David X. Marquez, Jacqueline Osborne, and Dori Rosenberg. Additionally, the authors would like to acknowledge Sarah Caban, Rachel Fisher, Noelle Harada, Carolyn Hinton, and Malorie Polster for their contributions to this project.

The Impact of Aerobic Exercise on HDL Quantity and Quality: A Narrative Review

High-density lipoproteins comprise roughly 25-30% of the circulating proteins involved in the transport of lipids in circulation. These particles differ in size and lipid composition. Recent evidence suggests that the quality of HDL particles (which depends on shape, size and the composition of proteins and lipids determining HDL functionality) may be more important than their quantity. The functionality of HDL is mirrored by its cholesterol efflux activity, as well as its antioxidant (including the protection of LDL against oxidation), anti-inflammatory and antithrombotic properties. The results of many studies and meta-analyses imply the beneficial impact of aerobic exercise on HDL-C levels. Physical activity was found to be usually associated with an increase in HDL cholesterol and a decrease in LDL cholesterol and triglycerides. Exercise, apart from inducing quantitative alterations in serum lipids, exerts a beneficial impact on HDL particle maturation, composition and functionality. The Physical Activity Guidelines Advisory Committee Report underlined the importance of establishing a program recommending exercises that enable attainment of maximal advantage at the lowest level of risk. The aim of this manuscript is to review the impact of different types of aerobic exercise (various intensities and durations) on the level and quality of HDL.

Association of Physical Activity and Screen Time With Body Mass Index Among US Adolescents

The Physical Activity Guidelines Advisory Committee Scientific Report identified important research gaps to inform future guidance for adolescents, including limited evidence on the importance of sedentary behaviors (screen time) and their interactions with physical activity for adolescent health outcomes, including overweight and obesity. To identify the independent associations of physical activity and screen time categories, and the interactions between physical activity and screen time categories, with body mass index (BMI) and overweight and obesity in adolescents. This cross-sectional study used data from the Adolescent Brain Cognitive Development (ABCD) Study collected from September 10, 2018, to September 29, 2020. Data were analyzed from July 8 to December 20, 2022. A total of 5797 adolescents aged 10 to 14 years from 21 racially and ethnically diverse study sites across the US were included in the analysis. Categories of total step count per day (with 1000 to 6000 steps per day indicating low, >6000 to 12 000 steps per day indicating medium, and >12 000 steps per day indicating high), as measured by a wearable digital device (Fitbit), and categories of self-reported screen time hours per day (with 0 to 4 hours per day indicating low, >4 to 8 hours per day indicating medium, and >8 hours per day indicating high). Participant BMI was calculated as weight in kilograms divided by height in meters squared and converted into sex- and age-specific percentiles in accordance with the Centers for Disease Control and Prevention growth curves and definitions. Individuals were classified as having overweight or obesity if their BMI was in the 85th percentile or higher for sex and age. Among 5797 adolescents included in the analytic sample, 50.4% were male, 61.0% were White, 35.0% had overweight or obesity, and the mean (SD) age was 12.0 (0.6) years. Mean (SD) reported screen time use was 6.5 (5.4) hours per day, and mean (SD) overall step count was 9246.6 (3111.3) steps per day. In models including both screen time and step count, medium (risk ratio [RR], 1.24; 95% CI, 1.12-1.37) and high (RR, 1.29; 95% CI, 1.16-1.44) screen time categories were associated with higher overweight or obesity risk compared with the low screen time category. Medium (RR, 1.19; 95% CI, 1.06-1.35) and low (RR, 1.30; 95% CI, 1.11-1.51) step count categories were associated with higher overweight or obesity risk compared with the high step count category. Evidence of effect modification between screen time and step count was observed for BMI percentile. For instance, among adolescents with low screen use, medium step count was associated with a 1.55 higher BMI percentile, and low step count was associated with a 7.48 higher BMI percentile. However, among those with high screen use, step count categories did not significantly change the association with higher BMI percentile (low step count: 8.79 higher BMI percentile; medium step count: 8.76 higher BMI percentile; high step count: 8.26 higher BMI percentile). In this cross-sectional study, a combination of low screen time and high step count was associated with lower BMI percentile in adolescents. These results suggest that high step count may not offset higher overweight or obesity risk for adolescents with high screen time, and low screen time may not offset higher overweight or obesity risk for adolescents with low step count. These findings addressed several research gaps identified by the Physical Activity Guidelines Advisory Committee Scientific Report and may be used to inform future screen time and physical activity guidance for adolescents.

Behavior Modification Techniques on Patients with Chronic Pain in the Context of COVID-19 Telerehabilitation: An Umbrella Review.

The aim of this systematic review (SR) of SRs was to assess the effectiveness of telerehabilitation based on behavior modification techniques (t-BMT) in patients with chronic musculoskeletal pain. We searched in PubMed, PEDro, Web of Science, CINAHL, PsycINFO, and Google Scholar (January 2022). The outcome measures were pain intensity, disability, psychological distress, pain-related fear of movement, disease impact, depressive symptoms, anxiety symptoms, and physical function. This review was previously registered on the international prospective register of systematic reviews PROSPERO (CRD42021262192). Methodological quality was analyzed using the AMSTAR and ROBIS scales, and the strength of evidence was established according to the Physical Activity Guidelines Advisory Committee grading criteria. Four SRs with and without meta-analyses covering 25 trials and involving 4593 patients were included. Of the three SRs that assessed pain intensity, two reported a significant decrease compared to usual care. Contradictory results were also found in the management of psychological distress, and of depressive and anxiety symptoms. However, two reviews found that t-BMT has significant effects on disability, and one review found that t-BMT seems to be effective for improving pain-related fear of movement and disease impact. Finally, one review found that t-BMT does not seem to be an effective modality to improve physical function. The quality of evidence was limited for all outcomes assessed. The results obtained showed that t-BMT was effective in improving disability, disease impact, and pain-related fear of movement, but it was not effective in improving physical function in patients with chronic pain. Mixed evidence was found for pain intensity, psychological distress, and depressive and anxiety symptoms, with a limited quality of evidence.

Effects of Neural Mobilization on Pain Intensity, Disability, and Mechanosensitivity: An Umbrella Review With Meta-Meta-Analysis.

The purpose of this study was to assess the current evidence for the effects of neural mobilization (NM) treatments. Three umbrella reviews with meta-meta-analyses were conducted to determine the effects of NM on pain intensity and disability in people with musculoskeletal disorders and on mechanosensitivity in participants who were asymptomatic. The study used the grading criteria proposed by the Physical Activity Guidelines Advisory Committee to assess the quality of evidence. One meta-meta-analysis revealed a statistically significant moderate effect on pain intensity (standardized mean difference [SMD] = -0.75, 95% CI = -1.12 to -0.38) but with evidence of heterogeneity (Q = 14.13; I2 = 65%). The study found a significantly large effect of NM on disability (SMD = -1.22, 95% CI = -2.19 to -0.26), again with evidence of heterogeneity (Q = 31.57; I2 = 87%). The third meta-meta-analysis showed a statistically significant moderate effect of NM on mechanosensitivity (SMD = 0.96, 95% CI = 0.35 to 1.57), with no evidence of heterogeneity (Q = 2.73; I2 = 63%). For all examined outcomes, the quality of evidence was limited. Overall, the results indicated that although NM treatment had a moderate to large beneficial clinical effect on pain intensity and disability in people with musculoskeletal disorders and on mechanosensitivity in individuals who were asymptomatic, the quality of evidence was limited. Neural mobilization treatments showed positive results on the pain intensity and disability in individuals with musculoskeletal conditions. Neural mobilization could be integrated into the physical therapy management, although more research is needed.

Exercise and Manual Therapy for the Treatment of Primary Headache: An Umbrella and Mapping Review.

The main aim of this study was to assess through systematic review the efficacy of exercise and manual therapy (MT) interventions in individuals with primary headache. In this umbrella review, 2 authors reviewed systematic reviews by searching the Cochrane Database of Systematic Reviews, MEDLINE, PEDro, Web of Science, and Google Scholar. Systematic reviews that evaluated the effectiveness of MT. Exercise-based interventions, or both in patients with primary headaches were included. Methodological quality was analyzed using the ROBIS scale, and the strength of evidence was established according to the Grading Criteria of the Physical Activity Guidelines Advisory Committee. Thirty-one systematic reviews containing 79 trials and involving 9103 patients were included. The 7 exercise-related systematic reviews reported beneficial effects on primary headache based on unclear to moderate evidence. Of the 23 MT-related systematic reviews, 11 reported enhanced effectiveness compared with usual care; however, overall heterogeneity and risk of bias were high. Systematic reviews that evaluated the effectiveness of MT, exercise-based interventions, or both in patients with primary headaches were included. Results show that exercise could be an effective therapy for the treatment of primary headache, with moderate to limited quality of evidence regarding the positive effects in terms of pain intensity and frequency and duration of headache. Moderate quality of evidence was found regarding the ability of MT to reduce pain intensity in patients with tension-type headaches, but quality of evidence was limited in terms of frequency of headache and disability and pain reduction in patients with migraine. Exercise could be an effective treatment in patients with primary headache. Manual therapy showed limited evidence to reduce pain intensity in patients with tension-type headache. It is not possible to establish a preferential exercise protocol or MT program, so psychosocial and behavioral variables need to be considered in future studies.

Best Practices for Meta-Reviews in Physical Activity and Health Research: Insights From the Physical Activity Guidelines for Americans Advisory Committee Scientific Report.

Systematic reviews (SRs) and meta-analyses (MAs) have proliferated with a concomitant increase in reviews of SRs/MAs or "meta-reviews" (MRs). As uncovered by the 2018 US Physical Activity Guidelines Advisory Committee (PAGAC), there is a paucity of best practice guidance on MRs on physical activity health-related research. This manuscript aims to fill this gap. In total, the PAGAC conducted 38 literature searches across 3 electronic databases and triaged 20,838 titles, 4913 abstracts, and 2139 full texts from which 1130 articles qualified for the PAGAC Scientific Report. During the MR process, the following challenges were encountered: (1)if the SR/MA authors had limited experience in synthesis methodology, they likely did not account for risk of bias in the conclusions they reached; (2)many SRs/MAs reviewed the same primary-level studies; (3)many SRs/MAs failed to disclose effect modifier analyses; (4)source populations varied; (5)physical activity exposures were nonstandardized; and (6)dose-response effects or effect modification of the physical activity exposure could not be identified. Using examples from the PAGAC Scientific Report, we provide (1)a high-level introduction to MRs; (2)recommended steps in conducting a MR; (3)challenges that can be encountered; and (4)guidance in addressing these challenges.

The association between guideline-based exercise thresholds and low testosterone among men in the United States.

Exercise and weight loss have been shown to improve serum testosterone (T) in obese individuals. However, the association between low T levels and guideline-based exercise thresholds has not been determined. Using the recently updated Physical Activity Guidelines Advisory Committee (PAGAC) recommendations, we sought to investigate the relationship between recommended activity levels and the prevalence of low T levels. The2011-2016 National Health and Nutrition Examination Survey (NHANES) was used to identify men ages 18 to 80years who answered the physical activity questionnaire and underwent serum T testing. Men were categorized based on PAGAC activity level: less than recommended, recommended and greater than recommended. Multivariable logistic regressions were used to determine the association between low T (<300ng/dL) and activity level across body mass index (BMI) categories while adjusting for potential confounders. Of the 7372 men who met the inclusion criteria, the majority (4372, 59.3%) exceeded the recommended amount of activity, whereas only 2326 (31.6%) exercised less than the recommended amount. On multivariable analysis, obese men whose activity exceeded the recommended amount were less likely to have low T (OR 0.523, 95% CI 0.409-0.669, P<.001) compared with men who did not meet the recommended activity level. Using a large, nationally representative cohort, we demonstrated that obese men whose activity exceeded PAGAC recommendations had a decreased likelihood of having low T levels. Given the numerous benefits of exercise, these data provide a basis for counseling obese patients regarding the association between exercise and decreased prevalence of low T.

Association Of Steps Per Day With Premature Mortality: RESULTS From The Cardia Study

PURPOSE: The 2018 Physical Activity Guidelines Advisory Committee Report calls for research to examine associations of step volume with long-term clinical endpoints, including mortality. To date, there are few prospective studies examining accelerometer-measured steps/day with mortality. METHODS: Data are from 2027 participants from the Coronary Artery Risk Development in Young Adults (CARDIA) study with valid (≥4 days, ≥10 hours/day) accelerometer wear (ActiGraph 7164) at the year 20 exam (2005-2006). Multivariable Cox models calculated hazard ratios (HR) and 95% confidence intervals (CI) for mortality for the total sample and by race and sex. RESULTS: The sample (45.3±3.6 years; 58% women, 41% black) had mean follow-up time of 10.8±0.9 years, and 67 total deaths occurred. The participants had a median [IQR] of 10004 [8061-12097] steps/day according to the raw output and 6670 [4987-8617] steps/day when applying a censoring equation omitting steps accumulated at low accelerations of <500 counts/minute. Black women accumulated significantly lower step volume vs. all other race-sex groups (p<0.05). Adjusting for demographics, lifestyle characteristics, and comorbidities, every 1000 higher steps/day was associated with a 10% lower risk of mortality (HR:0.90, 95% CI:0.83, 0.99). When stratifying by race or sex, HRs remained statistically significant for women (HR:0.77, 95%CI:0.66, 0.90) and blacks (HR:0.85, 95%CI:0.76, 0.96). Black women had 28% lower risk of mortality for every 1000 higher steps/day (HR:0.72, 95%CI:0.58, 0.88). CONCLUSIONS: Among this sample of middle-age adults, accumulating a higher volume of steps/day was associated with a lower risk of mortality.

High-intensity Interval Training And Resistance Training Favor Higher Improves On Cardio-metabolic Health Outcomes Compared With Combined Training Or Nutritional Guidance In Overweight Adults: Cardiometabolic Hiit-rt Study, A Randomized Controlled Trial

PURPOSE: The 2018 Physical Activity Guidelines Advisory Committee systematically searched existing literature reviews to assess the relationship between high-intensity interval training (HIIT), moderate-intensity continuous training (MICT), or resistance training (RT) and reduction in cardiometabolic disease risk. Against this background, the aim of the present study was to investigate whether 12 weeks of HIIT, RT, combination training (CT = HIIT+RT) or a NG plan induced improvement on metabolic syndrome risk factors, vascular function and physical fitness in sedentary and overweight, and to compare the responses between the four intervention groups. METHODS: The study included a total of 57 sedentary subjects with abdominal obesity or excess weight. Twelve-week randomized parallel design examining the effects of different exercise regimes and/or NG on anthropometric and body composition (fat and lean mass at whole body, trunk fat, fat mass index, appendicular muscle mass, and waist circumference); metabolic syndrome risk factors and vascular parameters (blood lipids, fasting glucose, blood pressure, flow-mediated vasodilation [FMD%], aortic pulse wave velocity (PWV), and augmentation index [AIx]); and physical fitness (cardiorespiratory fitness and grip strength). RESULTS: Adjusted mixed linear models revealed a significant improved in cardiorespiratory fitness (mL·kg·min-1): HIIT +8.3, RT +4.1, and CT +6.3 (all P < 0.001). The improvement difference between the groups was statistically significant between the HIIT and NG group (P = 0.014), [time x group interaction F(23.564); P < 0.001; η2 partial = 0.365]. In addition, RT and CT group, has a significant positive impact on PWV (m·s-1) (d = 0.391 and 0.229 respectively; P < 0.001, [time x group interaction F(5.457); P=0.003; η2 partial = 0.280]. Hereafter, RT group has a significant positive impact on the FMD (%) in comparison to HIIT, CT or NG group (time x group interaction F(2.942); P = 0.044; η2 partial = 0.174). CONCLUSIONS: The main findings of this study are that 12 weeks of HIIT leads to significant improvements in cardiorespiratory fitness while the RT resulted in improvements in the vascular profile, supporting the positive effect of both training programs for cardiometabolic risk factors in sedentary and overweight adults.

Diet and Physical Activity Prevention Research Supported by the U.S. NIH From 2012–2017

Poor diet and inadequate physical activity are common contributors to preventable death in the U.S. This paper provides a summary of the NIH-sponsored research on disease prevention that underlies public health and clinical recommendations to improve diet and physical activity. A representative sample (n=11,082) of research grants and cooperative agreements (research projects) representing the NIH prevention research portfolio between 2012 and 2017 were hand coded by trained analysts in 2017-2018. This manuscript describes the rationale(s), exposure(s), outcome(s), population(s), and study design(s) in prevention research focused on diet and physical activity and compares this research to identified research gaps in the field. A relatively stable 7.8% (95% CI=7.0%, 8.8%) and 5.0% (95% CI=4.4%, 5.7%) of the NIH prevention research projects were focused on diet and physical activity, respectively, during 2012-2017. These projects often explored diet and physical activity together in the context of obesity, included observational studies, and focused on a general adult population. Few of these projects focused on development of improved assessment methods. Approximately 50% of these studies were related to research gaps identified by the 2015 Dietary or 2018 Physical Activity Guidelines Advisory Committee Scientific Reports. Opportunities exist for more engagement by NIH and scientific investigators in diet- and physical activity-focused prevention research, particularly around assessment and known research gaps.

Sedentary Behavior and Health: Update from the 2018 Physical Activity Guidelines Advisory Committee.

To provide an overview of relationships between sedentary behavior and mortality as well as incidence of several noncommunicable diseases and weight status reported in the 2018 Physical Activity Guidelines Advisory Committee Scientific Report (2018 PAGAC Scientific Report), and to update the evidence from recent studies. Evidence related to sedentary behavior in the 2018 PAGAC Scientific Report was summarized, and a systematic review was undertaken to identify original studies published between January 2017 and February 2018. The 2018 PAGAC Scientific Report concluded there was strong evidence that high amounts of sedentary behavior increase the risk for all-cause and cardiovascular disease (CVD) mortality and incident CVD and type 2 diabetes. Moderate evidence indicated sedentary behavior is associated with incident endometrial, colon and lung cancer. Limited evidence suggested sedentary behavior is associated with cancer mortality and weight status. There was strong evidence that the hazardous effects of sedentary behavior are more pronounced in physically inactive people. Evidence was insufficient to determine if bout length or breaks in sedentary behavior are associated with health outcomes. The new literature search yielded seven new studies for all-cause mortality, two for CVD mortality, two for cancer mortality, four for type 2 diabetes, one for weight status, and four for cancer; no new studies were identified for CVD incidence. Results of the new studies supported the conclusions in the 2018 PAGAC Scientific Report. The results of the updated search add further evidence on the association between sedentary behavior and health. Further research is required on how sex, age, race/ethnicity, socioeconomic status, and weight status may modify associations between sedentary behavior and health outcomes.

High-Intensity Interval Training for Cardiometabolic Disease Prevention.

The 2018 Physical Activity Guidelines Advisory Committee systematically searched existing literature reviews to assess the relationship between high-intensity interval training (HIIT) and reduction in cardiometabolic disease risk. Duplicate independent screenings of 260 articles identified from PubMed®, Cochrane Library, and CINAHL databases yielded suitable data from one systematic review and two meta-analyses. Search terms included a combination of "high intensity" "physical activity/exercise" and "interval training" and outcome-specific terms. The quality of the included reviews was assessed using a tailored version of the AMSTARExBP report on quality. Exposure Subcommittee members graded scientific evidence strength based on a five-criteria rubric and assigned one of four grades: strong, moderate, limited, or not assignable. Moderate evidence indicates that HIIT can improve insulin sensitivity, blood pressure, and body composition in adults with group mean ages ranging from ~20 to ~77 yr. These HIIT-induced improvements in cardiometabolic disease risk factors are comparable with those resulting from moderate-intensity continuous training, and they are more likely to occur in adults at higher risk of cardiovascular disease and diabetes than in healthy adults. Moderate evidence also indicates that adults with overweight or obesity classification are more responsive than adults with normal weight to HIIT-related improvements in insulin sensitivity, blood pressure, and body composition. Insufficient evidence was available to determine whether a dose-response relationship exists between the quantity of HIIT performed and several risk factors for cardiovascular disease and diabetes, or whether the effects of HIIT on cardiometabolic disease risk factors are influenced by age, sex, race/ethnicity, or socioeconomic status. HIIT by adults, especially those with overweight and obesity classification, can improve insulin sensitivity, blood pressure, and body composition, comparable with those resulting from moderate-intensity continuous training.

Physical Activity in Cancer Prevention and Survival: A Systematic Review.

This article reviews and updates the evidence on the associations between physical activity and risk for cancer, and for mortality in persons with cancer, as presented in the 2018 Physical Activity Guidelines Advisory Committee Scientific Report. Systematic reviews of meta-analyses, systematic reviews, and pooled analyses were conducted through December 2016. An updated systematic review of such reports plus original research through February 2018 was conducted. This article also identifies future research needs. In reviewing 45 reports comprising hundreds of epidemiologic studies with several million study participants, the report found strong evidence for an association between highest versus lowest physical activity levels and reduced risks of bladder, breast, colon, endometrial, esophageal adenocarcinoma, renal, and gastric cancers. Relative risk reductions ranged from approximately 10% to 20%. Based on 18 systematic reviews and meta-analyses, the report also found moderate or limited associations between greater amounts of physical activity and decreased all-cause and cancer-specific mortality in individuals with a diagnosis of breast, colorectal, or prostate cancer, with relative risk reductions ranging almost up to 40% to 50%. The updated search, with five meta-analyses and 25 source articles reviewed, confirmed these findings. Levels of physical activity recommended in the 2018 Guidelines are associated with reduced risk and improved survival for several cancers. More research is needed to determine the associations between physical activity and incidence for less common cancers and associations with survival for other cancers. Future studies of cancer incidence and mortality should consider these associations for population subgroups, to determine dose-response relationships between physical activity and cancer risk and prognosis, and to establish mechanisms to explain these associations.

The US Physical Activity Guidelines Advisory Committee Report-Introduction.

The US Physical Activity Guidelines Advisory Committee Report-Introduction.

Physical Activity Promotion: Highlights from the 2018 Physical Activity Guidelines Advisory Committee Systematic Review.

This article describes effective interventions to promote regular physical activity and reduce sedentary behavior that were identified as part of the 2018 Physical Activity Guidelines Advisory Committee Scientific Report. A comprehensive literature search was conducted of eligible systematic reviews, meta-analyses, and relevant governmental reports published between 2011 and 2016. For the physical activity promotion question, articles were first sorted by four social ecological levels of impact (i.e., individual, community, communication environment, and physical environment and policy levels) and then further sorted into more specific categories that emerged during the review process. For the sedentary behavior reduction question, the literature was sorted directly into emergent categories (i.e., youth, adult, and worksite interventions). Effective physical activity promotion strategies were identified at each level of impact, including those based on behavior change theories and those occurring at different settings throughout the community. Effective interventions also included those delivered in person by trained staff or peer volunteers and through different information and communication technologies, such as by phone, Web or Internet, and computer-tailored print. A range of built environment features were associated with more transit-based and recreational physical activity in children and adults. Effective sedentary reduction interventions were found for youth and in the workplace. A promising number of interventions with demonstrated effectiveness were identified. Future recommendations for research include investigating the most useful methods for disseminating them to real-world settings; incorporating more diverse population subgroups, including vulnerable and underrepresented subgroups; collecting cost data to inform cost-effectiveness comparisons; and testing strategies across different levels of impact to determine which combinations achieve the greatest effects on different modes of physical activity across the week.

Physical Activity, Injurious Falls, and Physical Function in Aging: An Umbrella Review.

To review and update the evidence of the relationship between physical activity, risk of fall-related injury, and physical function in community-dwelling older people that was presented in the 2018 Physical Activity Guidelines Advisory Committee Scientific Report (PAGAC Report). Duplicate independent screenings of 1415 systematic reviews and meta-analyses published between 2006 and 2016 identified from PubMed®, Cochrane Library, and CINAHL databases yielded 111 articles used for the PAGAC Report. The PAGAC Aging Subcommittee members graded scientific evidence strength based upon a five-criteria rubric and assigned one of four grades: strong, moderate, limited, or not assignable. An updated search of 368 articles published between January 2017 and March 2018 yielded 35 additional pertinent articles. Strong evidence demonstrated that physical activity reduced the risk of fall-related injuries by 32% to 40%, including severe falls requiring medical care or hospitalization. Strong evidence also supported that physical activity improved physical function and reduced the risk of age-related loss of physical function in an inverse graded manner among the general aging population, and improved physical function in older people with frailty and with Parkinson's disease. Aerobic, muscle-strengthening, and/or multicomponent physical activity programs elicited the largest improvements in physical function in these same populations. Moderate evidence indicated that for older adults who sustained a hip fracture or stroke, extended exercise programs and mobility-oriented physical activity improved physical function. Regular physical activity effectively helps older adults improve or delay the loss of physical function and mobility while reducing the risk of fall-related injuries. These important public health benefits underscore the importance of physical activity among older adults, especially those living with declining physical function and chronic health conditions.

Physical Activity and the Prevention of Weight Gain in Adults: A Systematic Review.

To conduct a systematic literature review to determine if physical activity is associated with prevention of weight gain in adults. The primary literature search was conducted for the 2018 Physical Activity Guidelines Advisory Committee and encompassed literature through June 2017, with an additional literature search conducted to include literature published through March 2018 for inclusion in this systematic review. The literature review identified 40 articles pertinent to the research question. There is strong evidence of an association between physical activity and prevention of weight gain in adults, with the majority of the evidence from prospective cohort studies. Based on limited evidence in adults, however, there is a dose-response relationship and the prevention of weight gain is most pronounced when moderate-to-vigorous intensity physical activity (≥3 METs) is above 150 min·wk. Although there is strong evidence to demonstrate that the relationship between greater time spent in physical activity and attenuated weight gain in adults is observed with moderate-to-vigorous intensity physical activity, there is insufficient evidence available to determine if there is an association between light-intensity activity (<3 METs) and attenuated weight gain in adults. The scientific evidence supports that physical activity can be an effective lifestyle behavior to prevent or minimize weight gain in adults. Therefore, public health initiatives to prevent weight gain, overweight, and obesity should include physical activity as an important lifestyle behavior.

Physical Activity to Prevent and Treat Hypertension: A Systematic Review.

This systematic umbrella review examines and updates the evidence on the relationship between physical activity (PA) and blood pressure (BP) presented in the 2008 Physical Activity Guidelines Advisory Committee Scientific Report. We performed a systematic review to identify systematic reviews and meta-analyses involving adults with normal BP, prehypertension, and hypertension published from 2006 to February 2018. In total, 17 meta-analyses and one systematic review with 594,129 adults ≥18 yr qualified. Strong evidence demonstrates: 1) an inverse dose-response relationship between PA and incident hypertension among adults with normal BP; 2) PA reduces the risk of cardiovascular disease (CVD) progression among adults with hypertension; 3) PA reduces BP among adults with normal BP, prehypertension, and hypertension; and 4) the magnitude of the BP response to PA varies by resting BP, with greater benefits among adults with prehypertension than normal BP. Moderate evidence indicates the relationship between resting BP and the magnitude of benefit does not vary by PA type among adults with normal BP, prehypertension, and hypertension. Limited evidence suggests the magnitude of the BP response to PA varies by resting BP among adults with hypertension. Insufficient evidence is available to determine if factors such as sex, age, race/ethnicity, socioeconomic status, and weight status or the frequency, intensity, time, and duration of PA influence the associations between PA and BP. Future research is needed that adheres to standard BP measurement protocols and classification schemes to better understand the influence of PA on the risk of comorbid conditions, health-related quality of life, and CVD progression and mortality; the interactive effects between PA and antihypertensive medication use; and the immediate BP-lowering benefits of PA.