Studies from wearables show that even small doses of physical activity provide health benefits; guidelines should be updated to reflect this.

BACKGROUND:Physical activity (PA) surveillance, policy, and research efforts need to be periodically appraised to gain insight into national and global capacities for PA promotion. The aim of this paper was to assess the status and trends in PA surveillance, policy, and research in 164 countries. METHODS:We used data from the Global Observatory for Physical Activity (GoPA!) 2015 and 2020 surveys. Comprehensive searches were performed for each country to determine the level of development of their PA surveillance, policy, and research, and the findings were verified by the GoPA! Country Contacts. Trends were analyzed based on the data available for both survey years. RESULTS:The global 5-year progress in all 3 indicators was modest, with most countries either improving or staying at the same level. PA surveillance, policy, and research improved or remained at a high level in 48.1%, 40.6%, and 42.1% of the countries, respectively. PA surveillance, policy, and research scores decreased or remained at a low level in 8.3%, 15.8%, and 28.6% of the countries, respectively. The highest capacity for PA promotion was found in Europe, the lowest in Africa and low- and lower-middle-income countries. Although a large percentage of the world's population benefit from at least some PA policy, surveillance, and research efforts in their countries, 49.6 million people are without PA surveillance, 629.4 million people are without PA policy, and 108.7 million live in countries without any PA research output. A total of 6.3 billion people or 88.2% of the world's population live in countries where PA promotion capacity should be significantly improved. CONCLUSION:Despite PA is essential for health, there are large inequalities between countries and world regions in their capacity to promote PA. Coordinated efforts are needed to reduce the inequalities and improve the global capacity for PA promotion.

cardiac catheterization was deemed not feasible due to limited ability to perform thrombectomy without embolization.Therefore, we treated medically with systemic alteplase while maintaining the patient on continuous bivalirudin infusion at lower PTTs.We achieved successful resolution of the thrombus by echocardiogram with no significant complications or neurologic deficits.The patient was supported by the Berlin Heart for 5 months until transplant with no other complications.On evaluation of the explanted heart there was no residual thrombus.A head CT performed after heart transplant for follow up of an unrelated concern revealed no evidence of intracranial hemorrhage or infarct.Summary: Systemic tPA may be considered as a treatment option in patients with thrombosis on ventricular assist device in lieu of more invasive treatment options.

Physical activity (PA) is widely considered to improve sleep, but a comprehensive review of the research on this topic has not been performed. In this umbrella review, conducted initially for the 2018 Physical Activity Guidelines for Americans Advisory Committee and updated to reflect more recent research, we examined whether PA enhances sleep outcomes across the lifespan as well as among individuals with sleep disorders. Systematic reviews and meta-analyses were utilized to assess the evidence. We also examined dose–response considerations and whether the association between PA and sleep was moderated by various factors (e.g., timing, sociodemographic characteristics). We found strong evidence that both acute bouts of PA and regular PA improved sleep outcomes. Moderate evidence indicated that longer bouts of PA (both acute and regular) improved sleep, and that the effects of PA on sleep outcomes were generally preserved across adult age groups and sex. Finally, moderate evidence demonstrated that PA improved sleep in adults with insomnia symptoms or obstructive sleep apnea. Several important areas in need of future research were also identified. Overall, the review supported the claim that PA improves sleep, but highlighted gaps that need to be addressed to facilitate more widespread utilization of PA for improving sleep.

Maintaining or improving quality of life (QoL) and well-being is a universal goal across the lifespan. Being physically active has been suggested as one way to enhance QoL and well-being. In this systematic review, conducted in part for the 2018 U.S. Health and Human Services Physical Activity Guidelines for Americans Scientific Advisory Committee Report, we examined the relationship between physical activity (PA) and QoL and well-being experienced by the general population across the lifespan and by persons with psychiatric and neurologic conditions. Systematic reviews, meta-analyses, and pooled analyses from 2006 to 2018 were used for the evidence base. Strong evidence (predominantly from randomized controlled trials [RCTs]) demonstrated that, for adults aged 18-65 years and older adults (primarily 65 years and older), PA improves QoL and well-being when compared with minimal or no-treatment controls. Moderate evidence indicated that PA improves QoL and well-being in individuals with schizophrenia and Parkinson's disease, and limited evidence indicated that PA improves QoL and well-being for youth and for adults with major clinical depression or bipolar disorder. Insufficient evidence existed for individuals with dementia because of a small number of studies with mixed results. Future high-quality research designs should include RCTs involving longer interventions testing different modes and intensities of PA in diverse populations of healthy people and individuals with cognitive (e.g., dementia) and mental health conditions (e.g., schizophrenia) to precisely characterize the effects of different forms of PA on aspects of QoL and well-being.

The Canadian 24-Hour Movement Guidelines for Adults aged 18-64 years and Adults aged 65 years and older ("Guidelines") integrate recommendations for physical activity, sedentary, and sleep behaviours. Given the novelty of these integrated Guidelines, it was important to consider messaging strategies that would be most effective in reaching Canadian adults. The purpose of this study was to examine optimal messaging of the Guidelines as it pertains to communication channels and messages. Representative samples of Guideline end-users (N = 1017) and stakeholders (N = 877) each completed a cross-sectional survey. Descriptive statistics were calculated along with tests of statistical significance. Inductive content analysis was used to code stakeholders' comments (i.e., suggestions, concerns) on a draft version of the Guidelines. Most end-users had recently referred to online medical resources; family, friends, and co-workers; and physicians as communication channels for information regarding the movement behaviours. End-users and stakeholders felt that generic messages would foster self-efficacy to meet the Guidelines. Stakeholders highlighted a variety of considerations to ensure the Guidelines are inclusive towards diverse groups within the Canadian population. Findings will inform Guideline messaging. Novelty Most end-users referred to online medical resources; family, friends, and co-workers; and physicians as communication channels. End-users and stakeholders indicated that generic messages would foster self-efficacy to meet the Guidelines. Stakeholders expressed concerns about the inclusivity of the Guidelines for diverse socioeconomic groups.

The purpose of this overview of systematic reviews was to determine the relationship between different types and patterns of sedentary behaviour and selected health outcomes in adults and older adults. Five electronic databases were last searched in May, 2019, with a 10-year search limit. Included reviews met the a priori population (community-dwelling adults aged 18 years and older), intervention/exposure/comparator (various types and/or patterns of sedentary behaviour), and outcomes criteria. Eighteen systematic reviews were included in the evidence synthesis. High levels of sedentary behaviour are unfavourably associated with cognitive function, depression, function and disability, physical activity levels, and physical health-related quality of life in adults. Reducing or breaking up sedentary behaviour may benefit body composition and markers of cardiometabolic risk. Total sedentary behaviour and TV viewing were most consistently associated with unfavourable health outcomes, while computer and Internet use may be favourably associated with cognitive function for older adults. The quality of evidence within individual reviews (as assessed by review authors) varied from low to high, while the certainty of evidence was low to very low. These findings have important public health implications, suggesting that adults should avoid high levels of sedentary behaviour and break-up periods of prolonged sitting. (PROSPERO registration nos.: CRD42019123121 and CRD42019127157.) Novelty High levels of sedentary behaviour are unfavourably associated with important health outcomes in adults. Reducing or breaking up sedentary behaviour may benefit body composition and markers of cardiometabolic risk. Computer and Internet use may be favourably associated with cognitive function in older adults.

The new WHO 2020 Guidelines on Physical Activity and Sedentary Behaviour1WHOWHO 2020 guidelines on physical activity and sedentary behaviour. World Health Organization, Geneva2020https://apps.who.int/iris/bitstream/handle/10665/336656/9789240015128-eng.pdfDate accessed: November 25, 2020Google Scholar provide recommendations on the amount and types of physical activity for various age groups, pregnant and post-partum women, and people living with chronic conditions or disabilities. The 2020 WHO guidelines are built on a much larger evidence base than the 2010 guidelines,2WHOGlobal recommendations on physical activity for health. World Health Organization, Geneva2010Google Scholar and include some major developments. First, evidence for additional health benefits, such as improved cognitive health, health-related quality of life, mental health, and sleep, is reported, over and above what was included in the 2010 WHO guidelines—ie, cancer, cardiorespiratory, metabolic, musculoskeletal, and functional health. This development reflects the maturation of research on physical activity and the growing incorporation of the WHO definition of health as a state of complete physical, mental, and social wellbeing.3WHOWHO remains firmly committed to the principles set out in the preamble to the Constitution.https://www.who.int/about/who-we-are/constitutionDate: 2020Date accessed: October 6, 2020Google Scholar Second, the 2020 WHO guidelines, for the first time, on a global level, provide specific recommendations for pregnant and post-partum women and for people living with chronic conditions or disabilities, showing the increasing specificity and relevance of physical activity guidelines to different populations. Third, these guidelines have modified recommendations for how aerobic physical activity should be accumulated—eg, the previous requirement for 10-min minimum duration of continuous activity has been dropped and “some physical activity is better than none". Finally, the 2020 WHO guidelines provide general recommendations to reduce sitting time, which accords with growing interest in the health effects of sedentary behaviour.4Saunders TJ McIsaac T Douillette K et al.Sedentary behaviour and health in adults: an overview of systematic reviews.Appl Physiol Nutr Metabol. 2020; 45: S197-S217Crossref PubMed Scopus (15) Google Scholar The launch of the 2020 WHO guidelines follows other major physical activity guidelines, most recently in the USA5US Department of Health and Human ServicesPhysical activity guidelines for Americans.2nd edition. US Department of Health and Human Services, Washington, DC2018Google Scholar and UK.6Department of Health and Social CareUK Chief Medical Officer's physical activity guidelines. Department of Health and Social Care, London2019Google Scholar These guidelines provide similar recommendations for the types, intensity, volume, and duration of physical activity for both general and specific populations. Meanwhile, the new Canadian 24-Hour Movement Guidelines for Adults,7Ross R Chaput J-P Giangregorio LM et al.Canadian 24-hour movement guidelines for adults aged 18–64 years and adults aged 65 years or older: an integration of physical activity, sedentary behaviour, and sleep.Appl Physiol Nutr Metab. 2020; 45: S57-S102Crossref PubMed Scopus (46) Google Scholar launched in October, 2020, took a different approach by integrating recommendations for sleep, sedentary behaviour, and physical activity of various intensities. Such a 24-h activity spectrum approach, which aims to account for the interconnections across multiple behaviours, has also been applied in guidelines on physical activity, sedentary behaviour, and sleep for children younger than 5 years by WHO8Willumsen J Bull F Development of WHO guidelines on physical activity, sedentary behavior, and sleep for children less than 5 years of age.J Phys Act Health. 2020; 17: 96-100Crossref PubMed Scopus (22) Google Scholar and countries such as Australia9Okely AD Ghersi D Hesketh KD et al.A collaborative approach to adopting/adapting guidelines—the Australian 24-hour movement guidelines for the early years (birth to 5 years): an integration of physical activity, sedentary behavior, and sleep.BMC Public Health. 2017; 17: 869Crossref PubMed Scopus (144) Google Scholar and Canada.10Tremblay MS Chaput J-P Adamo KB et al.Canadian 24-hour movement guidelines for the early years (0–4 years): an integration of physical activity, sedentary behaviour, and sleep.BMC Public Health. 2017; 17: 874Crossref PubMed Scopus (206) Google Scholar Debate continues about certain aspects of physical activity guideline development. Although some experts consider existing evidence insufficient for supporting quantitative recommendations for sitting time,11Stamatakis E Ekelund U Ding D Hamer M Bauman AE Lee IM Is the time right for quantitative public health guidelines on sitting? A narrative review of sedentary behaviour research paradigms and findings.Br J Sports Med. 2019; 53: 377Crossref PubMed Scopus (127) Google Scholar others advocate that guidelines should be developed despite insufficient and low-quality evidence.12Tremblay MS Rollo S Saunders TJ Sedentary Behavior Research Network members support new Canadian 24-Hour Movement Guideline recommendations.J Sport Health Sci. 2020; (published online Oct 12.)https://doi.org/10.1016/j.jshs.2020.09.012Crossref Scopus (3) Google Scholar Furthermore, some researchers propose inclusion of the entire 24-h day in integrated movement guidelines,7Ross R Chaput J-P Giangregorio LM et al.Canadian 24-hour movement guidelines for adults aged 18–64 years and adults aged 65 years or older: an integration of physical activity, sedentary behaviour, and sleep.Appl Physiol Nutr Metab. 2020; 45: S57-S102Crossref PubMed Scopus (46) Google Scholar, 12Tremblay MS Rollo S Saunders TJ Sedentary Behavior Research Network members support new Canadian 24-Hour Movement Guideline recommendations.J Sport Health Sci. 2020; (published online Oct 12.)https://doi.org/10.1016/j.jshs.2020.09.012Crossref Scopus (3) Google Scholar whereas others raise concerns such as communication challenges and insufficient 24-h compositional evidence.13Stamatakis E Bauman AE The bold sedentary behavior recommendations in the new Canadian guidelines: are they evidence-based? Response to “Sedentary Behavior Research Network members support new Canadian 24-Hour Movement Guideline recommendations”.J Sport Health Sci. 2020; (published online Oct 12.)https://doi.org/10.1016/j.jshs.2020.09.013Crossref PubMed Scopus (1) Google Scholar Despite some differences, contemporary physical activity guidelines share many commonalities in their defined public health context, an emphasis on participation, and a socially inclusive approach for reaching the entire population. Current physical activity guidelines evolved from decades of evidence generation, syntheses, and updates (figure). Early physical activity guidelines focused on continuous vigorous aerobic exercise mainly for performance improvement14American College of Sports MedicineAmerican College of Sports Medicine position statement on the recommended quantity and quality of exercise for developing and maintaining fitness in healthy adults.Med Sci Sports. 1978; 10: vii-vixPubMed Google Scholar or cardiac rehabilitation.15Council on Scientific AffairsPhysician-supervised exercise programs in rehabilitation of patients with coronary heart disease.JAMA. 1981; 245: 1463-1466Crossref PubMed Scopus (6) Google Scholar With increasing evidence on the health benefits of moderate-intensity physical activity, such as walking, guidelines evolved to become more public health oriented and the focus shifted from exercise, which is planned and structured, to physical activity, which can be part of daily living.16Pate RR Pratt M Blair SN et al.Physical activity and public health. A recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine.JAMA. 1995; 273: 402-407Crossref PubMed Scopus (5667) Google Scholar In recent decades, evidence that incorporates device-based measures and sophisticated analytical approaches has further characterised the amount of physical activity associated with health benefits—eg, the curvilinear relationship between physical activity and health outcomes, the value of any duration of physical activity, and the benefits of light-intensity physical activity as a replacement for sedentary time.17Ding D Ramirez Varela A Bauman AE et al.Towards better evidence-informed global action: lessons learnt from the Lancet series and recent developments in physical activity and public health.Br J Sports Med. 2020; 54: 462-468Crossref PubMed Scopus (40) Google Scholar, 18Chastin SFM De Craemer M De Cocker K et al.How does light-intensity physical activity associate with adult cardiometabolic health and mortality? Systematic review with meta-analysis of experimental and observational studies.Br J Sports Med. 2019; 53: 370-376Crossref PubMed Scopus (101) Google Scholar Such developments have led to the emphasis on doing any physical activity in any duration in the current guidelines.1WHOWHO 2020 guidelines on physical activity and sedentary behaviour. World Health Organization, Geneva2020https://apps.who.int/iris/bitstream/handle/10665/336656/9789240015128-eng.pdfDate accessed: November 25, 2020Google Scholar, 5US Department of Health and Human ServicesPhysical activity guidelines for Americans.2nd edition. US Department of Health and Human Services, Washington, DC2018Google Scholar, 6Department of Health and Social CareUK Chief Medical Officer's physical activity guidelines. Department of Health and Social Care, London2019Google Scholar Overall, physical activity guidelines have shifted from exercise training to active living. Guidelines are an important way to bring scientific research to end-users, such as policy makers, health and non-health professionals, and the public. Updates to existing physical activity guidelines should influence priority setting, decision making, and community awareness and behaviour. An emphasis on doing any amount of physical activity, for example, aims to empower inactive individuals to reap benefits of physical activity, even when the recommended target range (ie, 75–150 min per week of vigorous-intensity physical activity or 150–300 min per week of moderate-intensity physical activity) is perceived to be out of reach. This message is particularly relevant during the COVID-19 pandemic, since lockdowns and physical distancing have imposed additional barriers to physical activity.19Porto LGG Molina GE Matsudo VK Physical activity and the coronavirus pandemic: an urgent time to change the recommendation focus.Ensaios Teóricos em Atividade Física e Saúde. 2020; 25: 1-5Google Scholar Additionally, specific recommendations for subpopulations underline social inclusion by engaging with community members left out by earlier guidelines, such as people living with disabilities. Recommendations to reduce sedentary time could lead to new physical activity promotion strategies, such as encouraging light-intensity physical activity among sedentary workers. Finally, the acknowledgment of the health benefits of incidental physical activity of any duration reinforces the importance of engaging sectors outside of health, such as urban planning, transportation, and architecture, to facilitate short bursts of activities, such as walking or stair climbing. Public health guidelines alone do not lead to progress. To reach the WHO global target of reducing physical inactivity by 15% by 2030,20WHOGlobal action plan on physical activity 2018–2030: more active people for a healthier world.http://www.who.int/ncds/prevention/physical-activity/gappa/action-planDate: 2018Date accessed: October 27, 2020Google Scholar guideline development must be supported by long-term political commitment and paired with coordinated and sustained dissemination and communication strategies across sectors.21Bull FC Saad Al-Ansari S Biddle S et al.World Health Organization 2020 guidelines on physical activity and sedentary behaviour.Br J Sports Med. 2020; (published online Nov 25.)https://doi.org/10.1136/bjsports-2020-102955Crossref Scopus (455) Google Scholar WHO encourages governments to consider national social and cultural contexts while adopting the global physical activity guidelines,21Bull FC Saad Al-Ansari S Biddle S et al.World Health Organization 2020 guidelines on physical activity and sedentary behaviour.Br J Sports Med. 2020; (published online Nov 25.)https://doi.org/10.1136/bjsports-2020-102955Crossref Scopus (455) Google Scholar which provide opportunities for governments to incorporate strategies on communication, dissemination, and implementation into national guidelines. Key questions to consider include who to engage, what message to communicate,22Williamson C Baker G Mutrie N Niven A Kelly P Get the message? A scoping review of physical activity messaging.Int J Behav Nutr Phys Act. 2020; 17: 51Crossref PubMed Scopus (24) Google Scholar and when, where, and how to deliver messages.23Milton K Bauman AE Faulkner G et al.Optimising the impact of physical activity guidelines through effective communication strategies.Br J Sports Med. 2020; (published online Nov 25.)https://doi.org/10.1136/bjsports-2020-102324Crossref PubMed Scopus (10) Google Scholar Furthermore, these guidelines should be used to advocate for long-term resource investment, policy making, and political commitment to reduce physical inactivity. Researchers, practitioners, and advocates need to work with decision makers and all stakeholders and sectors to catalyse change. Tailored guideline summaries and infographics can be disseminated through public health and medical associations to support and empower all practitioners in patient counselling and education. Partnering with non-health sectors, such as transportation, planning, education, and community services, can drive changes in legislation, policies, environments, and practice to facilitate active living.23Milton K Bauman AE Faulkner G et al.Optimising the impact of physical activity guidelines through effective communication strategies.Br J Sports Med. 2020; (published online Nov 25.)https://doi.org/10.1136/bjsports-2020-102324Crossref PubMed Scopus (10) Google Scholar Reducing physical inactivity is a mammoth societal challenge. Sustained commitment and investment, effective communication and dissemination, and cross-sectoral coordination and collaboration are all crucial to activate populations. We declare no competing interests.

The number and scope of established health-related benefits from physical activity continue to expand. Notable recent additions include improved weight status and bone health in children 3–5 years of age, prevention of excessive weight gain among adults, reduced risk of dementia, and improved cognition and a variety of other brain-health benefits. Greater flexibility in receiving health benefits is also apparent. No threshold of moderate to vigorous physical activity (MVPA) must be exceeded for benefits to accrue; small increments by individuals performing little to no MVPA produce larger reductions in risk than similarly sized increments in individuals already performing greater amounts of MVPA, bouts of MVPA <10 min in duration contribute to the accumulation of MVPA, and light-intensity physical activity can benefit individuals currently doing little or no MVPA. MVPA is indirectly related to the adverse effects of sedentary behavior. The definition of physical activity continues to be debated.

PURPOSE:This study aimed to conduct a systematic literature review to determine whether physical activity episodes of <10 min in duration have health-related benefits or, alternatively, if the benefits are only realized when the duration of physical activity episodes is ≥10 min. METHODS:The primary literature search was conducted for the 2018 Physical Activity Guidelines Advisory Committee Report 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. RESULTS:The literature review identified 29 articles that were pertinent to the research question that used either cross-sectional, prospective cohort, or randomized designs. One prospective cohort study (N = 4840) reported similar associations between moderate to vigorous physical activity (MVPA) and all-cause mortality when examined as total MVPA, MVPA in bouts ≥5 min in duration, or MVPA in bouts ≥10 min in duration. Additional evidence was identified from cross-sectional and prospective studies to support that bouts of physical activity <10 min in duration are associated with a variety of health outcomes. Randomized studies only examined bouts of physical activity ≥10 min in duration. CONCLUSIONS:The current evidence, from cross-sectional and prospective cohort studies, supports that physical activity of any bout duration is associated with improved health outcomes, which includes all-cause mortality. This may suggest the need for a contemporary paradigm shift in public health recommendations for physical activity, which supports total MVPA as an important lifestyle behavior regardless of the bout duration.

ABSTRACT Purpose Conduct a systematic umbrella review to evaluate the relationship of physical activity (PA) with all-cause mortality, cardiovascular mortality, and incident cardiovascular disease (CVD); to evaluate the shape of the dose–response relationships; and to evaluate these relationships relative to the 2008 Physical Activity Guidelines Advisory Committee Report . Methods Primary search encompassing 2006 to March, 2018 for existing systematic reviews, meta-analyses, and pooled analyses reporting on these relationships. Graded the strength of evidence using a matrix developed for the Physical Activity Guidelines Advisory Committee . Results The association of self-reported moderate-to-vigorous physical activity (MVPA) on all-cause mortality, CVD mortality, and atherosclerotic CVD—including incident coronary heart disease, ischemic stroke and heart failure—are very similar. Increasing MVPA to guidelines amounts in the inactive US population has the potential to have an important and substantial positive impact on these outcomes in the adult population. The following points are clear: the associations of PA with beneficial health outcomes begin when adopting very modest (one‐third of guidelines) amounts; any MVPA is better than none; meeting the 2008 PA guidelines reduces mortality and CVD risk to about 75% of the maximal benefit obtained by physical activity alone; PA amounts beyond guidelines recommendations amount reduces risk even more, but greater amounts of PA are required to obtain smaller health benefits; and there is no evidence of excess risk over the maximal effect observed at about three to five times the amounts associated with current guidelines. When PA is quantified in terms of energy expenditure (MET·h·wk −1 ), these relationships hold for walking, running, and biking. Conclusions To avoid the risks associated with premature mortality and the development of ischemic heart disease, ischemic stroke, and all-cause heart failure, all adults should strive to reach the 2008 Physical Activity Guidelines for Americans.

Objective To examine whether the associations between sedentary behaviours (ie, daily sitting/TV-viewing time) and mortality from cardiovascular disease (CVD) and cancer differ by different levels of physical activity (PA). Design Harmonised meta-analysis of prospective cohort studies. Data on exposure variables were harmonised according to a predefined protocol and categorised into four groups for sedentary behaviours and into quartiles of PA (MET-hour/week). Data sources PubMed, PsycINFO, Embase, Web of Science, Sport Discus and Scopus. Eligibility criteria for selecting studies Individual level data on both sedentary behaviours and PA and reported effect estimates for CVD or cancer mortality. Results Nine studies (n=850 060; deaths=25 730) and eight studies (n=777 696; deaths=30 851) provided data on sitting time and CVD and cancer mortality, respectively. Five studies had data on TV-viewing time and CVD (n=458 127; deaths=13 230) and cancer (n=458 091; deaths=16 430) mortality. A dose–response association between sitting time (9%–32% higher risk; p for trend <0.001) and TV time (3%–59% higher risk; p for trend <0.001) with CVD mortality was observed in the ‘inactive’, lowest quartile of PA. Associations were less consistent in the second and third quartiles of PA, and there was no increased risk for CVD mortality with increasing sedentary behaviours in the most active quartile. Associations between sedentary behaviours and cancer mortality were generally weaker; 6%–21% higher risk with longer sitting time observed only in the lowest quartile of PA. Conclusion PA modifies the associations between sedentary behaviours and CVD and cancer mortality. These findings emphasise the importance of higher volumes of moderate and vigorous activity to reduce, or even eliminate these risks, especially for those who sit a lot in their daily lives.

PURPOSE:A systematic primary literature review was conducted to evaluate the relationship of physical activity-as measured by daily step counts-with all-cause mortality, cardiovascular disease mortality, incident cardiovascular disease, and type 2 diabetes mellitus; to evaluate the shape of dose-response relationships; and to interpret findings in the context of development of the Physical Activity Guidelines for Americans, Second Edition. METHODS:A primary literature search encompassing 2011 to March 2018 for existing literature reporting on these relationships was conducted. RESULTS:Eleven pertinent articles were identified. Seven longitudinal studies examined the relationship between daily step counts and mortality, disease incidence, or risk. Two studies examined objectively measured steps per day and all-cause mortality; one was restricted to a relatively small elderly population. One study examined cardiovascular events, defined as cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke. The other four longitudinal studies addressed incident type 2 diabetes. All longitudinal studies reported an inverse relationship between steps per day and outcome risk. In one study, 531 cardiovascular events occurred during more than 45,000 person-years of follow-up. Before intervention, each increment of 2000 steps per day up to 10,000 steps was associated with a 10% lower cardiovascular event rate. Also, for every increase of 2000 steps per day over baseline, there was an 8% yearly reduction in cardiovascular event rate in individuals with impaired glucose tolerance. CONCLUSIONS:Daily step count is a readily accessible means by which to monitor and set physical activity goals. Recent evidence supports previously limited evidence of an inverse dose-response relationship of daily steps with important health outcomes, including all-cause mortality, cardiovascular events, and type 2 diabetes. However, more independent studies will be required before these observations can be translated into public health guidelines.

ABSTRACT Purpose To conduct a systematic literature review to determine if physical activity is associated with prevention of weight gain in adults. Methods 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. Results 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 −1 . 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. Conclusions 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.

PURPOSE: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. METHODS: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. RESULTS: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. CONCLUSIONS: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.

PURPOSE: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. METHODS: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. RESULTS: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. CONCLUSIONS: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.

Purpose 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. Methods 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. Results 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. Conclusions 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.

PURPOSE:Physical activity (PA) is known to improve cognitive and brain function, but debate continues regarding the consistency and magnitude of its effects, populations and cognitive domains most affected, and parameters necessary to achieve the greatest improvements (e.g., dose). METHODS:In this umbrella review conducted in part for the 2018 Health and Human Services Physical Activity Guidelines for Americans Advisory Committee, we examined whether PA interventions enhance cognitive and brain outcomes across the life span, as well as in populations experiencing cognitive dysfunction (e.g., schizophrenia). Systematic reviews, meta-analyses, and pooled analyses were used. We further examined whether engaging in greater amounts of PA is associated with a reduced risk of developing cognitive impairment and dementia in late adulthood. RESULTS:Moderate evidence from randomized controlled trials indicates an association between moderate- to vigorous-intensity PA and improvements in cognition, including performance on academic achievement and neuropsychological tests, such as those measuring processing speed, memory, and executive function. Strong evidence demonstrates that acute bouts of moderate- to vigorous-intensity PA have transient benefits for cognition during the postrecovery period after exercise. Strong evidence demonstrates that greater amounts of PA are associated with a reduced risk of developing cognitive impairment, including Alzheimer's disease. The strength of the findings varies across the life span and in individuals with medical conditions influencing cognition. CONCLUSIONS:There is moderate-to-strong support that PA benefits cognitive functioning during early and late periods of the life span and in certain populations characterized by cognitive deficits.

PURPOSE: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). METHODS: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. RESULTS: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. CONCLUSIONS: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.