The Effect of Sedentary Behaviour on Cardiorespiratory Fitness: A Systematic Review and Meta-Analysis.

BACKGROUND: Cardiorespiratory fitness (CRF) is an important indicator of current and future health. While the impact of habitual physical activity on CRF is well established, the role of sedentary behaviour (SB) remains less understood. OBJECTIVE: We aimed to determine the effect of SB on CRF. METHODS: Searches were conducted in MEDLINE, Embase, PsycINFO, CINAHL and SPORTDiscus from inception to August 2022. Randomised controlled trials, quasi-experimental studies and cohort studies that assessed the relationship between SB and CRF were eligible. Narrative syntheses and meta-analyses summarised the evidence, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) certainty was based on evidence from randomised controlled trials. RESULTS: This review included 18 studies that focused on youth (four randomised controlled trials, three quasi-experimental studies, 11 cohort studies) and 24 on adult populations (15 randomised controlled trials, five quasi-experimental studies, four cohort studies). In youth and adults, evidence from randomised controlled trials suggests mixed effects of SB on CRF, but with the potential for interventions to improve CRF. Quasi-experimental and cohort studies also support similar conclusions. Certainty of evidence was very low for both age groups. A meta-analysis of adult randomised controlled trials found that interventions targeting reducing SB, or increasing physical activity and reducing SB, had a significant effect on post-peak oxygen consumption (mean difference = 3.16 mL.kg-1.min-1, 95% confidence interval: 1.76, 4.57). CONCLUSIONS: Evidence from randomised controlled trials indicates mixed associations between SB and CRF, with the potential for SB to influence CRF, as supported by meta-analytical findings. Further well-designed trials are warranted to confirm the relationship between SB and CRF, explore the effects of SB independent from higher intensity activity, and investigate the existence of such relationships in paediatric populations. CLINICAL TRIAL REGISTRATION: PROSPERO CRD42022356218.

The ongoing impact of the COVID-19 pandemic on physical activity and screen time among Canadian youth.

Background: The COVID-19 pandemic has caused changes in health behaviours, including participation in physical activity and screen time. The purpose of this paper is to examine trends in physical activity and screen time among Canadian youth from January 2018 to February 2022. Methods: The Canadian Community Health Survey asks Canadian youth (aged 12 to 17 years) to report the time they spend active by domain: recreation, transportation, school and household. Survey respondents are also asked to report their screen time on school days and non-school days. The present analysis compares the physical activity from four cross-sectional samples collected during 2018 (January to December; n=3,952), January to March 2020 (n=911), September to December 2020 (n=1,573), and January 2021 to February 2022 (n=3,501). Screen time is compared between 2018 and 2021/2022. Sub-annual descriptive analyses examine how physical activity and screen time varied within and between these years. Results: Before the COVID-19 pandemic, half of Canadian youth met the physical activity recommendation (2018: 49.6%; January to March 2020: 53.7%). The percentage meeting the recommendation dropped in the first year of the pandemic (September to December 2020: 37.3%) and recovered slightly in 2021 (43.8%). From 2018 to 2021, total physical activity dropped by 8.3 minutes per day (58.1 minutes per week) among girls and by 2.1 minutes per day (14.7 minutes per week) among boys. The percentage of youth meeting the screen time recommendation on school days dropped from 40.7% in 2018 to 29.1% in 2021 and from 21.4% in 2018 to 13.2% in 2021 on non-school days. Interpretation: The COVID-19 pandemic had a detrimental impact on the physical activity and screen time of youth, in particular among girls. This analysis provides an update on how the pandemic has continued to affect the physical activity and screen habits of youth in 2020, 2021, and early 2022.

The ongoing impact of the COVID-19 pandemic on physical activity and screen time among Canadian adults.

Background: Canadian and international research has shown that the COVID-19 pandemic led to changes in health behaviours, including participation in physical activity and screen time. Methods: The Canadian Community Health Survey asks Canadian adults (aged 18 to 64 years) and older adults (aged 65 and older) to report the time they spend active by domain: recreation, transportation, and household and/or occupation. Survey respondents are also asked to report their screen time on days they worked and days they did not work. The present analysis compares the physical activity from four cross-sectional samples collected during 2018 (n=50,093), January to mid-March 2020 (n=13,933), September to December 2020 (n=25,661) and January 2021 to February 2022 (n=45,742). Screen time is compared between 2018 and 2021. Sub-annual analyses examine how physical activity and screen time varied within and between years. Results: The percentage of 18- to 64-year-old women meeting the physical activity recommendation did not change from 2018 (54.3%) to 2021 (55.1%), while a slight decrease was observed among men (63.0% in 2018 to 59.8% in 2021). The percentage of adults aged 65 years and older meeting the recommendation increased from 2018 to 2021 among both men (40.7% to 43.8%) and women (33.4% to 36.9%). Total physical activity decreased by 17.5 minutes per week among 18- to 64-year-old men and increased by 8.4 minutes per week among 18- to 64-year-old women. Men and women aged 65 and older increased their total physical activity by about 30 minutes per week from 2018 to 2021. The percentage of 18- to 64-year-old adults in the lowest screen time category decreased from 53.9% in 2018 to 45.0% in 2021 on work days and from 37.8% in 2018 to 28.0% in 2021 on non-work days. The percentage of adults aged 65 and older in the lowest screen time category decreased from 49.4% in 2018 to 37.8% in 2021 on work days and from 29.4% in 2018 to 21.5% in 2021 on non-work days. Interpretation: Physical activity among men aged 18 to 64 years decreased from 2018 to 2021, while women of this age group maintained their physical activity. Older adults increased their physical activity from 2018 to 2021. Many Canadian adults shifted from the lowest screen time category (two hours or less per day) to the highest screen time category (four hours or more per day) during the 2020 and 2021 pandemic years. It is unknown whether the short-term impact of the COVID-19 pandemic on physical activity and screen time will persist over time. Ongoing surveillance of the longer-term impacts of the pandemic on the health behaviours of Canadians is important.

Associations Between Type and Timing of Physical Activity and Sedentary Behavior With Mental Health in Adolescents and Young Adults.

BACKGROUND: This cross-sectional study analyzed the association of leisure-time physical activity (PA) and sedentary behavior (SB), nonleisure PA and SB, and total PA and SB in different time segments of the day with mental health among Dutch adolescents and young adults. METHODS: A total of 881 participants aged 16-25 years completed an online survey. Mental health was assessed using the Mental Health Inventory-5, and participants also reported sex, age, and income. They filled out a questionnaire of types of PA and SB for each hour of the day. Activities were categorized into nonleisure and leisure, during the morning, afternoon, evening, and for the whole day. RESULTS: Participants (52.8% female, on average 20.8 y) generally engaged in more leisure-time PA and SB during weekends compared with weekdays, and more nonleisure activities on weekdays. Associations varied between time segments and days of the week. Positive associations of leisure-time and total PA during the whole day and evenings with mental health were observed on weekdays. Total, leisure-time, and nonleisure-time SB were associated with worse mental health. Nonleisure PA was not associated with mental health. CONCLUSIONS: Leisure-time PA was found to have a favorable association with mental health, particularly in the evenings of weekdays and afternoons of weekend days. On the other hand, leisure SB was associated with poorer mental health in most of the time segments analyzed, and nonleisure SB in the evenings was also related to worse mental health. The type and timing of PA and SB behaviors play an important role in the relationship with mental health.

Scientific sinkhole: estimating the cost of peer review based on survey data with snowball sampling.

BACKGROUND: There are a variety of costs associated with publication of scientific findings. The purpose of this work was to estimate the cost of peer review in scientific publishing per reviewer, per year and for the entire scientific community. METHODS: Internet-based self-report, cross-sectional survey, live between June 28, 2021 and August 2, 2021 was used. Participants were recruited via snowball sampling. No restrictions were placed on geographic location or field of study. Respondents who were asked to act as a peer-reviewer for at least one manuscript submitted to a scientific journal in 2020 were eligible. The primary outcome measure was the cost of peer review per person, per year (calculated as wage-cost x number of initial reviews and number of re-reviews per year). The secondary outcome was the cost of peer review globally (calculated as the number of peer-reviewed papers in Scopus x median wage-cost of initial review and re-review). RESULTS: A total of 354 participants completed at least one question of the survey, and information necessary to calculate the cost of peer-review was available for 308 participants from 33 countries (44% from Canada). The cost of peer review was estimated at $US1,272 per person, per year ($US1,015 for initial review and $US256 for re-review), or US$1.1-1.7 billion for the scientific community per year. The global cost of peer-review was estimated at US$6 billion in 2020 when relying on the Dimensions database and taking into account reviewed-but-rejected manuscripts. CONCLUSIONS: Peer review represents an important financial piece of scientific publishing. Our results may not represent all countries or fields of study, but are consistent with previous estimates and provide additional context from peer reviewers themselves. Researchers and scientists have long provided peer review as a contribution to the scientific community. Recognizing the importance of peer-review, institutions should acknowledge these costs in job descriptions, performance measurement, promotion packages, and funding applications. Journals should develop methods to compensate reviewers for their time and improve transparency while maintaining the integrity of the peer-review process.

Association of daily and time-segmented physical activity and sedentary behaviour with mental health of school children and adolescents from rural Northeastern Ontario, Canada.

Physical activity (PA) and sedentary behaviour (SED) have been linked to the mental health of children and adolescents, yet the timing of behaviours may play a role in this relationship and clarifying this could inform interventions. We explored cross-sectional associations of PA and SED in varying time segments throughout the school day with the mental health of school-aged children and adolescents from rural Northeastern Ontario, Canada. A total of 161 students (56% female, M = 10.3 years old) wore accelerometers for 8 days (7 nights) and completed a self-report survey (parent reported for children younger than 11). Mental health was measured using the Strengths and Difficulties Questionnaire. Accelerometer-measured SED, light PA (LPA), and moderate and vigorous PA (MVPA) were estimated in the time-segments before school (06:00-08:44), school time (08:45-15:04), after school (15:05-16:59), and evenings (17:00-21:59). Associations were tested with multilevel linear regressions while adjusting for confounding factors. Students spent 72.6 min in MVPA, 209.0 min in LPA, and 621.0 min in SED per day. Daily SED was associated with less conduct problems (ß = -0.27, p < 0.05). Evening LPA was inversely associated with hyperactivity (ß = -1.45, p < 0.05), while SED was associated with hyperactivity and with peer problems before school (ß = 1.70 and ß = 1.01, respectively, p < 0.05), and during school (ß = -0.83 and ß = -0.57, respectively, p < 0.05). No associations were observed for MVPA, emotional symptoms, or prosocial behaviour. In conclusion, displacing SED with LPA in some specific periods of the day may benefit the mental health of students; taking this into account could strengthen interventions.

How sedentary are Canadian adults? It depends on the measure.

Introduction: The new Canadian 24-Hour Movement Guidelines for Adults aged 18-64 years and Adults aged 65 years and older recommend that adults limit daily sedentary time to eight hours or less, including three hours or less of recreational screen time. The eight-hour recommendation was centred between the evidence from research using self-reported sitting time (threshold: seven hours or less per day) and accelerometer-measured sedentary time (threshold: nine hours or less per day). The purpose of this study is to compare the percentages of Canadians meeting three different sedentary thresholds (three hours or less per day of screen time, seven hours or less per day of self-reported sitting time and nine hours or less per day of accelerometer-measured sedentary time). Methods: This analysis is based on 2,511 adults (aged 18 to 79 years) from Cycle 3 of the Canadian Health Measures Survey, in 2012 and 2013. Screen time and sitting time were assessed via self-report, and average daily sedentary time was assessed using a hip-worn Actical accelerometer. Results: Adults self-reported an average daily screen time of 3.2 hours (95% confidence interval [CI]: 3.0 to 3.5) and an average daily sitting time of 5.7 hours (95% CI: 5.4 to 6.0). According to accelerometry data, adults accumulated an average of 9.8 hours per day (95% CI: 9.7 to 9.9) of sedentary time. Adherence varied, with 57.7% meeting the self-reported recreational screen time threshold of three hours or less per day, 71.7% meeting the self-reported sitting time threshold of seven hours or less per day and 26.5% meeting the accelerometer-measured sedentary time threshold of nine hours or less per day. Interpretation: The percentage of Canadian adults meeting the three different sedentary behaviour thresholds varied widely. The findings in this article highlight the difference in sedentary time between what Canadians report versus what is measured by an accelerometer.

School-related sedentary behaviours and indicators of health and well-being among children and youth: a systematic review.

BACKGROUND: The purpose of this systematic review was to examine the associations between school-related sedentary behaviours and indicators of health and well-being in children and youth (~ 5-18 years) attending school. METHODS: This review was conducted to inform the development of School-Related Sedentary Behaviour Recommendations. Peer-reviewed, published, or in-press articles in English were included. Reviews, meta-analyses, and case studies were excluded; all other study designs were eligible. Further, articles had to meet the a priori study criteria for population, intervention, comparator (PROSPERO ID: CRD42021227600). Embase, MEDLINE® ALL, and PsycINFO were searched. Risk of bias was assessed for individual experimental studies using the Cochrane risk of bias assessment tool, and in observational studies based on the GRADE framework and in line with previous systematic reviews examining sedentary behaviours in children. Overall quality of evidence was assessed using the GRADE framework for each outcome category and study design. Results were synthesized narratively, grouped by study design and outcome category. Further, several high-level summaries were conducted to help interpret results. RESULTS: Evidence was synthesized from 116 reports, including 1,385,038 participants and 1173 extracted associations. More school-related sedentary behaviour was favourably associated with nearly one-third of extracted associations for cognitive (33%) and social-emotional (32%) indicators (e.g., less anxiety), but unfavourably associated with other movement behaviours (e.g., less physical activity) (35%). Active lessons were favourable (72%), compared to more school-related sedentary behaviours, when examining associations for all health and well-being indicators. More homework was favourable across all health and well-being indicators in 4% of extracted associations for primary school children, and 25% of extracted associations for secondary school children. However, ≥2 h/day of homework appeared to be unfavourable for health and well-being. Limitations for synthesized studies included generally low quality of evidence and a lack of studies in South American, African, or low-middle income countries. CONCLUSIONS: Findings can help inform policy makers, schools, and teachers, regarding the amount of homework assigned and the introduction of active lessons into the classroom to enhance health and well-being of children. More research is needed examining school-related sedentary behaviours and indicators of health and well-being in low- and middle-income countries.

International school-related sedentary behaviour recommendations for children and youth.

BACKGROUND: Existing sedentary behaviour guidelines for children and youth target overall sedentary behaviour and recreational screen time, without any specific recommendations regarding school-related sedentary behaviours (i.e., sedentary behaviours performed during the school day, or within the influence of school). The purpose of this paper is to describe the development of international evidence-based recommendations for school-related sedentary behaviours for children and youth, led by the Sedentary Behaviour Research Network (SBRN). METHODS: A panel of international experts was convened by SBRN in November 2020 to guide the development of these recommendations for children and youth aged ~ 5-18 years. The recommendations were informed by 1) age-relevant existing sedentary behaviour guidelines, 2) published research on the relationship between overall sedentary behaviour and health, 3) a de novo systematic review on the relationship between school-related sedentary behaviours and health and/or academic outcomes, and 4) a de novo environmental scan of the grey literature to identify existing recommendations for school-related sedentary behaviours. Draft recommendations were presented to the Expert Panel in June 2021. Following thorough discussion and modifications, updated recommendations were distributed for stakeholder feedback from July 9-26. Feedback was received from 148 stakeholders across 23 countries, leading to additional updates to the recommendations. Following further rounds of discussion and updates with the Expert Panel in August and September 2021, consensus was achieved on the final recommendations. RESULTS: A healthy day includes breaking up extended periods of sedentary behaviour and incorporating different types of movement into homework whenever possible, while limiting sedentary homework. School-related screen time should be meaningful, mentally or physically active, and serve a specific pedagogical purpose that enhances learning. Replacing sedentary learning activities with movement-based learning activities, and replacing screen-based learning activities with non-screen-based learning activities, can further support students' health and wellbeing. DISCUSSION: This paper presents the first evidence-based recommendations for school-related sedentary behaviours for children and youth. These recommendations will support the work of parents, caregivers, educators, school system administrators, policy makers, researchers and healthcare providers interested in promoting student health and academic success.

Timing of physical activity within the 24-hour day and its influence on health: a systematic review. / Moment choisi pour faire de l'activité physique sur 24 heures et son influence sur la santé : revue systématique.

BACKGROUND: Recent studies report that the health benefits of physical activity differ depending on whether the activity is performed in the morning, afternoon or evening. The purpose of this systematic review was to examine whether the timing of physical activity within the 24-hour day is associated with health. METHODS: Five databases were searched for English or French language peer-reviewed studies that examined whether the timing of physical activity within the day is associated with health. No limits were placed on publication year, study population, study design or health outcomes. Studies that examined acute effects of physical activity or timing of physical activity around food intake were excluded. RESULTS: This systematic review examined 35 studies, with 17 259 participants, and the following health outcomes: measures of sleep health, adiposity, fat-free mass and muscle size, cardiometabolic biomarkers, physical function and mobility, mental health, and risk of cardiovascular disease, cancer, and mortality. Heterogeneity across studies precluded meta-analyses, and we present our findings using narrative syntheses. Of the 35 studies, 11 reported that morning physical activity provides greater health benefits than afternoon/ evening physical activity, while 12 found that morning physical activity provides fewer health benefits than afternoon/evening physical. In the remaining 12 studies, there was no clear difference in health benefits based on the timing of physical activity. The quality of evidence for the different health outcomes across study designs was very low. CONCLUSION: There is no consistent evidence that physical activity at one time of day provides more favourable health benefits than physical activity at a different time of day. (PROSPERO registration no.: CRD42021231088).

Timing of sedentary behaviour and access to sedentary activities in the bedroom and their association with sleep quality and duration in children and youth: a systematic review. / Revue systématique des liens entre, d'une part, l'horaire des comportements sédentaires et l'accès à des activités sédentaires dans la chambre et, d'autre part, la qualité et la durée du sommeil chez les enfants et les adolescents.

BACKGROUND: The purpose of this study was to systematically review the relationship between the timing of sedentary behaviours and access to sedentary activities in the bedroom with sleep duration and quality in children and youth. A secondary purpose was to examine whether these relationships differ when comparing screen-based and non-screen-based sedentary activities. METHODS: We searched four databases for peer-reviewed studies published between 1 January 2010 and 19 January 2021. Risk of bias assessment for each study and certainty of evidence were assessed using the GRADE framework. RESULTS: We identified 44 eligible papers reporting data from 42 separate datasets and including 239 267 participants. Evening participation in screen-based sedentary behaviours and access to screen-based devices in the bedroom were associated with reduced sleep duration and quality. Daytime screen use was also associated with reduced sleep duration, although this was examined in relatively few studies. Whether performed during the day or night, non-screen-based sedentary behaviours were not consistently associated with sleep duration or quality. The quality of evidence was rated as low to very low for all outcomes. CONCLUSION: In order to maximize sleep duration and quality, children and youth should be encouraged to minimize screen time in the evening and remove screens from bedrooms. (PROSPERO registration no.: CRD42020189082).

Sleep timing and health indicators in children and adolescents: a systematic review. / Horaire de sommeil et indicateurs de santé chez les enfants et les adolescents : revue systématique.

INTRODUCTION: To continue to inform sleep health guidelines and the development of evidence-based healthy sleep interventions for children and adolescents, it is important to better understand the associations between sleep timing (bedtime, wake-up time, midpoint of sleep) and various health indicators. The objective of this systematic review was to examine the associations between sleep timing and 9 health indicators in apparently healthy children and adolescents 5 to 18 years old. METHODS: Studies published in the 10 years preceding January 2021 were identified from searches in four electronic databases. This systematic review followed the guidelines prescribed in PRISMA 2020, the methodological quality and risk of bias were scored, and the summary of results used a best-evidence approach for accurate and reliable reporting. RESULTS: Forty-six observational studies from 21 countries with 208 992 unique participants were included. Sleep timing was assessed objectively using actigraphy in 24 studies and subjectively in 22 studies. The lack of studies in some of the health outcomes and heterogeneity in others necessitated using a narrative synthesis rather than a metaanalysis. Findings suggest that later sleep timing is associated with poorer emotional regulation, lower cognitive function/academic achievement, shorter sleep duration/ poorer sleep quality, poorer eating behaviours, lower physical activity levels and more sedentary behaviours, but few studies demonstrated associations between sleep timing and adiposity, quality of life/well-being, accidents/injuries, and biomarkers of cardiometabolic risk. The quality of evidence was rated as "very low" across health outcomes using GRADE. CONCLUSION: The available evidence, which relies on cross-sectional findings, suggests that earlier sleep timing is beneficial for the health of school-aged children and adolescents. Longitudinal studies and randomized controlled trials are needed to better advance this field of research. (PROSPERO registration no.: CRD42020173585).

Timing of 24-hour movement behaviours: implications for practice, policy and research. / Répartition des comportements en matière de mouvement sur 24 heures : implications en termes de pratique, de politiques et de recherche.

For health benefits, Canadians need to: move when it suits them; remove screens from bedrooms and limit screen use prior to bedtime; and adjust bedtime so that they can sleep the recommended amount. The 24-Hour Movement Guidelines Communication Toolkit has resources that can be used across settings to help Canadians optimize movement behaviours throughout the day.

Pour obtenir des bienfaits sur leur santé, les Canadiens et Canadiennes doivent : bouger au moment qui leur convient; retirer les écrans de leur chambre et limiter l'utilisation d'écrans avant de se coucher; adapter l'heure de leur coucher de manière à avoir le nombre d'heures de sommeil recommandé. La trousse de communication des Directives canadiennes en matière de mouvement sur 24 heures propose des ressources utilisables en fonction de diverses situations et divers milieux pour aider la population canadienne à optimiser ses comportements en matière de mouvement tout au long de la journée.

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.

The Canadian Society for Exercise Physiology assembled a Consensus Panel representing national organizations, content experts, methodologists, stakeholders, and end-users and followed an established guideline development procedure to create the 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. These guidelines underscore the importance of movement behaviours across the whole 24-h day. The development process followed the strategy outlined in the Appraisal of Guidelines for Research and Evaluation (AGREE) II instrument. A large body of evidence was used to inform the guidelines including 2 de novo systematic reviews and 4 overviews of reviews examining the relationships among movement behaviours (physical activity, sedentary behaviour, sleep, and all behaviours together) and several health outcomes. Draft guideline recommendations were discussed at a 4-day in-person Consensus Panel meeting. Feedback from stakeholders was obtained by survey (n = 877) and the draft guidelines were revised accordingly. The final guidelines provide evidence-based recommendations for a healthy day (24-h), comprising a combination of sleep, sedentary behaviours, and light-intensity and moderate-to-vigorous-intensity physical activity. Dissemination and implementation efforts with corresponding evaluation plans are in place to help ensure that guideline awareness and use are optimized. Novelty First ever 24-Hour Movement Guidelines for Adults aged 18-64 years and Adults aged 65 years or older with consideration of a balanced approach to physical activity, sedentary behaviour, and sleep Finalizes the suite of 24-Hour Movement Guidelines for Canadians across the lifespan.

Balance and functional training and health in adults: an overview of systematic reviews.

This overview of systematic reviews examined the effect of balance and functional strength training on health outcomes in adults aged 18 years or older, to inform the Canadian 24-hour Movement Guidelines. Four electronic databases were searched for systematic reviews published between January 2009 and May 2019. Eligibility criteria were determined a priori for population (community-dwelling adults), intervention (balance and functional training), comparator (no intervention or different types/doses), and outcomes (critical: falls and fall-related injuries; adverse events; important: physical functioning and disability; health-related quality of life; physical activity; and sedentary behaviour). Two reviewers independently screened studies for eligibility and performed AMSTAR 2 assessment. One review was selected per outcome. Of 3288 records and 355 full-text articles, 5 systematic reviews were included, encompassing data from 15 890 participants in 23 countries. In adults 65 years and older, balance and functional training and Tai Chi reduced the rate of falls and the number of people who fell, and improved aspects of physical functioning and physical activity. The effect on health-related quality of life and falls requiring hospitalization was uncertain. While inconsistently monitored, only 1 serious adverse event was reported. No evidence was available in adults under age 65 years. Included systematic reviews and primary evidence reported by review authors ranged in quality. Overall, participation in balance and functional training reduced falls and improved health outcomes in adults 65 years of age and older. PROSPERO registration no.: CRD42019134865. Novelty This overview informs updated guidelines for balance training in adults. Balance and functional training reduced falls and improved health outcomes.

Resistance training and health in adults: an overview of systematic reviews.

The objective of this overview of systematic reviews was to determine the benefits and harms of resistance training (RT) on health outcomes in adults aged 18 years or older, compared with not participating in RT. Four electronic databases were searched in February 2019 for systematic reviews published in the past 10 years. Eligibility criteria were determined a priori for population (community dwelling adults), intervention (exclusively RT), comparator (no RT or different doses of RT), and health outcomes (critical: mortality, physical functioning, health-related quality of life, and adverse events; important: cardiovascular disease, type 2 diabetes mellitus, mental health, brain health, cognitive function, cancer, fall-related injuries or falls, and bone health). We selected 1 review per outcome and we used the GRADE process to assess the strength of evidence. We screened 2089 records and 375 full-text articles independently, in duplicate. Eleven systematic reviews were included, representing 364 primary studies and 382 627 unique participants. RT was associated with a reduction in all-cause mortality and cardiovascular disease incidence, and an improvement in physical functioning. Effects on health-related quality of life or cognitive function were less certain. Adverse events were not consistently monitored or reported in RT studies, but serious adverse events were not common. Systematic reviews for the remaining important health outcomes could not be identified. Overall, RT training improved health outcomes in adults and the benefits outweighed the harms. (PROSPERO registration no.: CRD42019121641.) Novelty This overview was required to inform whether there was new evidence to support changes to the recommended guidelines for resistance training.

Development and application of an outcome-centric approach for conducting overviews of reviews.

There are gaps in current guidance concerning how to conduct overviews of systematic reviews in an outcome-centric manner. Herein we summarize the methods and lessons learned from conducting 4 outcome-centric overviews to help inform the Canadian 24-Hour Movement Guidelines for Adults aged 18-64 years and Adults aged 65 years or older on the topics of resistance training, balance and functional training, sedentary behaviour, sleep duration. We defined "critical" and "important" outcomes a priori. We used AMSTAR 2 to assess review quality and sought 1 systematic review per outcome. If multiple reviews were required to address subgroups for an outcome, we calculated the corrected covered area (CCA) to quantify overlap. We report our methodology in a PRISMA table. Across the 4 overviews, authors reviewed 1110 full texts; 45 were retained (low to high quality per AMSTAR 2), representing 950 primary studies, enrolling over 5 385 500 participants. Of 46 outcomes, we identified data for 35. Nineteen outcomes required >1 review (CCA range: 0% to 71.4%). Our outcome-centric overviews addressed unique aspects of overviews, including selection and quality assessment of included reviews, and overlap. Lessons learned included consistent application of methodological principles to minimize bias and optimize reporting transparency. Novelty Overviews of reviews synthesize systematic reviews in a rigorous and transparent manner. Outcome-centric systematic reviews assess the quality of evidence for primary studies contributing to an outcome. This manuscript describes the development and application of extending the concept of outcome-centric systematic reviews to the design and conduct of outcome-centric overviews.

Sleep duration and health in adults: an overview of systematic reviews.

The objective of this overview of systematic reviews was to examine the associations between sleep duration and health outcomes in adults. Four electronic databases were searched in December 2018 for systematic reviews published in the previous 10 years. Included reviews met the a priori determined population (community-dwelling adults aged 18 years and older), intervention/exposure/comparator (various levels of sleep duration), and outcome criteria (14 outcomes examined). To avoid overlap in primary studies, we used a priority list to choose a single review per outcome; reviews that examined the effect of age and those that looked at dose-response were prioritized. A total of 36 systematic reviews were eligible and 11 were included. Reviews included comprised 4 437 101 unique participants from 30 countries. Sleep duration was assessed subjectively in 96% of studies and 78% of studies in the reviews were prospective cohort studies. The dose-response curves showed that the sleep duration that was most favourably associated with health was 7-8 h per day. Modification of the effect by age was not apparent. The quality of the evidence ranged from low to high across health outcomes. In conclusion, the available evidence suggests that a sleep duration of 7-8 h per day is the one most favourably associated with health among adults and older adults. (PROSPERO registration no.: CRD42019119529.) Novelty This is the first overview of reviews that examines the influence of sleep duration on a wide range of health outcomes in adults. Seven to 8 h of sleep per day was most favourably associated with health. Effect modification by age was not evident.

Sleep timing, sleep consistency, and health in adults: a systematic review.

The objective of this systematic review was to examine the associations between sleep timing (e.g., bedtime/wake-up time, midpoint of sleep), sleep consistency/regularity (e.g., intra-individual variability in sleep duration, social jetlag, catch-up sleep), and health outcomes in adults aged 18 years and older. Four electronic databases were searched in December 2018 for articles published in the previous 10 years. Fourteen health outcomes were examined. A total of 41 articles, including 92 340 unique participants from 14 countries, met inclusion criteria. Sleep was assessed objectively in 37% of studies and subjectively in 63% of studies. Findings suggest that later sleep timing and greater sleep variability were generally associated with adverse health outcomes. However, because most studies reported linear associations, it was not possible to identify thresholds for "late sleep timing" or "large sleep variability". In addition, social jetlag was associated with adverse health outcomes, while weekend catch-up sleep was associated with better health outcomes. The quality of evidence ranged from "very low" to "moderate" across study designs and health outcomes using GRADE. In conclusion, the available evidence supports that earlier sleep timing and regularity in sleep patterns with consistent bedtimes and wake-up times are favourably associated with health. (PROSPERO registration no.: CRD42019119534.) Novelty This is the first systematic review to examine the influence of sleep timing and sleep consistency on health outcomes. Later sleep timing and greater variability in sleep are both associated with adverse health outcomes in adults. Regularity in sleep patterns with consistent bedtimes and wake-up times should be encouraged.