Dose-dependent and joint associations between screen time, physical activity, and mental wellbeing in adolescents: an international observational study

BACKGROUND

Mental wellbeing in adolescents has declined considerably during past decades, making the identification of modifiable risk factors important. Prolonged screen time and insufficient physical activity appear to operate independently and synergistically to increase the risk of poor mental wellbeing in school-aged children. We aimed to examine the gender-stratified dose-dependent and joint associations of screen time and physical activity with mental wellbeing in adolescents.

METHODS

We used data from three rounds of Health Behaviour in School-aged Children cross-sectional surveys (2006, 2010, and 2014) from 42 European and North American countries. Survey participants, aged 11 years, 13 years, and 15 years, provided self-reported information by completing an anonymous questionnaire that included items on health indicators and related behaviours. We used the self-reported variables of life satisfaction and psychosomatic complaints as indicators of adolescents' mental wellbeing, combining these with the self-reported discretionary use of screens and engagement in physical activity. We used generalised additive models and multilevel regression modelling to examine the gender-stratified relationships between mental wellbeing and screen time and physical activity.

FINDINGS

Our sample included 577 475 adolescents (mean age 13·60 years, SD 1·64), with 296 542 (51·35%) girls and 280 933 (48·64%) boys. The mean reported life satisfaction score (on a scale of 0-10) was 7·70 (95% CI 7·69-7·71) in boys and 7·48 (7·46-7·50) in girls. Psychosomatic complaints were more common among girls (mean 9·26, 95% CI 9·23-9·28) than boys (6·89, 6·87-6·91). Generalised additive model analyses showed slightly non-linear associations of screen time and physical activity with life satisfaction and psychosomatic complaints for girls and boys. Detrimental associations between screen time and mental wellbeing started when screen time exceeded 1 h per day, whereas increases in physical activity levels were beneficially and monotonically associated with wellbeing. Multilevel modelling showed that screen time levels were negatively associated with life satisfaction and positively associated with psychosomatic complaints in a dose-dependent manner. Physical activity levels were positively associated with life satisfaction and negatively associated with psychosomatic complaints in a dose-dependent manner. Joint associations of screen time-physical activity with mental wellbeing showed that, compared with the least active participants with more than 8 h per day of screen time and no physical activity, most of the other screen time-physical activity groups had considerably higher life satisfaction and lower psychosomatic complaints.

INTERPRETATION

Higher levels of screen time and lower levels of physical activity were associated with lower life satisfaction and higher psychosomatic complaints among adolescents from high-income countries. Public health strategies to promote adolescents' mental wellbeing should aim to decrease screen time and increase physical activity simultaneously.

FUNDING

None.

Few Canadian children and youth were meeting the 24-hour movement behaviour guidelines 6-months into the COVID-19 pandemic: Follow-up from a national study

Daily life has changed for families due to the COVID-19 pandemic. The aim of this repeated cross-sectional study was to describe movement behaviours in Canadian children and youth six months into the pandemic (T2; October 2020) compared with the start of the pandemic (T1, April 2020). An online survey was distributed to parents (N=1568) of children and/or youth (5-17 years; 58% girls) in October 2020. The survey assessed changes in movement behaviours [physical activity (PA) and play, sedentary behaviours (SB), and sleep] from before the pandemic to October 2020 (T2). We compared these data to spring data (T1; April 2020; Moore et al., 2020) collected using identical methodology (N=1472; 54% girls). We report correlations between movement behaviours and relevant parental factors and provide word frequency distributions for open-ended responses. During the second wave, 4.5% of children (4.6% girls; 4.3% boys) and 1.9% of youth (1.3% girls, 2.4% boys) met the movement guidelines (3.1% overall). Whereas, during the first wave, 4.8% (2.8% girls, 6.5% boys) of children and 0.6% (0.8% girls, 0.5% boys) of youth were meeting combined guidelines (2.6% overall). Parental support was correlated with their child's movement behaviours (T1 and T2). Our study demonstrates the ongoing challenges for children and youth to engage in healthy movement during the pandemic. Novelty bullets: • Our large-scale national study demonstrates that children and youth were not meeting the 24-hour movement guidelines during the second wave of the pandemic. • Our findings illustrate the need to protect children and youth from the collateral consequences of the pandemic.

Sedentary behaviour and health in adults: an overview of systematic reviews

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.

Meeting Canadian 24-Hour Movement Guideline recommendations and risk of all-cause mortality

This study determined if meeting the Canadian 24-Hour Movement Guidelines recommendations are associated with all-cause mortality. Participants were 3,471 adults from the 2005-2006 U.S. National Health and Nutrition Examination Survey followed for mortality over 11 years. They were classified as meeting or not meeting recommendations for sleep duration, sedentary behaviour, and moderate-to-vigorous physical activity (MVPA). A total of 63.8%, 35.3%, and 41.5% of participants met recommendations for sleep, sedentary behavior, and physical activity while 12.3% met all three recommendations. The hazard ratio (HR) for all-cause mortality in participants meeting the recommendations relative to those not meeting the recommendations were 0.91 (0.72, 1.16) for sleep, 0.92 (0.61, 1.40) for sedentary behavior, and 0.42 (0.24, 0.74) for MVPA. The HR for meeting none, any one, any two, and all three recommendations were 1.00, 0.86 (0.65, 1.14), 0.49 (0.28, 0.86), and 0.72 (0.34, 1.50). When the cut-point used to denote acceptable sedentary time was changed from ≤8 to ≤10 hours/day, the HR for meeting none, any one, any two, and all three recommendations were 1.00, 0.83 (0.59, 1.15), 0.57 (0.34, 0.96), and 0.43 (0.20, 0.93). These findings provide some support for the ability of the 24-hour movement guidelines to predict mortality risk. NOVELTY - The 24-Hour Movement Guidelines provide recommendations for sleep, sedentary behavior, and physical activity. - The findings of this study provide some support of the ability of these new guidelines to predict mortality risk.

Temporal trends in step test performance for Chinese adults between 2000 and 2014

Backgroud/Objective

Cardiorespiratory endurance is an excellent marker of functional endurance and health among adults. The aim of this study was to estimate temporal trends in step test performance for Chinese adults between 2000 and 2014.

Methods

Apparently healthy adults aged 20–59 years were included. Nationally representative step test data (n = 603,977) from 2000, 2005, 2010, and 2014 were reported descriptively by the China Physical Fitness Surveillance Center. Temporal trends in means were estimated at the sex-age level for all adults and separate location/occupation groups using sample-weighted linear regression, with trends in distributional characteristics described visually and estimated as the ratio of coefficients of variation (CVs).

Results

Collectively, there was a negligible improvement in mean step test performance of 0.12 standardized effect sizes (95% confidence interval (95%CI): 0.11–0.13). Negligible to small improvements were observed for all age, sex, location, and occupation groups. Variability declined substantially over time (ratio of CVs (95%CI): 0.86 (0.86–0.86)), with negligible to large improvements in those below the 10th percentile, and negligible to moderate declines in those above the 90th percentile.

Conclusion

There have been negligible to large improvements in step test performance for low to average performing Chinese adults since 2000, which may be meaningful to public health because low endurance is an important risk factor for all-cause mortality.

Relationships of physical activity and sedentary behaviour with the previous and subsequent nights' sleep in children and youth: A systematic review and meta-analysis

The interrelationships between sleep and daytime movement behaviours have been examined at interindividual level. Studies of within-person, temporal relationships of daytime physical activity (PA) and sedentary behaviour with the previous and subsequent nights' sleep are increasing. The present systematic review and meta-analysis synthesised the results of studies in school-aged children and youth. Eight databases (MEDLINE, PsycINFO, EMBASE, Global Health, PubMed, Web of Science, SPORTDiscus, and CINAHL) were searched for peer-reviewed articles that examined the association between daytime movement behaviours (including PA, sedentary time, or sedentary recreational screen time) and night-time sleep on the same day, or the association between night-time sleep and daytime movement behaviours the next day, in children and youth. A total of 11 studies comprising 9,622 children and youth aged 5-15 years met the inclusion criteria. Sedentary time was negatively associated with the subsequent night's sleep duration (r = -0.12, 95% confidence interval -0.23 to -0.00; I²  = 93%; p = .04). Positive relationships between PA and the previous or subsequent night's sleep duration were observed only for studies that adjusted for accelerometer wear time. There was some evidence suggesting that a longer sleep duration was associated with less sedentary time and a higher proportion of the daytime spent being physically active and vice versa, although the association was weak and based on a limited number of studies. From a clinical perspective, promotion of either sleep hygiene or daytime PA should be planned with considerations of the virtuous or vicious circle between these behaviours and monitor concurrent effects on the others.

Global prevalence of physical activity for children and adolescents; inconsistencies, research gaps, and recommendations: a narrative review

BACKGROUND

One of the strategic actions identified in the Global Action Plan on Physical Activity (PA) 2018-2030 is the enhancement of data systems and capabilities at national levels to support regular population surveillance of PA. Although national and international standardized surveillance of PA among children and adolescents has increased in recent years, challenges for the global surveillance of PA persist. The aims of this paper were to: (i) review, compare, and discuss the methodological inconsistencies in children and adolescents' physical activity prevalence estimates from intercontinental physical activity surveillance initiatives; (ii) identify methodological limitations, surveillance and research gaps.

METHODS

Intercontinental physical activity surveillance initiatives for children and adolescents were identified by experts and through non-systematic literature searches. Prevalence of meeting PA guidelines by country, gender, and age were extracted when available. A tool was created to assess the quality of the included initiatives. Methods and PA prevalence were compared across data/studies and against the methodological/validity/translation differences.

RESULTS

Eight intercontinental initiatives were identified as meeting the selection criteria. Methods and PA definition inconsistencies across and within included initiatives were observed, resulting in different estimated national prevalence of PA, and initiatives contradicting each other's cross-country comparisons. Three findings were consistent across all eight initiatives: insufficient level of PA of children and adolescents across the world; lower levels of PA among girls; and attenuation of PA levels with age. Resource-limited countries, younger children, children and adolescents not attending school, with disability or chronic conditions, and from rural areas were generally under/not represented.

CONCLUSIONS

There are substantial inconsistencies across/within included initiatives, resulting in varying estimates of the PA situation of children and adolescents at the global, regional and national levels. The development of a new PA measurement instrument that would be globally accepted and harmonized is a global health priority to help improve the accuracy and reliability of global surveillance.

Influence of weather conditions on children’s school travel mode and physical activity in 3 diverse regions of Canada

Children who engage in active school transportation (AST) have higher levels of physical activity (PA). Climate and weather were shown to influence adults’ daily travel behaviours, but their influence on children’s AST and PA has been less examined. This study examined the influence of weather conditions on children’s AST and overall PA. Children in grades 4 to 6 (N = 1699; age, 10.2 ± 1.0 years) were recruited in schools located in urban, suburban and rural areas, stratified by area-level socioeconomic status, in 3 different regions of Canada (Trois-Rivières, Québec; Ottawa, Ontario; Vancouver, British Columbia). Mode of school travel was self-reported and physical activity was measured using a pedometer. We used publicly available data on total precipitation and early morning temperature. AST increased with temperature only among girls. Daily precipitation was negatively associated with boys’ and girls’ PA while warmer temperature was associated with increased PA on weekend days. We also observed that season and region moderated the relationship between weather conditions and children’s physical activity behaviours. Our results suggest that daily weather variations influence children’s AST and PA to a greater extent than seasonal variations. Interventions designed to help children and families adapt to weather-related barriers to AST and PA are needed.

Novelty: In Canada, weather conditions may influence children’s active behaviours daily. Associations between weather conditions, choice of travel mode and physical activity vary by sex, season, and region. Weather affects children's PA differently during the week than on weekends.

Meeting 24-h movement guidelines: Prevalence, correlates, and the relationships with overweight and obesity among Chinese children and adolescents

BACKGROUND

Meeting 24-h movement guidelines by children and adolescents has been associated with improved indicators of health, although it has been under-studied in China. Hence, this study aimed to investigate the prevalence of meeting the 24-h movement guidelines, its correlates, and its relationships with body mass index in children and adolescents in China.

METHODS

Cross-sectional data from the 2017 Youth Study in China of 114,072 children and adolescents (mean age = 13.75 years, 49.18% boys) were used. Meeting 24-h movement guidelines (≥60 min of daily moderate-to-vigorous physical activity, ≤2 h of daily leisure screen time, 9-11 h and 8-10 h nightly sleep duration for 6-13-year-olds and 14-17-year-olds, respectively) and height and weight of all participants were assessed. The prevalence of meeting the 24-h movement guidelines and World Health Organization weight status categories were determined. Generalized linear models were used to determine the correlates of meeting the 24-h movement guidelines and the relationships of meeting the 24-h movement guidelines with overweight (OW) and obesity (OB).

RESULTS

Only 5.12% of Chinese children and adolescents met the 24-h movement guidelines, and 22.44% were classified as OW/OB. Older children and adolescents were less likely to meet the 24-h movement guidelines. Parental education level and family income were positively related to meeting the 24-h movement guidelines. Children and adolescents meeting the 24-h movement guidelines showed lower odds ratios for OW/OB. Compared with participants meeting the 24-h movement guidelines, boys in 4th-6th grades met none of the recommendations (OR = 1.22, 95%CI: 1.06-1.40), met the screen time recommendation only (OR = 1.13, 95%CI: 1.01-1.28), met the nightly sleep duration recommendation only (OR = 1.14, 95%CI: 1.03-1.28), and had significantly higher odds ratios for OW/OB. Similar trends were observed for girls in 4th-6th grades: meeting none of the guidelines (OR = 1.35, 95%CI: 1.14-1.59), meeting sleep duration guidelines only (OR = 1.23, 95%CI: 1.08-1.39), and meeting moderate-to-vigorous physical activity + nightly sleep duration guidelines (OR = 1.24, 95%CI: 1.01-1.54). For girls in 7th-9th grades, the following trend was observed: meeting none of the guidelines (OR = 1.30, 95%CI: 1.01-1.67).

CONCLUSION

Very few Chinese children and adolescents met the 24-h movement guidelines. Age (negatively correlated), parental education level, and family income (both positively correlated) were correlates of meeting the 24-h movement guidelines. Children and adolescents meeting the 24-h movement guidelines were more likely to have lower risks for OW/OB, especially in the youngest age group (Grades 4-6); and girls in the middle age group (Grades 7-9) were also more likely to have lower risks for OW/OB. Further research studies should explore additional correlates and determinants for meeting the 24-h movement guidelines. Also, future studies should use longitudinal or interventional designs to determine the relationships between meeting the 24-h movement guidelines and OW/OB and other health indicators, while taking sex and age differences into account.

24-Hour Movement Behaviors and Internalizing and Externalizing Behaviors Among Youth

PURPOSE

The Canadian 24-Hour Movement Guidelines for Children and Youth (≥60 minutes of moderate-to-vigorous physical activity per day, ≤2 hours of recreational screen time per day, and 9-11 hours of sleep per night for 5-13 years old) are associated with better physical health, but less is known about how these behaviors are related to mental health. This study examined the association of meeting these guideline recommendations with internalizing and externalizing behaviors among youth.

METHODS

A large and broadly representative cross-sectional sample of 9- to 11-year-old U.S. youth (N = 11,875) from the Adolescent Brain and Cognitive Development study was analyzed. Internalizing and externalizing behaviors were measured using the Child Behaviour Checklist. Associations were examined using negative binomial regression adjusted for several confounders.

RESULTS

Compared to meeting none of the recommendations, meeting recommendations for screen time and sleep but not physical activity was associated with a lower prevalence ratio of total, internalizing, and externalizing behaviors. Meeting two or all three recommendations was more strongly associated with these outcomes than meeting one recommendation or none. The prevalence ratio of the group meeting all three recommendations was .77 (95% confidence interval [CI]: .68-.86) for total problem scores, .78 (95% CI: .68-.89) for internalizing problem scores, and .79 (95% CI: .68-.91) for externalizing problem scores.

CONCLUSIONS

Meeting the 24-hour movement guidelines was associated with a lower risk of internalizing and externalizing behaviors in youth. These associations were mainly explained by meeting the screen time and sleep duration recommendations.

Screen time is independently associated with serum brain-derived neurotrophic factor (BDNF) in youth with obesity

Low levels of brain derived-neurotrophic factor (BDNF) and excessive screen exposure are risk factors for neurocognitive deficits and obesity in youth, but the relationship between screen time and BDNF remains unknown. This study examined whether duration and/or type of sedentary screen time behaviour (TV viewing, video games, recreational computer use) are associated with serum BDNF levels in youth with obesity. The sample consisted of 250 inactive, postpubertal adolescents with obesity (172 females/78 males, aged 15.5 ± 1.4 years) at the baseline assessment of the Healthy Eating, Aerobic, Resistance Training in Youth Study. After controlling for self-reported age, sex, race, parental education, puberty stage, physical activity, and diet, higher total screen exposure was significantly associated with lower serum BDNF levels (β = -0.21, p = 0.002). TV viewing was the only type of screen behaviour that was associated with BDNF levels (β = -0.22, p = 0.001). Higher exposure to traditional forms of screen time was independently associated with lower serum BDNF levels, and this association appears to be driven primarily by TV viewing. Future intervention research is needed to determine whether limiting screen time is an effective way to increase BDNF and associated health benefits in a high-risk population of youth with obesity. Trial Registration: ClinicalTrials.Gov NCT00195858. Novelty: This study is the first to show that recreational screen time is inversely associated with serum BDNF levels. The inverse association between screen time and BDNF is driven primarily by TV viewing, indicating the type of screen might matter.

Systematic review of the correlates of outdoor play and time among children aged 3-12 years

BACKGROUND

Due to the myriad of benefits of children's outdoor play and time, there is increasing concern over its decline. This systematic review synthesized evidence on the correlates of outdoor play and outdoor time among children aged 3-12 years.

METHODS

A total of 12 electronic databases in five different languages (Chinese, English, Korean, Spanish, Portuguese) were searched between October 28, 2019 and July 27, 2020. Covidence software was used for screening and Microsoft Excel with a predesigned coding form was used for data extraction. Evidence was synthesized and correlates were categorized using the socioecological model framework.

RESULTS

Based on 107 studies representing 188,498 participants and 422 childcare centers from 29 countries, 85 studies examined potential correlates of outdoor play while 23 studies examined that of outdoor time (one examined both). The duration of outdoor play and outdoor time ranged between 60 and 165 min/d and 42-240 min/d, respectively. Out of 287 (outdoor play) and 61 (outdoor time) potential correlates examined, 111 correlates for outdoor play and 33 correlates for outdoor time were identified as significant correlates. Thirty-three variables were identified as key/common correlates of outdoor play/time, including eight correlates at the individual level (e.g., sex/gender, race/ethnicity, physical activity), 10 correlates at the parental level (e.g., parental attitude/support/behavior, parenting practice), nine at the microsystem level (e.g., proximal home/social environment such as residence type, peer influence), three at the macrosystem/community level (e.g., availability of space children can play), and three at the physical ecology/pressure for macrosystem change level (e.g., seasonality, rurality). No key correlates were found at the institutional level.

CONCLUSIONS

Individual, parental, and proximal physical (home) and social environments appear to play a role in children's outdoor play and time. Ecological factors (i.e., seasonality, rurality) also appear to be related to outdoor play/time. Evidence was either inconsistent or lacking at institutional and macrosystem/community levels. Standardizing terminology and measures of outdoor play/time is warranted. Future work should investigate the interactions and processes of multiple variables across different levels of socioecological modelling to better understand the mechanisms through which outdoor play/time opportunities can be optimized for children while paying special attention to varying conditions in which children are born, live, and play.

Protocol for a randomised trial evaluating a preconception-early childhood telephone-based intervention with tailored e-health resources for women and their partners to optimise growth and development among children in Canada: a Healthy Life Trajectory Initiative (HeLTI Canada)

INTRODUCTION

The 'Developmental Origins of Health and Disease' hypothesis suggests that a healthy trajectory of growth and development in pregnancy and early childhood is necessary for optimal health, development and lifetime well-being. The purpose of this paper is to present the protocol for a randomised controlled trial evaluating a preconception-early childhood telephone-based intervention with tailored e-health resources for women and their partners to optimise growth and development among children in Canada: a Healthy Life Trajectory Initiative (HeLTI Canada). The primary objective of HeLTI Canada is to determine whether a 4-phase 'preconception to early childhood' lifecourse intervention can reduce the rate of child overweight and obesity. Secondary objectives include improved child: (1) growth trajectories; (2) cardiometabolic risk factors; (3) health behaviours, including nutrition, physical activity, sedentary behaviour and sleep; and (4) development and school readiness at age 5 years.

METHOD AND ANALYSIS

A randomised controlled multicentre trial will be conducted in two of Canada's highly populous provinces-Alberta and Ontario-with 786 nulliparous (15%) and 4444 primiparous (85%) women, their partners and, when possible, the first 'sibling child.' The intervention is telephone-based collaborative care delivered by experienced public health nurses trained in healthy conversation skills that includes detailed risk assessments, individualised structured management plans, scheduled follow-up calls, and access to a web-based app with individualised, evidence-based resources. An 'index child' conceived after randomisation will be followed until age 5 years and assessed for the primary and secondary outcomes. Pregnancy, infancy (age 2 years) and parental outcomes across time will also be assessed.

ETHICS AND DISSEMINATION

The study has received approval from Clinical Trials Ontario (CTO 1776). The findings will be published in peer-reviewed journals and disseminated to policymakers at local, national and international agencies. Findings will also be shared with study participants and their communities.

TRIAL REGISTRATION NUMBER

ISRCTN13308752; Pre-results.

Changes in Healthy Behaviors and Meeting 24-h Movement Guidelines in Spanish and Brazilian Preschoolers, Children and Adolescents during the COVID-19 Lockdown

Background: The aim of this study was to assess changes in physical activity, screen time and sleep duration of preschoolers, children and adolescents and the prevalence of meeting the 24-h movement guidelines during the lockdown caused by COVID-19 in a sample from Spain and Brazil. Methods: A total of 1099 preschoolers, children and adolescents (aged 3–17 years) from Spain (12.1 ± 4.6 years) and Brazil (10.7 ± 4.3 years) were included. An online survey was created and distributed in each country using a snowball sampling strategy. This online survey was completed by parents (mother/father/responsible guardian). Results: The proportion of the sample who met the PA and ST recommendations decreased during the COVID-19 lockdown in both Spanish and Brazilian samples (p < 0.001), while sleep duration increased (p < 0.001). The proportion of the sample meeting the overall 24-h movement guidelines was very low before the lockdown (Spain 3.0%; Brazil 11.7%) and even worse during the lockdown (Spain 0.3%; Brazil 7.5%). Conclusions: The prevalence of preschoolers, children and adolescents in both the Spain and Brazil samples meeting the 24-h movement guidelines during COVID-19 restrictions was as low as previous studies in other countries. Efforts to protect and support healthy behaviors of young people during a period of pandemic restrictions need to be a priority.

Balancing time use for children's fitness and adiposity: Evidence to inform 24-hour guidelines for sleep, sedentary time and physical activity

PURPOSE

Daily time spent on one activity cannot change without compensatory changes in others, which themselves may impact on health outcomes. Optimal daily activity combinations may differ across outcomes. We estimated optimal daily activity durations for the highest fitness and lowest adiposity.

METHODS

Cross-sectional Child Health CheckPoint data (1182 11-12-year-olds; 51% boys) from the population-based Longitudinal Study of Australian Children were used. Daily activity composition (sleep, sedentary time, light physical activity [LPA], moderate-to-vigorous physical activity [MVPA]) was from 8-day, 24-hour accelerometry. We created composite outcomes for fitness (VO2max; standing long jump) and adiposity (waist-to-height ratio; body mass index; fat-to-fat-free log-ratio). Adjusted compositional models regressed activity log-ratios against each outcome. Best activity compositions (optimal time-use zones) were plotted in quaternary tetrahedrons; the overall optimal time-use composition was the center of the overlapping area.

RESULTS

Time-use composition was associated with fitness and adiposity (all measures p<0.001). Optimal time use differed for fitness and adiposity. While both maximized MVPA and minimized sedentary time, optimal fitness days had higher LPA (3.4 h) and shorter sleep (8.25 h), but optimal adiposity days had lower LPA (1.0 h) and longer sleep (10.9 h). Balancing both outcomes, the overall optimal time-use composition was (mean [range]): 10.2 [9.5; 10.5] h sleep, 9.9 [8.8; 11.2] h sedentary time, 2.4 [1.8; 3.2] h LPA and 1.5 [1.5; 1.5] h MVPA.

CONCLUSION

Optimal time use for children's fitness and adiposity involves trade-offs. To best balance both outcomes, estimated activity durations for sleep and LPA align with, but for MVPA exceed, 24-h guidelines.

Regional differences in access to the outdoors and outdoor play of Canadian children and youth during the COVID-19 outbreak

To reduce the spread of COVID-19, public health authorities across the country have recommended that Canadians keep their distance, wash their hands, and stay home. To enforce these measures, restrictions on outdoor behaviour have been implemented, limiting access to parks and recreational outdoor spaces. New evidence shows that COVID-19 restrictions are associated with an overall lower amount of time spent in outdoor play among Canadian children and youth. This is concerning, as outdoor play is important for children's physical and mental health and helps provide them with a sense of control during times of uncertainty and stress. As policies on access to the outdoors during the COVID-19 outbreak vary by province, it is possible that policy differences have led to regional differences in changes in outdoor play among children and youth. In this commentary, we examine regional differences in outdoor play among children and youth across Canada, and the association between provincial policies related to COVID-19 and outdoor play. We argue that through the recovery process, in the event of a second wave of infections, and in preparing for future public health challenges, policy decisions should consider ways to preserve outdoor play for Canadian children and youth.

The whole day matters: Understanding 24-hour movement guideline adherence and relationships with health indicators across the lifespan

BACKGROUND

New research suggests that the composition (mix) of movement behaviors within a 24-h period may have important implications for health across the lifespan. Consistent with this integrated movement behavior paradigm, a number of countries across the world have developed and released 24-h movement guidelines for specific age groups. The purpose of this systematic review was to examine the associations between the 24-h time-use composition of movement behaviors, or adherence to 24-h movement guidelines, and multiple health indicators across the lifespan.

METHODS

Five online databases (PsycINFO, PubMed, SPORTDiscus, Web of Science, and Ovid MEDLINE) were searched for relevant peer-reviewed studies published between January 2015 and January 2020 that met the a priori inclusion criteria, with no study design limits. The methodological quality of research evidence for each individual study and for each health indicator was assessed by using a modified version of the Downs and Black checklist.

RESULTS

A total of 51 studies from 20 different countries met the inclusion criteria. A total of 31 studies examined adherence (meeting vs. not meeting) to 24-h movement guidelines, and 20 studies used compositional analyses to explore the 24-h time-use composition of movement behaviors. Findings indicated that meeting the 24-h movement guidelines were (1) not associated with adiposity among toddlers, (2) favorably associated with health-related quality of life, social-cognitive development, and behavioral and emotional problems among preschoolers, (3) favorably associated with global cognition, health-related quality of life, and healthy dietary patterns in children, and (4) favorably associated with adiposity, fitness, and cardiometabolic, mental, social, and emotional health among children and youth. Significant associations were also found between the composition of 24-h movement behaviors and indicators of (1) adiposity and bone and skeletal health among preschoolers, (2) health-related quality of life among children, (3) adiposity, fitness, and cardiometabolic, social, and emotional health among children and youth, (4) cardiometabolic health in adults, (5) adiposity and fitness among adults and older adults, and (6) mental health and risk of mortality among older adults. The quality of the available evidence ranged from poor to good.

CONCLUSION

The current evidence indicates that the composition of movement behaviors within a 24-h period may have important implications for health at all ages and that meeting the current 24-h movement guidelines is associated with a number of desirable health indicators in children and youth. Future studies should employ longitudinal and experimental designs, include valid and reliable measures of 24-h movement behaviors, and examine a wide array of health indicators across all age groups. Such studies would confirm the results from the primarily cross-sectional evidence drawn from studies included in our review and further advance our understanding of the relationships between 24-h movement behaviors and health.

Association between 24-hour movement guidelines and physical fitness in children

BACKGROUND

Physical fitness levels in Japanese children are lower than those in the 1980s. Twenty-four hour movement guidelines were recently developed to improve both present and future health of children. This study examined whether meeting the 24 h movement guidelines was associated with physical fitness measures in primary school children.

METHODS

Participants were 243 Japanese children (9.4 ± 1.7 years). Moderate-to-vigorous physical activity (MVPA) was evaluated using accelerometry. Sleep duration and screen time were reported. Physical fitness was assessed by grip strength, sit-ups, sitting trunk flexion, and 20 m shuttle run test. Meeting the 24 h movement guidelines was defined as: 9-11 h / night of sleep, ≤2 h/day of screen time, and at least 60 min/day of MVPA. The associations between physical fitness and the recommendations were analyzed using analysis of covariance.

RESULTS

Children meeting the MVPA recommendation alone performed better on the 20 m shuttle run and sit-up test compared to those not meeting the recommendation (number of laps: 41 vs 36, P = 0.009 and number of repetitions: 16.3 vs 14.7, P = 0.021). Children meeting the combination of MVPA and sleep recommendation scored significantly higher on the sit-up test compared to those not meeting the recommendations (number of repetitions: 16.5 vs 15.0, P = 0.038) but the effect was similar to that of the MVPA reference only. Meeting all three 24 h movement guidelines was not associated with measures of fitness in this sample. Meeting the MVPA recommendation was associated with greater aerobic fitness and muscle endurance.

CONCLUSIONS

In order to enhance children's physical fitness, public health recommendations should primarily target MVPA.

Association of screen time and cardiometabolic risk in school-aged children

Screen use has become a pervasive behaviour among children and has been linked to adverse health outcomes. The objective of this study was to examine the association between screen time and a comprehensive total cardiometabolic risk (CMR) score in school-aged children (7-12-years), as well as individual CMR factors. In this longitudinal study, screen time was measured over time (average duration of follow-up was 17.4 months) via parent-report. Anthropometric measurements, blood pressure, and biospecimens were collected over time and used to calculate CMR score [sum of age and sex standardized z-scores of systolic blood pressure (SBP), glucose, log-triglycerides, waist circumference (WC), and negative high-density lipoprotein cholesterol (HDL-c)/square-root of 5]. Generalized estimating equations (GEE) were used to examine the association between screen time and total CMR score as well as individual CMR factors. A total of 567 children with repeated measures were included. There was no evidence of an association between parent-reported child screen time and total CMR score (adjusted β = -0.01, 95% CI [-0.03, 0.005], 0.16). Screen time was inversely associated HDL-c (adjusted β = -0.008, 95% CI [-0.011, -0.005], p = 0.016), but there was no evidence that the other CMR components were associated with screen time. Among children 7-12 years, there was no evidence of an association between parent-reported child screen time and total CMR, but increased screen time was associated with slightly lower HDL-c. Research is needed to understand screen-related contextual factors which may be related to CMR factors.

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

Prevalence and sociodemographic factors associated with meeting the 24-hour movement guidelines in a sample of Brazilian adolescents

Background

The present cross-sectional study aimed to determine the proportion of adolescents meeting the 24-hour movement guidelines, and investigate sociodemographic factors associated with meeting them.

Methods

Self-reported (average daily volume of MVPA, sleep duration, and time watching videos and playing videogames) and accelerometer-measured (MVPA and sleep duration) 24-hour movement behaviors were classified according to recommendations, and sex, age, socioeconomic status (SES), family structure, parental education, and number of people in the household were tested as correlates of meeting recommendations using multilevel logistic regressions.

Results

The proportion of adolescents (n = 867, mean age: 16.4 years, 50.3% girls) meeting the MVPA, ST, and sleep duration guidelines was of 25%, 28%, and 41%, respectively, for self-reported data. From accelerometer data (n = 688), 7.1% met MVPA and 31.7% met sleep duration recommendations. Adherence to all three recommendations was 3% with self-report and 0.2% with accelerometer data. Boys were more likely to meet MVPA, but not ST and sleep-duration recommendations. A positive relationship was observed between age and meeting the ST recommendation.

Conclusions

Adherence to the sleep duration recommendation was higher than to the screen-time and MVPA recommendations and few in this sample of Brazilian adolescents achieved the 24-hour guidelines. Efforts are needed to improve 24-hour movement behaviors.

Trends in physical fitness among Canadian children and youth

BACKGROUND

Physical fitness during childhood is an important indicator of current and future health. This paper provides an overview of the fitness of Canadian children and youth aged 6 to 19 years.

DATA AND METHODS

Data are from three cycles of the Canadian Health Measures Survey (CHMS) spanning a 10-year period: 2007 to 2009 (n = 2,081), 2009 to 2011 (n = 2,133) and 2016 to 2017 (n = 2,070). The CHMS is a comprehensive direct health measures survey conducted on a nationally representative sample of Canadians. Descriptive statistics for measures of cardiorespiratory fitness, muscular strength and power, flexibility, and body composition are provided by age group and sex. Physical fitness measures are presented for participants who met and did not meet the physical activity and screen time recommendations.

RESULTS

Few changes in the fitness measures occurred over the past decade. Cardiorespiratory fitness decreased between 2007-2009 and 2016-2017 in 8 to 10 (52.1 to. 51.0 mL•kg^-1•min^-1) and 11 to 14 (50.8 to 49.8 mL•kg^-1•min^-1) year old boys. Girls generally had lower levels of fitness compared to boys, except for flexibility which was higher in girls. Cardiorespiratory fitness was higher in children and youth who met the current Canadian recommendations for physical activity and screen time. Grip strength was higher in boys who met the current Canadian screen time recommendation.

DISCUSSION

Ongoing and periodic surveillance of fitness through the CHMS is important to monitor trends, assess future interventions designed to improve fitness levels at the population level and to increase our understanding of the relationships between fitness and health.