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Summary: Background: The association between adolescent time spent on social media use and body mass index z‐score (BMI z‐score) is unclear. Pathways of association and sex differences are also unclear. This study examined the association between time spent on social media use and BMI z‐score (primary objective) and potential explanatory pathways (secondary objective) for boys and girls. Methods: Data are from 5332 girls and 5466 boys aged 14 years in the UK Millennium Cohort Study. BMI z‐score was regressed on self‐reported time spent on social media use (h/day). Potential explanatory pathways explored included dietary intake, sleep duration, depressive symptoms, cyberbullying, body‐weight satisfaction, self‐esteem, and well‐being. Sex‐stratified multivariable linear regression and structural equation modelling were used to examine potential associations and explanatory pathways. Results: Using social media for ≥5 h/day (vs.

Made available in DSpace on 2022-04-28T19:41:54Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-11-01 Background: The evidence on the association between sedentary behaviour and depression in adolescence is mixed. We aimed to investigate the association between mentally-active and mentally-passive sedentary behaviours at 11 years (11y) and depressive symptoms at 14y, and to examine potential mediators. Methods: UK Millennium Cohort Study data were used (n=7,124; 49% boys). At 11y, participants self-reported frequency of mentally-passive (listening to music, internet use) and mentally-active sedentary behaviours (reading, playing electronic games). Additional parental-reported behaviours (mentally-passive: TV viewing; mentally-active: homework) were summed with self-reported behaviours to represent continuous indicators of mentally-active and mentally-passive sedentary behaviour. Depressive symptoms were assessed (at 11y and 14y) using the short-version of Mood and Feelings Questionnaire. Body mass index (BMI), mentally-passive sedentary behaviour and cognition at 14y were examined as potential mediators. Linear regression models were adjusted for confounders and stratified by sex. Subsequent mediation analyses reporting e-values were used to assess unmeasured confounding. Results: Among girls, mentally-passive sedentary behaviour at 11y was associated with later depressive symptoms (14y) [β:0.089 (95%CI:0.055-0.122), e-value:1.32]. This association was mediated by BMI [5.6% (95%CI:4.1%–8.6%)] and mentally-passive sedentary behaviour [105.6% (95%CI:79.6%–156.7%)]. No associations were observed in boys or between mentally-active sedentary behaviour and later depressive symptoms. Limitations: The parental report of behaviours and the assessment of mediators and outcome in the same wave are the main limitations. Conclusion: Future interventions aiming to improve mental health among girls could aim to reduce mentally-passive sedentary behaviour in early teens and could target potential mediators including BMI. MRC Epidemiology Unit and Centre for Diet and Activity Research (CEDAR) School of Clinical Medicine Institute of Metabolic Science Cambridge Biomedical Campus University of Cambridge Department of Physical Education Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP) Food & Mood Centre Centre for Innovation in Mental and Physical Health and Clinical Treatment School of Medicine Faculty of Health Deakin University Department of Psychological Medicine Institute of Psychiatry Psychology and Neuroscience King's College London, De Crespigny Park Maudsley NHS Foundation Trust Department of Physical Education Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP)

Acknowledgements: We thank the participants in the SWS for their commitment to and involvement in the study, and the dedicated team of research nurses and ancillary staff for their assistance in collecting and processing the data. The authors would also like to thank Stephanie Hollidge (MRC Epidemiology Unit) for her assistance in the processing of the physical activity data., Funder: Medical Research Council; funder-id: http://dx.doi.org/10.13039/501100000265, Funder: British Heart Foundation, Funder: Food Standards Agency; funder-id: http://dx.doi.org/10.13039/501100000354, Funder: British Lung Foundation; funder-id: http://dx.doi.org/10.13039/501100000351, Funder: Arthritis Research UK, Funder: National Osteoporosis Society; funder-id: http://dx.doi.org/10.13039/501100000300, Funder: International Osteoporosis Foundation; funder-id: http://dx.doi.org/10.13039/501100007478, Funder: Cohen Trust, Funder: NIHR Southampton Biomedical Research Centre, Funder: National Institute of Health Research Musculoskeletal Biomedical Research Unit, Oxford, Funder: National Institute of Health Research Musculoskeletal Biomedical Research Unit, BACKGROUND: Physical activity (PA) has many health benefits, but motherhood is often associated with reduced PA. Considering that ages and number of children may be associated with maternal PA, and that PA patterns may change as children transition to formal schooling, we aimed to investigate the associations between ages and number of children and device-measured maternal PA. METHODS: Cross-sectional analyses were conducted using data from 848 mothers from the Southampton Women's Survey at two different timepoints. Two-level random intercept linear models were used to investigate associations between ages (≤4y(ears) ("younger"), school-aged, both age groups) and number (1, 2, ≥3) of children, and their interaction, and accelerometer-assessed minutes of maternal moderate or vigorous PA (log-transformed MVPA) and light, moderate or vigorous PA (LMVPA). RESULTS: Women with any school-aged children engaged in more MVPA than those with only ≤4y (e.g. % difference in minutes of MVPA [95% confidence interval]: 46.9% [22.0;77.0] for mothers with only school-aged vs only ≤4y). Mothers with multiple children did less MVPA than those with 1 child (e.g. 12.5% [-1.1;24.3] less MVPA for those with 2 children). For mothers with multiple children, those with any school-aged children did less LMVPA than those with only ≤4y (e.g. amongst mothers with 2 children, those with only school-aged children did 34.0 [3.9;64.1] mins/day less LMVPA). For mothers with any ≤4y, those with more children did more LMVPA (e.g. amongst mothers with only ≤4y, those with 2 children did 42.6 [16.4;68.8] mins/day more LMVPA than those with 1 child). CONCLUSIONS: Mothers with multiple children and only children aged ≤4y did less MVPA. Considering that many of these women also did more LMVPA than mothers with fewer or older children, interventions and policies are needed to increase their opportunities for higher intensity PA to maximise health benefits. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04715945.

Peer reviewed: True, Schools play a significant role in promoting health and well-being and the reciprocal links between health and educational attainment are well-evidenced. Despite recognition of the beneficial impact of school-based health improvement programmes, significant barriers to improving health and well-being within schools remain. This study pilots a School Health Research Network in the South West of England (SW-SHRN), a systems-based health intervention bringing together schools, academic health researchers and public health and/or education teams in local authorities to share knowledge and expertise to improve the health and well-being of young people. A maximum of 20 secondary schools will be recruited to the pilot SW-SHRN. All students in Years 8 (age 12–13) and 10 (age 14–15) will be invited to complete a health and well-being questionnaire, generating a cohort of approximately 5000 adolescents. School environment questionnaires will also be completed with each school to build a regional picture of existing school health policies and programmes. Each school will be provided with a report summarising data for their students benchmarked against data for all schools in the network. Quantitative analysis will model associations between health risk behaviours and mental health outcomes and a qualitative process evaluation will explore the feasibility and sustainability of the network. This study will create adolescent health data to help provide schools and local authorities with timely and robust information on the health and well-being of their students and help them to identify areas in which public health interventions may be required. SW-SHRN will also help public health professionals focus their resources in the areas most at need.

BackgroundCardiovascular health shows significant socioeconomic inequalities, however there is little understanding of the role of early adulthood in generation of these inequalities. We assessed the contribution of socioeconomic trajectories during early adulthood (16–24 years) to cardiovascular health in mid-adulthood (46 years).MethodsParticipants from the 1970 British Cohort Study with socioeconomic data available in early adulthood were included (n=12 423). Longitudinal latent class analysis identified socioeconomic trajectories, based on patterns of economic activity throughout early adulthood. Cardiometabolic risk factors (46 years) were regressed on socioeconomic trajectory class (16–24 years), testing mediation by adult socioeconomic position (46 years). Models were stratified by sex and adjusted for childhood socioeconomic position (SEP) and adolescent health.ResultsSix early adulthood socioeconomic trajectories were identified: (1) Continued Education (20.2%), (2) Managerial Employment (16.0%), (3) Skilled Non-manual Employment (20.9%), (4) Skilled Manual Employment (18.9%), (5) Partly Skilled Employment (15.8%) and (6) Economically Inactive (8.1%). The ‘Continued Education’ trajectory class showed the best cardiovascular health at age 46 years, with the lowest levels of cardiometabolic risk factors. For example, systolic blood pressure was 128.9 mm Hg (95% CI 127.8 to 130.0) among men in the ‘Continued Education’ class, compared with 131.3 mm Hg (95% CI 130.4 to 132.2) among men in the ‘Skilled Manual’ class. Patterns across classes 2–6 differed by risk factor and sex. The observed associations were largely not mediated by SEP at age 46 years.ConclusionFindings suggest an independent contribution of early adulthood socioeconomic trajectories to development of later life cardiovascular inequalities. Further work is needed to understand mediators of this relationship and potential for interventions to mitigate these pathways.

Funder: Cambridge Commonwealth, European and International Trust; doi: http://dx.doi.org/10.13039/501100003343, BACKGROUND: Cities globally have started to make substantial investment in more sustainable forms of transportation. We aimed to evaluate whether the construction of new cycling infrastructure in Paris and Lyon, France, affected population cycling activity along new or improved routes. METHODS: Routinely collected cycle count data from January 2014 to March 2020 were acquired for the cities of Paris and Lyon. Improvements were identified at 15 locations with 6 months of pre- and post-intervention data. Comparison streets were chosen within Paris or Lyon for which pre-intervention trends in cycling were similar to those at intervention sites. Controlled interrupted time series analyses and autocorrelation were performed adjusting for seasonality. Random-effects meta-analysis combined results across streets within each city and overall. RESULTS: On average, cycling counts/day increased on both intervention and control streets in Paris and Lyon. In general, results of the ITS analysis indicated no significant change in the level or trend as a result of the improvements in either city. Meta-analysis suggested that intervention streets in Paris had a larger positive pooled effect size for level change (218 cycle counts, 95% CI -189, 626, I2 = 0%) compared to Lyon (34, 95% CI -65, 133, I2 = 14%); however, confidence intervals for both cities were wide and included no effect. CONCLUSIONS: The findings suggest that improving or constructing new cycle lanes may be necessary but not sufficient to induce significant changes in cycling levels. There is a need to understand how context, intervention design and other complementary interventions can improve the effectiveness of new cycling infrastructure., CX is funded by the Cambridge Commonwealth, European, and International Trust. SS, EvS, DO, and JP are supported by the Medical Research Council (Unit Programme number MC_UU_00006/7, MC_UU_12015/6 and MC_UU_12015/7). No funder had any role in the study design; data collection, analysis, or interpretation; in the writing of the report; or in the decision to submit the article for publication.

ObjectivesTo investigate associations of bedtimes and sleep durations with adiposity levels in children and adolescents.MethodsIndividual data were pooled for 12 247 children (5819 with follow-up adiposity at 2.3 ± 1.4 years post-baseline) and 3563 adolescents from 11 international studies. Associations between questionnaire-based sleep durations, bedtimes and four groups of combined bedtimes and sleep lengths (later-shorter [reference]/earlier-shorter/later-longer/earlier-longer) with measured adiposity (body mass index [BMI] and waist circumference z-scores) and weight status, were investigated.ResultsIn children, longer sleep durations were consistently associated with lower adiposity markers, and earlier bedtimes were related to lower BMI z-score. Compared to sleeping ConclusionsIf the associations are causal, longer sleep duration and earlier bedtimes should be targeted for obesity prevention, emphasizing longer sleep for children and earlier bedtimes for adolescents.

Highlights • Physical activity is associated with increased aerobic fitness and academic performance. • Little is known on mechanism of physical activity effects on academic performance. • We performed a cluster randomized controlled trial. • Aerobic fitness mediated the intervention effect on academic performance. • Activity increasing aerobic fitness is a strategy to improve academic performance., Little information exists on the mechanism of how physical activity interventions effects academic performance. We examined whether the effects of a school-based physical activity intervention on academic performance were mediated by aerobic fitness. The School in Motion study was a nine-month cluster randomized controlled trial between September 2017 and June 2018. Students from 30 Norwegian lower secondary schools (N = 2,084, mean age [SD] = 14 [0.3] years) were randomly assigned into three groups: the Physically Active Learning (PAL) intervention (n = 10), the Don’t Worry—Be Happy (DWBH) intervention (n = 10), or control (n = 10). Aerobic fitness was assessed by the Andersen test and academic performance by national tests in reading and numeracy. Mediation was assessed according to the causal steps approach using linear mixed models. In the PAL intervention, aerobic fitness partially mediated the intervention effect on numeracy by 28% from a total effect of 1.73 points (95% CI: 1.13 to 2.33) to a natural direct effect of 1.24 points (95% CI: 0.58 to 1.91), and fully mediated the intervention effect on reading, with the total effect of 0.89 points (95% CI: 0.15 to 1.62) reduced to the natural direct effect of 0.40 points (95% CI: −0.48 to 1.28). Aerobic fitness did not mediate the effects on academic performance in the DWBH intervention. As aerobic fitness mediated the intervention effect on academic performance in one intervention, physical activity of an intensity that increases aerobic fitness is one strategy to improve academic performance among adolescents.

Our aim was to assess the association between changes in active travel to school and changes in different intensities of physical activity (i.e. moderate - MPA and vigorous - VPA) and time spent sedentary (SED) among adolescents and assess the moderating effect of children’s sex, age and weight status. Data from six cohort studies in the International Children’s Accelerometry Database were used (4108 adolescents aged 10–13y at baseline, with 1.9±0.7y of follow-up). Participants self-reported travel mode to school at baseline and follow-up. Mutually exclusive categories of change were created using passive (e.g. by car) or active (cycling or walking) forms of transport (active/active, passive/active, active/passive, passive/passive). Multilevel linear regression analyses assessed associations with change in accelerometer-assessed time spent MPA, VPA and SED, adjusting for potential confounders. The moderation of sex, age and weight status was tested though the inclusion of interaction terms in the regression models. Relative to those remaining in active travel (active/active), participants classified as passive/active increased VPA (B: 2.23 min/d; 95%CI: 0.97–3.48), while active/passive (MPA: −5.38min/d; −6.77 to −3.98; VPA: −2.92min/d; −4.06 to −1.78) and passive/passive (MPA: −4.53min/d; −5.55 to −3.50; VPA: −2.84min/d; −3.68 to −2.01) decreased MPA and VPA. There were no associations with SED. An interaction was observed, age group moderated the association with change in VPA: among 12–13y-olds a greater increase in VPA was observed for the passive/active group compared to active/active. Promoting active travel to school can be a strategy to attenuate the decline in physical activity through adolescence.

Funder: Sue and Bob O'Donnell, Summary: Biases introduced in early���stage studies can lead to inflated early discoveries. The risk of generalizability biases (RGBs) identifies key features of feasibility studies that, when present, lead to reduced impact in a larger trial. This meta���study examined the influence of RGBs in adult obesity interventions. Behavioral interventions with a published feasibility study and a larger scale trial of the same intervention (e.g., pairs) were identified. Each pair was coded for the presence of RGBs. Quantitative outcomes were extracted. Multilevel meta���regression models were used to examine the impact of RGBs on the difference in the effect size (ES, standardized mean difference) from pilot to larger scale trial. A total of 114 pairs, representing 230 studies, were identified. Overall, 75% of the pairs had at least one RGB present. The four most prevalent RGBs were duration (33%), delivery agent (30%), implementation support (23%), and target audience (22%) bias. The largest reductions in the ES were observed in pairs where an RGB was present in the pilot and removed in the larger scale trial (average reduction ES ���0.41, range ���1.06 to 0.01), compared with pairs without an RGB (average reduction ES ���0.15, range ���0.18 to ���0.14). Eliminating RGBs during early���stage testing may result in improved evidence.

School active travel contributes to young people's physical activity levels, yet the prevalence is low, and declines with age. Based on determinants from the social-ecological model we investigated changes in school travel behaviour over the transition from childhood to adolescence in participants from the baseline and four-year follow-up of the SPEEDY cohort. Descriptive analysis examined how travel behaviours changed and were related to physical activity. Multinomial logistic regression investigated determinants. Some 38% of participants changed travel mode; 66% from active to passive. Passively traveling participants at follow-up showed a decrease in physical activity. Several social-ecological domains were associated with change. Findings suggest multicomponent interventions are required to support active travel in youth.

Funder: UK Clinical Research Collaboration; Id: http://dx.doi.org/10.13039/100011417, Funder: Wellcome Trust; Id: http://dx.doi.org/10.13039/100010269, Funder: National Institute for Health Research; Id: http://dx.doi.org/10.13039/501100000272, Funder: Economic and Social Research Council; Id: http://dx.doi.org/10.13039/501100000269, Funder: Cancer Research UK; Id: http://dx.doi.org/10.13039/501100000289, Funder: British Heart Foundation; Id: http://dx.doi.org/10.13039/501100000274, Funder: NIHR School for Public Health Children, Young people and Families Programme, Summary: This review aims to systematically identify and synthesize qualitative data on adolescents' experiences of the barriers to and facilitators of physical activity to understand whether these differ by socioeconomic position. Multiple databases (MEDLINE, Web of Science Core Collection, PsycINFO, and ERIC) were searched in August 2020. Duplicate title/abstract and full text screening was conducted. Studies were included if they reported qualitative data collected from adolescents (aged 10���19), a measure of socioeconomic position and focused on physical activity. Studies not published in English or published before 2000 were excluded. Relevant data were extracted and methodological quality assessed (in duplicate). Data were analyzed using Thomas and Harden's methods for the thematic synthesis. Four analytical themes emerged from the 25 included studies: (1) social support, (2) accessibility and the environment, (3) other behaviors and health, and (4) gendered experiences. These themes appeared across socioeconomic groups; however, their narratives varied significantly. For example, provision and access to local facilities was discussed as a facilitator to middle and high socioeconomic adolescents, but was a barrier to low socioeconomic adolescents. These findings can be used to inform how different socioeconomic groups may benefit from, or be disadvantaged by, current interventions.

Background Insufficient sleep is a public health problem, particularly among adolescents, where sleep duration is often lower than recommended. Insufficient sleep has been associated with weight gain and metabolic dysregulation, with one suggested mechanism being via a reduction in diet quality. To date however, findings have been based on either laboratory studies, which do not reflect variation seen in free-living populations, or observational analyses of cross-sectional associations between usual sleep timings and habitual diet, which are unable to support inferences about the possible direction of causality. In this analysis we use daily measures of sleep timings and diet quality to investigate the associations between each night of sleep and diet quality on the subsequent day, allowing us to assess short-term unidirectional associations over time. Methods Data are from the ROOTS study, a prospective cohort study recruited from secondary schools in Cambridgeshire and Suffolk (UK). Participants (n = 872) who took part in a sub-study at mean age 15.0y (SD 0.3y) completed a diet diary and wore a combined heart rate monitor and accelerometer over 4 consecutive days. Sleep onset and termination times were determined from review of accelerometer and heart rate traces, and sleep duration and midpoint calculated for each night of data. Daily energy density and daily energy-adjusted fruit and vegetable intakes were derived from diet diaries. Multilevel, random effects models were used to test associations between daily sleep and subsequent day diet, with daily measures nested within individuals and schools, and adjusted for sex, socioeconomic status and day of week. We additionally tested for confounding by daily physical activity energy expenditure, also measured using the combined heart rate monitor and accelerometer. Results Adolescents slept a mean of 7.9hrs (SD 1.0hr) per night, reporting a mean energy density of 2.09 kcal/g (SD 0.44) and median energy-adjusted daily fruit and vegetable intake of 111.2g (IQR 52.1;202.0). A one hour longer sleep duration was associated with reduced energy density of diet (-0.017 kcal/g, 95%CI -0.034, -0.003), and greater daily intake of fruit and vegetables (7.14 g, 95%CI 3.07, 11.21) the following day. Sleep midpoint did not show significant associations with either energy density diet (-0.001 kcal/g, 95%CI -0.021, 0.019) or fruit and vegetable intake (-4.39 g, 95%CI -9.28, 0.50). Adjustment of models for daily physical activity did not substantially alter the findings. Conclusion Longer sleep is associated with better diet quality the following day in this cohort of adolescents. This study supports the consideration of sleep duration when designing interventions to promote a healthy diet among adolescents.

Background Family-based physical activity promotion presents a promising avenue for promoting whole-family physical activity, but high-quality research is lacking. Objectives To assess the feasibility, acceptability and preliminary effectiveness of FRESH (Families Reporting Every Step to Health), a child-led online family-based physical activity intervention; and to identify effective and resource-efficient family recruitment strategies. Design The project consisted of (1) a randomised feasibility trial, (2) a randomised controlled pilot trial and (3) a systematic review and Delphi study. Setting Norfolk/Suffolk counties, UK. Participants Families, recruited from schools, workplaces and community settings, were eligible to participate if one child aged 7–11 years and one adult responsible for their care provided written consent; all family members could participate. Interventions The FRESH intervention, guided by self-determination theory, targeted whole families and was delivered via an online platform. All family members received pedometers and were given website access to select family step challenges to ‘travel’ to target cities around the world, log steps, and track progress as they virtually globetrotted. Families were randomised to FRESH intervention, pedometer-only or control arm. Main outcome measures Physical (e.g. blood pressure), psychosocial (e.g. family functioning) and behavioural (e.g. device-measured family physical activity) measures were collected at baseline and at 8- and 52-week follow-up. A mixed-methods process evaluation assessed the acceptability of the intervention and evaluation. Data sources review Systematic search of four databases (Cochrane Library, PubMed, PsycINFO and SCOPUS). Review methods Articles were screened in duplicate, and data extraction was fully checked. Academic experts participated in the three-round Delphi study. Data were combined to identify effective and resource-efficient family recruitment strategies. Inclusion criteria Included generally healthy school-aged children and at least one adult; intervention attempted to change physical activity, sedentary behaviour, screen use, diet, or prevent overweight/obesity in multiple family members; presented relevant measure of effect in children and adults. Results The feasibility study (12 families, 32 participants; 100% retention at 8 weeks) demonstrated the feasibility and acceptability of FRESH, but highlighted that adaptations were required. Of 41 families recruited in the pilot study (149 participants), 98% and 88% were retained at the 8-week and 52-week follow-up, respectively. More children in the FRESH arm self-reported doing more family physical activity, and they thought that FRESH was fun. There were no notable between-group differences in children’s outcomes. Change in moderate to vigorous physical activity at 8 weeks favoured FRESH intervention adults [vs. control: 9.4 minutes/week (95% confidence interval 0.4 to 18.4) vs. pedometer only: 15.3 (95% confidence interval 6.0 to 24.5)], and was stronger in fathers, but this was not maintained. In 49 included studies, apart from recruitment settings and strategies used (reported in 84% and 73% of the studies, respectively), recruitment details were scarce. School-based recruitment was predominant. The Delphi study identified a wide range of recruitment settings and strategies. Limitations Recruitment was the main limitation of the FRESH studies; generalisability of the proposed recruitment strategies may be limited. Conclusions This study has demonstrated the feasibility and acceptability of the FRESH intervention. However, we failed to recruit the target sample size and were unable to demonstrate a signal of effectiveness. Future research should employ a multifaceted recruitment approach. Future work Further refinements to intervention delivery and recruitment methods should be investigated. Study registration Current Controlled Trials ISRCTN12789422 and PROSPERO CRD42019140042. Funding This project was funded by the National Institute for Health Research (NIHR) Public Health Research programme and will be published in full in Public Health Research; Vol. 9, No. 9. See the NIHR Journals Library website for further project information.

Background While active travel policies may positively affect health and the environment, evidence suggests small or inconsistent effects in these policies in changing travel behaviour. To identify which types of interventions are more effective, this systematic review and meta-analysis aims to (1) compare the effectiveness of positive (‘carrot’) strategies, negative (‘stick’) strategies, or a combination of the two on modifying travel behaviour and (2) assess which functions have greater impacts on travel outcomes. Methods Nine databases were searched for controlled before-and-after studies of population-level interventions and travel behaviour (e.g. driving, active travel, public transit, walking, and cycling) from adults in the general population. Interventions were categorized into functions (how the intervention seeks to affect behaviour). Depending on whether gains or losses of functions could occur, interventions were classified as carrots (e.g. new bikeshare programs), combined carrot and stick (e.g. traffic calming), or stick interventions (e.g. congestion charging). Harvest plots were used to visually summarize the findings weighted by study quality. Where possible, outcomes were converted into standardized mean differences (SMD) and random-effects meta-analyses were conducted. Results We extracted data from 83 publications reporting 98 interventions. From these, we identified 20 intervention types and eight function categories. The majority of interventions were carrots (n=64), followed by carrot and stick (n=17) and stick (n=17). Harvest plots demonstrated that most evaluations, particularly those classified as higher quality, found changes in favour of the intervention. Results for carrot interventions, however, were more less consistent than for stick or combined interventions. This was consistent with findings from the meta-analysis, which were statistically nonsignificant but had point-estimates of greater magnitude for driving outcomes for sticks (SMD -0.21; 95%CI -0.43, 0.01) and combined carrot and stick interventions (-0.17; -0.65, 0.31) compared to carrots (-0.09; -0.21, 0.03). Likewise, for active travel outcomes, combined carrot and stick interventions had a higher SMD (0.39; -0.01, 0.78) compared to carrot interventions (0.10; -0.06, 0.25). Financial functions were found to be the most effective for driving outcomes, whereas access, convenience, safety, and space were more effective for active travel outcomes. Discussion This is the first review to compare whether positive, negative, or combined strategies and their functions differ in terms of effectiveness on travel behaviour, which can aid policymakers in designing sustainable transportation policies. Further research is needed for interventions with a stick component, which suggest greater effectiveness yet remain less well-studied, possibly because they are less conducive to experimental manipulation.

Young people aged 10-24 years constitute 24% of the world's population; investing in their health could yield a triple benefit-eg, today, into adulthood, and for the next generation. However, in physical activity research, this life stage is poorly understood, with the evidence dominated by research in younger adolescents (aged 10-14 years), school settings, and high-income countries. Globally, 80% of adolescents are insufficiently active, and many adolescents engage in 2 h or more daily recreational screen time. In this Series paper, we present the most up-to-date global evidence on adolescent physical activity and discuss directions for identifying potential solutions to enhance physical activity in the adolescent population. Adolescent physical inactivity probably contributes to key global health problems, including cardiometabolic and mental health disorders, but the evidence is methodologically weak. Evidence-based solutions focus on three key components of the adolescent physical activity system: supportive schools, the social and digital environment, and multipurpose urban environments. Despite an increasing volume of research focused on adolescents, there are still important knowledge gaps, and efforts to improve adolescent physical activity surveillance, research, intervention implementation, and policy development are urgently needed.

Funder: Cancer Research UK, Funder: British Heart Foundation, IntroductionSchool-based active mile initiatives such as The Daily Mile (TDM) are widely promoted to address shortfalls in meeting physical activity recommendations. The iMprOVE Study aims to examine the impact of TDM on children's physical and mental health and educational attainment throughout primary school. METHODS AND ANALYSIS: iMprOVE is a longitudinal quasi-experimental cohort study. We will send a survey to all state-funded primary schools in Greater London to identify participation in TDM. The survey responses will be used for non-random allocation to either the intervention group (Daily Mile schools) or to the control group (non-Daily Mile schools). We aim to recruit 3533 year 1 children (aged 5-6 years) from 77 primary schools and follow them up annually until the end of their primary school years. Data collection taking place at baseline (children in school year 1) and each primary school year thereafter includes device-based measures of moderate-to-vigorous physical activity (MVPA) and questionnaires to measure mental health (Strengths and Difficulties Questionnaire) and educational attainment (ratings from 'below expected' to 'above expected levels'). The primary outcome is the mean change in MVPA minutes from baseline to year 6 during the school day among the intervention group compared with controls. We will use multilevel linear regression models adjusting for sociodemographic data and participation in TDM. The study is powered to detect a 10% (5.5 min) difference between the intervention and control group which would be considered clinically significant.Ethics and disseminationEthics has been approved from Imperial College Research Ethics Committee, reference 20IC6127. Key findings will be disseminated to the public through research networks, social, print and media broadcasts, community engagement opportunities and schools. We will work with policy-makers for direct application and impact of our findings.

Background School-based physical activity interventions such as The Daily Mile (TDM) are widely promoted in children’s physical activity guidance. However, targeting such interventions to areas of greatest need is challenging since determinants vary across geographical areas. Our study aimed to identify local authorities in England with the greatest need to increase children’s physical activity and assess whether TDM reaches school populations in areas with the highest need. Methods This was a cross-sectional study using routinely collected data from Public Health England. Datasets on health, census and the built environment were linked. We conducted a hierarchical cluster analysis to group local authorities by ‘need’ and estimated the association between ‘need’ and registration to TDM. Results We identified three clusters of high, medium and low need for physical activity interventions in 123 local authorities. Schools in high-need areas were more likely to be registered with TDM (incidence rate ratio 1.25, 95% confidence interval: 1.12–1.39) compared with low-need areas. Conclusions Determinants of children’s physical activity cluster geographically across local authorities in England. TDM appears to be an equitable intervention reaching schools in local authorities with the highest needs. Health policy should account for clustering of health determinants to match interventions with populations most in need.

Made available in DSpace on 2021-06-25T10:22:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-01 National Institute for Health Research Wellcome Trust King's College London United Kingdom Clinical Research Collaboration Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Medical Research Council It is unclear if different types of sedentary behaviour during the adolescence are differentially associated with psychological distress during adolescence and adulthood. It is also unknown what may mediate this potential proposed association. The current study aimed to analyse the association of mentally-active and mentally-passive sedentary behaviours during adolescence (16y) with subsequent psychological distress during adulthood (42y), and to examine the role of potential mediators (42y). Data from the 1970 British Cohort Study was used (N = 1787). At age 16y participants reported time and frequency in mentally-passive (TV-viewing and watching movies) and mentally-active (reading books, doing homework and playing computer games) sedentary behaviours, psychological distress and organized sports participation. At 42y, participants reported cognition (vocabulary test), TV-viewing, psychological distress, self-rated health, body mass index and employment status. Education was collected throughout the follow-up years. Logistic regression and mediation models assessed associations. Multiple imputation using chained equations was used to assess the impact of missing data. Mentally-passive sedentary behaviour in adolescence was a risk factor for psychological distress during adulthood in complete-cases analysis [OR:1.44(95%CI:1.09–1.90)], which was confirmed by the model with multiple imputation. Mentally-active sedentary behaviour at 16y was not associated with psychological distress at 42y. Adult TV-viewing during weekends (24.7%), and self-rated health (19.0%) mediated the association between mentally-passive sedentary behaviour during adolescence and psychological distress during adulthood. However, the mediation was not clear in the models with multiple imputation. Mentally-passive sedentary behaviour during adolescence was associated with elevated psychological distress during adulthood and this association was mediated TV-viewing and self-rated health in adulthood. MRC Epidemiology Unit and Centre for Diet and Activity Research (CEDAR) University of Cambridge Department of Physical Education Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP) Food & Mood Centre Centre for Innovation in Mental and Physical Health and Clinical Treatment School of Medicine Faculty of Health Deakin University Department of Psychological Medicine Institute of Psychiatry Psychology and Neuroscience King's College London, De Crespigny Park, Box SE5 8AF Deakin University IMPACT Strategic Research Centre School of Medicine Barwon Health South London and Maudsley NHS Foundation Trust Department of Physical Education Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP) United Kingdom Clinical Research Collaboration: 087636/Z/08/Z FAPESP: 2018/19183-1 United Kingdom Clinical Research Collaboration: ES/G007462/1 Medical Research Council: MC_UU_12015/7 United Kingdom Clinical Research Collaboration: MR/K023187/1

BACKGROUND: We systematically identified effective and resource-efficient strategies for recruiting families into health promoting intervention research. METHODS: Four databases were searched for reviews. Interventions were extracted from included reviews. Additionally, a Delphi study was conducted with 35 experts in family-based research. We assessed extracted data from our review and Delphi participants’ opinions by collating responses into overarching themes based on recruitment setting then recruitment strategies to identify effective and resource-efficient strategies for recruiting families into intervention research. RESULTS: A total of 64 articles (n= 49 studies) were included. Data regarding recruitment duration (33%), target sample size (32%), reach (18%), expressions of interest (33%), and enrolment rate (22%) were scarcely reported. Recruitment settings (84%) and strategies (73%) used were available for most studies. However, the details were vague, particularly regarding who was responsible for recruitment or how recruitment strategies were implemented. The Delphi showed recruitment settings and strategies fell under 6 themes: school-based, print/electronic media, community settings-based, primary care-based, employer-based, and referral-based strategies. CONCLUSIONS: Under-recruitment in family-based trials is a major issue. Reporting on recruitment can be improved by better adherence to existing guidelines. Our findings suggest a multifaceted recruitment approach targeting adults and children with multiple exposures to study information.

South Africa (SA) launched their 24-h movement guidelines for birth to five years in December 2018. The guideline dissemination plan adopted a “train-the-trainer” strategy through dissemination workshops with community-based organisations (CBOs) working in early childhood development. The aim of this paper is to: (1) document this dissemination process, and (2) report on the feasibility of implementing the dissemination workshops, the acceptability of the workshops (and guidelines) for different end-user groups, and the extent to which CBO representatives disseminated the guidelines to end-users. Fifteen workshops were held in seven of SA’s nine provinces with a total of 323 attendees. Quantitative and qualitative findings (n = 281) indicate that these workshops were feasible for community-based dissemination of the guidelines and that this method of dissemination was acceptable to CBOs and end-users. Findings from follow-up focus groups (6 groups, n = 28 participants) indicate that the guidelines were shared with end-users of CBOs who participated in the focus groups. An additional musical storytelling resource, the “Woza, Mntwana” song, was well-received by participants, sharing via WhatsApp was believed to be the most effective way to disseminate this song. These findings confirm the feasibility and acceptability of culturally appropriate and context-specific community-based dissemination of behavioural guidelines in low-income settings.

Introduction Around 23% of adults worldwide are insufficiently active. Wearable devices paired with virtual coaching software could increase physical activity. The effectiveness of 3 minimal contact interventions (paper-based physical activity diaries, activity trackers, and activity trackers coupled with virtual coaching) in increasing physical activity energy expenditure and cardiorespiratory fitness were compared over 12 weeks among inactive adults. Methods This was an open label, parallel-group RCT. Inactive adults (aged ≥18 years, N=488) were randomized to no intervention (Control; n=121), paper-based diary (Diary; n=124), activity tracker (Activity Band; n=122), or activity tracker plus virtual coaching (Activity Band PLUS; n=121) groups. Coprimary outcomes included 12-week changes in physical activity energy expenditure and fitness (May 2012–January 2014). Analyses were conducted in 2019–2020. Results There were no differences between groups overall (physical activity energy expenditure: p=0.114, fitness: p=0.417). However, there was a greater increase in physical activity energy expenditure (4.21 kJ/kg/day, 95% CI=0.42, 8.00) in the Activity Band PLUS group than in the Diary group. There were also greater decreases in BMI and body fat percentage in the Activity Band PLUS group than in the Control group (BMI= −0.24 kg/m2, 95% CI= −0.45, −0.03; body fat= −0.48%, 95% CI= −0.88, −0.08) and in theActivity Band PLUS group than in the Diary group (BMI= −0.30 kg/m2, 95% CI= −0.50, −0.09; body fat= −0.57%, 95% CI= −0.97, −0.17). Conclusions Coupling activity trackers with virtual coaching may facilitate increases in physical activity energy expenditure compared with a traditional paper‒based physical activity diary intervention and improve some secondary outcomes compared with a traditional paper‒based physical activity diary intervention or no intervention. Trial registration This study is registered at www.clinicaltrials.gov ISRCTN31844443.

Funder: National Research Foundation; doi: http://dx.doi.org/10.13039/501100001321; Grant(s): UID:98561, Background: Nurturing care interventions have the potential to promote health and development in early childhood. Amagugu Asakhula was designed to promote developmentally important dietary and movement behaviours among children of preschool age (3–5 years) in South Africa. An initial formative study in Cape Town found the intervention to be feasible and acceptable when delivered by community health workers (CHWs) linked to a community-based organisation. This study evaluated the delivery of the Amagugu Asakhula intervention by CHWs linked to a public sector primary health care facility in Soweto, as this mode of delivery could have more potential for sustainability and scalability. Methods: A qualitative design was utilised to assess feasibility, acceptability, adoption, appropriateness, implementation, fidelity and context. CHWs (n = 14) delivered the intervention to caregivers (n = 23) of preschool-age children in Soweto over 6 weeks. Following the completion of the intervention, focus group discussions were held with CHWs and caregivers. Further data were obtained through observations, study records and key informant interviews (n = 5). Data were analysed using deductive thematic analysis guided by a process evaluation framework. Results: The delivery of the Amagugu Asakhula intervention through CHWs linked to a primary health care facility in Soweto was not found to be feasible due to contextual challenges such as late payment of salaries influencing CHW performance and willingness to deliver the intervention. CHWs expressed dissatisfaction with their general working conditions and were thus reluctant to take on new tasks. Despite barriers to successful delivery, the intervention was well received by both CHWs and caregivers and was considered a good fit with the CHWs’ scope of work. Conclusions: Based on these findings, delivery of the Amagugu Asakhula intervention is not recommended through public sector CHWs in South Africa. This feasibility study informs the optimisation of implementation and supports further testing of the intervention’s effectiveness when delivered by CHWs linked to community-based organisations. The present study further demonstrates how implementation challenges can be identified through qualitative feasibility studies and subsequently addressed prior to large-scale trials, avoiding the wasting of research and resources.

Purpose We examined the association between the school policy, social and physical environment and change in adolescent physical activity (PA) and explored how sex and socioeconomic status modified potential associations. Methods Data from the GoActive study were used for these analyses. Participants were adolescents (n = 1765, mean age±SD 13.2±0.4y) from the East of England, UK. Change in longitudinal accelerometer assessed moderate-to-vigorous physical activity (MVPA) was the outcome. School policy, social and physical environment features (n = 267) were exposures. The least absolute shrinkage and selection operator variable selection method (LASSO) was used to determine exposures most relevant to the outcome. Exposures selected by the LASSO were added to a multiple linear regression model with estimates of change in min/day of MVPA per 1-unit change in each exposure reported. Post-hoc analyses, exploring associations between change in variables selected by the LASSO and change in MVPA, were undertaken to further explain findings. Findings No school policy or physical environment features were selected by the LASSO as predictors of change in MVPA. The LASSO selected two school social environment variables (participants asking a friend to do physical activity; friend asking a participant to do physical activity) as potential predictors of change in MVPA but no significant associations were found in subsequent linear regression models for all participants (β [95%CI] -1.01 [-2.73;0.71] and 0.65 [-2.17;0.87] min/day respectively). In the post-hoc analyses, for every unit increase in change in participants asking a friend to do PA and change in a friend asking participants to do PA, an increase in MVPA of 2.78 (1.55;4.02) and 1.80 (0.48;3.11) min/day was predicted respectively. Conclusions The school social environment is associated with PA during adolescence. Further exploration of how friendships during adolescence may be leveraged to support effective PA promotion in schools is warranted.

Highlights • Starting cohabitation and getting married were associated with increased BMI. • Findings were mixed for the effect of starting cohabitation/marriage on PA. • Limited evidence for the effect of starting cohabitation/marriage on diet., Our aim was to systematically review the effect of cohabitation and marriage on physical activity, diet and weight-related outcomes during emerging adulthood. A systematic search of six electronic databases was conducted until July 2019 (PROSPERO:CRD42018106943). Prospective studies were included if data were presented for a weight-related outcome, physical activity, and/or diet among 15–35 years-old participants assessed pre- and post-cohabitation or marriage and compared to a consistently non-cohabiting/non-married (single) reference group. Following title/abstract screening, two reviewers independently screened full-text and assessed risk of bias. There were 11 studies that met inclusion criteria. Outcomes included: body mass index (BMI) only (n = 3), physical activity only (n = 4), diet only (n = 2), BMI and physical activity (n = 1), and all outcomes (n = 1). Cohabitation or marriage was associated with greater BMI increases compared to remaining single among both men and women. Three studies analysed separately cohabitation and marriage and 3 of 4 found that only marriage was associated with higher BMI. Compared to being consistently single, starting cohabitation or getting married were associated with decreased physical activity in 2 of 4 studies among men and 4 of 6 studies among women, with no differences between marriage and cohabitation. Of the three studies examining change in diet, two showed no difference between individuals beginning to cohabit compared to those remaining single; without gender differences. Starting cohabitation and getting married may be valuable targets for weight management interventions, but more studies are needed to investigate the effect of cohabitation and marriage on health behaviours.

Background Despite a growing body of evidence suggesting that short sleep duration may be linked to adverse metabolic outcomes, how these associations differ between age groups remains unclear. We use eight years of data from the UK National Diet and Nutritional Survey (NDNS) (2008–2016) to analyse cross-sectional relationships between sleep duration and metabolic risk in participants aged 11–70 years. Methods Participants (n = 2008) who provided both metabolic risk and sleep duration data were included. Self-reported sleep duration was standardised by age, to account for differences in age-related sleep requirements. A standardised metabolic risk score was constructed, comprising: waist circumference, blood pressure, serum triglycerides, serum high-density lipoprotein cholesterol, and fasting plasma glucose. Regression models were constructed across four age groups from adolescents to older adults. Results Overall, decreased sleep duration (hrs) was associated with an increased metabolic risk (standard deviations) with significant quadratic (B:0.028 [95%CI: 0.007, 0.050]) and linear (B:-0.061 [95%CI: -0.111, -0.011]) sleep duration coefficients. When separated by age group, stronger associations were seen among mid-aged adults (36-50y) (quadratic coefficient: 0.038 [95%CI: 0.002, 0.074]) compared to other age groups (e.g. adolescents (11-18y), quadratic coefficient: -0.009 [95%CI: -0.042, 0.025]). An increased difference between weekend and weekday sleep was only associated with increased metabolic risk in adults aged 51–70 years (B:0.18 [95%CI: 0.005, 0.348]). Conclusions Our results indicate that sleep duration is linked to adverse metabolic risk and suggest heterogeneity between age groups. Longitudinal studies with larger sample sizes are required to explore long-term effects of abnormal sleep and potential remedial benefits.

Objective:Childhood obesity is of increasing concern in South Africa, and interventions to promote healthy behaviours related to obesity in children are needed. Young children in urban low-income settings are particularly at risk of excess adiposity. The current study aimed to describe how parents of preschool children in an urban South African township view children’s movement and dietary behaviours, and associated barriers and facilitators.Design:A contextualist qualitative design was utilised with in-depth interviews conducted in the home setting and analysed using reflexive thematic analysis. Field notes were used to contextualise findings.Setting:Four neighbourhoods in a predominantly low-income urban township.Participants:Sixteen parents (fourteen mothers, two fathers) of preschool-age children were recruited via preschools.Results:Four themes were developed: children’s autonomy and the limits of parental control; balancing trust and fears; the appeal of screens; and aspirations and pressures of parenthood. Barriers to healthy behaviours included children’s food preferences, aspirations and pressures to consume unhealthy foods, other adults giving children snacks, lack of safe places to play, unhealthy food environments and underlying structural factors. Facilitators included set routines, the preschool environment, safe places to play and availability of healthy foods.Conclusions:Low-income families in Soweto face many structural challenges that cannot easily be addressed through public health interventions, but there may be opportunities for behavioural interventions targeting interpersonal and organisational aspects, such as bedtime routines and preschool snacks, to achieve positive changes. More research on preschoolers’ movement and dietary behaviours, and related interventions, is needed in South Africa.

Background Early adulthood is a period of rapid personal development when individuals experience major life transitions (e.g. leaving the parental home, leaving education, beginning employment, cohabitation and parenthood). Changes in social and physical environments associated with these transitions may influence development of health-related behaviours. Consumption of fast food is one behaviour associated with poor diet and long-term health outcomes. In this study we assess how frequency of fast food consumption changes across early adulthood, and how major life transitions are associated with changes in fast food intake. Methods Data were collected across four waves of the Project EAT study, from mean age 14.9 (SD = 1.6) to mean age 31.1 (SD = 1.6) years. Participants reporting data at two or more waves were included (n = 2902). Participants reported past week frequency of eating food from a fast food restaurant and responded to questions on living arrangements, education and employment participation, and having children. To assess changes in fast food we developed a latent growth model incorporating an underlying trajectory of fast food intake, five life transitions, and time-invariant covariates. Results Mean fast food intake followed an underlying quadratic trajectory, increasing through adolescence to a maximum of 1.88 (SE 0.94) times/week and then decreasing again through early adulthood to 0.76 (SE 2.06) times/week at wave 4. Beginning full-time employment and becoming a parent both contributed to increases in fast food intake, each resulting in an average increase in weekly fast food intake of 0.16 (p p = 0.004) and − 0.16 (p = 0.007) times/week respectively, while leaving full-time education was not associated with any change. Conclusions The transitions of beginning full-time employment and becoming a parent were associated with increases in fast food intake. Public health policy or interventions designed to reduce fast food intake in young adults may benefit from particular focus on populations experiencing these transitions, to ameliorate their impact.

There is good evidence that behavioural weight management interventions improve physical health, however the impact on mental health remains unclear. We evaluated the impact of behavioural weight management interventions on mental health-related outcomes in adults with overweight or obesity at intervention-end and 12-months from baseline. Eligible studies were randomised controlled trials (RCTs) or cluster-RCTs of adult behavioural weight loss interventions reporting affect, anxiety, binge-eating, body image, depression, emotional eating, quality of life, self-esteem, and stress. We searched seven databases from inception to 07/05/2019 and included 43 articles reporting 42 RCTs. Eighteen studies were deemed to be at high risk of bias. We conducted random-effects meta-analyses, stratified analyses, and meta-regression using Stata. Interventions generated greater improvements than comparators for depression, mental health-related quality of life, and self-efficacy at intervention-end and 12-months from baseline. There was no difference between groups for anxiety, overall quality of life, self-esteem, or stress at intervention-end. There was insufficient evidence to assess the impact on anxiety, binge-eating, body image, emotional eating, affect, life satisfaction, self-esteem, or stress at intervention-end and/or 12-months from baseline. While evidence suggests that interventions benefit some aspects of mental health, high-quality, transparently reported RCTs measuring a range of mental health outcomes over longer durations are required to strengthen the evidence base.

Funder: Cancer Research UK, Funder: British Heart Foundation, INTRODUCTION:This study assessed the feasibility and acceptability of FRESH (Families Reporting Every Step to Health), a theory-based child-led family physical activity (PA) intervention delivered online. We also assessed the preliminary effectiveness of the intervention on outcomes of interest and whether pre-specified criteria were met to progress to a full-scale definitive trial. METHODS:In a three-armed randomised pilot trial, 41 families (with a 7-11-year-old index child) were allocated to a: 'family' (FAM), 'pedometer-only' (PED), or a no-treatment control (CON) arm. The FAM arm received access to the FRESH website, allowing participants to select step challenges to 'travel' to target cities around the world, log their steps, and track progress as families virtually globetrot. FAM and PED arms also received family sets of pedometers. All family members could participate in the evaluation. Physical (e.g., fitness, blood pressure), psychosocial (e.g., social support), behavioural (e.g., objectively-measured PA), and economic (e.g., expenditure for PA) data were collected at baseline, 8- and 52-weeks. RESULTS:At 8- and 52-weeks, 98 and 88% of families were retained, respectively. Most children liked participating in the study (> 90%) and thought it was fun (> 80%). Compared to the PED (45%) and CON (39%) arms, a higher percentage of children in the FAM (81%) arm reported doing more activities with their family. Adults agreed that FRESH encouraged their family do more PA and made their family more aware of the amount of PA they do. No notable between-group differences were found for childrens' minutes in moderate-to-vigorous PA. Sizeable changes of 9.4 (95%CI: 0.4, 18.4) and 15.3 (95%CI: 6.0, 24.5) minutes in moderate-to-vigorous PA was found for adults in the FAM group compared to those in the PED or CON groups, respectively. No other notable differences were found. CONCLUSION:This study demonstrates feasibility and acceptability of the FRESH intervention. All progression criteria were at least partially satisfied. However, we failed to recruit the target sample size and did not find a signal of effectiveness on PA particularly long-term or in children. Further refinements are required to progress to a full-scale trial. TRIAL REGISTRATION:This study was prospectively registered ( ISRCTN12789422 ) on 16/03/2016.

Key Points Question Are mental health problems during childhood and adolescence associated with health behaviors during adolescence? Findings In this cohort study including 9369 participants, adolescents with self-reported mental health problems at both ages 7 years and 14 years and at age 14 years only were less likely to have at least 9 hours of sleep and to consume fruit and vegetables and reported greater use of social media compared with individuals who had no parent-reported mental health problems at age 7 years or self-reported problems at age 14 years. Meaning These findings suggest that mental health during childhood and adolescence was associated with health behavioral outcomes, and this should be considered in future efforts to improve health behaviors and in noncommunicable disease prevention efforts., This cohort study examines associations of reported mental health issues at ages 7 and 14 years with health behaviors in adolescence., Importance There is potential for mental health status to act as a determinant of an individual’s ability to engage in healthful lifestyle behaviors. Objective To investigate the associations of parent-reported mental health problems during childhood and self-reported mental health problems in adolescence with health behaviors in adolescence. Design, Setting, and Participants This cohort study used data from wave 4 (collected in 2008) and wave 6 (collected in 2015) of the Millennium Cohort Study, a UK population-representative longitudinal study of young people born during 2000 to 2001. Wave 4 included data on parent-reported mental health issues for children at age 7 years. Wave 6 included data on self-reported mental health problems as well as health behaviors for the same children at age 14 years. Data were analyzed July 5, 2020. Exposures Mental health problems at age 7 years were parent-reported using Strengths and Difficulties Questionnaire. Mental health problems at age 14 years were self-reported using the Short Mood and Feelings Questionnaire. Main Outcomes and Measures Health behaviors at age 14 years were the main outcome of interest. Sleep duration; fruit, vegetable, and soft drink consumption; and social media use were self-reported using recall on a typical day. Regression models were calculated for each lifestyle variable, with mental health change from ages 7 to 14 years as the exposure variable. Data were weighted to account for the potential clustering of region of sampling and adjusted for nonresponse. Results A total of 9369 participants were included in waves 4 and 6 of the Millennium Cohort Study, including 4665 (48.1%) girls and 6014 participants (81.9%) who were born in England. Adolescents who self-reported mental health problems at age 14 years only were less likely to have at least 9 hours of sleep (odds ratio [OR], 0.39; 95% CI, 0.34-0.45) and to consume fruit (OR, 0.55; 95% CI, 0.46-0.65) and vegetables (OR, 0.66; 95% CI, 0.52-0.83) reported greater use of social media (b = 0.62; 95% CI, 0.49-0.75) compared with individuals who did not have mental health problems at both time points. Similarly, those with mental health problems at both time points were less likely to achieve 9 hours sleep (OR, 0.68; 95% CI, 0.51-0.90), consume fruit (OR, 0.39; 95% CI, 0.26-0.58) and vegetables (OR, 0.57; 95% CI, 0.35-0.91), and reported greater social media use (b = 0.63; 95% CI, 0.34-0.91). Conclusions and Relevance These findings suggest that the presence of depressive symptoms at ages 7 and 14 years and at age 14 years only were associated with some health behaviors in adolescence. These findings are particularly important given that independent health behaviors can deteriorate and become habitual during adolescence, and adolescence is a known time for the first emergence of mental health problems that continue into adulthood.

BackgroundLess than 20% of adolescents globally meet recommended levels of physical activity, and not meeting these recommended levels is associated with social disadvantage and rising disease risk. The determinants of physical activity in adolescents are multilevel and poorly understood, but the school's social environment likely plays an important role. We conducted a cluster randomised controlled trial to assess the effectiveness of a school-based programme (GoActive) to increase moderate-to-vigorous physical activity (MVPA) among adolescents.Methods and findingsNon-fee-paying, co-educational schools including Year 9 students in the UK counties of Cambridgeshire and Essex were eligible for inclusion. Within participating schools (n = 16), all Year 9 students were eligible and invited to participate. Participants were 2,862 13- to 14-year-olds (84% of eligible students). After baseline assessment, schools were computer-randomised, stratified by school-level pupil premium funding (below/above county-specific median) and county (control: 8 schools, 1,319 participants, mean [SD] participants per school n = 165 [62]; intervention: 8 schools, 1,543 participants, n = 193 [43]). Measurement staff were blinded to allocation. The iteratively developed, feasibility-tested 12-week intervention, aligned with self-determination theory, trained older adolescent mentors and in-class peer-leaders to encourage classes to conduct 2 new weekly activities. Students and classes gained points and rewards for engaging in any activity in or out of school. The primary outcome was average daily minutes of accelerometer-assessed MVPA at 10-month follow-up; a mixed-methods process evaluation evaluated implementation. Of 2,862 recruited participants (52.1% male), 2,167 (76%) attended 10-month follow-up measurements; we analysed the primary outcome for 1,874 participants (65.5%). At 10 months, there was a mean (SD) decrease in MVPA of 8.3 (19.3) minutes in the control group and 10.4 (22.7) minutes in the intervention group (baseline-adjusted difference [95% confidence interval] -1.91 minutes [-5.53 to 1.70], p = 0.316). The programme cost £13 per student compared with control; it was not cost-effective. Overall, 62.9% of students and 87.3% of mentors reported that GoActive was fun. Teachers and mentors commented that their roles in programme delivery were unclear. Implementation fidelity was low. The main methodological limitation of this study was the relatively affluent and ethnically homogeneous sample.ConclusionsIn this study, we observed that a rigorously developed school-based intervention was no more effective than standard school practice at preventing declines in adolescent physical activity. Interdisciplinary research is required to understand educational-setting-specific implementation challenges. School leaders and authorities should be realistic about expectations of the effect of school-based physical activity promotion strategies implemented at scale.Trial registrationISRCTN Registry ISRCTN31583496.

Made available in DSpace on 2020-12-12T01:31:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-07-10 Background: We examined the association between family-related life events (cohabitation/marriage and becoming a parent) and change in physical activity. Methods: Longitudinal data (n = 8045) from the 1970 British Cohort Study (30 and 34 years) were included. Life events (beginning cohabitation/marriage and becoming a parent) were reported and coded: 0 no, 1 yes, for each event occurring between 30 and 34 years. Participants reported frequency of participation in leisure-time physical activity at 30 and 34 years (Likert scale: mean change calculated ranging between - 4 and 4). Linear regression models were used to examine the association between life events and physical activity change (comparing individuals experiencing events between 30 and 34 years versus never experiencing the event - excluding participants that experienced previous events - with a final analysis sample of n = 3833 in parenthood analysis; n = 1137 in cohabitation analysis). Interaction terms were used to analyse combined parenthood and cohabitation status. Analyses were adjusted for level of education achieved, ethnicity, country of origin and other life events. ANCOVA was used to examine associations between change in physical activity and child age. Results: Compared to remaining without children, becoming a parent was associated with a greater reduction in physical activity among men [β:-0.234(95%CI:-0.396 to - 0.072)] but not women [0.126(- 0.048;0.301)]. No associations were found between cohabitation and physical activity. Men who became fathers both while cohabitating [- 0.201(- 0.383;-0.020)] and without cohabiting [- 0.937(- 1.623;-0.250)] experienced greater physical activity declines than those remaining single and without children; the decline was greatest among non-cohabiting fathers. These associations did not differ by child age. Conclusions: Parenthood appears to differentially impact physical activity for men and women; this association also differs by cohabitation status. Parenthood appears to be most detrimental to physical activity levels among men. Interventions for physical activity could target new or soon-to-be parents, especially fathers. Further analyses with device-measured physical activity data would be valuable to advance understanding of these associations. Mrc Epidemiology Unit and Centre for Diet and Activity Research (CEDAR) University of Cambridge School of Clinical Medicine Institute of Metabolic Science Cambridge Biomedical Campus, Box 285 Department of Physical Education Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP) Department of Physical Education Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP)

Objectives Low and high birth weight is associated with higher levels of cardiometabolic risk factors and adiposity in children and adolescents, and increases the risk of cardiovascular diseases, obesity, and early mortality later in life. Moderate-to-vigorous physical activity (MVPA) is associated with lower cardiometabolic risk factors and may mitigate the detrimental consequences of high or low birth weight. Thus, we examined whether MVPA modified the associations between birth weight and cardiometabolic risk factors in children and adolescents. Methods We used pooled individual data from 12 cohort- or cross-sectional studies including 9,100 children and adolescents. Birth weight was measured at birth or maternally reported retrospectively. Device-measured physical activity (PA) and cardiometabolic risk factors were measured in childhood or adolescence. We tested for associations between birth weight, MVPA, and cardiometabolic risk factors using multilevel linear regression, including study as a random factor. We tested for interaction between birth weight and MVPA by introducing the interaction term in the models (birth weight x MVPA). Results Most of the associations between birth weight (kg) and cardiometabolic risk factors were not modified by MVPA (min/day), except between birth weight and waist circumference (cm) in children (p = 0.005) and HDL-cholesterol (mmol/l) in adolescents (p = 0.040). Sensitivity analyses suggested that some of the associations were modified by VPA, i.e., the associations between birth weight and diastolic blood pressure (mmHg) in children (p = 0.009) and LDL- cholesterol (mmol/l) (p = 0.009) and triglycerides (mmol/l) in adolescents (p = 0.028). Conclusion MVPA appears not to consistently modify the associations between low birth weight and cardiometabolic risk. In contrast, MVPA may mitigate the association between higher birth weight and higher waist circumference in children. MVPA is consistently associated with a lower cardiometabolic risk across the birth weight spectrum. Optimal prenatal growth and subsequent PA are both important in relation to cardiometabolic health in children and adolescents.

Background There is a need for high-quality research aiming to increase physical activity in families. This study assessed the feasibility and acceptability of FRESH (Families Reporting Every Step to Health), a child-led family-based physical activity intervention delivered online. Methods In a two-armed randomised feasibility study, 12 families (with an 8–10-year-old index child) were allocated to a ‘child-only’ (CO) or ‘family’ arm (FAM) of the theory-based FRESH intervention. Both received access to the FRESH website, allowing participants to select step challenges to ‘travel’ to target cities around the world, log their steps, and track their progress as they virtually globetrot. Only index children wore pedometers in CO; in FAM, all family members wore pedometers and worked towards collective goals. All family members were eligible to participate in the evaluation. Mixed-methods process evaluation (questionnaires and family focus groups) at 6-week follow-up consisted of completing questionnaires assessing acceptability of the intervention and accompanying effectiveness evaluation, focussed on physical (e.g. fitness, blood pressure), psychosocial (e.g. social support), and behavioural (e.g. objectively-measured family physical activity) measures. Results All families were retained (32 participants). Parents enjoyed FRESH and all children found it fun. More FAM children wanted to continue with FRESH, found the website easy to use, and enjoyed wearing pedometers. FAM children also found it easier to reach goals. Most CO families would have preferred whole family participation. Compared to CO, FAM exhibited greater website engagement as they travelled to more cities (36 ± 11 vs. 13 ± 8) and failed fewer challenges (1.5 ± 1 vs. 3 ± 1). Focus groups also revealed that most families wanted elements of competition. All children enjoyed being part of the evaluation, and adults disagreed that there were too many intervention measures (overall, 2.4 ± 1.3) or that data collection took too long (overall, 2.2 ± 1.1). Conclusion FRESH was feasible and acceptable to participating families; however, findings favoured the FAM group. Recruitment, intervention fidelity and delivery and some measurement procedures are particular areas that require further attention for optimisation. Testing the preliminary effectiveness of FRESH on family physical activity is a necessary next step. Trial registration This study was registered and given an International Standard Randomised Controlled Trials Number (ISRCTN12789422). Registered 16 March 2016. http://www.isrctn.com/ISRCTN12789422

The prevalence of overweight and obesity is high among preschool age (3–5 years) children in South Africa, and children in urban low-income settings are particularly at risk. A better understanding of how parents or caregivers of young children perceive children’s weight and size, as well as contextual factors influencing perceptions, is needed to inform interventions. The aim of this study was to examine how parents of preschool children in Soweto, South Africa, view childhood obesity, and to situate these perspectives in the context of the home environment in which preschool age children in Soweto live. Semi-structured in-depth interviews were conducted with 16 parents in four neighbourhoods of Soweto. Interviews were audio-recorded, transcribed verbatim, and analysed using reflexive thematic analysis following a contextualist approach. Three themes were developed: growing differently, the ‘right’ way to be, and weight is not health. These themes capture parents’ views on complex and reportedly inevitable causes of obesity, ideas about acceptable and preferred body sizes, and the low priority of weight per se compared to health. The findings suggest that childhood obesity prevention in South Africa needs to be done in a non-stigmatising way that recognises environmental and contextual factors, such as parents’ limited sense of agency in relation to their children’s health and weight, and concrete resource constraints. Environmental barriers to healthy behaviours need to be addressed in order to overcome the coexisting challenges of childhood undernutrition and obesity in urban low-income South African settings.

Summary The prevalence of childhood obesity is increasing at epidemic rates globally, with widening inequalities between advantaged and disadvantaged groups. Despite the promise of schools as a universal context to access and influence all children, the potential of school‐based interventions to positively impact children's physical activity behaviour, and obesity risk, remains uncertain. We searched six electronic databases to February 2017 for cluster randomized trials of school‐based physical activity interventions. Following data extraction, authors were sent re‐analysis requests. For each trial, a mean change score from baseline to follow‐up was calculated for daily minutes of accelerometer‐assessed moderate‐to‐vigorous physical activity (MVPA), for the main effect, by gender, and by socio‐economic position (SEP). Twenty‐five trials met the inclusion criteria; 17 trials provided relevant data for inclusion in the meta‐analyses. The pooled main effect for daily minutes of MVPA was nonexistent and nonsignificant. There was no evidence of differential effectiveness by gender or SEP. This review provides the strongest evidence to date that current school‐based efforts do not positively impact young people's physical activity across the full day, with no difference in effect across gender and SEP. Further assessment and maximization of implementation fidelity is required before it can be concluded that these interventions have no contribution to make.

Summary Obesity prevalence rises fastest during young adulthood when weight, diet, and physical activity may be influenced by life events, including becoming a parent, but the impact is uncertain. We searched six electronic databases to July 2019 for longitudinal studies (both sexes) aged 15 to 35 years with a prospective pre‐pregnancy/parenthood and post‐delivery outcome. Of 11 studies (across 15 papers), six studies (women only) were eligible for meta‐analysis of the difference in change in body mass index (BMI; kg/m2) between remaining without children and becoming a parent. Mean (±SD) BMI gain for non‐mothers was 2.8 ± 1.3 kg/m2 (~7.5 kg for 164‐cm woman) over 5.6 ± 3.1 years; 12.3% of baseline BMI (22.8 ± 2.5 kg/m2). Becoming a mother was associated with an additional BMI increase of 0.47 ± 0.26 kg/m2 (~1.3 kg), 4.3% of baseline BMI (22.8 ± 5.6 kg/m2); the one study including men reported no difference in change. Physical activity results were equivocal; 2/4 studies (women) and 2/2 (men) showed a greater decline in parents versus non‐parents; diet (three studies) varied by dietary measure, mostly indicating no difference. Becoming a mother is associated with 17% greater absolute BMI gain than remaining childless. Motherhood BMI gain is additional to an alarming BMI increase among young women, highlighting the need for obesity prevention among all young women, including mothers.

Background Early adulthood is a period associated with poor diet and rapid weight gain. This is also an age of transition, including environmental, social and lifestyle changes which may be associated with changes in diet. We assess longitudinal associations between four early adulthood life transitions (leaving home, leaving education, entering employment, and cohabitation) and changes in consumption of fruit, vegetables, confectionery and sugar-sweetened beverages (SSBs). Methods Participants (n = 1100) from the Norwegian Longitudinal Health Behaviour Study, reported data on diet and life transitions on up to eight occasions from age 14 to age 30. Diet data were self-reported in response to questions on intake of fruit, vegetables, confectionery and sugar-sweetened beverages. Growth models were developed to describe changing intake of each of the four diet indicators with age. Fixed-effects regression models assessed associations between the four life transitions and within-individual changes in diet indicators, with adjustment for the remaining transitions and parenthood. Results Diet indicators showed quadratic trajectories with age: fruit and vegetable intakes declined from age 14 to ages 23 and 21 respectively, before increasing to age 30. SSB and confectionery intakes increased to age 18, before subsequently decreasing. Leaving the parental home was associated with a decrease in fruit intake of − 0.54 times/week (95% confidence interval (95%CI): -0.87;-0.22) and vegetable intake of − 0.43 times/week (95%CI: -0.70;-0.15). Leaving education was associated with increases in confectionery (0.33 times/week (95%CI: 0.04;0.62)) and SSB intakes (0.49 times/week (95%CI: 0.10;0.87). Conclusions Leaving home and leaving education are associated with negative changes in diet and may present opportunities for effective diet and obesity intervention. Further study of these transitions is needed to understand the mechanisms mediating associations between life transitions and changes in diet.

Objectives: To determine the role of physical activity intensity and bout-duration in modulating associations between physical activity and cardiometabolic risk markers.Methods: A cross-sectional study using the International Children’s Accelerometry Database (ICAD) including 38,306 observations (in 29,734 individuals aged 4–18 years). Accelerometry data was summarized as time accumulated in 16 combinations of intensity thresholds (≥500 to ≥3000 counts/min) and bout-durations (≥1 to ≥10 min). Outcomes were body mass index (BMI, kg/m2), waist circumference, biochemical markers, blood pressure, and a composite score of these metabolic markers. A second composite score excluded the adiposity component. Linear mixed models were applied to elucidate the associations and expressed per 10 min difference in daily activity above the intensity/bout-duration combination. Estimates (and variance) from each of the 16 combinations of intensity and bout-duration examined in the linear mixed models were analyzed in meta-regression to investigate trends in the association.Results: Each 10 min positive difference in physical activity was significantly and inversely associated with the risk factors irrespective of the combination of intensity and bout-duration. In meta-regression, each 1000 counts/min increase in intensity threshold was associated with a −0.027 (95% CI: −0.039 to −0.014) standard deviations lower composite risk score, and a −0.064 (95% CI: −0.09 to −0.038) kg/m2 lower BMI. Conversely, meta-regression suggested bout-duration was not significantly associated with effect-sizes (per 1 min increase in bout-duration: −0.002 (95% CI: −0.005 to 0.0005) standard deviations for the composite risk score, and −0.005 (95% CI: −0.012 to 0.002) kg/m2 for BMI).Conclusions: Time spent at higher intensity physical activity was the main determinant of variation in cardiometabolic risk factors, not bout-duration. Greater magnitude of associations was consistently observed with higher intensities. These results suggest that, in children and adolescents, physical activity, preferably at higher intensities, of any bout-duration should be promoted.

Background Process evaluations are critical for interpreting and understanding outcome trial results. By understanding how interventions function across different settings, process evaluations have the capacity to inform future dissemination of interventions. The complexity of Get others Active (GoActive), a 12-week, school-based physical activity intervention implemented in eight schools, highlights the need to investigate how implementation is achieved across a variety of school settings. This paper describes the mixed methods GoActive process evaluation protocol that is embedded within the outcome evaluation. In this detailed process evaluation protocol, we describe the flexible and pragmatic methods that will be used for capturing the process evaluation data. Methods A mixed methods design will be used for the process evaluation, including quantitative data collected in both the control and intervention arms of the GoActive trial, and qualitative data collected in the intervention arm. Data collection methods will include purposively sampled, semi-structured interviews and focus group interviews, direct observation, and participant questionnaires (completed by students, teachers, older adolescent mentors, and local authority-funded facilitators). Data will be analysed thematically within and across datasets. Overall synthesis of findings will address the process of GoActive implementation, and through which this process affects outcomes, with careful attention to the context of the school environment. Discussion This process evaluation will explore the experience of participating in GoActive from the perspectives of key groups, providing a greater understanding of the acceptability and process of implementation of the intervention across the eight intervention schools. This will allow for appraisal of the intervention’s conceptual base, inform potential dissemination, and help optimise post-trial sustainability. The process evaluation will also assist in contextualising the trial effectiveness results with respect to how the intervention may or may not have worked and, if it was found to be effective, what might be required for it to be sustained in the ‘real world’. Furthermore, it will offer suggestions for the development and implementation of future initiatives to promote physical activity within schools. Trial registration ISRCTN, ISRCTN31583496. Registered on 18 February 2014. Electronic supplementary material The online version of this article (10.1186/s13063-018-2661-0) contains supplementary material, which is available to authorized users.

Background Globally most children do not engage in enough physical activity. Day length and weather conditions have been identified as determinants of physical activity, although how they may be overcome as barriers is not clear. We aim to examine if and how relationships between children’s physical activity and weather and day length vary between countries and identify settings in which children were better able to maintain activity levels given the weather conditions they experienced. Methods In this repeated measures study, we used data from 23,451 participants in the International Children’s Accelerometry Database (ICAD). Daily accelerometer-measured physical activity (counts per minute; cpm) was matched to local weather conditions and the relationships assessed using multilevel regression models. Multilevel models accounted for clustering of days within occasions within children within study-cities, and allowed us to explore if and how the relationships between weather variables and physical activity differ by setting. Results Increased precipitation and wind speed were associated with decreased cpm while better visibility and more hours of daylight were associated with increased cpm. Models indicated that increases in these variables resulted in average changes in mean cpm of 7.6/h of day length, −13.2/cm precipitation, 10.3/10 km visibility and −10.3/10kph wind speed (all p

Background Cycling has the potential to encourage physical activity as well as advancing societal goals such as reducing carbon emissions; encouraging cycling is therefore a policy goal in many contexts. We analysed individual level data from the whole of England on factors associated with cycling among adolescents, including cycle training delivered by the age of 11 years in primary schools. Methods Data came from the nationally representative Millennium Cohort Study collected when participants were aged 13–15 years (adolescents). We assessed frequency of cycling at least once per week (regular cycling) and used logistic regression to assess how this differed across characteristics including demographic, health and environmental factors, as well as receiving cycle training (‘Bikeability’) in primary school. Results We found that 21.0% of adolescents cycled at least once per week. In fully adjusted analyses, this was more common among boys than girls (32.5% vs. 9.4%, p, Highlights • Approximately one in five cycles regularly. • This was more common among boys, in rural areas and in areas with higher levels of adult cycle commuting. • Receiving cycle training at age 10/11 years is not linked to more cycling as an adolescent.

BackgroundUK and global policies recommend whole-school approaches to improve childrens’ inadequate physical activity (PA) levels. Yet, recent meta-analyses establish current interventions as ineffective due to suboptimal implementation rates and poor sustainability. To create effective interventions, which recognise schools as complex adaptive sub-systems, multi-stakeholder input is necessary. Further, to ensure ‘systems’ change, a framework is required that identifies all components of a whole-school PA approach. The study’s aim was to co-develop a whole-school PA framework using the double diamond design approach (DDDA).MethodologyFifty stakeholders engaged in a six-phase DDDA workshop undertaking tasks within same stakeholder (n= 9; UK researchers, public health specialists, active schools coordinators, headteachers, teachers, active partner schools specialists, national organisations, Sport England local delivery pilot representatives and international researchers) and mixed (n= 6) stakeholder groupings. Six draft frameworks were created before stakeholders voted for one ‘initial’ framework. Next, stakeholders reviewed the ‘initial’ framework, proposing modifications. Following the workshop, stakeholders voted on eight modifications using an online questionnaire.ResultsFollowing voting, the Creating Active Schools Framework (CAS) was designed. At the centre, ethos and practice drive school policy and vision, creating the physical and social environments in which five key stakeholder groups operate to deliver PA through seven opportunities both within and beyond school. At the top of the model, initial and in-service teacher training foster teachers’ capability, opportunity and motivation (COM-B) to deliver whole-school PA. National policy and organisations drive top-down initiatives that support or hinder whole-school PA.SummaryTo the authors’ knowledge, this is the first time practitioners, policymakers and researchers have co-designed a whole-school PA framework from initial conception. The novelty of CAS resides in identifying the multitude of interconnecting components of a whole-school adaptive sub-system; exposing the complexity required to create systems change. The framework can be used to shape future policy, research and practice to embed sustainable PA interventions within schools. To enact such change, CAS presents a potential paradigm shift, providing a map and method to guide future co-production by multiple experts of PA initiatives ‘with’ schools, while abandoning outdated traditional approaches of implementing interventions ‘on’ schools.

We assessed which intervention components were associated with change in moderate-to-vigorous physical activity (MVPA) and wellbeing through proposed psychosocial mediators. Eight schools (n = 1319, 13&ndash, 14 years) ran GoActive, where older mentors and in-class-peer-leaders encouraged classes to conduct two new activities/week, students gained points and rewards for activity. We assessed exposures: participant-perceived engagement with components (post-intervention): older mentorship, peer leadership, class sessions, competition, rewards, points entered online, potential mediators (change from baseline): social support, self-efficacy, group cohesion, friendship quality, self-esteem, and outcomes (change from baseline): accelerometer-assessed MVPA (min/day), wellbeing (Warwick-Edinburgh). Mediation was assessed using linear regression models stratified by gender (adjusted for age, ethnicity, language, school, BMI z-score, baseline values), assessing associations between (1) exposures and mediators, (2) exposures and outcomes (without mediators) and (3) exposure and mediator with outcome using bootstrap resampling. No evidence was found to support the use of these components to increase physical activity. Among boys, higher perceived teacher and mentor support were associated with improved wellbeing via various mediators. Among girls, higher perceived mentor support and perception of competition and rewards were positively associated with wellbeing via self-efficacy, self-esteem and social support. If implemented well, mentorship could increase wellbeing among adolescents. Teacher support and class-based activity sessions may be important for boys&rsquo, wellbeing, whereas rewards and competition warrant consideration among girls.

Background: Childhood obesity is increasing globally with widening socioeconomic inequalities. It is unclear if differences in the accumulation and intensity distribution of children’s physical activity is contributing to these rising disparities. We investigated if the intensity patterning of physical activity differs between socioeconomic groups across Europe and if this relationship differs by national level income inequality and age to help explain obesity disparities. Methods: We pooled and harmonised individual-participant accelerometer-assessed activity and socioeconomic position (SEP) data from 36 European child studies. Included participants were between 5 to 16 years of age with valid accelerometer data (≥480 minutes of daily wear time on 3 days), parental education and anthropometric measurements. Study-level multivariable linear regression models were run to assess differences in moderate-vigorous physical activity (MVPA), vigorous physical activity (VPA) and adiposity by socioeconomic position (by parental education). Effects were pooled in random effect meta-analyses. Findings: 26,915 participants (mean age: 10·1y [SD:1.2]; 51·7% female) from 16 European countries met the inclusion criteria. Meta-analyses revealed proportionally more average daily minutes of VPA were performed by children from a higher socioeconomic position (High vs low SEP, b: 0·57, 95%CI: 0·28, 0·85 mins), despite lower overall levels of physical activity (MVPA; b: -1·51, 95%CI: -2·36, -0·67 mins). Higher intensity activity in children from a higher socioeconomic position was paralleled by lower levels of adiposity measured by BMI z-score (b: -0·20, 95%CI: -0·24, -0·16). Stepwise differences were apparent moving from low to medium to high socioeconomic position [e.g. BMI z-score: (Low vs Med SEP; b: -0·10, 95%CI: -0·14, -0·07) (Low vs High SEP; b: -0·20, 95%CI: -0·24, -0·16)]. Inequalities in VPA and BMI z-score widened with age and were not affected by national level income inequality. Interpretation: Lower levels of adiposity in children from a higher socioeconomic position are paralleled by relatively higher amounts of VPA despite overall lower levels of MVPA. Physical activity promotion efforts should focus on providing opportunities for less affluent children to be vigorously active. Funding Statement: BHF, CRUK, ESCR, MRC, Wellcome Trust, Research Council of Norway Declaration of Interests: All authors declare that they have no conflicts of interest. Ethics Approval Statement: The authors declared not applicable.