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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)

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.

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.

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.

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.

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.

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)

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.

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.

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 To gain more understanding of the potential health effects of sedentary time, knowledge is required about the accumulation and longitudinal development of young people’s sedentary time. This study examined tracking of young peoples’ total and prolonged sedentary time as well as their day-to-day variation using the International Children’s Accelerometry Database. Methods Longitudinal accelerometer data of 5991 children (aged 4-17y) was used from eight studies in five countries. Children were included if they provided valid (≥8 h/day) accelerometer data on ≥4 days, including ≥1 weekend day, at both baseline and follow-up (average follow-up: 2.7y; range 0.7–8.2). Tracking of total and prolonged (i.e. ≥10-min bouts) sedentary time was examined using multilevel modelling to adjust for clustering of observations, with baseline levels of sedentary time as predictor and follow-up levels as outcome. Standardized regression coefficients were interpreted as tracking coefficients (low: 0.6). Results Average total sedentary time at study level ranged from 246 to 387 min/day at baseline and increased annually by 21.4 min/day (95% confidence interval [19.6–23.0]) on average. This increase consisted almost entirely of prolonged sedentary time (20.9 min/day [19.2–22.7]). Total (standardized regression coefficient (B) = 0.48 [0.45–0.50]) and prolonged sedentary time (B = 0.43 [0.41–0.45]) tracked moderately. Tracking of day-to-day variation in total (B = 0.04 [0.02–0.07]) and prolonged (B = 0.07 [0.04–0.09]) sedentary time was low. Conclusion Young people with high levels of sedentary time are likely to remain among the people with highest sedentary time as they grow older. Day-to-day variation in total and prolonged sedentary time, however, was rather variable over time.

ObjectiveTo investigate if daily vigorous physical activity (VPA), adjusted for minutes of moderate physical activity (MPA) performed, differs by socioeconomic position or ethnicity in a large sample of UK children with objectively measured physical activity.DesignNationally representative prospective cohort study.SettingUK children born between 2000 and 2002.Participants5172 children aged 7–8 with valid accelerometer data for ≥10 hour on ≥3 days, including 1 weekend day.Main outcome measuresTime spent in VPA (>3841 counts per min).Explanatory measuresMaternal education, annual household Organisation for Economic Co-Operation and Development equivalised income, ethnicity.ResultsMultivariable linear regression models fitted to explore differences in average daily minutes of VPA (adjusted for MPA, mean accelerometer wear time, season of measurement, age and sex), revealed significantly higher amounts of VPA accumulated as a child’s socioeconomic position increased (highest vs lowest level of maternal education: β: 2.96, p: 0.00; annual household equivalised income: β: 0.58, p: 0.00, per £10 000 annual increase). Additionally, children from certain minority ethnicities (Bangladeshi and Pakistani: β: −3.34, p: 0.00; other ethnic groups: β:−2.27, p: 0.02) accrued less daily VPA compared with their white British counterparts.ConclusionsThe socioeconomic and ethnic patterning of vigorous activity observed in this study mirrors parallel inequalities in rates of childhood obesity. Given the stronger association of VPA with adiposity than of MPA, intensity specific differences may be contributing to widening inequalities in obesity. Accordingly, these findings suggest that the current global focus on overall moderate-to-vigorous intensity activity may mask important behavioural inequalities.

ObjectivesAssess feasibility, acceptability and costs of delivering a physically active lessons (PAL) training programme to secondary school teachers and explore preliminary effectiveness for reducing pupils’ sedentary time.Design and settingSecondary schools in East England; one school participated in a pre-post feasibility study, two in a pilot cluster-randomised controlled trial. In the pilot trial, blinding to group assignment was not possible.ParticipantsAcross studies, 321 randomly selected students (51% male; mean age: 12.9 years), 78 teachers (35% male) and 2 assistant head teachers enrolled; 296 (92%) students, 69 (88%) teachers and 2 assistant head teachers completed the studies.InterventionPAL training was delivered to teachers over two after-school sessions. Teachers were made aware of how to integrate movement into lessons; strategies included students collecting data from the environment for class activities and completing activities posted on classroom walls, instead of sitting at desks.Primary and secondary outcomesQuantitative and qualitative data were collected to assess feasibility and acceptability of PAL training and delivery. Outcomes were assessed at baseline and ~8 weeks post-training; measures included accelerometer-assessed activity, self-reported well-being and observations of time-on-task. Process evaluation was conducted at follow-up.ResultsIn the feasibility study, teachers reported good acceptability of PAL training and mixed experiences of delivering PAL. In the pilot study, teachers’ acceptability of training was lower and teachers identified aspects of the training in need of review, including the outdoor PAL training and learning challenge of PAL strategies. In both studies, students and assistant head teachers reported good acceptability of the intervention. Preliminary effectiveness for reducing students’ sedentary time was not demonstrated in either study.ConclusionsNo evidence of preliminary effectiveness on the primary outcome and mixed reports of teachers’ acceptability of PAL training suggest the need to review the training. The results do not support continuation of research with the current intervention.Trial registration numberISRCTN38409550.

Highlights • Gender disparity was consistent throughout components. • Competition was disliked by girls and shy/inactive students. • Adolescents liked the idea of older mentors, but mentors did not meet expectations. • Boys enjoyed trying new activities more than girls did. • Participants wanted to try new activities but identified barriers to choosing them., Purpose To examine adolescent experiences and perspectives of the GoActive intervention (ISRCTN31583496) using mixed methods process evaluation to determine satisfaction with intervention components and interpret adolescents’ experiences of the intervention process in order to provide insights for future intervention design. Methods Participants (n = 1542; 13.2 ± 0.4 years, mean ± SD) provided questionnaire data at baseline (shyness, activity level) and post-intervention (intervention acceptability, satisfaction with components). Between-group differences (boys vs. girls and shy/inactive vs. others) were tested with linear regression models, accounting for school clustering. Data from 16 individual interviews (shy/inactive) and 11 focus groups with 48 participants (mean = 4; range 2–7) were thematically coded. Qualitative and quantitative data were merged in an integrative mixed methods convergence matrix, which denoted convergence and dissonance across datasets. Results Effect sizes for quantitative results were small and may not represent substantial between-group differences. Boys (vs. girls) preferred class-based sessions (β = 0.2, 95% confidence interval (CI): 0.1–0.3); qualitative data suggested that this was because boys preferred competition, which was supported quantitatively (β = 0.2, 95%CI: 0.1–0.3). Shy/inactive students did not enjoy the competition (β = –0.3, 95%CI: –0.5 to –0.1). Boys enjoyed trying new activities more (β = 0.1, 95%CI: 0.1–0.2); qualitative data indicated a desire to try new activities across all subgroups but identified barriers to choosing unfamiliar activities with self-imposed choice restriction leading to boredom. Qualitative data highlighted critique of mentorship; adolescents liked the idea, but older mentors did not meet expectations. Conclusion We interpreted adolescent perspectives of intervention components and implementation to provide insights into future complex interventions aimed at increasing young people's physical activity in school-based settings. The intervention component mentorship was liked in principle, but implementation issues undesirably impacted satisfaction; competition was disliked by girls and shy/inactive students. The results highlight the importance of considering gender differences in preference of competition and extensive mentorship training., Graphical abstract Image, graphical abstract

Background Sedentary time increases and total physical activity decreases with age. The magnitude and correlates of changes in sedentary time, light-intensity physical activity (LPA), moderate-to-vigorous intensity physical activity (MVPA), and overall physical activity remain unclear. We quantified these changes and identified their individual and sociodemographic correlates. Methods We used data from 1259 adults (67.8 ± 6.9 years; 41.9% women) who participated in the EPIC-Norfolk Study. Activity was assessed at baseline (2004–2011) and follow-up (2012–2016) for 7 days using accelerometers. Potential correlates of change were specified a priori. We used unadjusted and adjusted sex-stratified linear regressions to identify correlates of change. Results Only 3.7% of adults met the current MVPA recommendations. Sedentary time increased by 3.0 min/day/year (SD = 12.3). LPA, MVPA, and overall PA decreased by 1.7 min/day/year (SD = 5.4), 3.0 min/day/year (SD = 6.0), and 8.8 cpm/year (SD = 18.8), respectively. Correlates of greater rates of increase in sedentary time included older age and higher BMI in men, and older age, higher BMI, smoking, and urban dwelling in women. Correlates of greater rates of decrease in physical activity included older age, higher BMI, living alone, depression, car use, and/or fair/poor self-rated health in men, and older age, higher BMI, depression, smoking, and/or urban dwelling in women (e.g. depressed women had a 1.0 min/day/year greater rate of decline in MVPA than non-depressed women, 95% CI -1.8, − 0.2). Conclusions Most (> 95%) adults are insufficiently active. Sedentary time increases and LPA, MVPA and overall physical activity decreases over time, with more pronounced rates of change observed in specific sub-groups (e.g. among older and depressed adults). To promote active living, the correlates of these changes should be considered in future interventions. Electronic supplementary material The online version of this article (10.1186/s12966-018-0746-5) contains supplementary material, which is available to authorized users.

Late adolescence to early adulthood is the period of life when prevalence of overweight and obesity rises the fastest, and an important time to understand changes in dietary risk factors. In this study we assess the variation in diet quality through analysis of cross-sectional data from 2957 individuals aged 13 to 30 from the National Diet and Nutrition Study (2008&ndash, 2016). Diet data were self-reported using four-day food diaries and coded to give diet quality using the dietary approaches to stop hypertension (DASH) index (range 0&ndash, 80) and DASH component food groups (grams/day). The mean DASH index score was low at 34.8 (95% confidence interval (CI) = 34.3&ndash, 35.4). The regression of diet quality score and food groups on age categories revealed no significant change in diet quality score with age category in males, but an improved diet quality score among females aged 19&ndash, 21 (&beta, = 2.04, 95% CI = 0.05&ndash, 4.02), 25&ndash, 27 (&beta, = 3.77, 95% CI = 1.36&ndash, 6.18) and 28&ndash, 30 (&beta, = 2.39, 95% CI = 0.53&ndash, 4.26), compared to age 13&ndash, 15. Both sexes showed increased vegetable intake with age. Dairy intake was lower in early adult ages among males, while in females there was an increase in the proportion of low-fat dairy consumed with age. Further research should address the determinants of changes in diet in early adulthood to provide evidence for the targeting of public health policy.

Introduction -- Sedentary time and time spent in various intensity-specific physical activity are co-dependent, and increasing time spent in one behaviour requires decreased time in another. Objective -- The aim of the present study was to examine the theoretical associations with reallocating time between categories of intensities and cardiometabolic risk factors in a large and heterogeneous sample of children and adolescents. Methods -- We analysed pooled data from 13 studies comprising 18,200 children and adolescents aged 4–18 years from the International Children’s Accelerometry Database (ICAD). Waist-mounted accelerometers measured sedentary time, light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA). Cardiometabolic risk factors included waist circumference (WC), systolic blood pressure (SBP), fasting high- and low-density lipoprotein cholesterol (HDL-C and LDL-C), triglycerides, insulin, and glucose. Associations of reallocating time between the various intensity categories with cardiometabolic risk factors were explored using isotemporal substitution modelling. Results -- Replacing 10 min of sedentary time with 10 min of MVPA showed favourable associations with WC, SBP, LDL-C, insulin, triglycerides, and glucose; the greatest magnitude was observed for insulin (reduction of 2–4%), WC (reduction of 0.5–1%), and triglycerides (1–2%). In addition, replacing 10 min of sedentary time with an equal amount of LPA showed beneficial associations with WC, although only in adolescents. Conclusions -- Replacing sedentary time and/or LPA with MVPA in children and adolescents is favourably associated with most markers of cardiometabolic risk. Efforts aimed at replacing sedentary time with active behaviours, particularly those of at least moderate intensity, appear to be an effective strategy to reduce cardiometabolic risk in young people.

Late adolescence to early adulthood is the period of life when prevalence of overweight and obesity rises the fastest, and an important time to understand changes in dietary risk factors. In this study we assess the variation in diet quality through analysis of cross-sectional data from 2957 individuals aged 13 to 30 from the National Diet and Nutrition Study (2008–2016). Diet data were self-reported using four-day food diaries and coded to give diet quality using the dietary approaches to stop hypertension (DASH) index (range 0–80) and DASH component food groups (grams/day). The mean DASH index score was low at 34.8 (95% confidence interval (CI) = 34.3–35.4). The regression of diet quality score and food groups on age categories revealed no significant change in diet quality score with age category in males, but an improved diet quality score among females aged 19–21 (β = 2.04, 95% CI = 0.05–4.02), 25–27 (β = 3.77, 95% CI = 1.36–6.18) and 28–30 (β = 2.39, 95% CI = 0.53–4.26), compared to age 13–15. Both sexes showed increased vegetable intake with age. Dairy intake was lower in early adult ages among males, while in females there was an increase in the proportion of low-fat dairy consumed with age. Further research should address the determinants of changes in diet in early adulthood to provide evidence for the targeting of public health policy.

ObjectiveAdolescence is a critical period for development of depression and understanding of behavioural risk factors is needed to support appropriate preventive strategies. We examined associations between adolescent diet quality and depressive symptoms, cross-sectionally and prospectively, in a large community cohort, adjusting for behavioural and psychosocial covariates.DesignProspective community-based cohort study (ROOTS).SettingSecondary schools in Cambridgeshire and Suffolk, UK.SubjectsStudy participants (n 603) who completed 4 d diet diaries at age 14 years and reported depressive symptoms (Moods and Feelings Questionnaire (MFQ)) at 14 and 17 years of age.ResultsDiet data were processed to derive a Mediterranean diet score (MDS) and daily servings of fruit and vegetables, and fish. At age 14 years, a negative association between fruit and vegetable intake and MFQ score was seen in the unadjusted cross-sectional regression model (β=−0·40; 95 % CI −0·71,−0·10), but adjustment for behavioural covariates, including smoking and alcohol consumption, attenuated this association. Fish intake and MDS were not cross-sectionally associated with MFQ score. No prospective associations were found between MDS, fruit and vegetable intake or fish intake and later MFQ score.ConclusionsDiet quality was not associated with depressive symptoms in mid-adolescence. Previously reported associations in this age range may be due to confounding. Further longitudinal studies are needed that investigate associations between adolescent diet and depression across different time frames and populations, ensuring appropriate adjustment for covariates.

Background Large, heterogeneous datasets are required to enhance understanding of the multi-level influences on children’s physical activity and sedentary behaviour. One route to achieving this is through the pooling and co-analysis of data from multiple studies. Where this approach is used, transparency of the methodology for data collation and harmonisation is essential to enable appropriate analysis and interpretation of the derived data. In this paper, we describe the acquisition, management and harmonisation of non-accelerometer data in a project to expand the International Children’s Accelerometry Database (ICAD). Method Following a consultation process, ICAD partners were requested to share accelerometer data and information on selected behavioural, social, environmental and health-related constructs. All data were collated into a single repository for cataloguing and harmonisation. Harmonised variables were derived iteratively, with input from the ICAD investigators and a panel of invited experts. Extensive documentation, describing the source data and harmonisation procedure, was prepared and made available through the ICAD website. Results Work to expand ICAD has increased the number of studies with longitudinal accelerometer data, and expanded the breadth of behavioural, social and environmental characteristics that can be used as exposure variables. A set of core harmonised variables, including parent education, ethnicity, school travel mode/duration and car ownership, were derived for use by the research community. Guidance documents and facilities to enable the creation of new harmonised variables were also devised and made available to ICAD users. An expanded ICAD database was made available in May 2017. Conclusion The project to expand ICAD further demonstrates the feasibility of pooling data on physical activity, sedentary behaviour and potential determinants from multiple studies. Key to this process is the rigorous conduct and reporting of retrospective data harmonisation, which is essential to the appropriate analysis and interpretation of derived data. These documents, made available through the ICAD website, may also serve as a guide to others undertaking similar projects.

Background Large, heterogeneous datasets are required to enhance understanding of the multi-level influences on children’s physical activity and sedentary behaviour. One route to achieving this is through the pooling and co-analysis of data from multiple studies. Where this approach is used, transparency of the methodology for data collation and harmonisation is essential to enable appropriate analysis and interpretation of the derived data. In this paper, we describe the acquisition, management and harmonisation of non-accelerometer data in a project to expand the International Children’s Accelerometry Database (ICAD). Method Following a consultation process, ICAD partners were requested to share accelerometer data and information on selected behavioural, social, environmental and health-related constructs. All data were collated into a single repository for cataloguing and harmonisation. Harmonised variables were derived iteratively, with input from the ICAD investigators and a panel of invited experts. Extensive documentation, describing the source data and harmonisation procedure, was prepared and made available through the ICAD website. Results Work to expand ICAD has increased the number of studies with longitudinal accelerometer data, and expanded the breadth of behavioural, social and environmental characteristics that can be used as exposure variables. A set of core harmonised variables, including parent education, ethnicity, school travel mode/duration and car ownership, were derived for use by the research community. Guidance documents and facilities to enable the creation of new harmonised variables were also devised and made available to ICAD users. An expanded ICAD database was made available in May 2017. Conclusion The project to expand ICAD further demonstrates the feasibility of pooling data on physical activity, sedentary behaviour and potential determinants from multiple studies. Key to this process is the rigorous conduct and reporting of retrospective data harmonisation, which is essential to the appropriate analysis and interpretation of derived data. These documents, made available through the ICAD website, may also serve as a guide to others undertaking similar projects.

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

ObjectiveTo develop a model to assess the long-term costs and health outcomes of physical activity interventions targeting adolescents.DesignA Markov cohort simulation model was constructed with the intention of being capable of estimating long-term costs and health impacts of changes in activity levels during adolescence. The model parameters were informed by published literature and the analysis took a National Health Service perspective over a lifetime horizon. Univariate and probabilistic sensitivity analyses were undertaken.SettingSchool and community.ParticipantsA hypothetical cohort of adolescents aged 16 years at baseline.InterventionsTwo exemplar school-based: a comparatively simple, after-school intervention and a more complex multicomponent intervention compared with usual care.Primary and secondary outcome measuresIncremental cost-effectiveness ratio as measured by cost per quality-adjusted life year gained.ResultsThe model gave plausible estimates of the long-term effect of changes in physical activity. The use of two exemplar interventions suggests that the model could potentially be used to evaluate a number of different physical activity interventions in adolescents. The key model driver was the degree to which intervention effects were maintained over time.ConclusionsThe model developed here has the potential to assess long-term value for money of physical activity interventions in adolescents. The two applications of the model indicate that complex interventions may not necessarily be the ones considered the most cost-effective when longer-term costs and consequences are taken into account.

Using a sample of English school children, we use accelerometery and global positioning systems to identify whether different intensities of activity (light, moderate, and vigorous) occur in different environments, and whether environments for bouts of moderate to vigorous activity (MVPA) vary from those for non-bout MVPA. We find that land uses such as buildings and roads and pavements were generally used for light activity, whilst green environments such as gardens, parks, grassland and farmland appear supportive of vigorous activity. Built land uses such as hard surface play areas were particularly used for activity of short duration. Future work may consider differentiating light activity from moderate and vigorous, and separating bout and non-bout MVPA to better identify environmental supportiveness for activity in children.

Background: Sedentary behaviours (SB) are highly prevalent in young people and may be adversely associated with physical and mental health. Understanding of the modifiable determinants of SB is necessary to inform the design of behaviour change interventions but much of the existing research is cross-sectional and focussed upon screen-based behaviours. Purpose: To examine the social, psychological and environmental determinants of change in children’s objectively measured sedentary time from age 11 to 14 years. Methods: Data are from the second (2008) and third (2011) waves of assessment in the Sport, Physical Activity, and Eating Behaviour: Environmental Determinants in Young People (SPEEDY) study, conducted in the county of Norfolk, United Kingdom. Longitudinal data on accelerometer assessed sedentary time were available for 316 (53.5% female, 11.2±0.3 years at baseline) and 264 children after-school and at the weekend respectively. Information on 14 candidate determinants, including school travel mode and electronic media ownership, was self-reported. Change in the proportion of registered time spent sedentary was used as the outcome variable in cross-classified linear regression models, adjusted for age, sex, body mass index and baseline sedentary time. Simple and multiple models were run and interactions with sex explored. Results: Daily sedentary time increased by 30–40 minutes after-school and at the weekend from baseline to follow-up. Participants who travelled to school by cycle exhibited smaller increases in after-school sedentary time (beta; 95%CI for change in % time spent sedentary: -3.3;-6.7,-0.07). No significant determinants of change in weekend sedentary time were identified. Conclusions: Time spent sedentary increased during the three-year duration of follow-up but few of the variables examined were significantly associated with changes in sedentary time. Children’s mode of school travel may influence changes in their sedentary time over this period and should be examined further, alongside broader efforts to identify modifiable determinants of SB during childhood.

$\textbf{Background}$ Information about genetic and phenotypic risk of type 2 diabetes is now widely available and is being incorporated into disease prevention programs. Whether such information motivates behavior change or has adverse effects is uncertain. We examined the effect of communicating an estimate of genetic or phenotypic risk of type 2 diabetes in a parallel group, open, randomized controlled trial. $\textbf{Methods and Findings}$ We recruited 569 healthy middle-aged adults from the Fenland Study, an ongoing population-based, observational study in the east of England (Cambridgeshire, UK). We used a computer-generated random list to assign participants in blocks of six to receive either standard lifestyle advice alone (control group, $n$ = 190) or in combination with a genetic ($n$ = 189) or a phenotypic ($n$ = 190) risk estimate for type 2 diabetes (intervention groups). After 8 wk, we measured the primary outcome, objectively measured physical activity (kJ/kg/day), and also measured several secondary outcomes (including self-reported diet, self-reported weight, worry, anxiety, and perceived risk). The study was powered to detect a between-group difference of 4.1 kJ/kg/d at follow-up. 557 (98%) participants completed the trial. There were no significant intervention effects on physical activity (difference in adjusted mean change from baseline: genetic risk group versus control group 0.85 kJ/kg/d (95% CI −2.07 to 3.77, $p$ = 0.57); phenotypic risk group versus control group 1.32 (95% CI −1.61 to 4.25, $p$ = 0.38); and genetic risk group versus phenotypic risk group −0.47 (95% CI −3.40 to 2.46, $p$ = 0.75). No significant differences in self-reported diet, self-reported weight, worry, and anxiety were observed between trial groups. Estimates of perceived risk were significantly more accurate among those who received risk information than among those who did not. Key limitations include the recruitment of a sample that may not be representative of the UK population, use of self-reported secondary outcome measures, and a short follow-up period. $\textbf{Conclusions}$ In this study, we did not observe short-term changes in behavior associated with the communication of an estimate of genetic or phenotypic risk of type 2 diabetes. We also did not observe changes in worry or anxiety in the study population. Additional research is needed to investigate the conditions under which risk information might enhance preventive strategies. (Current Controlled Trials ISRCTN09650496; Date applied: April 4, 2011; Date assigned: June 10, 2011). $\textbf{Trial Registration}$ The trial is registered with Current Controlled Trials, ISRCTN09650496.

BACKGROUND: Factors associated with parental awareness of children's physical activity (PA) levels have not been explored in preschool-aged children. This paper investigates maternal awareness of preschool-aged children's PA levels and determined correlates associated with maternal overestimation of PA. METHODS: Data from the Southampton Women's Survey, a UK population-based study, were collected March 2006 through June 2009. Daily minutes of moderate-to-vigorous PA (MVPA) were derived using accelerometry in 478 4-year-old children. Mothers who were realistic or overestimated their child's PA were identified. Log-binomial regression was used to analyse correlates of maternal overestimation of PA levels in children whose mothers perceived them to be active (n = 438). RESULTS: 40.8% of children were classified as inactive: 89.7% of these were perceived to be active by their mothers (over-estimators). These mothers were more likely to think their child sometimes lacked skills required to be physically active (RR (95% CI) = 1.29(1.03-1.63)) and their child was more likely to attend nursery full-time (RR = 1.53(1.14-2.04)). They were less likely to have older children at home (RR = 0.71(0.56-0.90)). CONCLUSIONS: Almost 90% of mothers of inactive preschool-aged children perceive their child to be active. Nursery-school attendance and having older siblings at home may be important to consider when designing behavioural interventions to increase PA in preschool children.

OBJECTIVES: To investigate the association between objectively measured maternal and preschool-aged children’s physical activity, determine how this association differs by demographic and temporal factors, and identify factors associated with maternal activity levels. METHODS: In the UK Southampton Women’s Survey, physical activity levels of 554 4-year-olds and their mothers were measured concurrently by using accelerometry for ≤7 days. Two-level mixed-effects linear regression was used to model the association between maternal and children’s minutes spent sedentary, in light (LPA) and moderate-to-vigorous physical activity (MVPA). Linear regression was used to investigate correlates of maternal activity. RESULTS: Mother-child daily activity levels were positively associated at all activity intensities (sedentary, LPA, and MVPA; all P < .001). The association for sedentary time was stronger for normal-weight children (versus those who were overweight/obese), and those attending preschool part-time (versus full-time). The mother-child association for LPA differed by maternal education and was stronger at the weekend (versus weekdays). The opposite was true for MVPA. Sedentary time and MVPA were most strongly associated in mornings, with LPA most strongly associated in the evenings. Maternal BMI, age leaving school, number and age of children at home, and working hours were independently associated with maternal daily sedentary time and LPA. CONCLUSIONS: Physical activity levels in mothers and their 4-year-old children are directly associated, with associations at different activity intensities influenced by temporal and demographic factors. Influences on maternal physical activity levels also differ by activity intensity. Providing targeted interventions for mothers of young children may increase both groups’ activity.

Background Investigating socioeconomic variation in physical activity (PA) and sedentary time is important as it may represent a pathway by which socioeconomic position (SEP) leads to ill health. Findings on the association between children's SEP and objectively assessed PA and/or sedentary time are mixed, and few studies have included international samples. Objective Examine the associations between maternal education and adolescent's objectively assessed PA and sedentary time. Methods This is an observational study of 12 770 adolescents (10–18 years) pooled from 10 studies from Europe, Australia, Brazil and the USA. Original PA data were collected between 1997 and 2009. The associations between maternal education and accelerometer variables were examined using robust multivariable regression, adjusted for a priori confounders (ie, body mass index, monitor wear time, season, age and sex) and regression coefficients combined across studies using random effects meta-analyses. Analyses were conducted in March 2014. Results Adolescents of university educated mothers spent more time sedentary (9.5 min/day, p=0.005) and less time in light activity (10 min/day, p Conclusions Across a number of international samples, adolescents of mothers with lower education may not be at a disadvantage in terms of overall objectively measured PA.

Background There is increasing policy interest in ensuring that the school environment supports healthy behaviours. We examined the cross-sectional and longitudinal associations between schools’ policies, programmes and facilities for physical activity (PA) and adolescents’ objectively-measured activity intensity during the school day and lunchtime. Methods Accelerometer-derived PA (proportion of time spent in sedentary (SED), light PA (LPA) and moderate-to-vigorous PA (MVPA)) during school hours and lunchtime from 325 participants in the SPEEDY study were obtained from baseline measurements (primary school, age 9/10 years) and +4y follow-up (secondary school). School environment characteristics were assessed by teacher questionnaire. Multivariable multi-level linear regression analyses accounting for school and adjusted for sex, age, BMI and family socio-economic status assessed cross-sectional associations with lunchtime and school-day SED, LPA and MVPA; effect modification by sex was investigated. The association of changes in school environment with changes in outcomes was examined using multivariable cross-classified linear regression models. Results There were significant differences between primary and secondary schools for 6/10 school environment characteristics investigated (including secondary schools reporting shorter breaks, more lunchtime PA opportunities, and higher number of sports facilities). Cross-sectional analyses showed that boys attending secondary schools with longer breaks spent significantly less time in SED and more time in MVPA during the school day. Longitudinally, an increase in break-time duration between primary and secondary school was associated with smaller reductions in MVPA during the school day. Moreover, participants who moved from a primary school that did not provide opportunities for PA at lunchtime to a secondary school that did provide such opportunities exhibited smaller increases in SED and smaller reductions in MVPA at lunchtime. Conclusions Schools should consider the potential negative impact of reducing break time duration on students’ MVPA and SED during the school day. School-based interventions that combine longer breaks and more PA opportunities during lunchtime may be a fruitful direction for future research. Further research should also explore other factors in the school environment to explain the school-level clustering observed, and study sex differences in the way that the school environment influences activity intensity for adolescent populations. Electronic supplementary material The online version of this article (doi:10.1186/s12966-016-0378-6) contains supplementary material, which is available to authorized users.

We examine the relative importance of both objective and perceived environmental features for physical activity in older English adults. Self-reported physical activity levels of 8,281 older adults were used to compute volumes of outdoor recreational and commuting activity. Perceptions of neighborhood environment supportiveness were drawn from a questionnaire survey and a geographical information system was used to derive objective measures. Negative binominal regression models were fitted to examine associations. Perceptions of neighborhood environment were more associated with outdoor recreational activity (over 10% change per standard deviation) than objective measures (5–8% change). Commuting activity was associated with several objective measures (up to 16% change). We identified different environmental determinants of recreational and commuting activity in older adults. Perceptions of environmental supportiveness for recreational activity appear more important than actual neighborhood characteristics. Understanding how older people perceive neighborhoods might be key to encouraging outdoor recreational activity.

Background: Family- and home-related factors have been shown to be associated with children’s physical activity (PA), but may be time-dependent. Here we investigate whether family- and home-related correlates of children’s PA are different for the after-school period on weekdays than for the weekend. Methods: Data on 21 family- and home-related variables and objectively measured PA (Actigraph GT1M) were available from 1608 Year 5 children (9–10 years old) from 92 schools in Norfolk participating in the SPEEDY (Sport, Physical activity and Eating behaviour: Environmental Determinants in Young people) study. Multi-level multiple linear regression was used to quantify cross-sectional associations between the family/home variables and average min per day of moderate-to-vigorous PA (MVPA, ≥2000 counts/min) after school on weekdays and at the weekend. Models were additionally adjusted for age, sex, BMI z -score and registered accelerometer wear time. Results: After-school MVPA was associated with parent education (s: −1.1; 95% CI −2.0 to −0.2), being allowed to play out in the neighbourhood (s: 1.3; 0.7–1.8), restrictions on walking/cycling to friends’ houses (s: −1.1; −1.6 to −0.7), restrictions on sedentary behaviour (s: −0.3; −0.5 to −0.02) and family social support (s: 1.0; 0.7–1.3). Weekend MVPA was associated with number of siblings (s: 2.6; 0.5–4.8), family encouragement (s: 1.1; 0.2–2.0) and family social support (s: 1.5; 0.5–2.5). Conclusion: Family social support is positively associated with children’s out-of-school PA both at weekdays and in weekends. However, rules and restrictions appear to be important only on weekdays. The results of this study merit consideration when identifying appropriate timing of PA-promotion strategies.

The rising prevalence of childhood obesity is a key public health issue worldwide. Increased eating frequency (EF) is one aspect of diet that has been beneficially associated with obesity, although the mechanisms are unclear. The aims of the current study were to determine whether increased EF was associated with improved adiposity in children, and if this was due to differences in dietary and activity behaviors. Cross-sectional data from 1,700 children aged 9-10 year were analyzed to examine the associations between EF, as estimated from diet diaries, measures of adiposity, and activity measured by accelerometer. Analyses were stratified by obesity status using waist-to-height ratio to define obesity as it has been shown to be a good predictor of adverse health outcomes. Mean EF was 4.3 occasions/day and after adjustment for underreporting, energy intake (EI), and activity significant relative mean differences of -2.4% for body weight (P = 0.001), -1.0% for BMI (P = 0.020), -33% for BMI z-score (P = 0.014), and -0.6% for waist circumference (P = 0.031) per increase in eating occasion were found in healthy-weight but not centrally obese children. Differences between the extreme quartiles of EF were observed for total fat intake at breakfast (-18%, P < 0.001), fruit and vegetables from snacks (201% healthy-weight and 209% centrally obese children, P < 0.01), and for healthy-weight children, vigorous activity (4%, P = 0.003). Increased EF was favorably associated with adiposity, diet quality, and activity behaviors in healthy-weight but not centrally obese children. Future obesity interventions should consider the mediating role of diet quality and activity in the relationship between EF and adiposity in children.

Background: Few prospective studies have examined predictors of change in specific physical activity (PA) behaviours in different ethnic groups. Purpose: To assess predictors of change in sports participation in Latino and non-Latino 5–8 year-old children in San Diego, California. Methods: Average sports participation frequency (days/week) was assessed by validated parent-report at baseline (Nov 2006–May 2008) and 1 year later in 541 children (45.0% male, 41.1% Latino; mean±SD age: 6.6±0.7 years) taking part in an obesity prevention study (Project MOVE). Biological (sex, age, Body Mass Index z-score), socio-cultural (ethnicity, income, care giver education), parental (PA rules, PA encouragement) and environmental factors (home PA equipment, PA location) were assessed at baseline. Associations between change in sports participation and potential predictors were studied using multilevel linear regression stratified by Latino ethnicity, adjusted for sex, baseline sport participation, study condition and recruitment area. Results: Sports participation increased over 1 year (mean change: +0.5 days; p < 0.001) and change was similar for boys and girls (p=0.95), but Latino children showed a greater increase (p=0.03). The number of locations used for PA (p=0.024) and the total frequency of PA location use (p=0.018) were positively associated with increased sports participation among Latinos. No predictors were identified for non-Latino children. Conclusions: Only factors relating to PA location were identified as predictors of change in sports participation for Latino children. Interventions targeting specific PA behaviours such as sports participation may need to consider PA locations for Latino children and be tailored for specific ethnic groups.

We investigated whether physical activity (PA) correlates differed for 9–10 year-old British children living in urban, suburban and rural settings. We analysed cross-sectional data on 1653 children (SPEEDY study). Exposure variables were self-reported, whilst PA was measured using Actigraph accelerometers. Data were analysed using multilevel hierarchical regression models, stratified by home setting. PA levels did not differ by home setting. Boys, those of normal weight and those having a preference for PA had higher PA levels in all strata, but additional correlates were identified within each setting. These results highlight the potential importance of tailoring interventions to specific environmental and population strata.

Context Data are available on correlates of physical activity in children and adolescents, less is known about the determinants of change. This review aims to systematically review the published evidence regarding determinants of change in physical activity in children and adolescents. Evidence acquisition Prospective quantitative studies investigating change in physical activity in children and adolescents aged 4–18 years were identified from seven databases (to November 2010): PubMed, SCOPUS, PsycINFO, Ovid MEDLINE, SPORTDdiscus, Embase, and Web of Knowledge. Study inclusion, quality assessment, and data extraction were independently validated by two researchers. Semi-quantitative results were stratified by age (4–9 years, 10–13 years, and 14–18 years). Evidence synthesis Of the 46 studies that were included, 31 used self-reported physical activity; average methodologic quality was 3.2 (SD=1.2), scored 0–5. Of 62 potential determinants identified, 30 were studied more than three times and 14 reported consistent findings (66% of the reported associations were in the same direction). For children aged 4–9 years, girls reported larger declines than boys. Among those aged 10–13 years, higher levels of previous physical activity and self-efficacy resulted in smaller declines. Among adolescents (aged 14–18 years), higher perceived behavioral control, support for physical activity, and self-efficacy were associated with smaller declines in physical activity. Conclusions Few of the variables studied were consistently associated with changes in physical activity, although some were similar to those identified in cross-sectional studies. The heterogeneity in study samples, exposure and outcome variables, and the reliance on self-reported physical activity limit conclusions and highlight the need for further research to inform development and targeting of interventions.

We examined the associations between the physical, social, and policy environments of schools and adiposity in 9–10 year old children in Norfolk, UK. The relationships between 56 school-level variables and Fat Mass Index (FMI; fat mass (kg)/height (m 2 )) were investigated among 1724 well characterised children from 92 schools in this cross-sectional study. After stepwise removal of variables from multilevel linear regression models stratified by gender, only three variables were significantly associated with FMI. Among girls, attending a school with more pupils in the year group was associated with lower FMI, and attending a school with better cycle provision was associated with higher FMI. In boys being allowed to eat any food at break-time was associated with higher FMI. There was some evidence of moderation of the relationship between cycle provision and FMI by urban–rural location. These data suggest that few school factors are associated with FMI, and provide limited pointers to inform potential future school-based interventions to reduce obesity.

Background Next to the school environment, the family and community environment are key for young people9s behaviour and for promoting physical activity (PA). Methods A review of reviews was conducted, after which a literature search was conducted (in PubMed, Scopus and PsychInfo) from August 2007 (search date of the most recent review) to October 2010. Inclusion criteria were study population aged 18 years or younger, controlled trial, no PA control condition, PA promotion intervention and reported analyses of a PA-related outcome. Methodological quality was assessed, and data on intervention details, methods and effects on primary and secondary outcomes (PA, body composition and fitness) were extracted. Results Three previous reviews were reviewed, including 13 family-based and three community-based interventions. Study inclusion differed for each review, but all concluded that the evidence was limited, although the potential of family-based interventions delivered in the home and including self-monitoring was highlighted. A further six family-based and four community-based interventions were included in the updated review, with a methodological quality score ranging from 2 to 10 and five studies scoring 6 or higher. Significant positive effects on PA were observed for one community-based and three family-based studies. No distinctive characteristics of the effective interventions compared with those that were ineffective were identified. Conclusions The effect of family- and community-based interventions remains uncertain despite improvements in study quality. Of the little evidence of effectiveness, most comes from those targeted at families and set in the home. Further detailed research is needed to identify key approaches for increasing young people9s PA levels in family and community settings.

OBJECTIVE: We measured physical activity changes among 10-year-old British children over 12 months and assessed biological and demographic determinants. METHODS: Physical activity was measured with accelerometers (counts per minute) over ≥3 days at baseline and 1 year later in a prospective study of 844 children (41.6% male; mean ± SD baseline age: 10.2 ± 0.3 years) from 92 schools. Meeting physical activity recommendations was defined as ≥60 minutes/day at ≥2000 counts per minute. Biological (height, weight, and fat percentage) and demographic factors (gender, rural/urban home location, and socioeconomic status) were assessed at baseline. Associations between physical activity changes and multiple factors were studied. RESULTS: Physical activity decreased over 1 year (baseline: 665.7 ± 209.8 counts per minute; follow-up: 623.2 ± 179.2 counts per minute; P < .001), with 70.4% of children meeting physical activity recommendations at the baseline evaluation and 65.8% at the follow-up evaluation (P < .001). The decrease occurred mainly on weekends (−47.2 ± 395.8 counts per minute; P = .002), with no significant change on weekdays (8.0 ± 201.6 counts per minute; P = .20). Girls (P < .001), participants with greater body fat percentage (P = .001), and participants of higher socioeconomic status (P = .008) were more likely to exhibit physical activity decreases. CONCLUSIONS: Physical activity decreased over 1 year among children in primary school, predominantly during the weekend. Because these children were relatively active at baseline, prevention of physical activity decreases in childhood, particularly among girls and on weekends, may be a suitable health promotion target.

Background: Walking and cycling to school represent an opportunity for children to achieve regular physical activity. These behaviors may be influenced by characteristics of the environment around homes and schools, yet few studies have quantified the potential associations between these two sets of factors. Purpose: This study aims to assess whether objectively measured characteristics of the neighborhood, route, and school environments are associated with active commuting to school among children, and it explores whether distance acts as a moderator in this association. Methods: A cross-sectional study was conducted of 2012 children (899 boys and 1113 girls) aged 9-10 years attending 92 schools in the county of Norfolk, United Kingdom. Questionnaires were completed by children and parents during Summer 2007. Attributes around the home and children's route to school were assessed using a GIS. School environments were assessed using a newly developed school audit and via questionnaires completed by head teachers. Data were analyzed in 2008. Results: Almost half of the children usually walked or cycled to school. Children who lived in a more deprived area and whose route to school was direct were less likely to walk or cycle to school, whereas those who had a higher density of roads in their neighborhood were more likely to walk. Further, children whose routes had a high density of streetlights were less likely to cycle to school. Distance did not moderate the observed associations. Conclusions: Objectively measured neighborhood and route factors are associated with walking and cycling to school. However, distance did not moderate the associations found here. Creating safe environments by improving urban design may influence children's commuting behavior. Intervention studies are needed to confirm the findings from this observational cross-sectional study.

The impact of poor childhood nutrition has consequences for both short-term and long-term health(1,2) and the escalating rates of obesity in childhood are becoming a significant public health issue(3). A number of factors contribute to poor food intake, including socio-economic status, parental and child food choice and preferences, and the accessibility of foods. There is growing evidence to show that those of lower socio-economic status have to spend a higher proportion of their income on food(4) and tend to consume less healthy diets(5,6). Research in the USA has shown that people living in areas of low socio-economic status have poorer access to supermarkets, resulting in less access to healthier foods, and the foods that could be purchased were more expensive(7). Other research shows that those living in deprived areas had much greater access to fast-food retailers and other retailers selling less healthy products(8–11). To date there has been limited and inconsistent evidence that these ‘food deserts’, where residents have limited access to healthy food, exist in the UK(12). However, the available previous research has focused on more densely populated urban areas(13) and there may be particular problems with access to or availability of healthier foods for those living in smaller towns and villages. Furthermore, there have been few studies on the relationship between neighbourhood food outlets and food intake in children, although the findings from the limited available evidence suggest that children living in areas with higher densities of fast-food retailers tend to make poorer dietary choices(14–16). While there has been some previous research on the role of the neighbourhood environment in determining food choice, there have been limited studies employing Geographic Information Systems (GIS)(14,16–19) in order to produce objective indicators of different domains of the local food environment, such as distance to and density of food outlets. Furthermore, all previous studies of children that have used GIS data have focused only on fruit and vegetable consumption(14,16,18), whereas the food environment is likely to influence other food choices as well. Since childhood nutrition is important for future health, and rates of childhood obesity are rising, it is important to understand the relationship between food intake and food access among this group. Therefore the present study was undertaken to investigate the relationship between distance to and density of foods in the local neighbourhood and both healthy and less healthy food choices in a population of 9- to 10-year-old children in the UK.

To assess the association between active travel to school and physical activity (PA) in a large population-based sample of 11-year old children.Cross-sectional analyses using data from the Avon Longitudinal Study of Parents and Children (Bristol, UK), collected in 2002-2004. The analyses include all children providing valid data on objectively measured PA (Actigraph accelerometer), and having parent-proxy reported data on travel mode (walk, cycle, public transport, car) and distance to school (N=4688).43.5% of children regularly walked or cycled to school (i.e. on every or most days). Compared with car travelers, walking to school was associated with 5.98 (95%CI: 3.82-8.14) more minutes of moderate-to-vigorous PA (MVPA) on weekdays in those living 0.5-1 miles from school, and with 9.77 (95%CI: 7.47-12.06) more minutes in those living at 1-5 miles. This equates to 24.6 to 40.2% of the average daily minutes of MVPA. Only modest differences were observed in those living0.5 mile from school.Children who regularly walk to school are more active during the week than those travelling by car, especially if the distance is0.5 mile. Increasing participation in active travel might be a useful part of an overall strategy to increase population PA.

Background: It is unclear whether it is possible to accurately estimate physical activity energy expenditure (PAEE) by self-report in youth. Objective: We assessed the validity and reliability of 4 self-reports to assess PAEE and time spent at moderate and vigorous intensity physical activity (MVPA) over the previous week in British young people between 4 and 17 y of age. Design: PAEE and MVPA were derived from the Children’s Physical Activity Questionnaire, Youth Physical Activity Questionnaire, and Swedish Adolescent Physical Activity Questionnaire; a lifestyle score indicative of habitual activity was derived from the Child Heart and Health Study in England Questionnaire. These data were compared with criterion methods, PAEE, and MVPA derived from simultaneous measurements by doubly labeled water and accelerometry in 3 age groups: 4–5 y (n ¼ 27), 12–13 y (n ¼ 25), and 16– 17 y (n ¼ 24). Validity was assessed by using Spearman correlations and the Bland-Altman method, and reliability was assessed by using intraclass correlation coefficients. Results: The strength of association between questionnaire and criterion methods varied (r ¼ 0.09 to r ¼ 0.46). Some questionnaires were able to accurately assess group-level PAEE and MVPA for some age groups, but the error was large for individual-level estimates throughout. Reliability of the Youth Physical Activity Questionnaire and Child Heart and Health Study in England Questionnaire was good (intraclass correlation coefficient: 0.64–0.92). Conclusions: Absolute PAEE and MVPA estimated from these selfreports were not valid on an individual level in young people, although some questionnaires appeared to rank individuals accurately. Age (the outcome of interest) and whether individual or group-level estimates are necessary will influence the best choice of self-report method when assessing physical activity in youth. Am J Clin Nutr 2009;89:862– 70.

Cross-sectional associations between sociocultural factors and objectively-measured physical activity in a sample of 397 children (aged 9) and 213 adolescents (aged 15) were investigated. Associations with children’s physical activity were found for mothers’ physical activity (β=80,p < .01), parental participation (β=67,p = .01), mother’s age (β=−8,p < .01) and, in girls, fathers’ physical activity (β=73, p = .045; R2 for final model: 10.6%). No sociocultural factors were significantly associated with adolescents’ physical activity. Parental factors might be important targets for interventions to increase children’s physical activity but other factors may have greater influence. For adolescents’ physical activity, factors from other domains may be more important to target.