Consolidated guidance for behavioral intervention pilot and feasibility studies.

BACKGROUND: In the behavioral sciences, conducting pilot and/or feasibility studies (PFS) is a key step that provides essential information used to inform the design, conduct, and implementation of a larger-scale trial. There are more than 160 published guidelines, reporting checklists, frameworks, and recommendations related to PFS. All of these publications offer some form of guidance on PFS, but many focus on one or a few topics. This makes it difficult for researchers wanting to gain a broader understanding of all the relevant and important aspects of PFS and requires them to seek out multiple sources of information, which increases the risk of missing key considerations to incorporate into their PFS. The purpose of this study was to develop a consolidated set of considerations for the design, conduct, implementation, and reporting of PFS for interventions conducted in the behavioral sciences. METHODS: To develop this consolidation, we undertook a review of the published guidance on PFS in combination with expert consensus (via a Delphi study) from the authors who wrote such guidance to inform the identified considerations. A total of 161 PFS-related guidelines, checklists, frameworks, and recommendations were identified via a review of recently published behavioral intervention PFS and backward/forward citation tracking of a well-known PFS literature (e.g., CONSORT Ext. for PFS). Authors of all 161 PFS publications were invited to complete a three-round Delphi survey, which was used to guide the creation of a consolidated list of considerations to guide the design, conduct, and reporting of PFS conducted by researchers in the behavioral sciences. RESULTS: A total of 496 authors were invited to take part in the three-round Delphi survey (round 1, N = 46; round 2, N = 24; round 3, N = 22). A set of twenty considerations, broadly categorized into six themes (intervention design, study design, conduct of trial, implementation of intervention, statistical analysis, and reporting) were generated from a review of the 161 PFS-related publications as well as a synthesis of feedback from the three-round Delphi process. These 20 considerations are presented alongside a supporting narrative for each consideration as well as a crosswalk of all 161 publications aligned with each consideration for further reading. CONCLUSION: We leveraged expert opinion from researchers who have published PFS-related guidelines, checklists, frameworks, and recommendations on a wide range of topics and distilled this knowledge into a valuable and universal resource for researchers conducting PFS. Researchers may use these considerations alongside the previously published literature to guide decisions about all aspects of PFS, with the hope of creating and disseminating interventions with broad public health impact.

Total and temporal patterning of physical activity in adolescents and associations with mental wellbeing.

BACKGROUND: There is limited understanding of the extent to which differences in physical activity across the day and week may be associated with mental wellbeing. Such an understanding is needed for better targeting of interventions. In this study, we describe total and temporal patterning of physical activity across the week in adolescents (age 13-14y) and assess their prospective associations with mental wellbeing. METHODS: 1,983 13-14-year-old adolescent participants based in Cambridgeshire and Essex, recruited between 2016 and 2017 into the Get Others Active Trial provided data at baseline and 4 months. Physical activity was measured at baseline using wrist-worn accelerometers across different time segments (whole week, weekday schooltime, weekday out of school, and weekend), and operationalized as average movement-related acceleration for each time segment. Mental Wellbeing at baseline and 4 months was measured using the Warwick Edinburgh MentalWellbeing Scale. Associations between physical activity across different time segments (whole week, weekday schooltime, weekday out of school, and weekend) and mental wellbeing at 4 months were investigated using sex-stratified multi-level regression models, adjusted for covariates, and both adjusted and unadjusted for baseline mental wellbeing. RESULTS: Our analyses found positive associations between physical activity and mental wellbeing at 4 months, unadjusted for baseline wellbeing. Among girls, positive associations were shown when considering physical activity across the whole week 0.07 (95% CI, 0.03-0.12), and across all separate time periods studied: weekday schooltime 0.07 (95% CI, 0.02-0.11), weekday out-of-school time 0.07 (95% CI, 0.03-0.12), and weekend 0.07 (95% CI, 0.02-0.11). For boys, similar associations were observed for activity across the week 0.07 (95% CI, 0.03-0.11), during weekday schooltime 0.08 (95% CI, 0.04-0.12), and weekday out-of-school time 0.07 (95% CI, 0.03-0.11), but not the weekend 0.01 (95% CI, -0.03-0.05). For both girls and boys, associations were attenuated below significance after adjusting for baseline wellbeing. CONCLUSIONS: This longitudinal analysis showed positive associations between physical activity and later mental wellbeing in both male and female adolescents across most time segments. Higher physical activity throughout the week may be associated with better mental wellbeing in the adolescent population. Further research is required to understand determinants of change in wellbeing over time. TRIAL REGISTRATION: Registration Number: ISRCTN31583496. Registered: 18/02/2014.

Activity Behaviors Before and During Pregnancy Are Associated With Women's Device-Measured Physical Activity and Sedentary Time in Later Parenthood: A Longitudinal Cohort Analysis.

PURPOSE: To explore how activity behaviors before/during pregnancy relate to those in later parenthood, we assessed associations between sitting and moderate-/strenuous exercise before/during pregnancy, and sedentary time (SED) and moderate to vigorous physical activity (MVPA) 4-7 years postpartum ("later parenthood"). METHODS: Longitudinal data were from the Southampton Women's Survey, United Kingdom. Women reported time spent sitting (in hours per day), in moderate-strenuous exercise (hours per week), and in strenuous exercise (hours per week) at 3 time points before/during pregnancy (ie, preconception, at ∼12-wk and ∼34-wk gestation). From this, we derived 3 behavior trajectories for each woman. In later parenthood, women wore an accelerometer for ≤7 days (mean: 5.4 [SD: 1.8] d), which we used to derive 2 outcomes: minutes per day SED and in MVPA. Multilevel linear regression was used to explore associations between trajectories before/during pregnancy and device-measured SED/MVPA in later parenthood. RESULTS: A total of 780 women provided valid data before/during pregnancy and in later parenthood. Consistent high sitters (vs low) were more sedentary 4-7 years postpartum (ß = 39.5 min/d [95% confidence interval, 23.26 to 55.82]), as were women in groups who sat more in later pregnancy. Consistently high moderate/-strenuous exercisers (vs low) were 22% (95% confidence interval, 2%-47%) more active in later parenthood; those engaging in strenuous activity preconception tended to have higher MVPA as parents. CONCLUSIONS: Trajectories of sitting and exercise before/during pregnancy are associated with SED and MVPA, respectively, in later parenthood. Interventions to reduce sitting in pregnancy and to encourage higher intensity activity preconception may benefit maternal and child health.

Conducting school-based health surveys with secondary schools in England: advice and recommendations from school staff, local authority professionals, and wider key stakeholders, a qualitative study.

BACKGROUND: Improving the health and well-being of young people is a public health priority. Schools present an ideal setting to implement strategies to improve young people's health and well-being. A key strategy involves conducting surveys to assess student health needs, inform interventions, and monitor health over time. Conducting research in schools is, however, challenging. Schools can find it difficult to participate and adhere to research processes, even when they are keen to be involved in research, because of competing priorities (e.g., attendance and educational achievement), as well as time and resource constraints. There is a lack of literature on the perspectives of school staff and other key stakeholders working in young people's health on how best to work with schools to conduct health research, and in particular, health surveys. METHODS: Participants (n = 26) included members of staff from 11 secondary schools (covering students aged 11-16 years), 5 local authority professionals, and 10 wider key stakeholders in young people's health and well-being (e.g., a school governor, a national government member), based in South West England. Participants took part in semi-structured interviews that were conducted either over the phone or via an online platform. Data were analysed using the Framework Method. RESULTS: Three main themes were identified: Recruitment and Retention, Practicalities of Data Collection in Schools, and Collaboration from Design to Dissemination. It is important to acknowledge the role of local authorities and academy trusts in the English education system, and work closely with these when conducting school-based health surveys. School staff prefer to be contacted about research via email and in the summer term, following exams. Researchers should contact a member of staff involved in student health/well-being, as well as senior leadership, during recruitment. Data collection during the start and end of the school year is undesirable. Research should be collaborative with school staff and young people, consistent with school priorities and values, and flexible and tailored to school timetables and resources. CONCLUSIONS: Overall the findings demonstrate that survey-based research methods should be school-led and tailored to each school.

Pre-pubertal accelerometer-assessed physical activity and timing of puberty in British boys and girls: the Millennium Cohort Study.

BACKGROUND: Early puberty timing is associated with adverse health outcomes. We aimed to examine prospective associations between objectively measured physical activity and puberty timing in boys and girls. METHODS: In the UK Millennium Cohort Study, physical activity volume and intensities at 7 years were measured using accelerometers. Status of several pubertal traits and age at menarche were reported at 11, 14 and 17 years. Age at menarche in girls was categorized into tertiles. Other puberty traits were categorized into earlier or later than the median ages calculated from probit models, separately in boys and girls. Multivariable regression models, with adjustment for maternal and child characteristics including body mass index (BMI) at age 7 years as potential confounders, were performed to test the associations of total daily activity counts and fractions of activity counts across intensities (in compositional models) with puberty timing, separately in boys (n = 2531) and girls (n = 3079). RESULTS: Higher total daily activity counts were associated with lower risks for earlier (vs later) growth spurt, body hair growth, skin changes and menarche in girls, and more weakly with lower risks for earlier skin changes and voice breaking in boys (odds ratios = 0.80-0.87 per 100 000 counts/day). These associations persisted on additional adjustment for BMI at 11 years as a potential mediator. No association with puberty timing was seen for any physical activity intensity (light, moderate or vigorous). CONCLUSIONS: More physical activity regardless of intensity may contribute to the avoidance of earlier puberty timing, independently of BMI, particularly in girls.

Time spent on social media use and BMI z-score: A cross-sectional explanatory pathway analysis of 10798 14-year-old boys and girls.

BACKGROUND: The association between adolescent time spent on social media use and body mass index z-score (BMI z-score) is unclear. Pathways of association and sex differences are also unclear. This study examined the association between time spent on social media use and BMI z-score (primary objective) and potential explanatory pathways (secondary objective) for boys and girls. METHODS: Data are from 5332 girls and 5466 boys aged 14 years in the UK Millennium Cohort Study. BMI z-score was regressed on self-reported time spent on social media use (h/day). Potential explanatory pathways explored included dietary intake, sleep duration, depressive symptoms, cyberbullying, body-weight satisfaction, self-esteem, and well-being. Sex-stratified multivariable linear regression and structural equation modelling were used to examine potential associations and explanatory pathways. RESULTS: Using social media for ≥5 h/day (vs. <1 h/day) was positively associated with BMI z-score for girls (ß [95% CI]) (0.15 [0.06, 0.25]) (primary objective, multivariable linear regression). For girls, the direct association was attenuated when sleep duration (0.12 [0.02, 0.22]), depressive symptoms (0.12 [0.02, 0.22]), body-weight satisfaction (0.07 [-0.02, 0.16]), and well-being (0.11 [0.01, 0.20]) were included (secondary objective, structural equation modelling). No associations were observed for boys and potential explanatory pathway variables were not examined. CONCLUSIONS: In girls, high time spent on social media use (≥5 h/day) was positively associated with BMI z-score, and this association was partially explained by sleep duration, depressive symptoms, body-weight satisfaction, and well-being. Associations and attenuations between a self-reported summary variable of time spent on social media use and BMI z-score were small. Further research should examine whether time spent on social media use is related to other adolescent health metrics.

Shorter sleep among adolescents is associated with lower fruit and vegetable consumption the following day.

BACKGROUND: Insufficient sleep has been associated with weight gain and metabolic dysregulation, with one suggested mechanism being through reduction in diet quality. Experimental evidence supports a causal effect of sleep timings on diet but this may not be applicable to a free-living adolescent population. In this analysis we use daily measures of sleep timings and diet quality, to examine the effect of sleep duration and timing on diet quality the following day among free-living adolescents. METHODS: The ROOTS study is a prospective cohort recruited from secondary schools in Cambridgeshire and Suffolk (UK). Participants (n = 815) at mean age 15.0y (SD 0.3y) completed a diet diary and wore a combined heart rate and accelerometer device over 4 consecutive days. Sleep duration and timing (midpoint) were derived from acceleration and heart rate traces, while daily energy density and fruit and vegetable intake were calculated from dietary data. Analyses were performed at day-level (1815 person-days). Multilevel random effects models were used to test associations between sleep each night and subsequent day diet, with daily sleep and diet measures nested within individuals and schools, and adjusted for day-level and individual-level confounding variables. RESULTS: Adolescents slept a mean of 7.88 hrs (SD 1.10) per night, reporting a mean energy density of 2.12 kcal/g (SD 0.48) and median energy-adjusted daily fruit and vegetable intake of 137.3 g (IQR 130.4). One hour shorter sleep duration was associated with lower intake of fruit and vegetables (-6.42 g, 95%CI -1.84, -10.99) the following day. An association with higher dietary energy density (0.016 kcal/g, 95%CI 0.034, -0.002) the following day was observed but did not reach statistical significance. Sleep timing was not associated with either fruit and vegetable intake (-2.52 g/d, 95%CI -7.66, 2.62) or dietary energy density (-0.001 kcal/g, 95%CI -0.022, 0.020). CONCLUSIONS: Our observational findings from a free-living adolescent population support the experimental evidence for a causal role of sleep on diet, with shorter sleep duration at night leading to a small decrease in diet quality the following day. These findings support experimental evidence to suggest inclusion of sleep duration as one component of interventions designed to improve diet quality and weight status in adolescents.

Recruitment and retention into longitudinal health research from an adolescent perspective: a qualitative study.

BACKGROUND: High quality longitudinal studies investigating changes in health behaviours over the transition into early adulthood are critical. However, recruiting and retaining adolescents is challenging. This study explored adolescents' perspectives of signing up to and continuing involvement in a hypothetical longitudinal health research study. METHODS: Forty-eight individuals (15-20y) participated in nine in-person focus groups about recruitment and retention in research. Participants were (a) school students in the last year of compulsory school (Year 11, 15-16y), (b) school/college students in Sixth Form (Year 13, 17-18y), (c) Further Education students studying after secondary education, but not higher education (16-18y) and (d) young adults not in education, employment, or training (18-20y) across England. Thematic analysis resulted in seven themes. RESULTS: Driving factors for sign-up included social connection e.g., joining with peer groups, personalised feedback, and incentives, primarily financial. Key barriers were lack of interest, the perception of commitment, and timing of recruitment. Young people preferred recruitment processes via social media with messages tailored to their motivations, monthly data collection of maximally 20-30 min, and hybrid data collection with some in-person contact with a consistent, non-judgemental researcher. The provision of autonomy, choice, and financial incentives were perceived to promote retention. CONCLUSIONS: Adolescent recruitment and retention strategies need to align with contemporary interests and motivations. Studies should involve adolescents early to develop a planned, systematic approach to participant sign-up and follow-up. Effective and ineffective recruitment and retention strategies should be reported as part of study findings. Future research should trial how perceived barriers to study engagement can be overcome.

The association between number and ages of children and the physical activity of mothers: Cross-sectional analyses from the Southampton Women's Survey.

BACKGROUND: Physical activity (PA) has many health benefits, but motherhood is often associated with reduced PA. Considering that ages and number of children may be associated with maternal PA, and that PA patterns may change as children transition to formal schooling, we aimed to investigate the associations between ages and number of children and device-measured maternal PA. METHODS: Cross-sectional analyses were conducted using data from 848 mothers from the Southampton Women's Survey at two different timepoints. Two-level random intercept linear models were used to investigate associations between ages (≤4y(ears) ("younger"), school-aged, both age groups) and number (1, 2, ≥3) of children, and their interaction, and accelerometer-assessed minutes of maternal moderate or vigorous PA (log-transformed MVPA) and light, moderate or vigorous PA (LMVPA). RESULTS: Women with any school-aged children engaged in more MVPA than those with only ≤4y (e.g. % difference in minutes of MVPA [95% confidence interval]: 46.9% [22.0;77.0] for mothers with only school-aged vs only ≤4y). Mothers with multiple children did less MVPA than those with 1 child (e.g. 12.5% [-1.1;24.3] less MVPA for those with 2 children). For mothers with multiple children, those with any school-aged children did less LMVPA than those with only ≤4y (e.g. amongst mothers with 2 children, those with only school-aged children did 34.0 [3.9;64.1] mins/day less LMVPA). For mothers with any ≤4y, those with more children did more LMVPA (e.g. amongst mothers with only ≤4y, those with 2 children did 42.6 [16.4;68.8] mins/day more LMVPA than those with 1 child). CONCLUSIONS: Mothers with multiple children and only children aged ≤4y did less MVPA. Considering that many of these women also did more LMVPA than mothers with fewer or older children, interventions and policies are needed to increase their opportunities for higher intensity PA to maximise health benefits. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04715945.

Creation of a Pilot School Health Research Network in an English Education Infrastructure to Improve Adolescent Health and Well-Being: A Study Protocol.

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

Activity Behaviors in British 6-Year-Olds: Cross-Sectional Associations and Longitudinal Change During the School Transition.

BACKGROUND: To explore activity behaviors at school entry, we describe temporal/demographic associations with accelerometer-measured physical activity in a population-based sample of British 6-year-olds, and examine change from ages 4 to 6. METHODS: A total of 712 six-year-olds (308 at both ages) wore Actiheart accelerometers for ≥3 (mean 6.0) days. We derived minutes per day sedentary (<20 cpm) and moderate to vigorous physical activity (MVPA, ≥460 cpm), also segmented across mornings (06:00 AM to 09:00 AM), school (09:00 AM to 3:00 PM), and evenings (3:00 PM to 11:00 PM). Using mixed effects linear regression, we analyzed associations between temporal/demographic factors and children's activity intensities at age 6, and change between ages 4 and 6. RESULTS: Six-year-old children engaged in MVPA (mean [SD]): 64.9 (25.7) minutes per day (53% met UK guidelines). Girls did less MVPA than boys, particularly during school hours. Children were less active on weekends (vs weekdays) and more active on spring/summer evenings (vs winter). Longitudinally, 6-year-old children did less light physical activity (-43.0; 95% confidence interval, -47.5 to -38.4 min/d) but were more sedentary (29.4; 24.6 to 34.2), and engaged in greater MVPA (7.1; 5.2 to 9.1) compared to when they were aged 4. CONCLUSION: Half of 6-year-old children met current activity guidelines; MVPA levels were lower in girls and at weekends. UK children became more sedentary but did more MVPA as they entered formal schooling. Physical activity promotion efforts should capitalize on these changes in MVPA, to maintain positive habits.

Impacts of new cycle infrastructure on cycling levels in two French cities: an interrupted time series analysis.

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

Device-measured sleep onset and duration in the development of depressive symptoms in adolescence.

BACKGROUND: Sleep deprivation in adolescence is increasing in prevalence and may be linked to subsequent depression. Findings regarding associations between sleep duration, sleep onset time, and the development of depressive symptoms over time in adolescents are mixed, and rely on subjective measures of sleep. METHODS: Sleep onset and duration were assessed using a combined heart rate monitor and accelerometer and self-report in 688 participants from the ROOTS study at age 15. Participants reported depressive symptoms at ages 14.5, 16, and 17.5, using the Mood and Feelings Questionnaire. Latent growth curve modelling was used to model development of depressive symptoms and test associations with baseline sleep onset and duration. RESULTS: Cross-sectionally, falling asleep later and shorter sleep duration were both associated with higher depressive symptoms in males and females, using both device-measured and self-reported sleep. There were no longitudinal associations between baseline sleep duration and change in depressive symptoms. A later sleep onset-time was associated with a decrease in depressive symptoms over time, in females only, using device-measured sleep only. LIMITATIONS: The current sample was more economically advantaged and ethnically white than the UK average, and with lower MFQ symptoms than the original cohort, which may reduce generalisability. CONCLUSIONS: Adolescents who fall asleep later or sleep less have higher levels of depressive symptoms cross-sectionally, but do not show increases in depressive symptoms over time. Interventions targeting sleep onset and duration in adolescence may improve mental health in the short-term but the possibility of reverse causality should be explored further.

Descriptive epidemiology of the prevalence of adolescent active travel to school in Asia: a cross-sectional study from 31 countries.

OBJECTIVE: This study aimed to examine the prevalence of adolescent active travel to school (ATS) across 31 countries and territories in Asia, overall and by age group, sex and body mass index (BMI) category. DESIGN: Cross-sectional study. SETTING: 31 Asian countries. PARTICIPANTS: 152 368 adolescents aged 13-17 years with complete data for age, sex, measured weight and height and active travel to school from 31 Asian countries from the Global School-based student Health Survey (GSHS). PRIMARY OUTCOME: Self-reported active travel to school categorised into passive (0 days) and active (1-7 days). RESULTS: Overall prevalence of adolescent ATS in Asia based on random-effect meta-analysis was 55%, ranging from 18% (UAE) to 84% (Myanmar). There was limited subregional variation: 47% in the Eastern Mediterranean (EM), 56% in the South East Asia and 64% in the Western Pacific. Summarised by random-effect meta-analysis, being an older adolescent aged 16 years and older (vs younger age below 16 years: OR: 1.08; 95% CI: 1.00 to 1.16) was positively associated with ATS. This association was strongest in EM countries. Summarised by random-effect meta-analysis, females (vs males: OR: 0.79; 95% CI: 0.71 to 0.89) and adolescents with overweight/obesity (vs underweight and normal BMI: OR: 0.92; 95% CI: 0.86 to 0.99) were less likely to use ATS. Association with sex was strongest in EM countries. Heterogeneity was considerable in all meta-analyses. CONCLUSION: The prevalence of adolescent ATS in Asia varies substantially. Overall, older and male adolescents, and adolescents with underweight and normal BMI category are more likely to actively travel to school. However, the main contributor to differences in ATS between and within regions remain unknown. Although there is substantial scope for improving ATS rates in Asia, any policy actions and interventions should be cognisant of local built, social and natural environmental contexts that may influence active travel behaviour.

Influence of Guideline Operationalization on Youth Activity Prevalence in the International Children's Accelerometry Database.

INTRODUCTION: The United Kingdom and World Health Organization recently changed their youth physical activity (PA) guidelines from 60 min of moderate- to vigorous-intensity PA (MVPA) every day, to an average of 60 min of MVPA per day, over a week. The changes are based on expert opinion due to insufficient evidence comparing health outcomes associated with different guideline definitions. This study used the International Children's Accelerometry Database to compare approaches to calculating youth PA compliance and associations with health indicators. METHODS: Cross-sectional accelerometer data (n = 21,612, 5-18 yr) were used to examine compliance with four guideline definitions: daily method (DM; ≥60 min MVPA every day), average method (AM; average of ≥60 min MVPA per day), AM5 (AM compliance and ≥5 min of vigorous PA [VPA] on ≥3 d), and AM15 (AM compliance and ≥15 min VPA on ≥3 d). Associations between compliance and health indicators were examined for all definitions. RESULTS: Compliance varied from 5.3% (DM) to 29.9% (AM). Associations between compliance and health indicators were similar for AM, AM5, and AM15. For example, compliance with AM, AM5, and AM15 was associated with a lower BMI z-score (statistics are coefficient [95% CI]): AM (-0.28 [-0.33 to -0.23]), AM5 (-0.28 [-0.33 to -0.23], and AM15 (-0.30 [-0.35 to -0.25]). Associations between compliance and health indicators for DM were similar/weaker, possibly reflecting fewer DM-compliant participants with health data and lower variability in exposure/outcome data. CONCLUSIONS: Youth completing 60 min of MVPA every day do not experience superior health benefits to youth completing an average of 60 min of MVPA per day. Guidelines should encourage youth to achieve an average of 60 min of MVPA per day. Different guideline definitions affect inactivity prevalence estimates; this must be considered when analyzing data and comparing studies.

Perceptions of the South African 24-Hour Movement Guidelines for Birth to 5 Years: A Qualitative Study.

BACKGROUND: South Africa launched 24-hour movement guidelines for birth to 5 years in 2018. Perceptions of these guidelines were assessed as part of the dissemination process with community-based organizations in 2019. METHODS: Fifteen dissemination workshops were held with community-based organization representatives and a range of stakeholders. Discussions were held with workshop attendees (n = 281) to obtain qualitative feedback on the guidelines and workshop. Six follow-up focus groups (n = 28) were conducted to obtain additional feedback on the guidelines and their dissemination. Discussions and focus groups were thematically analyzed. RESULTS: Participants recognized the importance of the guidelines for the health and development of young South African children. Participants' perceptions of the guidelines were consistently positive. The participants acknowledged the alignment of the guidelines with other South African programs and initiatives, and that they addressed gaps. Screen time and sleep were identified as the behaviors needing particular attention among young South African children. The negative impact of COVID-19 on young children's movement behaviors was acknowledged, especially regarding screen time. CONCLUSION: These findings provide evidence of stakeholders' positive perceptions of the South African guidelines and support the dissemination and implementation of these guidelines for the promotion of early childhood health and development in South Africa.

Cross-sectional and prospective associations of sleep duration and bedtimes with adiposity and obesity risk in 15 810 youth from 11 international cohorts.

OBJECTIVES: To investigate associations of bedtimes and sleep durations with adiposity levels in children and adolescents. METHODS: Individual 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. RESULTS: In children, longer sleep durations were consistently associated with lower adiposity markers, and earlier bedtimes were related to lower BMI z-score. Compared to sleeping <10 h, longer baseline sleep duration favourably predicted Δwaist z-score in girls (≥10 and <11 h (ß-coefficient (95% confidence interval [CI])): -0.06 (-0.12 to -0.01)) and boys (≥11 h: -0.10 [-0.18 to -0.01]). Combined groups that were defined by longer sleep (later-longer and earlier-longer sleep patterns) were associated with lower adiposity, and later-longer sleep favourably predicted Δwaist z-score in girls (-0.09 [-0.15 to -0.02]). In adolescents, longer sleep durations and earlier bedtimes were associated with lower BMI z-score in the whole sample, and also with lower waist z-score in boys. Combined groups that were characterized by earlier bedtimes were associated with the same outcomes. For example, earlier-shorter (-0.22 (-0.43 to -0.01) and earlier-longer (-0.16 (-0.25 to -0.06) sleep were both associated with lower BMI z-score. CONCLUSIONS: If 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.

The socio-ecological determinants of change in school travel mode over the transition from childhood to adolescence and the association with physical activity intensity.

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

Association of change in the school travel mode with changes in different physical activity intensities and sedentary time: A International Children's Accelerometry Database Study.

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

Early adulthood socioeconomic trajectories contribute to inequalities in adult cardiovascular health, independently of childhood and adulthood socioeconomic position.

BACKGROUND: Cardiovascular 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). METHODS: Participants 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. RESULTS: Six 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. CONCLUSION: Findings 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.