Improving physical activity and screen time in Australian Outside School Hours Care: Study protocol.

BACKGROUND: Children's physical activity and screen time behaviours impact their physical health and well-being. In Australia, less than half of children meet daily physical activity recommendations and only one-third meet daily screen time recommendations. Nearly half a million Australian school children aged 5-12 attend Outside School Hours Care (OSHC) weekly, activities undertaken at OSHC play a key role in meeting these recommendations. Currently, physical activity and screen time practices in OSHC vary and lack policy guidance. The Activated OSHC program is a policy-based intervention that supports OSHC services to implement the physical activity and screen time guidelines. METHODS: 192 OSHC services across Australia will be recruited. 96 services will be randomly allocated to receive the Activated OSHC program. OSHC coordinators will complete online surveys examining physical activity and screen time scheduling, cost, acceptability, and feasibility. Primary outcome; changes in the proportion of intervention and control services meeting OSHC sector physical activity and screen time guidelines, and secondary outcomes; changes in children's physical activity and screen time behaviours; changes in staff behaviour will be assessed using mixed-effects regression models. DISCUSSION: The aim of this study is to examine the impact of the Activated OSHC program on children's physical activity and screen time. IMPACT: Recent Australian research in Outside School Hours Care (OSHC) has identified significant inconsistency in practices related to physical activity and screen time, compounded by an absence of explicit policy guidance. The Activated OSHC program is a policy-based intervention that supports OSHC services to implement the Australian OSHC physical activity and screen time guidelines. This study will assess the implementation and effectiveness of the Activated OSHC program in an effectiveness-implementation hybrid type 2 trial design. Implementation of outside school hours care sector physical activity and screen time guidelines may improve children's physical activity and screen time behaviours.

Differences in elementary-age children's accelerometer - measured physical activity between school and summer: three-year findings from the What's UP (Undermining Prevention) with summer observational cohort study.

BACKGROUND: Among elementary-aged children (5-12yrs), summer vacation is associated with accelerated gains in Body Mass Index (BMI). A key behavioral driver of BMI gain is a lack of physical activity (PA). Previous studies indicate PA decreases during summer, compared to the school year but whether this difference is consistent among boys and girls, across age, and by income status remains unclear. This study examined differences in school and summer movement behaviors in a diverse cohort of children across three years. METHODS: Children (N = 1,203, age range 5-14 years, 48% girls) wore wrist-placed accelerometers for a 14-day wear-period during school (April/May) and summer (July) in 2021 to 2023, for a total of 6 timepoints. Mixed-effects models examined changes in school vs. summer movement behaviors (moderate-to-vigorous physical activity [MVPA], sedentary) for boys and girls, separately, and by age and household income groups (low, middle, and upper based on income-to-poverty ratio). RESULTS: Children provided a total of 35,435 valid days of accelerometry. Overall, boys (+ 9.1 min/day, 95CI 8.1 to 10.2) and girls (+ 6.2 min/day, 95CI 5.4 to 7.0) accumulated more MVPA during school compared to summer. Boys accumulated less time sedentary (-9.9 min/day, 95CI -13.0 to -6.9) during school, while there was no difference in sedentary time (-2.7 min/day, 95CI -5.7 to 0.4) for girls. Different patterns emerged across ages and income groups. Accumulation of MVPA was consistently greater during school compared to summer across ages and income groups. Generally, the difference between school and summer widened with increasing age, except for girls from middle-income households. Accumulation of sedentary time was higher during school for younger children (5-9yrs), whereas for older children (10-14yrs), sedentary time was greater during summer for the middle- and upper-income groups. For boys from low-income households and girls from middle-income households, sedentary time was consistently greater during summer compared to school across ages. CONCLUSIONS: Children are less active and more sedentary during summer compared to school, which may contribute to accelerated BMI gain. However, this differs by biological sex, age, and income. These findings highlight the complex factors influencing movement behaviors between school and summer.

Evaluating the feasibility and acceptability of a co-designed physical activity intervention for rural middle schoolers: a pilot study.

BACKGROUND: Lack of physical activity is a concern for children across diverse backgrounds, particularly affecting those in rural areas who face distinct challenges compared to their urban counterparts. Community-derived interventions are needed that consider the unique context and additional physical activity barriers in under-resourced rural settings. Therefore, a prospective pre-post pilot/feasibility study of Hoosier Sport was conducted over 8-weeks with 6th and 7th grade children in a low-socioeconomic rural middle school setting. The primary objective of the present study was to assess trial- and intervention-related feasibility indicators; and the secondary objective was to collect preliminary assessment data for physical activity levels, fitness, psychological needs satisfaction, and knowledge of physical activity and nutrition among participating youth. METHODS: This prospective 8-week pilot/feasibility study took place in the rural Midwestern United States where twenty-four middle school students participated in a mixed-methods pre-post intervention during physical education classes. The intervention included elements like sport-based youth development, individualized goal setting, physical activity monitoring, pedometer usage, and health education. Data were collected at baseline (T1) and post-intervention (T3), with intermediate measures during the intervention (T2). Qualitative data were integrated through semi-structured interviews. Analytical methods encompassed descriptive statistics, correlations, repeated measures ANOVA, and thematic analysis. RESULTS: Key findings indicate robust feasibility, with intervention-related scores (FIM, AIM, and IAM) consistently surpassing the "good" threshold and 100% retention and recruitment success. Additionally, participants showed significant physical performance improvement, shifting from the 25th to the 50th percentile in the 6-minute walk test (p < 0.05). Autonomy and competence remained high, reflecting positive perceptions of program practicality. Nutrition knowledge, initially low, significantly improved at post-intervention (p < 0.01), highlighting the efficacy of targeted nutritional education in Hoosier Sport. CONCLUSIONS: This study pioneers a community-engaged model for physical activity intervention in under-resourced rural settings. Positive participant feedback, coupled with improvements in physical fitness and psychosocial factors, highlights the potential of the co-design approach. The findings offer valuable insights and a practical template for future community-based research, signaling the promising impact of such interventions on holistic well-being. This research lays the foundation for subsequent phases of the ORBIT model, emphasizing collaborative, community-driven approaches to address the complex issue of declining physical activity levels among adolescents.

Supporting Physical Activity in Patients and Populations During Life Events and Transitions: A Scientific Statement From the American Heart Association.

Achieving recommended levels of physical activity is important for optimal cardiovascular health and can help reduce cardiovascular disease risk. Emerging evidence suggests that physical activity fluctuates throughout the life course. Some life events and transitions are associated with reductions in physical activity and, potentially, increases in sedentary behavior. The aim of this scientific statement is to first provide an overview of the evidence suggesting changes in physical activity and sedentary behavior across life events and transitions. A second aim is to provide guidance for health care professionals or public health workers to identify changes and promote physical activity during life events and transitions. We offer a novel synthesis of existing data, including evidence suggesting that some subgroups are more likely to change physical activity behaviors in response to life events and transitions. We also review the evidence that sedentary behavior changes across life events and transitions. Tools for health care professionals to assess physical activity using simple questions or wearable devices are described. We provide strategies for health care professionals to express compassion as they ask about life transitions and initiate conversations about physical activity. Last, resources for life phase-specific, tailored physical activity support are included. Future research needs include a better characterization of physical activity and sedentary behavior across life events and transitions in higher-risk subgroups. Development and testing of interventions designed specifically to combat declines in physical activity or increases in sedentary behavior during life events and transitions is needed to establish or maintain healthy levels of these cardiovascular health-promoting behaviors.

Are parent-reported sleep logs essential? A comparison of three approaches to guide open source accelerometry-based nocturnal sleep processing in children.

We examined the comparability of children's nocturnal sleep estimates using accelerometry data, processed with and without a sleep log. In a secondary analysis, we evaluated factors associated with disagreement between processing approaches. Children (n = 722, age 5-12 years) wore a wrist-based accelerometer for 14 days during Autumn 2020, Spring 2021, and/or Summer 2021. Outcomes included sleep period, duration, wake after sleep onset (WASO), and timing (onset, midpoint, waketime). Parents completed surveys including children's nightly bed/wake time. Data were processed with parent-reported bed/wake time (sleep log), the Heuristic algorithm looking at Distribution of Change in Z-Angle (HDCZA) algorithm (no log), and an 8 p.m.-8 a.m. window (generic log) using the R-package 'GGIR' (version 2.6-4). Mean/absolute bias and limits of agreement were calculated and visualised with Bland-Altman plots. Associations between child, home, and survey characteristics and disagreement were examined with tobit regression. Just over half of nights demonstrated no difference in sleep period between sleep log and no log approaches. Among all nights, the sleep log approach produced longer sleep periods (9.3 min; absolute mean bias [AMB] = 28.0 min), shorter duration (1.4 min; AMB = 14.0 min), greater WASO (11.0 min; AMB = 15.4 min), and earlier onset (13.4 min; AMB = 17.4 min), midpoint (8.8 min; AMB = 15.3 min), and waketime (3.9 min; AMB = 14.8 min) than no log. Factors associated with discrepancies included smartphone ownership, bedroom screens, nontraditional parent work schedule, and completion on weekend/summer nights (range = 0.4-10.2 min). The generic log resulted in greater AMB among sleep outcomes. Small mean differences were observed between nights with and without a sleep log. Discrepancies existed on weekends, in summer, and for children with smartphones and screens in the bedroom.

A Sliding Scale Signal Quality Metric of Photoplethysmography Applicable to Measuring Heart Rate across Clinical Contexts with Chest Mounting as a Case Study.

Photoplethysmography (PPG) signal quality as a proxy for accuracy in heart rate (HR) measurement is useful in various public health contexts, ranging from short-term clinical diagnostics to free-living health behavior surveillance studies that inform public health policy. Each context has a different tolerance for acceptable signal quality, and it is reductive to expect a single threshold to meet the needs across all contexts. In this study, we propose two different metrics as sliding scales of PPG signal quality and assess their association with accuracy of HR measures compared to a ground truth electrocardiogram (ECG) measurement. METHODS: We used two publicly available PPG datasets (BUT PPG and Troika) to test if our signal quality metrics could identify poor signal quality compared to gold standard visual inspection. To aid interpretation of the sliding scale metrics, we used ROC curves and Kappa values to calculate guideline cut points and evaluate agreement, respectively. We then used the Troika dataset and an original dataset of PPG data collected from the chest to examine the association between continuous metrics of signal quality and HR accuracy. PPG-based HR estimates were compared with reference HR estimates using the mean absolute error (MAE) and the root-mean-square error (RMSE). Point biserial correlations were used to examine the association between binary signal quality and HR error metrics (MAE and RMSE). RESULTS: ROC analysis from the BUT PPG data revealed that the AUC was 0.758 (95% CI 0.624 to 0.892) for signal quality metrics of STD-width and 0.741 (95% CI 0.589 to 0.883) for self-consistency. There was a significant correlation between criterion poor signal quality and signal quality metrics in both Troika and originally collected data. Signal quality was highly correlated with HR accuracy (MAE and RMSE, respectively) between PPG and ground truth ECG. CONCLUSION: This proof-of-concept work demonstrates an effective approach for assessing signal quality and demonstrates the effect of poor signal quality on HR measurement. Our continuous signal quality metrics allow estimations of uncertainties in other emergent metrics, such as energy expenditure that relies on multiple independent biometrics. This open-source approach increases the availability and applicability of our work in public health settings.

Examining adolescents' obesogenic behaviors on structured days: a systematic review and meta-analysis.

BACKGROUND: The structured days hypothesis posits that 'structured days' (i.e., days with pre-planned, segmented, and adult-supervised environments) reduce youth obesogenic behaviors. Structured days may be especially important for adolescents', as adolescence (12-19 years) is a period of developmental milestones and increased autonomy. Therefore, the objective of this systematic review and meta-analysis is to evaluate the relationship between structured days and adolescents' obesogenic behaviors (i.e., physical activity, diet, screen time, and/or sleep). METHODS: From February to April of 2020, four databases (i.e., Embase, PubMed, Web of Science, and PsychINfo) were searched for cross-sectional, longitudinal, and intervention (i.e., baseline data only) studies reporting obesogenic behaviors on more structured versus less structured days (i.e., weekday versus weekend or school year versus summer/holiday). RESULTS: A total of 42,878 unique titles and abstracts were screened with 2767 full-text articles retrieved. After review of full-text articles, 296 studies were identified (sleep k = 147, physical activity k = 88, screen time k = 81, diet k = 8). Most studies were conducted in North America, Europe & Central Asia, or East Asia & the Pacific used self-report measures and compared school days to weekend days. Meta-analyses indicated that adolescents' physical activity (standardized mean difference [SMD] = -0.25 [95%CI - 0.48, -0.03]) and screen time (SMD = -0.48 [95%CI - 0.66, -0.29]) were less healthy on less structured days. Differences did not reach statistical significance for sleep (SMD = -0.23 [95%CI - 0.48, 0.02]) and diet (SMD = -0.13 [95%CI - 0.77, 0.51]), however, sleep timing (SMD = -1.05 [95%CI - 1.31, -0.79]) and diet quantity (SMD = -0.29 [95%CI - 0.35, -0.23]) were less healthy on less structured days. The review identified studies with large heterogeneity. CONCLUSIONS: Findings indicate that adolescents' physical activity, screen time, sleep timing, and diet quantity are less healthy on less structured days. Interventions for adolescents to prevent and treat obesity may be more successful if they are designed to target times that are less structured.

Foods and beverages provided in out of school hours care services: an observational study.

INTRODUCTION: Out of school hours care (OSHC) is a fast-growing childcare setting in Australia, however the types of foods and beverages offered are relatively unknown. This study describes the food and beverages offered and investigates sector-level and setting-level factors which may impact OSHC in meeting the Australian Dietary Guidelines (ADG). METHODS: This cross-sectional, observational study was conducted in 89 OSHC services (between 2018 and 2019). Food and beverages offered, kitchen facilities and menus were captured via direct observation. Foods were categorised into five food groups or discretionary foods, based on the ADG, and frequencies determined. Short interviews with OSHC directors ascertained healthy eating policies, staff training, food quality assessment methods and food budgets. Fisher's exact test explored the influence of sector-level and setting-level factors on food provision behaviours. RESULTS: Discretionary foods (1.5 ± 0.68) were offered more frequently than vegetables (0.82 ± 0.80) (p < .001), dairy (0.97 ± 0.81) (p = .013) and lean meats (0.22 ± 0.54) (p < .001). OSHC associated with long day care and reported using valid food quality assessment methods offered more lean meats (p= .002, and p= .004). Larger organisations offered more vegetables (p = .015) and discretionary foods (p= .007). Menus with clearly worded instructions to provide fruits and vegetables daily offered more fruit (p= .009), vegetables (p < .001) and whole grains (p= .003). No other sector or setting-level factors were associated with services aligning with the ADG. CONCLUSION: Future interventions could benefit from trialling menu planning training and tools to assist OSHC services in NSW meet the ADG requirements.

Identifying effective intervention strategies to reduce children's screen time: a systematic review and meta-analysis.

BACKGROUND: Excessive screen time ([Formula: see text] 2 h per day) is associated with childhood overweight and obesity, physical inactivity, increased sedentary time, unfavorable dietary behaviors, and disrupted sleep. Previous reviews suggest intervening on screen time is associated with reductions in screen time and improvements in other obesogenic behaviors. However, it is unclear what study characteristics and behavior change techniques are potential mechanisms underlying the effectiveness of behavioral interventions. The purpose of this meta-analysis was to identify the behavior change techniques and study characteristics associated with effectiveness in behavioral interventions to reduce children's (0-18 years) screen time. METHODS: A literature search of four databases (Ebscohost, Web of Science, EMBASE, and PubMed) was executed between January and February 2020 and updated during July 2021. Behavioral interventions targeting reductions in children's (0-18 years) screen time were included. Information on study characteristics (e.g., sample size, duration) and behavior change techniques (e.g., information, goal-setting) were extracted. Data on randomization, allocation concealment, and blinding was extracted and used to assess risk of bias. Meta-regressions were used to explore whether intervention effectiveness was associated with the presence of behavior change techniques and study characteristics. RESULTS: The search identified 15,529 articles, of which 10,714 were screened for relevancy and 680 were retained for full-text screening. Of these, 204 studies provided quantitative data in the meta-analysis. The overall summary of random effects showed a small, beneficial impact of screen time interventions compared to controls (SDM = 0.116, 95CI 0.08 to 0.15). Inclusion of the Goals, Feedback, and Planning behavioral techniques were associated with a positive impact on intervention effectiveness (SDM = 0.145, 95CI 0.11 to 0.18). Interventions with smaller sample sizes (n < 95) delivered over short durations (< 52 weeks) were associated with larger effects compared to studies with larger sample sizes delivered over longer durations. In the presence of the Goals, Feedback, and Planning behavioral techniques, intervention effectiveness diminished as sample size increased. CONCLUSIONS: Both intervention content and context are important to consider when designing interventions to reduce children's screen time. As interventions are scaled, determining the active ingredients to optimize interventions along the translational continuum will be crucial to maximize reductions in children's screen time.

Physical activity in out of school hours care: an observational study.

BACKGROUND: Opportunities for physical activity within out of school hours care (OSHC) are not well documented in Australia. This study explored factors associated with children (5-12 years) meeting 30 min of moderate to vigorous physical activity (MVPA) while attending OSHC in the afternoon period. METHODS: A cross-sectional study, conducted in 89 OSHC services in New South Wales, Australia, serving 4,408 children. Each service was visited twice between 2018-2019. Physical activity promotion practices were captured via short interviews and System for Observing Staff Promotion of Physical Activity and Nutrition (SOSPAN). Physical activity spaces was measured (m2) and physical activity of 3,614 child days (42% girls), were collected using Acti-Graph accelerometers. Association between program practices and children accumulation of MVPA was tested using mixed effects logistic regression, adjusted by OSHC service and child. RESULTS: Twenty-six percent of children (n = 925) accumulated 30 min or more of MVPA. Factors associated with children reaching MVPA recommendations included: services scheduling greater amounts of child-led free play, both 30-59 min (OR 2.6, 95%CI 1.70, 3.98) and ≥ 60 min (OR 6.4, 95%CI 3.90, 10.49); opportunities for staff-led organised play of ≥ 30 min (OR 2.3, 95%CI 1.47, 3.83); and active games that engaged the majority of children (OR 1.7, 95%CI 1.11, 2.61). Children were less likely to meet MVPA recommendations if services played games with elimination components (OR 0.56, 95%CI 0.37, 0.86). CONCLUSION: Improvements to service-level physical activity promotion practices, specifically the type of physical activity scheduled and the structure of games, may be an effective strategy to increase MVPA of children attending OSHC afterschool in NSW, Australia.

Children's moderate-to-vigorous physical activity on weekdays versus weekend days: a multi-country analysis.

PURPOSE: The Structured Days Hypothesis (SDH) posits that children's behaviors associated with obesity - such as physical activity - are more favorable on days that contain more 'structure' (i.e., a pre-planned, segmented, and adult-supervised environment) such as school weekdays, compared to days with less structure, such as weekend days. The purpose of this study was to compare children's moderate-to-vigorous physical activity (MVPA) levels on weekdays versus weekend days using a large, multi-country, accelerometer-measured physical activity dataset. METHODS: Data were received from the International Children's Accelerometer Database (ICAD) July 2019. The ICAD inclusion criteria for a valid day of wear, only non-intervention data (e.g., baseline intervention data), children with at least 1 weekday and 1 weekend day, and ICAD studies with data collected exclusively during school months, were included for analyses. Mixed effects models accounting for the nested nature of the data (i.e., days within children) assessed MVPA minutes per day (min/day MVPA) differences between weekdays and weekend days by region/country, adjusted for age, sex, and total wear time. Separate meta-analytical models explored differences by age and country/region for sex and child weight-status. RESULTS/FINDINGS: Valid data from 15 studies representing 5794 children (61% female, 10.7 ± 2.1 yrs., 24% with overweight/obesity) and 35,263 days of valid accelerometer data from 5 distinct countries/regions were used. Boys and girls accumulated 12.6 min/day (95% CI: 9.0, 16.2) and 9.4 min/day (95% CI: 7.2, 11.6) more MVPA on weekdays versus weekend days, respectively. Children from mainland Europe had the largest differences (17.1 min/day more MVPA on weekdays versus weekend days, 95% CI: 15.3, 19.0) compared to the other countries/regions. Children who were classified as overweight/obese or normal weight/underweight accumulated 9.5 min/day (95% CI: 6.9, 12.2) and 10.9 min/day (95% CI: 8.3, 13.5) of additional MVPA on weekdays versus weekend days, respectively. CONCLUSIONS: Children from multiple countries/regions accumulated significantly more MVPA on weekdays versus weekend days during school months. This finding aligns with the SDH and warrants future intervention studies to prioritize less-structured days, such as weekend days, and to consider providing opportunities for all children to access additional opportunities to be active.

Systematic observation of healthy eating environments in after-school services: a cross-sectional study.

OBJECTIVES: Few studies have examined the healthy eating environments within the Australian out of school hours care (OSHC) setting. This study aims to describe healthy eating environments, consisting of: (a) the alignment of provided food and beverages to Australian Dietary Guidelines; (b) healthy eating promotion practices; (c) nutrition education through cooking experiences; (d) staff role modelling healthy eating and (e) regular water availability. DESIGN: A cross-sectional study was conducted using direct observations and the validated System for Observing Staff Promotion of Activity and Nutrition (SOSPAN) tool. SETTING: OSHC located in urban and semi-rural regions of NSW, Australia. PARTICIPANTS: Staff (151) and children (1549) attending twelve OSHC services operating in the hours after school. RESULTS: Fifty per cent (50 %) of services offered fruits and 100 % offered water as a part of the afternoon snack on all four observation days. Discretionary foods were offered on more days compared to vegetables (+1·9/d, P = 0·009), lean meats (+2·7/d, P =·0 004) and wholegrains (+2·8/d, P = 0 002). Staff promoted healthy eating on 15 % of days, sat and ate with children 52 %, consumed high sugar drinks 15 % and ate discretionary foods in front of children 8 % of days, respectively. No opportunities for cooking or nutrition education were observed. CONCLUSION: Afternoon snacks regularly contained fruits and water. Opportunities exist to improve the frequency by which vegetables, wholegrains and lean meats are offered in addition to staff healthy eating promotion behaviours. Future research is warranted to further explore healthy eating behaviours, practices and policies within the after-school sector.

Disparities by household income and race/ethnicity: the utility of BMI for surveilling excess adiposity in children.

Objectives: Low-income children (6-19 years) are at higher risk for BMI-determined overweight and obesity, but this relationship varies by children's race/ethnicity. BMI, however, is a poor marker of excess adiposity in minority children. The objective of this study was to determine if the relationships of income and/or race/ethnicity with weight status was consistent between BMI-determined overweight or obesity and adiposity measured via dual energy X-ray absorptiometry (DXA).Design: This study included a nationally representative sample of U.S. children (N = 9857, 14.0 years, 52.8% male, 31.8% low-income, 52.1% middle-income). Disparities in household income-to-poverty ratio (low-income = 0.00-1.00, middle-income = 1.01-4.00, high-income > 4.00) was the exposure with prevalence of BMI-determined overweight or obesity (i.e. age/sex specific CDC cutoffs) and DXA-determined excess adiposity (i.e. body fat%≥75th percentile) as the outcome.Results: For DXA, children from high-income households were 0.47 (95CI = 0.35, 0.65) and 0.55 (95CI = 0.44, 0.70) times as likely to have excess adiposity compared to children in middle and low-income households, respectively. Similar findings were observed with BMI-determined overweight and obesity. Stratified analyses by individual racial/ethnic groups showed children from high-income households were less likely to have excess adiposity compared to their low-income peers for White, Black, and Hispanic children. However, these relationships did not hold for BMI-determined overweight and obesity in Black and Hispanic children.Conclusions: This study revealed that the relationships between income and DXA-determined adiposity differed from the relationships between income and BMI-determined overweight and obesity for children who are Black and Hispanic. This suggests that BMI may be an inappropriate surveillance tool when exploring relationships between race/ethnicity, income, and adiposity.

Daring to share requires intentional and collective commitment to civil discourse.

Communicating and challenging ideas through written scholarly dialogue is a cornerstone of scientific progress. In the current social and political climate, it is important to reflect upon what constitutes appropriate ways to engage in scholarly dialogues and consider the ramifications of failing to create an environment where individuals are willing to share ideas openly. In this commentary, we provide examples of scholarly dialogues representing antagonistic and collegial tones and discuss the consequences of failing to communicate appropriately in the areas of gatekeeping, mentoring, and most importantly, the silencing of ideas.

Physical activity and sedentary time of youth in structured settings: a systematic review and meta-analysis.

BACKGROUND: Structured settings, such as school, childcare, afterschool programs, summer camps, and physical activity/sport programs are crucial to promoting physical activity (PA) opportunities and reducing sedentary (ST) for children and adolescents. However, little is known about how much PA and ST children and adolescents accumulate in structured settings. The aim of this study is to conduct a systematic review and meta-analysis of the absolute amount of time youth spend physically active and sedentary in different structured settings (Prospero number: 42018111804). METHODS: Observational and experimental/quasi-experimental studies (baseline data only) with full-text available, written in English and published in a peer-reviewed journal, reporting the total amount of objectively measured PA (light, moderate, vigorous, and/or total physical activity) and/or time spent ST during structured settings among youth (3 to 18 years) were eligible. Adjusted meta-analysis was conducted to estimate the pooled mean of time spent in PA and ST, by settings and sex. RESULTS: A total of 187 studies (childcare n=60; school n=91; afterschool programs n=14; summer camp n=4; and Physical activity/ sport programs n=18) from 30 countries (47.9% United States), representing 74,870 youth (mean age 8.6 years old) were included. Overall, there was a high variation between studies in outcomes and settings. The meta-analyses revealed, on average, youth spend 221.8 minutes (36.7 min/hour) in ST and 32.1 minutes (5.1 min/hour) in MVPA during childcare hours, and 223.9 minutes (36.7min/hour) in ST and 27.8 min (4.4 min/hour) in MVPA at school. Relatively, youth are engaged in more MVPA in afterschool programs (11.7 min/hour), PA/ sport programs (20.9 min/hour), and summer camps (6.4 min/hour), when compared to childcare and school. CONCLUSION: Total PA accumulated during childcare and MVPA accumulated during schools hours were close to recommendations, despite high proportion of ST. Afterschool programs, summer camp and PA/ sport programs are important settings that can contribute to daily PA and reduced ST. Ensuring all youth have access to these structured settings may be an important step forward for public health.

The impact of summer vacation on children's obesogenic behaviors and body mass index: a natural experiment.

BACKGROUND: Children's BMI gain accelerates during summer. The Structured Days Hypothesis posits that the lack of the school day during summer vacation negatively impacts children's obesogenic behaviors (i.e., physical activity, screen time, diet, sleep). This natural experiment examined the impact of summer vacation on children's obesogenic behaviors and body mass index (BMI). METHODS: Elementary-aged children (n = 285, 5-12 years, 48.7% male, 57.4% African American) attending a year-round (n = 97) and two match-paired traditional schools (n = 188) in the United States participated in this study. Rather than taking a long break from school during the summer like traditional schools, year-round schools take shorter and more frequent breaks from school. This difference in school calendars allowed for obesogenic behaviors to be collected during three conditions: Condition 1) all children attend school, Condition 2) year-round children attend school while traditional children were on summer vacation, and Condition 3) summer vacation for all children. Changes in BMI z-score were collected for the corresponding school years and summers. Multi-level mixed effects regressions estimated obesogenic behaviors and monthly zBMI changes. It was hypothesized that children would experience unhealthy changes in obesogenic behaviors when entering summer vacation because the absence of the school day (i.e., Condition 1 vs. 2 for traditional school children and 2 vs. 3 for year-round school children). RESULTS: From Condition 1 to 2 traditional school children experienced greater unhealthy changes in daily minutes sedentary (∆ = 24.2, 95CI = 10.2, 38.2), screen time minutes (∆ = 33.7, 95CI = 17.2, 50.3), sleep midpoint time (∆ = 73:43, 95CI = 65:33, 81:53), and sleep efficiency percentage (-∆ = 0.7, 95CI = -1.1, - 0.3) when compared to year-round school children. Alternatively, from Condition 2 to 3 year-round school children experienced greater unhealthy changes in daily minutes sedentary (∆ = 54.5, 95CI = 38.0, 70.9), light physical activity minutes (∆ = - 42.2, 95CI = -56.2, - 28.3) MVPA minutes (∆ = - 11.4, 95CI = -3.7, - 19.1), screen time minutes (∆ = 46.5, 95CI = 30.0, 63.0), and sleep midpoint time (∆ = 95:54, 95CI = 85:26, 106:22) when compared to traditional school children. Monthly zBMI gain accelerated during summer for traditional (∆ = 0.033 95CI = 0.019, 0.047) but not year-round school children (∆ = 0.004, 95CI = -0.014, 0.023). CONCLUSIONS: This study suggests that the lack of the school day during summer vacation negatively impacts sedentary behaviors, sleep timing, and screen time. Changes in sedentary behaviors, screen time, and sleep midpoint may contribute to accelerated summer BMI gain. Providing structured programming during summer vacation may positively impact these behaviors, and in turn, mitigate accelerated summer BMI gain. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03397940 . Registered January 12th 2018.

Identification and evaluation of risk of generalizability biases in pilot versus efficacy/effectiveness trials: a systematic review and meta-analysis.

BACKGROUND: Preliminary evaluations of behavioral interventions, referred to as pilot studies, predate the conduct of many large-scale efficacy/effectiveness trial. The ability of a pilot study to inform an efficacy/effectiveness trial relies on careful considerations in the design, delivery, and interpretation of the pilot results to avoid exaggerated early discoveries that may lead to subsequent failed efficacy/effectiveness trials. "Risk of generalizability biases (RGB)" in pilot studies may reduce the probability of replicating results in a larger efficacy/effectiveness trial. We aimed to generate an operational list of potential RGBs and to evaluate their impact in pairs of published pilot studies and larger, more well-powered trial on the topic of childhood obesity. METHODS: We conducted a systematic literature review to identify published pilot studies that had a published larger-scale trial of the same or similar intervention. Searches were updated and completed through December 31st, 2018. Eligible studies were behavioral interventions involving youth (≤18 yrs) on a topic related to childhood obesity (e.g., prevention/treatment, weight reduction, physical activity, diet, sleep, screen time/sedentary behavior). Extracted information included study characteristics and all outcomes. A list of 9 RGBs were defined and coded: intervention intensity bias, implementation support bias, delivery agent bias, target audience bias, duration bias, setting bias, measurement bias, directional conclusion bias, and outcome bias. Three reviewers independently coded for the presence of RGBs. Multi-level random effects meta-analyses were performed to investigate the association of the biases to study outcomes. RESULTS: A total of 39 pilot and larger trial pairs were identified. The frequency of the biases varied: delivery agent bias (19/39 pairs), duration bias (15/39), implementation support bias (13/39), outcome bias (6/39), measurement bias (4/39), directional conclusion bias (3/39), target audience bias (3/39), intervention intensity bias (1/39), and setting bias (0/39). In meta-analyses, delivery agent, implementation support, duration, and measurement bias were associated with an attenuation of the effect size of - 0.325 (95CI - 0.556 to - 0.094), - 0.346 (- 0.640 to - 0.052), - 0.342 (- 0.498 to - 0.187), and - 0.360 (- 0.631 to - 0.089), respectively. CONCLUSIONS: Pre-emptive avoidance of RGBs during the initial testing of an intervention may diminish the voltage drop between pilot and larger efficacy/effectiveness trials and enhance the odds of successful translation.

Validity of Wrist-Worn photoplethysmography devices to measure heart rate: A systematic review and meta-analysis.

Heart rate (HR), when combined with accelerometry, can dramatically improve estimates of energy expenditure and sleep. Advancements in technology, via the development and introduction of small, low-cost photoplethysmography devices embedded within wrist-worn consumer wearables, have made the collection of heart rate (HR) under free-living conditions more feasible. This systematic review and meta-analysis compared the validity of wrist-worn HR estimates to a criterion measure of HR (electrocardiography ECG or chest strap). Searches of PubMed/Medline, Web of Science, EBSCOhost, PsycINFO, and EMBASE resulted in a total of 44 articles representing 738 effect sizes across 15 different brands. Multi-level random effects meta-analyses resulted in a small mean difference (beats per min, bpm) of -0.40 bpm (95 confidence interval (CI) -1.64 to 0.83) during sleep, -0.01 bpm (-0.02 to 0.00) during rest, -0.51 bpm (-1.60 to 0.58) during treadmill activities (walking to running), while the mean difference was larger during resistance training (-7.26 bpm, -10.46 to -4.07) and cycling (-4.55 bpm, -7.24 to -1.87). Mean difference increased by 3 bpm (2.5 to 3.5) per 10 bpm increase of HR for resistance training. Wrist-worn devices that measure HR demonstrate acceptable validity compared to a criterion measure of HR for most common activities.

Income, Race and its Association with Obesogenic Behaviors of U.S. Children and Adolescents, NHANES 2003-2006.

OBJECTIVES: To describe the associations of income and race with obesogenic behaviors and % body fat among a large sample of U.S. children and adolescents. DESIGN: Data were obtained from the 2003-2004 and 2005-2006 National Health and Nutritional Examination Survey. Multiple linear regression models and interactions were used to examine the associations of moderate-to-vigorous physical activity (MVPA), sedentary time, diet quality, and screen-time with income-to-poverty ratio and race. Separate stratified analyses explored associations among individual obesogenic behaviors within race and income groups. RESULTS: This study included children and adolescents (n = 3551, mean = 13.1 years, SD = 3.9 years) who were 37% Hispanic, 27% White, and 35% Black. Overall, Hispanic children/adolescents had significantly higher levels of adiposity (3.6, 95 CI = 0.9, 6.3) than white children and adolescents. Medium-income children and adolescents engaged in less MVPA (- 3.3 min, 95 CI = - 5.1, - 1.5), had poorer diet quality (- 1.1, 95 CI = - 1.9, - 0.2), and used screens less (- 33.9 min, 95 CI = - 45.4, - 22.4) than children and adolescents from low-income households. High-income children and adolescents also engaged in less MVPA (- 3.1 min, 95 CI = - 5.5, - 0.7) and used screens less (- 62.9 min, 95 CI = - 78.3, - 47.4) than children and adolescents from low-income households. However, there were significant race/ethnicity-by-income interactions for high-income Hispanic children and adolescents with diet quality (- 3.5 HEI-2010 score, 95 CI = - 6.6, - 0.4) and screen time (66.9 min, 95 CI = 24.7, 109.0). There was also a significant race/ethnicity-by-income interaction for the screen-time of Black children and adolescents from medium (33.8 min, 95% CI 0.2, 67.3) and high (75.8 min, 95% CI 34.7, 117.0) income households. CONCLUSIONS: There appears to be a complex relationship that varies by race/ethnicity between income, obesogenic behaviors, and adiposity levels among children and adolescents. More work is needed to identify the behavioral mechanisms that are driving disparate rates of overweight and obesity among minority children and those from low-income households.

Understanding differences between summer vs. school obesogenic behaviors of children: the structured days hypothesis.

BACKGROUND: Although the scientific community has acknowledged modest improvements can be made to weight status and obesogenic behaviors (i.e., physical activity, sedentary/screen time, diet, and sleep) during the school year, studies suggests improvements are erased as elementary-age children are released to summer vacation. Emerging evidence shows children return to school after summer vacation displaying accelerated weight gain compared to the weight gained occurring during the school year. Understanding how summer days differ from when children are in school is, therefore, essential. DISCUSSION: There is limited evidence on the etiology of accelerated weight gain during summer, with few studies comparing obesogenic behaviors on the same children during school and summer. For many children, summer days may be analogous to weekend days throughout the school year. Weekend days are often limited in consistent and formal structure, and thus differ from school days where segmented, pre-planned, restrictive, and compulsory components exist that shape obesogenic behaviors. The authors hypothesize that obesogenic behaviors are beneficially regulated when children are exposed to a structured day (i.e., school weekday) compared to what commonly occurs during summer. This is referred to as the 'Structured Days Hypothesis' (SDH). To illustrate how the SDH operates, this study examines empirical data that compares weekend day (less-structured) versus weekday (structured) obesogenic behaviors in U.S. elementary school-aged children. From 190 studies, 155 (~80%) demonstrate elementary-aged children's obesogenic behaviors are more unfavorable during weekend days compared to weekdays. CONCLUSION: In light of the SDH, consistent evidence demonstrates the structured environment of weekdays may help to protect children by regulating obesogenic behaviors, most likely through compulsory physical activity opportunities, restricting caloric intake, reducing screen time occasions, and regulating sleep schedules. Summer is emerging as the critical period where childhood obesity prevention efforts need to be focused. The SDH can help researchers understand the drivers of obesogenic behaviors during summer and lead to innovative intervention development.