A school-based intervention improves physical fitness in Ecuadorian adolescents: a cluster-randomized controlled trial

Role of dietary intake and physical activity in reducing weight social inequalities among adolescents: an application of G-formula to PRALIMAP-INÈS trial

Interventions aiming to reduce social inequalities of weight status in adolescents usually focus on lifestyle behaviours, but their effectiveness is limited. This study analysed the effect of achieving levels of dietary intake (DI) and/or physical activity (PA) guidelines on reducing social inequalities in weight status among adolescents. We included adolescents from the PRomotion de l'ALIMentation et de l'Activité Physique - INÉgalité de Santé (PRALIMAP-INÈS) trial with weight status data available at baseline and 1-year follow-up (n 1130). PA and DI were measured using the International Physical Activity Questionnaire and a validated FFQ, respectively. We estimated the likelihood of a 1-year reduction in BMI z-score (BMIz) and population risk difference (PRD) under hypothetical DI and PA levels and socio-economic status using the parametric G-formula. When advantaged and less advantaged adolescents maintained their baseline DI and PA, we found social inequalities in weight status, with a PRD of a 1-year reduction in BMIz of -1·6 % (-3·0 %, -0·5 %). These inequalities were not observed when less advantaged adolescents increased their proportion of achieving DI guidelines by 30 % (PRD = 2·2 % (-0·5 %, 5·0 %)) unlike the same increase in PA (PRD = -3·9 % (-6·8 %, -1·3 %)). Finally, social inequalities of weight status were not observed when levels of achievement of both PA and DI guidelines increased by 30 % (PRD = 2·2 % (-0·5 %, 4·0 %)). Enhancing DI rather than PA could be effective in reducing social inequalities in weight status among adolescents. Future interventions aiming to reduce these inequalities should mostly target DI to be effective.

Interventions to prevent obesity in children aged 12 to 18 years old

BACKGROUND

Prevention of obesity in adolescents is an international public health priority. The prevalence of overweight and obesity is over 25% in North and South America, Australia, most of Europe, and the Gulf region. Interventions that aim to prevent obesity involve strategies that promote healthy diets or 'activity' levels (physical activity, sedentary behaviour and/or sleep) or both, and work by reducing energy intake and/or increasing energy expenditure, respectively. There is uncertainty over which approaches are more effective, and numerous new studies have been published over the last five years since the previous version of this Cochrane Review.

OBJECTIVES

To assess the effects of interventions that aim to prevent obesity in adolescents by modifying dietary intake or 'activity' levels, or a combination of both, on changes in BMI, zBMI score and serious adverse events.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was February 2023.

SELECTION CRITERIA

Randomised controlled trials in adolescents (mean age 12 years and above but less than 19 years), comparing diet or 'activity' interventions (or both) to prevent obesity with no intervention, usual care, or with another eligible intervention, in any setting. Studies had to measure outcomes at a minimum of 12 weeks post baseline. We excluded interventions designed primarily to improve sporting performance.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our outcomes were BMI, zBMI score and serious adverse events, assessed at short- (12 weeks to < 9 months from baseline), medium- (9 months to < 15 months) and long-term (≥ 15 months) follow-up. We used GRADE to assess the certainty of the evidence for each outcome.

MAIN RESULTS

This review includes 74 studies (83,407 participants); 54 studies (46,358 participants) were included in meta-analyses. Sixty studies were based in high-income countries. The main setting for intervention delivery was schools (57 studies), followed by home (nine studies), the community (five studies) and a primary care setting (three studies). Fifty-one interventions were implemented for less than nine months; the shortest was conducted over one visit and the longest over 28 months. Sixty-two studies declared non-industry funding; five were funded in part by industry. Dietary interventions versus control The evidence is very uncertain about the effects of dietary interventions on body mass index (BMI) at short-term follow-up (mean difference (MD) -0.18, 95% confidence interval (CI) -0.41 to 0.06; 3 studies, 605 participants), medium-term follow-up (MD -0.65, 95% CI -1.18 to -0.11; 3 studies, 900 participants), and standardised BMI (zBMI) at long-term follow-up (MD -0.14, 95% CI -0.38 to 0.10; 2 studies, 1089 participants); all very low-certainty evidence. Compared with control, dietary interventions may have little to no effect on BMI at long-term follow-up (MD -0.30, 95% CI -1.67 to 1.07; 1 study, 44 participants); zBMI at short-term (MD -0.06, 95% CI -0.12 to 0.01; 5 studies, 3154 participants); and zBMI at medium-term (MD 0.02, 95% CI -0.17 to 0.21; 1 study, 112 participants) follow-up; all low-certainty evidence. Dietary interventions may have little to no effect on serious adverse events (two studies, 377 participants; low-certainty evidence). Activity interventions versus control Compared with control, activity interventions do not reduce BMI at short-term follow-up (MD -0.64, 95% CI -1.86 to 0.58; 6 studies, 1780 participants; low-certainty evidence) and probably do not reduce zBMI at medium- (MD 0, 95% CI -0.04 to 0.05; 6 studies, 5335 participants) or long-term (MD -0.05, 95% CI -0.12 to 0.02; 1 study, 985 participants) follow-up; both moderate-certainty evidence. Activity interventions do not reduce zBMI at short-term follow-up (MD 0.02, 95% CI -0.01 to 0.05; 7 studies, 4718 participants; high-certainty evidence), but may reduce BMI slightly at medium-term (MD -0.32, 95% CI -0.53 to -0.11; 3 studies, 2143 participants) and long-term (MD -0.28, 95% CI -0.51 to -0.05; 1 study, 985 participants) follow-up; both low-certainty evidence. Seven studies (5428 participants; low-certainty evidence) reported data on serious adverse events: two reported injuries relating to the exercise component of the intervention and five reported no effect of intervention on reported serious adverse events. Dietary and activity interventions versus control Dietary and activity interventions, compared with control, do not reduce BMI at short-term follow-up (MD 0.03, 95% CI -0.07 to 0.13; 11 studies, 3429 participants; high-certainty evidence), and probably do not reduce BMI at medium-term (MD 0.01, 95% CI -0.09 to 0.11; 8 studies, 5612 participants; moderate-certainty evidence) or long-term (MD 0.06, 95% CI -0.04 to 0.16; 6 studies, 8736 participants; moderate-certainty evidence) follow-up. They may have little to no effect on zBMI in the short term, but the evidence is very uncertain (MD -0.09, 95% CI -0.2 to 0.02; 3 studies, 515 participants; very low-certainty evidence), and they may not reduce zBMI at medium-term (MD -0.05, 95% CI -0.1 to 0.01; 6 studies, 3511 participants; low-certainty evidence) or long-term (MD -0.02, 95% CI -0.05 to 0.01; 7 studies, 8430 participants; low-certainty evidence) follow-up. Four studies (2394 participants) reported data on serious adverse events (very low-certainty evidence): one reported an increase in weight concern in a few adolescents and three reported no effect.

AUTHORS' CONCLUSIONS

The evidence demonstrates that dietary interventions may have little to no effect on obesity in adolescents. There is low-certainty evidence that activity interventions may have a small beneficial effect on BMI at medium- and long-term follow-up. Diet plus activity interventions may result in little to no difference. Importantly, this updated review also suggests that interventions to prevent obesity in this age group may result in little to no difference in serious adverse effects. Limitations of the evidence include inconsistent results across studies, lack of methodological rigour in some studies and small sample sizes. Further research is justified to investigate the effects of diet and activity interventions to prevent childhood obesity in community settings, and in young people with disabilities, since very few ongoing studies are likely to address these. Further randomised trials to address the remaining uncertainty about the effects of diet, activity interventions, or both, to prevent childhood obesity in schools (ideally with zBMI as the measured outcome) would need to have larger samples.

Effectiveness of Intervention Strategies to Increase Adolescents' Physical Activity and Reduce Sedentary Time in Secondary School Settings, Including Factors Related to Implementation: A Systematic Review and Meta-Analysis

BACKGROUND

Globally, just one in five adolescents meet physical activity guidelines and three-quarters of the school day is spent sitting. It is unclear which types of school-based interventions strategies increase physical activity and reduce sedentary time among adolescents, or how these interventions are implemented influences their effectiveness.

OBJECTIVE

The three aims of our systematic review were to (a) identify intervention strategies used within secondary school settings to improve students' movement behaviours throughout school-based initiatives, delivered at or by the school; (b) determine the overall effect of the interventions (meta-analysis) on physical activity (all intensities), sedentary time, cognitive/academic, physical health and/or psychological outcomes; and (c) describe factors related to intervention implementation.

METHODS

Searches were conducted in MEDLINE complete, EMBASE, CINAHL, SPORTDiscus, APA PsycINFO, and ERIC in January 2023 for studies that (a) included high school-aged adolescents; (b) involved a school-based intervention to increase physical activity and/or decrease sedentary time; and (c) were published in English. Reported effects were pooled in meta-analyses where sufficient data were obtained.

RESULTS

Eighty-five articles, representing 61 interventions, met the inclusion criteria, with 23 unique intervention strategies used. Interventions that involved whole-school approaches (i.e., physical activity sessions, environmental modifications, teacher training, peer support and/or educational resources) were favourably associated with most of the outcomes. The meta-analyses showed: (a) non-significant effects for sedentary time (Standardized mean difference [SMD] = -0.02; 95%CI, -0.14, 0.11), physical activity at all intensities (light: SMD= -0.01; 95%CI, -0.08, 0.05; moderate: SMD = 0.06; 95%CI, -0.09, 0.22; vigorous: SMD = 0.08; 95%CI, -0.02, 0.18; moderate-to-vigorous: SMD = 0.05; 95%CI, -0.01, 0.12) and waist circumference (SMD = 0.09; 95%CI, -0.03, 0.21), and (b) a small statistically significant decrease in body mass index (SMD= -0.09, 95%CI -0.16, -0.0). Factors related to intervention implementation were reported in 51% of the articles.

CONCLUSION

While some intervention approaches demonstrated promise, small or null effects were found in meta-analyses. Future school-based interventions should utilize a whole-school approach designed to increase adolescents' activity across the day. Consistent reporting of implementation will increase understanding of how interventions are adopted, implemented and sustained.

REGISTRATION

PROSPERO (CRD42020169988).

Effectiveness of multi-component modular intervention on screen-based and non-screen-based sedentary time among adolescents in an urban area of Mangalore: a school-based cluster randomised controlled trial-protocol

Background

Behavioural risk factors may often present during adolescence and account for 70% of premature deaths during adulthood. Excessive sedentary behaviour and screen time have become significant concerns, especially among adolescents, due to their potential negative impact on physical and mental health. Adolescents with a high screen-based sedentary time are more likely to be physically inactive, have unhealthy body structure and poor academic performance. The objective of our study is to assess the effect of multi-component modular educational intervention on screen-based sedentary time (SST) and non-screen-based Sedentary time (NSST) among adolescents.

Methods

Ethical approval for the study has been obtained from the institutional Ethics Committee of Kasturba Medical College in Mangalore, India. This cluster randomized control trial will be carried out in schools located in the urban area of Mangalore. Using simple randomization, the eligible schools will be randomized into intervention and control arms, each consisting of 10 clusters. A multi-component modular educational intervention will be administered to participants in the intervention group at baseline, second and fourth month. The control group will receive the standard curriculum. Both the groups will be assessed at baseline and at second month, fourth month and sixth month of follow up for SST, NSST and level of physical activity. Anthropometric measurements like height, weight, waist circumference and hip circumference will be taken at baseline and sixth month of follow up.

Results

A comprehensive school-based modular educational intervention can have cumulative advantages by reducing screen- and non-screen-based sedentary time, and encouraging physical activity. Similar modular teaching can be incorporated into the curriculum, which will promote healthy life-style among the adolescents.

School environments and obesity: a systematic review of interventions and policies among school-age students in Latin America and the Caribbean

BACKGROUND

The rapid rise in obesity rates among school children in Latin America and the Caribbean (LAC) could have a direct impact on the region's physical and mental health, disability, and mortality. This review presents the available interventions likely to reduce, mitigate and/or prevent obesity among school children in LAC by modifying the food and built environments within and around schools.

METHODS

Two independent reviewers searched five databases: MEDLINE, Web of Science, Cochrane Library, Scopus and Latin American and Caribbean Health Sciences Literature for peer-reviewed literature published from 1 January 2000 to September 2021; searching and screening prospective studies published in English, Spanish and Portuguese. This was followed by data extraction and quality assessment using the Cochrane risk-of-bias tool (RoB 2) and the Risk of Bias in Non-Randomized Studies of Interventions (ROBINS-I), adopting also the PRISMA 2020 guidelines. Due to the heterogeneity of the intervention's characteristics and obesity-related measurements across studies, a narrative synthesis was conducted.

RESULTS

A total of 1342 research papers were screened, and 9 studies were included; 4 in Mexico, and 1 each in Argentina, Brazil, Chile, Colombia, and Ecuador. Four studies reported strategies for modifying food provision; four other targeted the built environment, (modifying school premises and providing materials for physical activity); a final study included both food and built environment intervention components. Overall, two studies reported that the intervention was significantly associated with a lower increase over time in BMI/obesity in the intervention against the control group. The remaining studies were non-significant.

CONCLUSIONS

Data suggest that school environmental interventions, complementing nutritional and physical education can contribute to reduce incremental childhood obesity trends. However, evidence of the extent to which food and built environment components factor into obesogenic environments, within and around school grounds is inconclusive. Insufficient data hindered any urban/rural comparisons. Further school environmental intervention studies to inform policies for preventing/reducing childhood obesity in LAC are needed.

Interventions to prevent obesity in school-aged children 6-18 years: An update of a Cochrane systematic review and meta-analysis including studies from 2015-2021

Background

Childhood obesity remains a global public health priority due to the enormous burden it generates. Recent surveillance data suggests there has been a sharp increase in the prevalence of childhood obesity during the COVID-19 pandemic. The Cochrane review of childhood obesity prevention interventions (0-18 years) updated to 2015 is the most rigorous and comprehensive review of randomised controlled trials (RCTs) on this topic. A burgeoning number of high quality studies have been published since that are yet to be synthesised.

Methods

An update of the Cochrane systematic review was conducted to include RCT studies in school-aged children (6-18 years) published to 30 June 2021 that assessed effectiveness on child weight (PROSPERO registration: CRD42020218928). Available cost-effectiveness and adverse effect data were extracted. Intervention effects on body mass index (BMI) were synthesised in random effects meta-analyses by setting (school, after-school program, community, home), and meta-regression examined the association of study characteristics with intervention effect.

Findings

Meta-analysis of 140 of 195 included studies (183,063 participants) found a very small positive effect on body mass index for school-based studies (SMD -0·03, 95%CI -0·06,-0·01; trials = 93; participants = 131,443; moderate certainty evidence) but not after-school programs, community or home-based studies. Subgroup analysis by age (6-12 years; 13-18 years) found no differential effects in any setting. Meta-regression found no associations between study characteristics (including setting, income level) and intervention effect. Ten of 53 studies assessing adverse effects reported presence of an adverse event. Insufficient data was available to draw conclusions on cost-effectiveness.

Interpretation

This updated synthesis of obesity prevention interventions for children aged 6-18 years, found a small beneficial impact on child BMI for school-based obesity prevention interventions. A more comprehensive assessment of interventions is required to identify mechanisms of effective interventions to inform future obesity prevention public health policy, which may be particularly salient in for COVID-19 recovery planning.

Funding

This research was funded by the National Health and Medical Research Council (NHMRC), Australia (Application No APP1153479).

Parent-based interventions to improve multiple lifestyle risk behaviors among adolescents: A systematic review and meta-analysis

Lifestyle risk behaviors often co-occur and are prevalent among adolescents. Parent-based interventions addressing risk behaviors concurrently have the potential to improve youth and parent outcomes. This systematic review evaluated the efficacy of parent-based interventions targeting multiple lifestyle risk behaviors among adolescents and parents. MEDLINE (Ovid), Embase (Ovid), PsycInfo (Ovid), Scopus, CINAHL, the Cochrane Database of Systematic Reviews (CDSR) and Cochrane Central Register of Controlled Trials (CENTRAL) were searched from 2010-May 2021. Eligible studies were randomised controlled trials (RCTs) of parent-based interventions addressing 2+ risk behaviors: alcohol use, smoking, poor diet, physical inactivity, sedentary behaviors, and poor sleep. Studies directly targeting parents, and that assessed adolescent outcomes (11-18 years) were eligible. Where possible, random-effects meta-analysis was conducted. From 11,975 identified records, 46 publications of 36 RCTs (n = 28,322 youth, n = 7385 parents) were eligible. Parent-based interventions were associated with improved adolescent moderate-to-vigorous physical activity (MVPA) [Odds Ratio (OR) = 1.82, 95% CI = 1.18, 2.81; p = 0.007], and reduced screen time (SMD = -0.39, 95% CI = -0.62, -0.16, p = 0.0009) and discretionary food intake (SMD = -0.18; 95% CI = -0.30, -0.06; p = 0.002) compared to controls. However, there was some evidence that interventions increased the odds of ever using tobacco in the medium-term (OR = 1.47, 95% CI = 0.99, 2.18, p = 0.06) and of past month tobacco use in the long-term (OR = 1.46, 95% CI = 1.12, 1.90; p = 0.005). Overall, the quality of evidence was moderate. Parent-based interventions targeting multiple risk behaviors improved adolescent MVPA, and reduced screen time discretionary food intake. Further research is needed to address sleep problems and increase intervention efficacy, particularly for alcohol and tobacco use.

School-based physical activity programs for promoting physical activity and fitness in children and adolescents aged 6 to 18

BACKGROUND

Physical activity among children and adolescents is associated with lower adiposity, improved cardio-metabolic health, and improved fitness. Worldwide, fewer than 30% of children and adolescents meet global physical activity recommendations of at least 60 minutes of moderate to vigorous physical activity per day. Schools may be ideal sites for interventions given that children and adolescents in most parts of the world spend a substantial amount of time in transit to and from school or attending school.

OBJECTIVES

The purpose of this review update is to summarise the evidence on effectiveness of school-based interventions in increasing moderate to vigorous physical activity and improving fitness among children and adolescents 6 to 18 years of age. Specific objectives are: • to evaluate the effects of school-based interventions on increasing physical activity and improving fitness among children and adolescents; • to evaluate the effects of school-based interventions on improving body composition; and • to determine whether certain combinations or components (or both) of school-based interventions are more effective than others in promoting physical activity and fitness in this target population.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, PsycINFO, BIOSIS, SPORTDiscus, and Sociological Abstracts to 1 June 2020, without language restrictions. We screened reference lists of included articles and relevant systematic reviews. We contacted primary authors of studies to ask for additional information.

SELECTION CRITERIA

Eligible interventions were relevant to public health practice (i.e. were not delivered by a clinician), were implemented in the school setting, and aimed to increase physical activity among all school-attending children and adolescents (aged 6 to 18) for at least 12 weeks. The review was limited to randomised controlled trials. For this update, we have added two new criteria: the primary aim of the study was to increase physical activity or fitness, and the study used an objective measure of physical activity or fitness. Primary outcomes included proportion of participants meeting physical activity guidelines and duration of moderate to vigorous physical activity and sedentary time (new to this update). Secondary outcomes included measured body mass index (BMI), physical fitness, health-related quality of life (new to this update), and adverse events (new to this update). Television viewing time, blood cholesterol, and blood pressure have been removed from this update.  DATA COLLECTION AND ANALYSIS: Two independent review authors used standardised forms to assess each study for relevance, to extract data, and to assess risk of bias. When discrepancies existed, discussion occurred until consensus was reached. Certainty of evidence was assessed according to GRADE. A random-effects meta-analysis based on the inverse variance method was conducted with participants stratified by age (children versus adolescents) when sufficient data were reported. Subgroup analyses explored effects by intervention type.

MAIN RESULTS

Based on the three new inclusion criteria, we excluded 16 of the 44 studies included in the previous version of this review. We screened an additional 9968 titles (search October 2011 to June 2020), of which 978 unique studies were potentially relevant and 61 met all criteria for this update. We included a total of 89 studies representing complete data for 66,752 study participants. Most studies included children only (n = 56), followed by adolescents only (n = 22), and both (n = 10); one study did not report student age. Multi-component interventions were most common (n = 40), followed by schooltime physical activity (n = 19), enhanced physical education (n = 15), and before and after school programmes (n = 14); one study explored both enhanced physical education and an after school programme. Lack of blinding of participants, personnel, and outcome assessors and loss to follow-up were the most common sources of bias.  Results show that school-based physical activity interventions probably result in little to no increase in time engaged in moderate to vigorous physical activity (mean difference (MD) 0.73 minutes/d, 95% confidence interval (CI) 0.16 to 1.30; 33 studies; moderate-certainty evidence) and may lead to little to no decrease in sedentary time (MD -3.78 minutes/d, 95% CI -7.80 to 0.24; 16 studies; low-certainty evidence). School-based physical activity interventions may improve physical fitness reported as maximal oxygen uptake (VO₂max) (MD 1.19 mL/kg/min, 95% CI 0.57 to 1.82; 13 studies; low-certainty evidence). School-based physical activity interventions may result in a very small decrease in BMI z-scores (MD -0.06, 95% CI -0.09 to -0.02; 21 studies; low-certainty evidence) and may not impact BMI expressed as kg/m² (MD -0.07, 95% CI -0.15 to 0.01; 50 studies; low-certainty evidence). We are very uncertain whether school-based physical activity interventions impact health-related quality of life or adverse events.

AUTHORS' CONCLUSIONS

Given the variability of results and the overall small effects, school staff and public health professionals must give the matter considerable thought before implementing school-based physical activity interventions. Given the heterogeneity of effects, the risk of bias, and findings that the magnitude of effect is generally small, results should be interpreted cautiously.

Effectiveness of a school-based randomized controlled trial aimed at increasing physical activity time in adolescents

BACKGROUND

This study aimed to evaluate the effectiveness of obesity prevention educational activities, isolated or combined with the modification of the school environment on total physical activity time.

METHODS

This is a school-based randomized controlled trial, conducted with 2511 students from fifth and sixth-grade in Brazil, that employed a parallel, three-group experimental arms: control group (CG), PAAPPAS group (PG) and PAAPPAS-environment group (PEG). During the 2016 school year, the PG received educational activities in the classroom, providing a general basis for a healthy lifestyle. The PEG received the same educational activities and also modifications in the school environment to stimulate physical activity practice during one month. Physical activity was evaluated through a validated physical activity questionnaire. Intention-to-treat analysis was performed to evaluate the rate of change of physical activity time between groups using PROC GENMOD procedure. All analyses were performed using SAS.

RESULTS

Total physical activity time increased by 22% in PEG compared with CG (P = 0.003). No difference was observed between PEG and PG (Δ = 60.20 vs. 36.37, respectively; P = 0.27) and between PG and CG (Δ = 36.37 vs. 9.70, respectively; P = 0.23). The proportion of individuals who attended at least 150 min week-1 of physical activity increased in PEG compared with PG (P = 0.04); however, no difference was observed between PEG and CG (P = 0.19) and between PG and CG (P = 0.26). For 300 min week-1, no difference was observed between groups.

CONCLUSION

A school-based multi-component intervention including modification of the school environment was effective for increasing physical activity time among adolescents.

Impacts of a School-Based Intervention That Incorporates Nutrition Education and a Supportive Healthy School Canteen Environment among Primary School Children in Malaysia

In this study, a school nutrition program (SNP) that incorporates nutrition education and a healthy school canteen environment was developed to improve nutrition knowledge among intervention respondents and provide a healthier environment for them to practice healthy eating. In the current study, we evaluated the impacts of the SNP on eating behaviors, physical activity, body mass index-for-age (BAZ), and cognitive performance at pre-intervention, post-intervention, and 3-month follow-up points between intervention and comparison groups. This intervention study involved 523 primary school children (7–11 years old) from six selected schools in Batu Pahat District, Malaysia. Each respondent completed anthropometric and cognitive performance assessments and a set of standardized questionnaire at pre-intervention, post-intervention, and 3-month follow-up points. Multiple linear mixed model analysis was performed to determine the impacts of that SNP after being adjusted for covariates. After the program, the intervention group increased their frequency of breakfast, lunch, and dinner consumption and morning tea snacking and showed more frequent physical activity and better cognitive performance as compared to the comparison group overtime (p < 0.05). At 3-month follow-up, the intervention group showed lower BAZ scores than their comparison counterparts (p < 0.05). The SNP showed positive effects on eating behaviors, physical activity, BAZ, and cognitive performance in school children. Hence, the SNP is highly recommended for all primary school children.

Physical Fitness and Motor Competence in Chinese and German Elementary School Children in Relation to Different Physical Activity Settings

(1) Background: Children with greater physical activity (PA) may show a higher physical fitness (PF) and motor competence (MC) compared to peers with less PA. The purpose of this study was to examine the relationship between moderate-to-vigorous physical activity (MVPA), PF, and MC in 8- to 9-year old children in Germany and China. MVPA was differentiated into five PA settings: family sport, club training, school sport, leisure sport, and outside play. (2) Methods: This longitudinal study comprised N = 577 children (n = 311 girls, n = 266 boys) who were studied over a one-year period. Each child's PF and MC was determined using sports motor tests. The children's PAs were measured using a questionnaire. (3) Results: The children's PA was positively associated with PF and MC. The MVPA-settings: family sport, leisure sport, outside play, school, and club sport, explained between 18 and 23 percent of the variance in selected PF and MC characteristics in a multivariate linear regression analysis. (4) Conclusions: An increase in the children's MVPA might be an appropriate aim in the school sport in Germany as well as in the club sport system in China. Furthermore, family sport should be enhanced in Germany and outside play activities in China, respectively.

Interventions to prevent obesity in Latinx children globally: protocol for a systematic review and meta-analysis

BACKGROUND

Rates of childhood obesity have accelerated rapidly over the past decade in low- and middle-income countries and in Latin America in particular. At the same time, Latinx children in high-income countries have been disproportionately affected by obesity. Public health and medical experts have called for greater focus on multi-sector approaches to obesity prevention, including policy, systems, and environmental strategies, but current evidence for effective intervention strategies among Latinx children is lacking. Several systematic reviews have investigated obesity prevention interventions in Latinx children in the United States and in Latin America, including our own review, but these are now a decade old. Thus, an updated review of existing interventions is needed. To address this gap, we will conduct a systematic review and summary of interventions for obesity prevention among Latinx children published over the past 10 years. The objective of this paper is to outline the protocol for conducting the systematic review and possible meta-analysis.

METHODS

We will conduct a literature search using PubMed, ERIC, PsycINFO, Scopus, Scientific Electronic Library Online, and Google Scholar databases for studies of interventions to prevent obesity in Latinx children ages birth to 18 years of age. To meet our definition of an intervention, we will include study designs that evaluate the either the efficacy or effectiveness of obesity prevention interventions, including randomized controlled trials, quasi-experimental studies, and non-randomized interventions with a control or comparison group. We will exclude interventions that aimed to treat rather than prevent overweight or obesity. Interventions may take place in any country or setting. The primary outcome of interest will be child overweight or obesity, measured as adiposity, body mass, or similar anthropometric measures. We will assess risk of bias of included studies using the Cochrane risk of bias tool for randomized and non-randomized studies, as appropriate. We may conduct meta-analyses if studies with comparable exposure and outcome variables are available.

DISCUSSION

This protocol paper establishes a methodology for a future systemic review of obesity prevention interventions in Latinx children. A systematic review of this topic will provide an important update to the literature regarding interventions to prevent obesity in Latinx child populations globally over the past decade. Review results will be relevant to stakeholders across multiple sectors engaged in childhood obesity prevention among Latinx children.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020161339.

Effects of School-Based Physical Activity Programs on Health-Related Physical Fitness of Korean Adolescents: A Preliminary Study

As adolescents spend the majority of their time focused on exams and assignments, they do not have sufficient time to engage in physical activity; this lack of physical activity is an important public health concern. This study aimed to investigate how school-based physical activity programs affect the health-related physical fitness of adolescents in the Republic of Korea. For this study, a total of 120 high school students participated in a school-based physical activity program that included badminton and table tennis for 15 weeks each (35 min/day, three times a week), with a total of 30 weeks for one academic year. The parameters for health-related physical fitness measured muscle strength (handgrip strength), power (standing long jump), cardiorespiratory fitness (shuttle run test), flexibility (sit and reach), body mass index (BMI), and the total score. The results revealed a statistically significant improvement in muscle strength (p < 0.001), power (p < 0.001), cardiorespiratory fitness (p < 0.001), flexibility (p = 0.005), and the overall health-related physical fitness score (p = 0.001). However, students’ BMI showed no significant difference before and after participation (p = 0.825). The results of this study indicated that school-based physical activity programs can have a positive effect on the health-related physical fitness of adolescents.

Sample size considerations for matched-pair cluster randomization design with incomplete observations of continuous outcomes

Matched-pair cluster randomization design is becoming increasingly used in clinical and health behavioral studies. Investigators often encounter incomplete observations in the data collected. Statistical inference for matched-pair cluster randomization design with incomplete observations has been extensively studied in literature. However, sample size method for such study design is sparsely available. We propose a closed-form sample size formula for matched-pair cluster randomization design with continuous outcomes, based on the generalized estimating equation approach by treating incomplete observations as missing data in a marginal linear model. The sample size formula is flexible to accommodate different correlation structures, missing patterns, and magnitude of missingness. In the presence of missing data, the proposed method would lead to a more accurate sample size estimation than the crude adjustment method. Simulation studies are conducted to evaluate the finite-sample performance of the proposed sample size method under various design configurations. We use bias-corrected variance estimators to address the issue of inflated type I error when the number of clusters per group is small. A real application example of physical fitness study in Ecuadorian adolescents is presented for illustration.

School-based interventions modestly increase physical activity and cardiorespiratory fitness but are least effective for youth who need them most: an individual participant pooled analysis of 20 controlled trials

OBJECTIVES

To determine if subpopulations of students benefit equally from school-based physical activity interventions in terms of cardiorespiratory fitness and physical activity. To examine if physical activity intensity mediates improvements in cardiorespiratory fitness.

DESIGN

Pooled analysis of individual participant data from controlled trials that assessed the impact of school-based physical activity interventions on cardiorespiratory fitness and device-measured physical activity.

PARTICIPANTS

Data for 6621 children and adolescents aged 4-18 years from 20 trials were included.

MAIN OUTCOME MEASURES

Peak oxygen consumption (VO2Peak mL/kg/min) and minutes of moderate and vigorous physical activity.

RESULTS

Interventions modestly improved students' cardiorespiratory fitness by 0.47 mL/kg/min (95% CI 0.33 to 0.61), but the effects were not distributed equally across subpopulations. Girls and older students benefited less than boys and younger students, respectively. Students with lower levels of initial fitness, and those with higher levels of baseline physical activity benefitted more than those who were initially fitter and less active, respectively. Interventions had a modest positive effect on physical activity with approximately one additional minute per day of both moderate and vigorous physical activity. Changes in vigorous, but not moderate intensity, physical activity explained a small amount (~5%) of the intervention effect on cardiorespiratory fitness.

CONCLUSIONS

Future interventions should include targeted strategies to address the needs of girls and older students. Interventions may also be improved by promoting more vigorous intensity physical activity. Interventions could mitigate declining youth cardiorespiratory fitness, increase physical activity and promote cardiovascular health if they can be delivered equitably and their effects sustained at the population level.

The effect of a school-based intervention on physical activity, cardiorespiratory fitness and muscle strength: the School in Motion cluster randomized trial

Background

Physical activity (PA) declines throughout adolescence, therefore PA promotion during this period is important. We analyzed the effect of two school-based PA interventions on daily PA levels, cardiorespiratory fitness (CRF) and muscle strength among adolescents.

Methods

For the nine-month School in Motion intervention study (ScIM), we cluster-randomized 30 Norwegian secondary schools (N = 2084, mean age [SD] = 14 [0.3] years) to one of three study arms. The physically active learning (PAL) intervention included 30 min physically active learning, 30 min PA and a 60 min physical education (PE) lesson per week. The Don’t worry-Be happy (DWBH) intervention included a 60 min PA lesson and a 60 min PE lesson per week, both tailored to promote friendships and wellbeing. Both intervention arms were designed to engage the adolescents in 120 min of PA per week in addition to recess and mandatory PE lessons. The control group continued as per usual, including the standard amount of mandatory PE. PA (main outcome) was assessed by accelerometers, CRF and muscle strength (secondary outcomes) were assessed by an intermittent running test and selected tests from the Eurofit test battery.

Results

Daily PA and time spent in moderate- to vigorous-intensity PA (MVPA) decreased in all groups throughout the intervention. The mean difference in PA level and MVPA for participants in the PAL-intervention arm was 34.7 cpm (95% CI: 4.1, 65.3) and 4.7 min/day (95% CI: 0.6, 8.8) higher, respectively, compared to the control arm. There were no significant intervention effects on daily PA level, MVPA or time spent sedentary for adolescents in the DWBH-intervention arm. Adolescents in the PAL-intervention arm increased distance covered in the running test compared to controls (19.8 m, 95% CI: 10.4, 29.1), whilst a negative intervention effect was observed among adolescents in the DWBH-intervention arm (− 11.6 m, 95% CI: − 22.0, − 1.1).

Conclusion

The PAL-intervention resulted in a significantly smaller decrease in daily PA level, time spent in MVPA, and increased CRF compared to controls. Our results indicate that a teacher-led intervention, including three unique intervention components, is effective in curbing the decline in PA observed across our cohort and improving CRF.

Trial registration

ClinicalTrials.gov ID nr: NCT03817047. Registered 01/25/2019 ‘retrospectively registered’.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12966-020-01060-0.

Impact of a Three-Year Obesity Prevention Study on Healthy Behaviors and BMI among Lebanese Schoolchildren: Findings from Ajyal Salima Program

Most school-based obesity prevention programs in low- to middle-income countries are of short duration, and few undertake follow-up analyses after the termination of the project. The aims of the current study are to investigate (1) the long-term effects of a school-based intervention program when implemented over two years on body mass index (BMI), healthy dietary behaviors, and physical activity (PA); and (2) whether the effects are sustained after one-year washout. The study is a cluster-randomized trial; 36 public and private schools were randomized into either intervention or control groups. Students (8-12 years) completed pre-and post-assessment anthropometric measurements and questionnaires about their eating and physical activity habits. Students in the intervention groups received the program components for two consecutive years. Multiple logistic regression models were used to examine the effect of the intervention on BMI and healthy behaviors. Students in the intervention groups were less likely to be overweight at washout, only in public schools. The number of children reporting change in dietary behaviors significantly increased in intervention groups, with a sustained effect only in public schools. Policies aiming at securing a positive nutrition environment in schools, and adoption of nutrition programs, are needed for achieving sustained behavior and prompting BMI changes in children.

A Sex/Gender Perspective on Interventions to Reduce Sedentary Behaviour in Girls and Boys: Results of the genEffects Systematic Review

This systematic review aims to evaluate the extent of sex/gender consideration and effectiveness of interventions designed to reduce sedentary behaviour (SB). We searched for randomised or non-randomised controlled trials with the outcome SB and a sex/gender analysis in eleven electronic databases. Sixty-seven studies were included. Sex/gender considerations were qualitatively rated. Sex/gender was reported separately in 44.8% of studies, 14.9% of studies conducted a sex/gender interaction analysis, and 19.4% enrolled either girls or boys. SB was significantly reduced for girls in 16.4%, for boys in 11.9% and for both in 13.4%. No sex/gender intervention effect was found in 38.8%. According to the qualitative rating, studies without significant sex/gender effects reached "detailed" rating twice as often as studies finding a significant intervention effect for either girls or boys, or both. Overall, no clear pattern according to the qualitative rating and in terms of intervention effectiveness can be drawn. The results reveal a lack of sufficient sex/gender information in intervention planning and delivery. Further research should consider analysing sex/gender intervention effects as well as consider sex/gender inclusive intervention planning and delivery.

Latin American interventions in children and adolescents' sedentary behavior: a systematic review

OBJECTIVE To identify and evaluate the effects of community-based interventions on the sedentary behavior (SB) of Latin American children and adolescents. METHODS A systematic review on community-based trials to reduce and/or control SB in Latin American countries (Prospero: CRD42017072157). Five databases (PubMed, Web of Science, Scopus, SciELO and Lilacs) and a reference lists were searched. RESULTS Ten intervention studies met the eligibility criteria and composed the descriptive synthesis. These studies were conducted in Brazil (n=5), Mexico (n=3), Ecuador (n=1) and Colombia (n=1). Most interventions were implemented in schools (n=8) by educational components, such as meetings, lessons, and seminars, on health-related subjects (n=6). Only two studies adopted specific strategies to reduce/control SB; others focused on increasing physical activity and/or improving diet. Only one study used an accelerometer to measure SB. Seven studies investigated recreational screen time. Eight studies showed statistically significant effects on SB reduction (80%). CONCLUSIONS Latin America community-based interventions reduced children and adolescents' SB. Further studies should: define SB as a primary outcome and implement strategies to reduce such behaviour; focus in different SBs and settings, other than recreational screen time or at-home sitting time; and use objective tools together with questionnaires to measure sedentary behaviour in.

The effectiveness and complexity of interventions targeting sedentary behaviour across the lifespan: a systematic review and meta-analysis

BACKGROUND

Evidence suggests that sedentary behaviour (SB) is associated with poor health outcomes. SB at any age may have significant consequences for health and well-being and interventions targeting SB are accumulating. Therefore, the need to review the effects of multicomponent, complex interventions that incorporate effective strategies to reduce SB are essential.

METHODS

A systematic review and meta-analysis were conducted investigating the impact of interventions targeting SB across the lifespan. Six databases were searched and two review authors independently screened studies for eligibility, completed data extraction and assessed the risk of bias and complexity of each of the included studies.

RESULTS

A total of 77 adult studies (n=62, RCTs) and 84 studies (n=62, RCTs) in children were included. The findings demonstrated that interventions in adults when compared to active controls resulted in non-significant reductions in SB, although when compared to inactive controls significant reductions were found in both the short (MD -56.86; 95%CI -74.10, -39.63; n=4632; I2 83%) and medium-to-long term (MD -20.14; 95%CI -34.13, -6.16; n=4537; I2 65%). The findings demonstrated that interventions in children when compared to active controls may lead to relevant reductions in daily sedentary time in the short-term (MD -59.90; 95%CI -102.16, -17.65; n=267; I2 86%), while interventions in children when compared to inactive controls may lead to relevant reductions in the short-term (MD -25.86; 95%CI -40.77, -10.96; n=9480; I2 98%) and medium-to-long term (MD -14.02; 95%CI -19.49, -8.55; n=41,138; I2 98%). The assessment of complexity suggested that interventions may need to be suitably complex to address the challenges of a complex behaviour such as SB, but demonstrated that a higher complexity score is not necessarily associated with better outcomes in terms of sustained long-term changes.

CONCLUSIONS

Interventions targeting reductions in SB have been shown to be successful, especially environmental interventions in both children and adults. More needs to be known about how best to optimise intervention effects. Future intervention studies should apply more rigorous methods to improve research quality, considering larger sample sizes, randomised controlled designs and valid and reliable measures of SB.

Integrating Diabetes Prevention Education Among Teenagers Involved in Summer Employment: Encouraging Environments for Health in Adolescence (ENHANCE)

Type 2 diabetes (T2D) in youth is a growing healthcare and public health concern. It is costly, and youth suffer from disabling and deadly comorbid conditions at a faster pace than adult onset. However, T2D is preventable. The population of obese youth at greatest risk for T2D is of minority race/ethnicity and socioeconomically disadvantaged background, which creates barriers to health promoting lifestyles. Despite being the first line of prevention efforts for T2D, efficacious behavioral lifestyle interventions are still lacking at the community level. During the summers of 2016 and 2017, a study integrated obesity and diabetes prevention health education into TeenWorks summer employment program at Indy Urban Acres in Indianapolis, Indiana. Results were analyzed using paired sample t-tests. Participants (N = 168) had a mean age of 15.8 ± 0.7 years, 61% female, 13% Hispanic, 80% Black. By the end of the intervention, physical activity (p = 0.000) and prevention knowledge (p = 0.000) were significantly higher. Dietary intake (p = 0.204), self-efficacy (p = 0.58), food insecurity (p = 0.058) and depression screening scores (p = 0.809) were not significantly different. In light of the continuing childhood obesity epidemic and increasing prevalence of prediabetes and T2D in youth, there is a pressing need to understand and reduce barriers to obesity and diabetes prevention in high-risk populations. This study demonstrated the feasibility of integrating obesity and T2D prevention health education into a teen summer employment program.

The Role of Recreational Online Activities in School-Based Screen Time Sedentary Behaviour Interventions for Adolescents: A Systematic and Critical Literature Review

Sedentary behaviours are highly associated with obesity and other important health outcomes in adolescence. This paper reviews screen time and its role within school-based behavioural interventions targeting adolescents between the years 2007 and 2019. A systematic literature review following PRISMA guidelines was conducted across five major databases to identify interventions targeting screen time—in addition to TV/DVD viewing. The review identified a total of 30 papers analysing 15 studies across 16 countries aiming at addressing reduction of recreational screen time (internet use and gaming) in addition to television/DVD viewing. All of the interventions focused exclusively on behaviour change, targeting in the majority both reduction of sedentary behaviours along with strategies to increase physical activity levels. A mix of intervention effects were found in the reviewed studies. Findings suggest aiming only for reduction in time spent on screen-based behaviour within interventions could be a limited strategy in ameliorating excessive screen use, if not targeted, in parallel, with strategies to address other developmental, contextual and motivational factors that are key components in driving the occurrence and maintenance of adolescent online behaviours. Additionally, it raises the need for a differential treatment and assessment of each online activity within the interventions due to the heterogeneity of the construct of screen time. Recommendations for enhancing the effectiveness of school-based sedentary behaviour interventions and implications for public policy are discussed.

The effect of an intervention on physical activity of moderate-and-vigorous intensity, and sedentary behavior during adolescents' time at school

INTRODUCTION

This study evaluated the effect of an intervention on the engagement in physical activity (PA) and sedentary behavior (SB) of sixth to ninth grade students during school-time, physical education (PE) classes, and recesses at two public schools in Florianopolis, SC, Brazil.

METHOD

Schools were divided into control and experimental groups. Participants wore accelerometers during school-time, and PA and SB were estimated for school-time, PE classes and recesses at the baseline and after the intervention. The intervention was composed of four components: changes were made in the PE classes, including giving instruction to teachers; sports equipment was made available for use during recesses; educational sessions on the format of classes were conducted; folders and posters were distributed. Data was analyzed using an Analysis of Covariance for repeated measures comparing baseline data with post intervention data, and for independent samples when comparing control and intervention groups.

RESULTS

A low proportion of engagement in PA and a large engagement in SB was observed on the baseline. PA decreased in the intervention group during PE classes, while it increased in the control group with regard to school-time, PE classes, and recess. The intervention group accumulated more SB during school-time and PE classes after the intervention, while a decrease in the control group's SB during school-time was observed.

CONCLUSION

The intervention was not effective in increasing PA or decreasing SB. Environmental and school's organizational factors impact how interventions are conducted, and should be considered beforehand.

Interventions for preventing obesity in children

EDITORIAL NOTE

This Cochrane review is now out of date and should not be used for reference. It has been split into four age groups and updated. Please refer to the 5‐11 and 12‐18 age group Cochrane reviews which were published in May 2024: https://doi.org/10.1002/14651858.CD015328.pub2 https://doi.org/10.1002/14651858.CD015330.pub2 The 2‐4 age group Cochrane review is planned for publication in September 2024.

BACKGROUND

Prevention of childhood obesity is an international public health priority given the significant impact of obesity on acute and chronic diseases, general health, development and well-being. The international evidence base for strategies to prevent obesity is very large and is accumulating rapidly. This is an update of a previous review.

OBJECTIVES

To determine the effectiveness of a range of interventions that include diet or physical activity components, or both, designed to prevent obesity in children.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, PsychINFO and CINAHL in June 2015. We re-ran the search from June 2015 to January 2018 and included a search of trial registers.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of diet or physical activity interventions, or combined diet and physical activity interventions, for preventing overweight or obesity in children (0-17 years) that reported outcomes at a minimum of 12 weeks from baseline.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data, assessed risk-of-bias and evaluated overall certainty of the evidence using GRADE. We extracted data on adiposity outcomes, sociodemographic characteristics, adverse events, intervention process and costs. We meta-analysed data as guided by the Cochrane Handbook for Systematic Reviews of Interventions and presented separate meta-analyses by age group for child 0 to 5 years, 6 to 12 years, and 13 to 18 years for zBMI and BMI.

MAIN RESULTS

We included 153 RCTs, mostly from the USA or Europe. Thirteen studies were based in upper-middle-income countries (UMIC: Brazil, Ecuador, Lebanon, Mexico, Thailand, Turkey, US-Mexico border), and one was based in a lower middle-income country (LMIC: Egypt). The majority (85) targeted children aged 6 to 12 years.Children aged 0-5 years: There is moderate-certainty evidence from 16 RCTs (n = 6261) that diet combined with physical activity interventions, compared with control, reduced BMI (mean difference (MD) -0.07 kg/m2, 95% confidence interval (CI) -0.14 to -0.01), and had a similar effect (11 RCTs, n = 5536) on zBMI (MD -0.11, 95% CI -0.21 to 0.01). Neither diet (moderate-certainty evidence) nor physical activity interventions alone (high-certainty evidence) compared with control reduced BMI (physical activity alone: MD -0.22 kg/m2, 95% CI -0.44 to 0.01) or zBMI (diet alone: MD -0.14, 95% CI -0.32 to 0.04; physical activity alone: MD 0.01, 95% CI -0.10 to 0.13) in children aged 0-5 years.Children aged 6 to 12 years: There is moderate-certainty evidence from 14 RCTs (n = 16,410) that physical activity interventions, compared with control, reduced BMI (MD -0.10 kg/m2, 95% CI -0.14 to -0.05). However, there is moderate-certainty evidence that they had little or no effect on zBMI (MD -0.02, 95% CI -0.06 to 0.02). There is low-certainty evidence from 20 RCTs (n = 24,043) that diet combined with physical activity interventions, compared with control, reduced zBMI (MD -0.05 kg/m2, 95% CI -0.10 to -0.01). There is high-certainty evidence that diet interventions, compared with control, had little impact on zBMI (MD -0.03, 95% CI -0.06 to 0.01) or BMI (-0.02 kg/m2, 95% CI -0.11 to 0.06).Children aged 13 to 18 years: There is very low-certainty evidence that physical activity interventions, compared with control reduced BMI (MD -1.53 kg/m2, 95% CI -2.67 to -0.39; 4 RCTs; n = 720); and low-certainty evidence for a reduction in zBMI (MD -0.2, 95% CI -0.3 to -0.1; 1 RCT; n = 100). There is low-certainty evidence from eight RCTs (n = 16,583) that diet combined with physical activity interventions, compared with control, had no effect on BMI (MD -0.02 kg/m2, 95% CI -0.10 to 0.05); or zBMI (MD 0.01, 95% CI -0.05 to 0.07; 6 RCTs; n = 16,543). Evidence from two RCTs (low-certainty evidence; n = 294) found no effect of diet interventions on BMI.Direct comparisons of interventions: Two RCTs reported data directly comparing diet with either physical activity or diet combined with physical activity interventions for children aged 6 to 12 years and reported no differences.Heterogeneity was apparent in the results from all three age groups, which could not be entirely explained by setting or duration of the interventions. Where reported, interventions did not appear to result in adverse effects (16 RCTs) or increase health inequalities (gender: 30 RCTs; socioeconomic status: 18 RCTs), although relatively few studies examined these factors.Re-running the searches in January 2018 identified 315 records with potential relevance to this review, which will be synthesised in the next update.

AUTHORS' CONCLUSIONS

Interventions that include diet combined with physical activity interventions can reduce the risk of obesity (zBMI and BMI) in young children aged 0 to 5 years. There is weaker evidence from a single study that dietary interventions may be beneficial.However, interventions that focus only on physical activity do not appear to be effective in children of this age. In contrast, interventions that only focus on physical activity can reduce the risk of obesity (BMI) in children aged 6 to 12 years, and adolescents aged 13 to 18 years. In these age groups, there is no evidence that interventions that only focus on diet are effective, and some evidence that diet combined with physical activity interventions may be effective. Importantly, this updated review also suggests that interventions to prevent childhood obesity do not appear to result in adverse effects or health inequalities.The review will not be updated in its current form. To manage the growth in RCTs of child obesity prevention interventions, in future, this review will be split into three separate reviews based on child age.

Positive Youth Development Programs in Low- and Middle-Income Countries: A Conceptual Framework and Systematic Review of Efficacy

PURPOSE

Positive youth development (PYD) has served as a framework for youth programs in high-income countries since the 1990s and has demonstrated broad behavioral health and developmental benefits. PYD programs build skills, assets, and competencies; foster youth agency; build healthy relationships; strengthen the environment; and transform systems to prepare youth for successful adulthood. The goal of this article was to systematically review the impact of PYD programs in low- and middle-income countries (LMICs).

METHODS

Targeted searches of knowledge repository Web sites and keyword searches of Scopus and PubMed identified over 21,500 articles and over 3,700 evaluation reports published between 1990 and mid-2016. Ninety-four PYD programs with evaluations in LMICs were identified, of which 35 had at least one experimental or rigorous quasi-experimental evaluation.

RESULTS

Sixty percent of the 35 programs with rigorous evaluations demonstrated positive effects on behaviors, including substance use and risky sexual activity, and/or more distal developmental outcomes, such as employment and health indicators.

CONCLUSIONS

There is promising evidence that PYD programs can be effective in LMICs; however, more rigorous examination with long-term follow-up is required to establish if these programs offer benefits similar to those seen in higher income countries.

Are school-based physical activity interventions effective and equitable? A meta-analysis of cluster randomized controlled trials with accelerometer-assessed activity

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.

Trends in Physical Fitness Among 12-Year-Old Children in Urban and Rural Areas During the Social Transformation Period in China

AIMS

To investigate the 29-year (1985-2014) trends in body dimensions and physical fitness test performances among 12-year-old Chinese children living in urban and rural areas.

METHODS

The data were from the findings of seven cross-sectional surveys from the Chinese National Survey on Students' Constitution and Health. In the seven surveys, there were 34,238; 11,664; 17,485; 18,057; 19,254; 17,962; and 17,906 children, respectively. Anthropometric measurements and physical fitness performances of 12-year-old Chinese children living in rural and urban areas were analyzed. Polynomial models were used to analyze trends in test performances. Analysis of variance was used to assess the urban-rural differentials.

RESULTS

The height and weight of both urban and rural children substantially increased from 1985 to 2014. Urban children were taller and heavier than rural children. A slight narrowing of the urban-rural differential in height was observed. The disparity in weight increased from 1985 to 2000 and decreased thereafter. Urban children performed better in most of the physical fitness tests examined, such as standing long jump, 50-m run, and sit-ups. The urban-rural disparity decreased from 1985 to 2014 in 50-m run, standing long jump, and sit-up score; the largest difference in 10 × 50 m run and pull-up score was observed in 2000 and 2005, respectively.

CONCLUSIONS

There was a general decline in physical fitness in both urban and rural children after 2000. Urgent, targeted actions need to be taken by public health policy officials and parents to maintain or improve the physical fitness of children.

The prospective association between objectively measured sedentary time, moderate-to-vigorous physical activity and cardiometabolic risk factors in youth: a systematic review and meta-analysis

Sedentary time and moderate-to-vigorous physical activity (MVPA) may be uniquely related to cardiometabolic health. Excessive sedentary time is suggested as an independent cardiometabolic risk factor, while MVPA is favourably associated with cardiometabolic health. This systematic review and meta-analysis summarizes the evidence on a prospective relationship between objectively measured sedentary time, MVPA and cardiometabolic health indicators in youth. PubMed, Embase, CINAHL, PhyscINFO and SPORTDiscus were systematically searched from January 2000 until April 2018. Studies were included if sedentary time and physical activity were measured objectively and examined associations with body mass index, waist circumference, triglycerides, high-density lipoprotein, insulin, blood pressure or the clustering of these cardiometabolic risk factors. We identified 30 studies, of which 21 were of high quality. No evidence was found for an association between sedentary time and cardiometabolic outcomes. The association between MVPA and individual cardiometabolic risk factors was inconsistent. The meta-analysis for prospective studies found a small but significant effect size between MVPA at baseline and clustered cardiometabolic risk at follow-up (ES -0.014 [95% CI, -0.024 to -0.004]). We conclude that there is no prospective association between sedentary time and cardiometabolic health, while MVPA is beneficially associated with cardiometabolic health in youth.

Regional Variations in Physical Fitness and Activity in Healthy and Overweight Ecuadorian Adolescents

Background: Insufficient physical activity (PA) and excessive sedentary behavior (SB) are the main contributors to adolescent obesity. However, it is uncertain whether recent economic growth and urbanization in Ecuador are contributing to an obesogenic environment. This study assessed the relationships among fitness, PA, SB, and perceived social support for PA in adolescents from urban (Quito) and rural (Loja) Ecuador. Methods: Fitness was estimated using 3-min step test and PA and SB participation and social support for PA were self-reported in 407 adolescents. T-tests and analysis of variance assessed differences by sex, obesity status, and region of Ecuador. Pearson correlations assessed relationships among PA, SB, fitness, and social support. Results: Males and rural adolescents (48.3 ± 9.4 and 47.1 ± 9.6 mL/kg/min) were more fit than females and urban adolescents (41.1 ± 7.5 and 39.7 ± 6.1 mL/kg/min). Fitness was negatively correlated with obesity only in rural Ecuador. Few adolescents reported ≥60 min/day of PA (8.4%) or ≤2 h/day of SB (30.2%), with greater SB participation in rural Ecuador. Weak correlations were observed among fitness, PA, SB, and parental/peer support for PA (r = -0.18 to 0.19; p < 0.05). Conclusion: While fitness varied by sex, weight status, and region, SB participation and parent/peer support for PA, not PA participation itself, predicted fitness in rural Ecuadorean adolescents.

Comparison of registered and published intervention fidelity assessment in cluster randomised trials of public health interventions in low- and middle-income countries: systematic review

BACKGROUND

Cluster randomised trials (CRTs) are a key instrument to evaluate public health interventions. Fidelity assessment examines study processes to gauge whether an intervention was delivered as initially planned. Evaluation of implementation fidelity (IF) is required to establish whether the measured effects of a trial are due to the intervention itself and may be particularly important for CRTs of complex interventions conducted in low- and middle-income countries (LMICs). However, current CRT reporting guidelines offer no guidance on IF assessment. The objective of this review was to study current practices concerning the assessment of IF in CRTs of public health interventions in LMICs.

METHODS

CRTs of public health interventions in LMICs that planned or reported IF assessment in either the trial protocol or the main trial report were included. The MEDLINE/PubMed, CINAHL and EMBASE databases were queried from January 2012 to May 2016. To ensure availability of a study protocol, CRTs reporting a registration number in the abstract were included. Relevant data were extracted from each study protocol and trial report by two researchers using a predefined screening sheet. Risk of bias for individual studies was assessed.

RESULTS

We identified 90 CRTs of public health interventions in LMICs with a study protocol in a publicly available trial registry published from January 2012 to May 2016. Among these 90 studies, 25 (28%) did not plan or report assessing IF; the remaining 65 studies (72%) addressed at least one IF dimension. IF assessment was planned in 40% (36/90) of trial protocols and reported in 71.1% (64/90) of trial reports. The proportion of overall agreement between the trial protocol and trial report concerning occurrence of IF assessment was 66.7% (60/90). Most studies had low to moderate risk of bias.

CONCLUSIONS

IF assessment is not currently a systematic practice in CRTs of public health interventions carried out in LMICs. In the absence of IF assessment, it may be difficult to determine if CRT results are due to the intervention design, to its implementation, or to unknown or external factors that may influence results. CRT reporting guidelines should promote IF assessment.

TRIAL REGISTRATION

Protocol published and available at: https://doi.org/10.1186/s13643-016-0351-0.

Socio-demographic differences in Colombian children's muscular fitness: Does scaling for differences in body size present a challenge to conventional thinking?

OBJECTIVES

In low- to middle-income countries, children from less-deprived areas (from families of higher socio-economic status [SES]) have superior muscular fitness than those from low-SES groups. They are also taller and heavier, factors associated with muscular fitness. The purpose of this study was to identify any socio-demographic differences in Colombian children's muscular fitness and examine how these conclusions can be modified by scaling for differences in body size.

METHODS

A total of 38,098 youths (46% girls), ninth grade students (aged 14-15 years), participated in a study of cross-sectional design. We recorded SES and family incomes, stature, and mass. Standing broad jump and handgrip strength were used to assess muscular fitness. A multiplicative allometric model was adopted to adjust for body-size differences.

RESULTS

Children from the mid- to high-SES groups jumped significantly higher than children from the lowest SES group, although no SES group difference in grip strength was observed. After adjusting for body size, children from higher SES and with higher family incomes had significantly lower handgrip strength, and their superior jump height performances remained but were greatly reduced. Only children from the highest SES now jumped significantly higher that the lowest SES group.

CONCLUSIONS

The superior jump performance and no difference in handgrip strength of Colombian children from higher SES may simply reflect their superior physiques. When body size is accounted for, these differences are reduced or even reversed, suggesting that children from higher SES groups should not be complacent regarding their apparent superior muscular fitness.

Effect of a pilot multi-component intervention on motor performance and metabolic risks in overweight/obese youth

This study evaluated the effect of a multi-component intervention on motor performance (MP) and metabolic risk markers (MRM) in overweight/obese youth. A secondary aim was to examine whether changes in MP are associated to changes in MRM. A 3-month multi-component intervention was performed, consisting of physical exercise sessions (twice/week;1h), nutritional education sessions (once/month), and parental support (twice/week). The sample included 35 volunteers (7-13 y.o), allocated to intervention (INT, n = 17) and control (CONT, n = 18) group. Variables were measured pre (T0) and post intervention (T1). Fasting blood samples were analyzed for MRM. MP tests included the measurement of health related physical fitness components and motor coordination performance (KTK battery). To assess food intake, a 24-hour recall diary was used. GLM-ANCOVA was performed. Standardized scores were calculated for the outcome variables, and multilinear regressions were applied to analyze associations between the key variables. INT group showed improvements in MP, glycolytic and hepatic profiles. After adjustments for MVPA, SB, total intake and maturational stage, negative associations between %ΔMP and %Δglycolytic (β = -.424; 95%CI:-0.343:-0.022), and %Δhepatic scores (β = -.382 95%CI:-0.001:-0.009) were observed. The intervention produced a moderate-to-high effect on the MP and some MRM. Changes in MP were inversely associated with changes in glycolytic and hepatic markers.

A school-based intervention improved dietary intake outcomes and reduced waist circumference in adolescents: a cluster randomized controlled trial

BACKGROUND

In Ecuador, adolescents' food intake does not comply with guidelines for a healthy diet. Together with abdominal obesity adolescent's inadequate diets are risk factors for non-communicable diseases. We report the effectiveness of a school-based intervention on the dietary intake and waist circumference among Ecuadorian adolescents.

METHODS

A pair-matched cluster randomized controlled trial including 1430 adolescents (12-14 years old) was conducted. The program aimed at improving the nutritional value of dietary intake, physical activity (primary outcomes), body mass index, waist circumference and blood pressure (secondary outcomes). This paper reports: (i) the effect on fruit and vegetable intake, added sugar intake, unhealthy snacking (consumption of unhealthy food items that are not in line with the dietary guidelines eaten during snack time; i.e. table sugar, sweets, salty snacks, fast food, soft drinks and packaged food), breakfast intake and waist circumference; and, (ii) dose and reach of the intervention. Dietary outcomes were estimated by means of two 24-h recall at baseline, after the first 17-months (stage one) and after the last 11-months (stage two) of implementation. Dose and reach were evaluated using field notes and attendance forms. Educational toolkits and healthy eating workshops with parents and food kiosks staff in the schools were implemented in two different stages. The overall effect was assessed using linear mixed models and regression spline mixed effect models were applied to evaluate the effect after each stage.

RESULTS

Data from 1046 adolescents in 20 schools were analyzed. Participants from the intervention group consumed lower quantities of unhealthy snacks (-23.32 g; 95% CI: -45.25,-1.37) and less added sugar (-5.66 g; 95% CI: -9.63,-1.65) at the end of the trial. Daily fruit and vegetable intake decreased in both the intervention and control groups compared to baseline, albeit this decrease was 23.88 g (95% CI: 7.36, 40.40) lower in the intervention group. Waist circumference (-0.84 cm; 95% CI: -1.68, 0.28) was lower in the intervention group at the end of the program; the effect was mainly observed at stage one. Dose and reach were also higher at stage one.

CONCLUSIONS

The trial had positive effects on risk factors for non-communicable diseases, i.e. decreased consumption of unhealthy snacks. The program strategies must be implemented at the national level through collaboration between the academia and policy makers to assure impact at larger scale.

TRIAL REGISTRATION

ClinicalTrial.gov-NCT01004367 .

Effects of a multi-level intervention on the pattern of physical activity among in-school adolescents in Oyo state Nigeria: a cluster randomised trial

Background

Physical inactivity contributes to the global burden of non-communicable diseases. The pattern of physical activity in adulthood are often established during adolescence and sedentary behaviours in the early years could influence the development of diseases later in life. Studies on physical activity in Nigeria have focused largely on individual behaviours and the effects of school-based interventions have not been well investigated. The aim of the proposed study is to identify factors influencing; and evaluate the effects of a multi-level intervention on the physical activity behaviours of in-school adolescents in Oyo state, Nigeria.

Methods

The study will adopt a cluster randomised controlled trial design and schools will serve as the unit of randomisation. The sample size is 1000 in-school adolescents aged 10–19 years. The study will be guided by the socio-ecological model and theory of reasoned action and baseline data will be obtained through a mixed methods approach comprising a cross sectional survey to document the self-reported physical activity levels coupled with objectively measured physical activity levels using pedometers for a subset of the sample. Other measurements including weight, height, waist and hip circumferences, fitness level using the 20-m shuttle run test (20-mSRT) and blood pressure will be obtained. The schools’ built environment and policy support for physical activity will be assessed using structured questionnaires coupled with key informant interviews and focus group discussions with the school authorities. Baseline findings will guide the design and implementation of a 12-week multi-level intervention. The primary outcome measures are self–reported and 7-day objectively measured physical activity. Other secondary outcome measures are body-mass-index for age, waist-to-hip ratio, cardioresiratory fitness and blood pressure. The association between behavioural factors and physical activity levels will be assessed. Follow-up measurements will be taken immediately after the intervention and 3-months post intervention.

Discussion

Physical activity behaviours of adolescents in Nigeria are influenced by multiple factors. There is an urgent need for effective school-based interventions with a potential to improve the physical activity behaviours of adolescents in Nigeria and other low and middle income countries.

Trial registration

Pan African Clinical Trial Registry. Trial registration number: PACTR201706002224335, registered 26 June 2017.

Equity effects of children's physical activity interventions: a systematic scoping review

BACKGROUND

Differential effects of physical activity (PA) interventions across population sub-groups may contribute to inequalities in health. This systematic scoping review explored the state of the evidence on equity effects in response to interventions targeting children's PA promotion. The aims were to assess and summarise the availability of evidence on differential intervention effects of children's PA interventions across gender, body mass index, socioeconomic status, ethnicity, place of residence and religion.

METHODS

Using a pre-piloted search strategy, six electronic databases were searched for controlled intervention trials, aiming to increase PA in children (6-18 years of age), that used objective forms of measurement. Screening and data extraction were conducted in duplicate. Reporting of analyses of differential effects were summarized for each equity characteristic and logistic regression analyses run to investigate intervention characteristics associated with the reporting of equity analyses.

RESULTS

The literature search identified 13,052 publications and 7963 unique records. Following a duplicate screening process 125 publications representing 113 unique intervention trials were included. Although the majority of trials collected equity characteristics at baseline, few reported differential effects analyses across the equity factors of interest. All 113 included interventions reported gender at baseline with 46% of non-gender targeted interventions reporting differential effect analyses by gender. Respective figures were considerably smaller for body mass index, socioeconomic status, ethnicity, place of residence and religion. There was an increased likelihood of studying differential effects in school based interventions (OR: 2.9 [1.2-7.2]) in comparison to interventions in other settings, larger studies (per increase in 100 participants; 1.2 [1.0 - 1.4]); and where a main intervention effect on objectively measured PA was reported (3.0 [1.3-6.8]).

CONCLUSIONS

Despite regularly collecting relevant information at baseline, most controlled trials of PA interventions in children do not report analyses of differences in intervention effect across outlined equity characteristics. Consequently, there is a scarcity of evidence concerning the equity effects of these interventions, particularly beyond gender, and a lack of understanding of subgroups that may benefit from, or be disadvantaged by, current intervention efforts. Further evidence synthesis and primary research is needed to effectively understand the impact of PA interventions on existing behavioural inequalities within population subgroups of children.

TRIAL REGISTRATION

PROSPERO (PROSPERO 2016: CRD42016034020 ).

Methodological considerations and impact of school-based interventions on objectively measured physical activity in adolescents: a systematic review and meta-analysis

OBJECTIVE

The aims of this systematic review and meta-analysis are (i) to determine the impact of school-based interventions on objectively measured physical activity among adolescents and (ii) to examine accelerometer methods and decision rule reporting in previous interventions.

METHODS

A systematic search was performed to identify randomized controlled trials targeting adolescents (age: ≥10 years), conducted in the school setting, and reporting objectively measured physical activity. Random effects meta-analyses were conducted to determine the pooled effects of previous interventions on total and moderate-to-vigorous physical activity. Potential moderators of intervention effects were also explored.

RESULTS

Thirteen articles met the inclusion criteria, and twelve were included in the meta-analysis. The pooled effects were small and non-significant for both total physical activity (standardized mean difference = 0.02 [95% confidence interval = -0.13 to 0.18]) and moderate-to-vigorous physical activity (standardized mean difference = 0.24 [95% confidence interval = -0.08 to 0.56]). Sample age and accelerometer compliance were significant moderators for total physical activity, with a younger sample and higher compliance associated with larger effects.

CONCLUSION

Previous school-based physical activity interventions targeting adolescents have been largely unsuccessful, particularly for older adolescents. There is a need for more high-quality research using objective monitoring in this population. Future interventions should comply with best-practice recommendations regarding physical activity monitoring protocols.

Promoting physical activity for children and adolescents in low- and middle-income countries: An umbrella systematic review: A review on promoting physical activity in LMIC

OBJECTIVE

It is unknown how much previous reviews on promoting physical activity (PA) for children and adolescents (aged 6-18years) take into account studies from low- and middle-income countries (LMIC, based on the World Bank definition) and the level of evidence of the effect of PA interventions in this population. This study aims to answer such questions using an umbrella systematic review approach.

METHODS

We searched for peer-reviewed systematic reviews and original studies in eight electronic databases, screening of reference lists and expert contacts. Information in systematic reviews on PA interventions for children and adolescents from LMIC was discussed. Original studies on PA interventions (randomized-controlled trials [RCT], cluster-RCT and non-RCT) with children and adolescents from LMIC were eligible. We assessed the methodological quality in all studies, and the evidence level of effect on PA in intervention studies.

RESULTS

Fifty systematic reviews (nine meta-analyses) and 25 original studies (20 different interventions) met eligibility criteria. Only 3.1% of mentioned studies in previous reviews were from LMIC. Strong and LMIC-specific evidence was found that school-based, multicomponent, and short-term (up to six months) interventions, focused on adolescents primarily (aged 13-18years), can promote PA in children and adolescents from LMIC. Other intervention characteristics had inconclusive evidence due to the low number of studies, low methodological quality, and/or small sample size.

CONCLUSION

A minimal part of PA interventions mentioned in previous reviews are from LMIC. Our LMIC-specific analyses showed priorities of implementation and practical implication that can be used in public policies for PA promotion in LMIC.

The effectiveness of sedentary behaviour interventions for reducing body mass index in children and adolescents: systematic review and meta-analysis

Intervention studies have been undertaken to reduce sedentary behaviour (SB) and thereby potentially ameliorate unhealthy weight gain in children and adolescents. We synthesised evidence and quantified the effects of SB interventions (single or multiple components) on body mass index (BMI) or BMI z-score in this population. Publications up to March 2015 were located through electronic searches. Inclusion criteria were interventions targeting SB in children that had a control group and objective measures of weight and height. Mean change in BMI or BMI z-score from baseline to post-intervention were quantified for intervention and control groups and meta-analyzed using a random effects model. The pooled mean reduction in BMI and BMI z-score was significant but very small (standardized mean difference = -0.060, 95% confidence interval: -0.098 to -0.022). However, the pooled estimate was substantially greater for an overweight or obese population (standardized mean difference = -0.255, 95% confidence interval: -0.400 to -0.109). Multicomponent interventions (SB and other behaviours) delivered to children from 5 to 12 years old in a non-educational setting appear to favour BMI reduction. In summary, SB interventions are associated with very small improvement in BMI in mixed-weight populations. However, SB interventions should be part of multicomponent interventions for treating obese children. © 2016 World Obesity.

Two years of school-based intervention program could improve the physical fitness among Ecuadorian adolescents at health risk: subgroups analysis from a cluster-randomized trial

Background

Adolescents with overweight and poor physical fitness have an increased likelihood of developing cardiovascular diseases during adulthood. In Ecuador, a health promotion program improved the muscular strength and speed-agility, and reduced the decline of the moderate-to-vigorous physical activity of adolescents after 28 months. We performed a sub-group analysis to assess the differential effect of this intervention in overweight and low-fit adolescents.

Methods

We performed a cluster-randomized pair matched trial in schools located in Cuenca–Ecuador. In total 20 schools (clusters) were pair matched, and 1440 adolescents of grade 8 and 9 (mean age of 12.3 and 13.3 years respectively) participated in the trial. For the purposes of the subgroup analysis, the adolescents were classified into groups according to their weight status (body mass index) and aerobic capacity (scores in the 20 m shuttle run and FITNESSGRAM standards) at baseline. Primary outcomes included physical fitness (vertical jump, speed shuttle run) and physical activity (proportion of students achieving over 60 min of moderate–to-vigorous physical activity/day). For these primary outcomes, we stratified analysis by weight (underweight, normal BMI and overweight/obese) and fitness (fit and low fitness) groups. Mixed linear regression models were used to assess the intervention effect.

Results

The prevalence of overweight/obesity, underweight and poor physical fitness was 20.3 %, 5.8 % and 84.8 % respectively. A higher intervention effect was observed for speed shuttle run in overweight (β = −1.85 s, P = 0.04) adolescents compared to underweight (β = −1.66 s, P = 0.5) or normal weight (β = −0.35 s, P = 0.6) peers. The intervention effect on vertical jump was higher in adolescents with poor physical fitness (β = 3.71 cm, P = 0.005) compared to their fit peers (β = 1.28 cm, P = 0.4). The proportion of students achieving over 60 min of moderate-to-vigorous physical activity/day was not significantly different according to weight or fitness status.

Conclusion

Comprehensive school-based interventions that aim to improve diet and physical activity could improve speed and strength aspects of physical fitness in low-fit and overweight/obese adolescents.

Trial registration

Clinicaltrials.gov identifier NCT01004367. Registered October 28, 2009.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-016-0588-8) contains supplementary material, which is available to authorized users.

Improved Designs for Cluster Randomized Trials

Studies in which clusters of individuals are randomized to conditions are increasingly common in public health research. However, the designs utilized for such studies are often suboptimal and inefficient. We review strategies to improve the design of cluster randomized trials. We discuss both older but effective design concepts that are underutilized, such as stratification and factorial designs, as well as emergent ideas including fractional factorial designs and cluster randomized crossover studies. We draw examples from the recent literature and provide resources for sample size and power planning. Given the inherent inefficiencies of cluster randomized trials, these design strategies merit wider consideration and can lead to studies that are more cost-effective and potentially more rigorous than traditional approaches.

School-based intervention on healthy behaviour among Ecuadorian adolescents: effect of a cluster-randomized controlled trial on screen-time

Background

Effective interventions on screen-time behaviours (television, video games and computer time) are needed to prevent non-communicable diseases in low- and middle-income countries. The present manuscript investigates the effect of a school-based health promotion intervention on screen-time behaviour among 12- to 15-year-old adolescents. We report the effect of the trial on screen-time after two stages of implementation.

Methods

We performed a cluster-randomised pair matched trial in urban schools in Cuenca-Ecuador. Participants were adolescents of grade eight and nine (mean age 12.8 ± 0.8 years, n = 1370, control group n = 684) from 20 schools (control group n = 10). The intervention included an individual and environmental component tailored to the local context and resources. The first intervention stage focused on diet, physical activity and screen-time behaviour, while the second stage focused only on diet and physical activity. Screen-time behaviours, primary outcome, were assessed at baseline, after the first (18 months) and second stage (28 months). Mixed linear models were used to analyse the data.

Results

After the first stage (data from n = 1224 adolescents; control group n = 608), the intervention group had a lower increase in TV-time on a week day (β = −15.7 min; P = 0.003) and weekend day (β = −18.9 min; P = 0.005), in total screen-time on a weekday (β = −25.9 min; P = 0.03) and in the proportion of adolescents that did not meet the screen-time recommendation (β = −4 percentage point; P = 0.01), compared to the control group. After the second stage (data from n = 1078 adolescents; control group n = 531), the TV-time on a weekday (β = 13.1 min; P = 0.02), and total screen-time on a weekday (β = 21.4 min; P = 0.03) increased more in adolescents from the intervention group. No adverse effects were reported.

Discussion and Conclusion

A multicomponent school-based intervention was only able to mitigate the increase in adolescents’ television time and total screen-time after the first stage of the intervention or in other words, when the intervention included specific components or activities that focused on reducing screen-time. After the second stage of the intervention, which only included components and activities related to improve healthy diet and physical activity and not to decrease the screen-time, the adolescents increased their screen-time again. Our findings might imply that reducing screen-time is only possible when the intervention focuses specifically on reducing screen-time.

Trial registration

Clinicaltrials.gov identifier NCT01004367.