Recreational screen time trajectories during early childhood and imaging-measured body composition at age 7 in the Odense child cohort.

BACKGROUND: Children spend increasing amounts of time on recreational screen media, which may lead to an obesogenic environment. OBJECTIVES: We investigated the association of trajectories of screen time across ages 3, 5 and 7 years with body composition at age 7 in the Odense Child Cohort. METHODS: Data were collected in the Municipality of Odense, Denmark, between 2010 and 2019. Group-based trajectory modelling was applied to group participants into four trajectories of prospective parent-reported screen time. Body composition was assessed using dual-energy x-ray absorptiometry with calculated fat-mass index (FMI) as the primary outcome. Primary models were linear multivariable regression models adjusted for participants' sex, age, birthweight, maternal origin, maternal education, maternal body-mass-index, and maternal age. Further models were adjusted for additional possible confounders. Selection bias was addressed by inverse probability weighting. RESULTS: In total, 803 children (48.2% female) were included in the primary analysis. Participants with screen time at all time points were assigned to four trajectory groups [constant low screen time (12.7%), low increase (36.3%), high increase between ages 3 and 5 (33.5%) and high increase in screen time (17.5%)]. Sample characteristics differed across missing data status and trajectories. Mean FMI (kg/m2 ) and standard deviation (SD) were 3.7 (SD 1.3) and 3.9 (SD 1.6) for the constant low versus high screen time, respectively. No differences in FMI were found between screen time trajectory groups at age 7 (adjusted mean difference 0.1 kg/m2 , 95% confidence interval -0.3, 0.5 for constant low versus high screen time). No consistent associations between screen time groups and secondary body composition outcomes were found. CONCLUSIONS: Results from this study do not suggest that recreational screen time from age 3 to 7 years is associated with adiposity or other measures of body composition.

How to get children moving? The effectiveness of school-based interventions promoting physical activity in children and adolescents - A systematic review and meta-analysis of randomized controlled- and controlled studies.

This systematic review and meta-analysis summarizes the effectiveness of school-based physical activity (PA) interventions on children's and adolescents' PA. As no robust empirical evidence exists regarding what seems to characterize the school-based PA interventions that are most effective, we further aimed to map key factors of particular importance when trying to increase PA in early stages of life through school-based strategies. Intervention effects were calculated as standardized between-group (i.e., intervention vs. control) mean differences (SMD) in PA from baseline to follow-up. In total, 189 publications were included. Few studies (7%) were of high quality. Our results demonstrate that school-based interventions only have a small positive effect on children's and adolescents' PA levels. Compared to the effect observed during total day (SMD = 0.27, p < 0.001), a slightly larger effect was observed during school hours (SMD = 0.37, p < 0.001), while no intervention effect was observed during leisure time (SMD = 0.07, p = 0.20). There was a tendency for interventions to be more effective if theoretical frameworks for behavior changes were used in the design phase. The largest effect size was observed when experts from outside school delivered the program (SMD = 0.56, p = 0.01), but training of personnel involved in delivery was the determining factor for program effectiveness as no effect was observed if interventions were delivered primarily by schools' untrained staff (SMD = 0.06, p = 0.61). Intervention effects where larger if parents were involved in the intervention program (parents involved: SMD = 0.35, p < 0.001; parents not involved: SMD = 0.16, p = 0.02). Small positive intervention effects were sustained at long-term follow-up after end of intervention. Overall, the certainty of the evidence of the findings is rated as low.

Screen Media Use and Mental Health of Children and Adolescents: A Secondary Analysis of a Randomized Clinical Trial.

Importance: Excessive screen media use has been associated with poorer mental health among children and adolescents in several observational studies. However, experimental evidence supporting this hypothesis is lacking. Objective: To investigate the effects of a 2-week screen media reduction intervention on children's and adolescents' mental health. Design, Setting, and Participants: This prespecified secondary analysis of a cluster randomized clinical trial with a 2-week follow-up included 89 families (with 181 children and adolescents) from 10 Danish municipalities in the region of Southern Denmark. All study procedures were carried out in the home of the participants. Enrollment began on June 6, 2019, and ended on March 30, 2021. This analysis was conducted between January 1 and November 30, 2023. Intervention: Families were randomly allocated to a screen media reduction group or a control group. The 2-week screen media reduction intervention was designed to ensure a high level of compliance to the reduction in leisure-time screen media use. Participants allocated to the intervention group had to reduce their leisure-time screen media use to 3 hours per week or less per person and hand over smartphones and tablets. Main Outcomes and Measures: The main outcome was the between-group mean difference in change in total behavioral difficulties, measured by the Strengths and Difficulties Questionnaire at 2-week follow-up. Results were estimated using mixed-effects tobit regression models. Analyses were carried out as both intention to treat and complete case. Results: In the sample of 89 families including 181 children and adolescents (intervention group [45 families]: 86 children; mean [SD] age, 8.6 [2.7] years; 42 girls [49%]; control group [44 families]: 95 children; mean [SD] age, 9.5 [2.5] years; 57 girls [60%]), there was a statistically significant between-group mean difference in the total difficulties score, favoring the screen media reduction intervention (-1.67; 95% CI, -2.68 to -0.67; Cohen d, 0.53). The greatest improvements were observed for internalizing symptoms (emotional symptoms and peer problems; between-group mean difference, -1.03; 95% CI, -1.76 to -0.29) and prosocial behavior (between-group mean difference, 0.84; 95% CI, 0.39-1.30). Conclusions and Relevance: This secondary analysis of a randomized clinical trial found that a short-term reduction in leisure-time screen media use within families positively affected psychological symptoms of children and adolescents, particularly by mitigating internalizing behavioral issues and enhancing prosocial behavior. More research is needed to confirm whether these effects are sustainable in the long term. Trial Registration: ClinicalTrials.gov Identifier: NCT04098913.

Facilitating ambulatory heart rate variability analysis using accelerometry-based classifications of body position and self-reported sleep.

Objective.This study aimed to examine differences in heart rate variability (HRV) across accelerometer-derived position, self-reported sleep, and different summary measures (sleep, 24 h HRV) in free-living settings using open-source methodology.Approach.HRV is a biomarker of autonomic activity. As it is strongly affected by factors such as physical behaviour, stress, and sleep, ambulatory HRV analysis is challenging. Beat-to-beat heart rate (HR) and accelerometry data were collected using single-lead electrocardiography and trunk- and thigh-worn accelerometers among 160 adults participating in the SCREENS trial. HR files were processed and analysed in the RHRV R package. Start time and duration spent in physical behaviours were extracted, and time and frequency analysis for each episode was performed. Differences in HRV estimates across activities were compared using linear mixed models adjusted for age and sex with subject ID as random effect. Next, repeated-measures Bland-Altman analysis was used to compare 24 h RMSSD estimates to HRV during self-reported sleep. Sensitivity analyses evaluated the accuracy of the methodology, and the approach of employing accelerometer-determined episodes to examine activity-independent HRV was described.Main results.HRV was estimated for 31 289 episodes in 160 individuals (53.1% female) at a mean age of 41.4 years. Significant differences in HR and most markers of HRV were found across positions [Mean differences RMSSD: Sitting (Reference) - Standing (-2.63 ms) or Lying (4.53 ms)]. Moreover, ambulatory HRV differed significantly across sleep status, and poor agreement between 24 h estimates compared to sleep HRV was detected. Sensitivity analyses confirmed that removing the first and last 30 s of accelerometry-determined HR episodes was an accurate strategy to account for orthostatic effects.Significance.Ambulatory HRV differed significantly across accelerometry-assigned positions and sleep. The proposed approach for free-living HRV analysis may be an effective strategy to remove confounding by physical activity when the aim is to monitor general autonomic stress.

Parental Recreational Screen Media Practices and Behavioral Difficulties Among Danish 7-Year-Old Children.

OBJECTIVE: This study aimed to investigate the association of parental recreational screen media practices, including time use and level of smartphone addiction, with behavioral difficulties in 7-year-old children. METHODS: The study was based on cross-sectional data from the Odense Child Cohort, a community-based birth-cohort study. A total of 1152 parent-child dyads with complete data were included based on data from the 7-year examination conducted in 2018-21. Parental recreational screen use was self-reported as hours/day using the SCREENS-questionnaire, and their smartphone addiction was self-reported using the Smartphone Addiction Scale Short Version. Child behavioral difficulties were assessed by the parent-reported version of the Strengths and Difficulties Questionnaire (SDQ). RESULTS: Parental recreational screen time was not consistently associated with behavioral difficulty SDQ subscales and total difficulty scores when adjusted for other determinants of child mental well-being such as sociodemographic factors, parental well-being, and number of siblings. Children had higher total behavioral difficulty scores (adjusted mean difference 2.12 (95% CI, 1.19-3.05)) when comparing fourth quartile versus first quartile of maternal smartphone addiction score. Also, higher maternal smartphone addiction scores were associated with more externalizing and internalizing behavioral problems of their child (adjusted mean difference 1.61 points (95% CI, 0.95-2.27), and 0.81 points (95% CI, 0.19-1.43)) for fourth quartile versus first quartile, respectively. CONCLUSIONS: No cross-sectional association was found between total parental recreational screen use and behavioral difficulties in their 7-year-old children, but an association between maternal obsessive smartphone use and behavioral difficulties of their children was found.