Longitudinal associations of screen time, physical activity, and sleep duration with body mass index in U.S. youth.

BACKGROUND: Youth use different forms of screen time (e.g., streaming, gaming) that may be related to body mass index (BMI). Screen time is non-independent from other behaviors, including physical activity and sleep duration. Statistical approaches such as isotemporal substitution or compositional data analysis (CoDA) can model associations between these non-independent behaviors and health outcomes. Few studies have examined different types of screen time, physical activity, and sleep duration simultaneously in relation to BMI. METHODS: Data were baseline (2017-2018) and one-year follow-up (2018-2019) from the Adolescent Brain Cognitive Development Study, a multi-site study of a nationally representative sample of U.S. youth (N = 10,544, mean [SE] baseline age = 9.9 [0.03] years, 48.9% female, 45.4% non-White). Participants reported daily minutes of screen time (streaming, gaming, socializing), physical activity, and sleep. Sex-stratified models estimated the association between baseline behaviors and follow-up BMI z-score, controlling for demographic characteristics, internalizing symptoms, and BMI z-score at baseline. RESULTS: In females, isotemporal substitution models estimated that replacing 30 min of socializing (ß [95% CI] = -0.03 [-0.05, -0.002]), streaming (-0.03 [-0.05, -0.01]), or gaming (-0.03 [-0.06, -0.01]) with 30 min of physical activity was associated with a lower follow-up BMI z-score. In males, replacing 30 min of socializing (-0.03 [-0.05, -0.01]), streaming (-0.02 [-0.03, -0.01]), or gaming (-0.02 [-0.03, -0.01]) with 30 min of sleep was associated with a lower follow-up BMI z-score. In males, replacing 30 min of socializing with 30 min of gaming was associated with a lower follow-up BMI z-score (-0.01 [-0.03, -0.0001]). CoDA estimated that in males, a greater proportion of time spent in baseline socializing, relative to the remaining behaviors, was associated with a higher follow-up BMI z-score (0.05 [0.02, 0.08]). In females, no associations between screen time and BMI were observed using CoDA. CONCLUSIONS: One-year longitudinal associations between screen time and BMI may depend on form of screen time, what behavior it replaces (physical activity or sleep), and participant sex. The alternative statistical approaches yielded somewhat different results. Experimental manipulation of screen time and investigation of biopsychosocial mechanisms underlying the observed sex differences will allow for causal inference and can inform interventions.

Physical Activity and Public Health for Adults: Is the Glass Mostly Empty or Half Full?

ABSTRACT: Early observations that only a small proportion of United States (US) adults were engaging in enough aerobic physical activity to provide substantial health benefit helped shape our public health messaging for physical activity. This messaging has consistently indicated that most adults should increase their activity levels. However, it has been difficult to accurately estimate the proportion of adults who engage in sufficient levels of aerobic activity in the population, with survey-based estimates ranging from 22% in 1994 to 54% in 2018 and widely differing estimates from device-based measures. Recent accelerometer-based studies of physical activity and mortality risk provide new evidence that at least 50% of US adults engage in enough aerobic physical activity to be at low risk for premature mortality. We argue that this observation should lend greater confidence to our current survey-based surveillance estimates which indicate that a large proportion of adults is physically active. This new insight may also provide clues that could further strengthen our public health messaging for physical activity by placing more emphasis on the maintenance of healthy activity levels throughout life and possibly by using descriptive social norms as an additional intervention element-while continuing current efforts to encourage the adoption of healthy activity levels for less active adults in the population.

Parks, Trails, and Greenways for Physical Activity: A Community Guide Systematic Economic Review.

INTRODUCTION: This systematic economic review examined the cost-benefit and cost-effectiveness of park, trail, and greenway infrastructure interventions to increase physical activity or infrastructure use. METHODS: The search period covered the date of inception of publications databases through February 2022. Inclusion was limited to studies that reported cost-benefit or cost-effectiveness outcomes and were based in the U.S. and other high-income countries. Analyses were conducted from March 2022 through December 2022. All monetary values reported are in 2021 U.S. dollars. RESULTS: The search yielded 1 study based in the U.S. and 7 based in other high-income countries, with 1 reporting cost-effectiveness and 7 reporting cost-benefit outcomes. The cost-effectiveness study based in the United Kingdom reported $23,254 per disability-adjusted life year averted. The median benefit-to-cost ratio was 3.1 (interquartile interval=2.9-3.9) on the basis of 7 studies. DISCUSSION: The evidence shows that economic benefits exceed the intervention cost of park, trail, and greenway infrastructure. Given large differences in the size of infrastructure, intervention costs and economic benefits varied substantially across studies. There was insufficient number of studies to determine the cost-effectiveness of these interventions.

The intersection of health and housing: Analysis of the research portfolios of the National Institutes of Health, Centers for Disease Control and Prevention, and U.S. Department of Housing and Urban Development.

BACKGROUND: Housing is a major social determinant of health that affects health status and outcomes across the lifespan. OBJECTIVES: An interagency portfolio analysis assessed the level of funding invested in "health and housing research" from fiscal years (FY) 2016-2020 across the National Institutes of Health (NIH), the United States Department of Housing and Urban Development (HUD), and the Centers for Disease Control and Prevention (CDC) to characterize the existing health and housing portfolio and identify potential areas for additional research and collaboration. METHODS/RESULTS: We identified NIH, HUD, and CDC research projects that were relevant to both health and housing and characterized them by housing theme, health topic, population, and study design. We organized the assessment of the individual housing themes by four overarching housing-to-health pathways. From FY 2016-2020, NIH, HUD, and CDC funded 565 health and housing projects combined. The Neighborhood pathway was most common, followed by studies of the Safety and Quality pathway. Studies of the Affordability and Stability pathways were least common. Health topics such as substance use, mental health, and cardiovascular disease were most often studied. Most studies were observational (66%); only a little over one fourth (27%) were intervention studies. DISCUSSION: This review of the research grant portfolios of three major federal funders of health and housing research in the United States describes the diversity and substantial investment in research at the intersection between housing and health. Analysis of the combined portfolio points to gaps in studies on causal pathways linking housing to health outcomes. The findings highlight the need for research to better understand the causal pathways from housing to health and prevention intervention research, including rigorous evaluation of housing interventions and policies to improve health and well-being.

Examining the Bidirectional Associations Between Sleep Duration, Screen Time, and Internalizing Symptoms in the ABCD Study.

PURPOSE: The likelihood of meeting sleep duration and screen time guidelines decreases as children develop toward adolescence. Simultaneously, the prevalence of internalizing symptoms increases. The purpose of this paper was to examine the bidirectional associations between sleep duration and screen time with internalizing symptoms in a one-year longitudinal study starting in late childhood. METHODS: Participants were 10,828 youth (47.8% female) enrolled in the Adolescent Brain Cognitive Development Study. At baseline (mean age 9.9 years) and one-year follow-up (mean age 10.9 years), youth self-reported screen time for weekdays and weekend days. Responses were separately dichotomized as >2 versus ≤2 hours/day (meeting behavioral guidelines). Caregiver-reported youth sleep duration was dichotomized as <9 versus 9-11 hours/night (meeting behavioral guidelines). Caregivers reported internalizing symptoms via the child behavior checklist. The withdrawn/depressed, anxious/depressed, and somatic symptom child behavior checklist subscale t-scores were separately dichotomized as ≥65 (borderline clinical levels of symptoms and above) versus <65. Analyses were gender-stratified. RESULTS: In females, longer baseline sleep duration was protective against withdrawn/depressed symptoms (odds ratio [OR] 0.6, 95% confidence interval [CI] 0.4-0.8) and somatic complaints (OR 0.8, 95% CI 0.6-0.97) one year later. In females, greater baseline weekend screen time was associated with increased risk of withdrawn/depressed symptoms (OR 1.6, 95% CI 1.1-2.2) one year later. No other significant associations were observed. DISCUSSION: Longitudinal associations between sleep duration, weekend screen time, and internalizing symptoms were unidirectional (behavior preceding internalizing symptoms), among females only, and specific to withdrawn/depressed and somatic symptoms. These prospective study findings warrant attention and inform future research in this cohort.

Changes in Perceptions of the Near-Home Walking Environment Among US Adults-2015 and 2020 National Health Interview Survey.

BACKGROUND: The built environments in which we work, live, and play can influence physical activity behaviors, and perceptions of these environments are associated with walking behavior. This study's objective is to compare national-level data on perceptions of the near-home walking environment from the 2015 and 2020 National Health Interview Survey. METHODS: Adults in 2015 (n = 30,811) and 2020 (n = 29,636) reported perceptions of walkable supports (roads, sidewalks, paths, or trails; sidewalks on most streets), destinations (shops, stores, or markets; bus or transit stops; movies, libraries, or churches; places that help you relax, clear your mind, and reduce stress), and barriers to walking (traffic; crime; animals). Age-adjusted prevalence estimates, prevalence differences, and 95% confidence intervals were calculated overall and by demographic characteristics. RESULTS: The reported prevalence of roads, sidewalks, paths, or trails for walking increased overall (85.3% in 2015 to 88.0% in 2020) and for many subgroups. Perceived places to walk to for relaxation, to clear your mind, and to reduce stress increased overall (72.1% in 2015 to 77.1% in 2020) and for all subgroups. Perceptions of crime as a barrier to walking decreased overall (12.5% in 2015 to 11.2% in 2020) and for some subgroups. From 2015 to 2020, the proportion of adults perceiving roads, sidewalks, paths, or trails; places to relax; and crime as a barrier to walking improved. CONCLUSIONS: Continuing to monitor perceptions of the walking environment could contribute to progress toward national walking and walkability goals in the United States.

Association of Recess Provision With Accelerometer-Measured Physical Activity and Sedentary Time in a Representative Sample of 6- to 11-Year-Old Children in the United States.

PURPOSE: To assess the association between the amount of recess provision and children's accelerometer-measured physical activity (PA) levels. METHODS: Parents/guardians of 6- to 11-year-olds (n = 451) in the 2012 National Youth Fitness Survey reported recess provision, categorized as low (10-15 min; 31.9%), medium (16-30 min; 48.0%), or high (>30 min; 20.1%). Children wore a wrist-worn accelerometer for 7 days to estimate time spent sedentary, in light PA, and in moderate to vigorous PA using 2 different cut points for either activity counts or raw acceleration. Outcomes were compared between levels of recess provision while adjusting for covariates and the survey's multistage, probability sampling design. RESULTS: Children with high recess provision spent less time sedentary, irrespective of type of day (week vs weekend) and engaged in more light or moderate to vigorous PA on weekdays than those with low recess provision. The magnitude and statistical significance of effects differed based on the cut points used to classify PA (eg, 4.7 vs 11.9 additional min·d-1 of moderate to vigorous PA). CONCLUSIONS: Providing children with >30 minutes of daily recess, which exceeds current recommendations of ≥20 minutes, is associated with more favorable PA levels and not just on school days. Identifying the optimal method for analyzing wrist-worn accelerometer data could clarify the magnitude of this effect.

Differential associations between television viewing, computer use, and adiposity by age, gender, and race/ethnicity in United States youth: A cross-sectional NHANES analysis.

BACKGROUND: Time spent on screens and adiposity change rapidly from childhood to adolescence, with differences by gender and race/ethnicity. OBJECTIVE: Apply time-varying effect models (TVEMs) to a nationally representative sample of youth to identify the age ranges when the cross-sectional associations between television viewing, computer use, and adiposity are significant. METHODS: Data from 8 to 15-year-olds (n = 3593) from the National Health and Nutrition Examination Survey (2011-2018) were extracted. TVEMs estimated the associations between television viewing, computer use, and fat mass index as dynamic functions of the participants' age, stratified by gender and race/ethnicity. RESULTS: TVEMs revealed age-specific statistically significant associations that differed by gender and race/ethnicity. Notably, computer use was related to higher adiposity in non-Hispanic White females aged 9.3-11.4 years (slope ß-range: 0.1-0.2) and in non-Hispanic Black females older than 14.8 years (ß-range: 0.1-0.5). In males, these age windows were 13.5-15.0 years (non-Hispanic White, ß-range: 0.1-0.2), 11.4-13.0 years (non-Hispanic Black, ß-range: 0.1-0.14), and older than 13.0 years (Hispanic, ß-range: 0.1-0.4). CONCLUSIONS: More research during the specific age ranges in the demographic subgroups identified here could increase our understanding of tailored interventions in youth.

Adherence to Recess Guidelines in the United States Using Nationally Representative Data: Implications for Future Surveillance Efforts.

BACKGROUND: National adherence to the recess recommendations of the Centers for Disease Control and Prevention (CDC) has not been comprehensively studied in the United States. METHODS: Data from 6 nationally representative data sets over the last decade (Classification of Laws Associated with School Students, Early Childhood Longitudinal Study, National Health and Nutrition Examination Survey, National Youth Fitness Survey, School Health Policies and Practices Survey, and the School Nutrition and Meal Cost Study) provided estimates for adherence to CDC recess guidelines. RESULTS: While approximately 65-80% of elementary school-children receive the recommended 20+ minutes of daily recess according to parent-, principal-, and school-report, adherence declines by sixth grade, and little information is available for middle/high school students. Adherence to playground safety was high (90%), but adherence to recommendations about recess before lunch (<50%), withholding recess as punishment (∼50%), and training recess staff (<50%) were lower. CONCLUSIONS: School policy and practice should align with CDC recommendations, with the aim of providing sufficient quality recess to all youth, K-12th grade. Comprehensive, on-going national surveillance of multiple recess domains is needed to inform policy and ensure equitable provision of recess.

Impact of the built, social, and food environment on long-term weight loss within a behavioral weight loss intervention.

Background: Behavioral weight loss interventions can lead to an average weight loss of 5%-10% of initial body weight, however there is wide individual variability in treatment response. Although built, social, and community food environments can have potential direct and indirect influences on body weight (through their influence on physical activity and energy intake), these environmental factors are rarely considered as predictors of variation in weight loss. Objective: Evaluate the association between built, social, and community food environments and changes in weight, moderate-to-vigorous physical activity (MVPA), and dietary intake among adults who completed an 18-month behavioral weight loss intervention. Methods: Participants included 93 adults (mean ± SD; 41.5 ± 8.3 years, 34.4 ± 4.2 kg/m2, 82% female, 75% white). Environmental variables included urbanicity, walkability, crime, Neighborhood Deprivation Index (includes 13 social economic status factors), and density of convenience stores, grocery stores, and limited-service restaurants at the tract level. Linear regressions examined associations between environment and changes in body weight, waist circumference (WC), MVPA (SenseWear device), and dietary intake (3-day diet records) from baseline to 18 months. Results: Grocery store density was inversely associated with change in weight (ß = -0.95; p = 0.02; R 2 = 0.062) and WC (ß = -1.23; p < 0.01; R 2 = 0.109). Participants living in tracts with lower walkability demonstrated lower baseline MVPA and greater increases in MVPA versus participants with higher walkability (interaction p = 0.03). Participants living in tracts with the most deprivation demonstrated greater increases in average daily steps (ß = 2048.27; p = 0.02; R 2 = 0.039) versus participants with the least deprivation. Limited-service restaurant density was associated with change in % protein intake (ß = 0.39; p = 0.046; R 2 = 0.051). Conclusion: Environmental factors accounted for some of the variability (<11%) in response to a behavioral weight loss intervention. Grocery store density was positively associated with weight loss at 18 months. Additional studies and/or pooled analyses, encompassing greater environmental variation, are required to further evaluate whether environment contributes to weight loss variability.

Uncertainty: a neglected determinant of health behavior?

Health behaviors are critical determinants of the well-being of individuals and populations, and understanding the determinants of these behaviors has been a major focus of research. One important determinant that has received little direct attention in past health research is uncertainty: a complex phenomenon that pertains not only to scientific issues regarding the diagnosis, prognosis, prevention, and treatment of health problems, but also to personal issues regarding other important health-related concerns. Here, we make the case for greater attention to uncertainty in health behavior theory and research, and especially to personal uncertainties. We discuss three exemplary types of personal uncertainty-value uncertainty, capacity uncertainty, and motive uncertainty-which relate, respectively, to moral values, capacities to enact or change behaviors, and the motives and intentions of other persons or institutions. We argue that that personal uncertainties such as these influence health behaviors, but their influence has historically been obscured by a focus on other constructs such as self-efficacy and trust. Reconceptualizing and investigating health behavior as a problem of uncertainty can advance both our understanding of the determinants of healthy behaviors and our ability to promote them.

Relationship between neighborhood walkability and the prevalence, type, timing, and temporal characteristics of walking.

We examined associations of neighborhood walkability with the prevalence, type, timing, and temporal characteristics of walking in a representative sample of United States adults. Adults (N = 2649) completed the ACT24 previous-day recall. Home address was linked to block-group National Walkability Index. Survey-adjusted Poisson and logistic regression examined the association of walkability with outcomes. Those who lived in more walkable neighborhoods were more likely to walk overall, for transport, or in the evening. In those who walked, higher walkability was associated with less morning but more evening walking. There were no associations of walkability with the frequency or duration of walking episodes.

Physical Activity Levels (PAL) in US Adults-2019.

PURPOSE: Physical activity levels (PAL) are associated with mortality risk and were instrumental in estimating national energy requirements, but we are unaware of population-based estimates of PAL in US adults. Thus, we conducted a nationwide survey using a validated previous-day recall method to estimate PAL and the behavioral determinants of low and higher PAL. METHODS: Participants from the AmeriSpeak panel 20-75 yr of age ( N = 2640) completed Activities Completed over Time in 24-hours previous-day recalls. PAL values were estimated as the average metabolic equivalent value over 24 h. Recalls were conducted on randomly selected days in October and November 2019. Survey sample design weights were applied to reflect the US population. RESULTS: Mean age was 45.3 yr, 51% were female, 67% were non-Hispanic White, and 37% had a body mass index of ≥30 kg·m -2 . US adults reported a mean PAL of 1.63 (95% confidence interval, 1.60-1.65), and 39% (37%-42%) of adults reported PAL ≥1.6 on a given day. Men reported higher PAL than women (1.67 vs 1.59), and older adults reported lower PAL. Adults with PAL <1.4 spent 81% (12.1 h·d -1 ) of their waking day sedentary and 19% (2.7 h·d -1 ) in total physical activity. Adults with PAL considered to be "active"(1.6-1.89) spent only 49% (8.0 h·d -1 ) of their waking day sedentary, and 51% (8.3 h·d -1 ) physically active. CONCLUSIONS: Our study provides novel estimates of PAL in a nationwide sample of US adults and a description of the type and intensity of sedentary and physically active behaviors contributing to low and higher PAL. These findings may inform public health messages aimed at increasing physical activity in adults and potentially contribute to obesity prevention efforts.

Validation of ACT24 Version 2.0 for Estimating Behavioral Domains, Active and Sedentary Time.

PURPOSE: The purpose of this study was to determine the criterion validity of Activities Completed over Time (ACT24), an automated previous-day recall tool designed for mobile devices for 1) estimating sedentary versus active time compared with an activPAL, and 2) estimating time spent in activity domains (e.g., work, household, leisure) compared with direct observation (DO). METHODS: Over a 7-d study period, 53 participants were sent invitations to complete three automated ACT24 recalls and to wear an activPAL device. A subset ( N = 24) consented to two, 3-h video-recorded DO sessions. activPAL and ACT24 data were matched by date, and agreement for sedentary versus active time was compared between methods using paired t -tests for mean differences and spearman correlations. We compared DO and ACT24 results by domain for overall time use and separately for sedentary and active time using κ statistics and tested mean differences with linear mixed models. RESULTS: Compared with the activPAL, the mean difference in ACT24 sedentary time was 1.9% (mean (95% confidence interval), -0.17 (-0.75 to 0.40) h·d -1 ), and the mean difference for ACT24 active time was 2.2% (0.14 (-0.32 to 0.60) h·d -1 ). Correlations were R = 0.61 (95% confidence interval, 0.39 to 0.76) and R = 0.65 (0.44 to0.78) for sedentary and active time, respectively. Domain-specific agreement was substantial for leisure-time, work, and shopping/errands ( κ range, 0.63-0.79), moderate for transportation ( κ = 0.49), and fair for personal care and household activities ( κ = 0.24 and 0.33). ACT24 estimates of average time within each domain were not significantly different from DO. CONCLUSIONS: The present study confirms that ACT24 is accurate for group-level estimation of active and sedentary time. Domain-specific agreement tended to be higher for more commonly reported activities and those that were of longer duration.

Association of Recess Provision With Elementary School-Aged Children's Physical Activity, Adiposity, and Cardiorespiratory and Muscular Fitness.

PURPOSE: To identify associations between amount of school recess provision and children's physical activity (PA), weight status, adiposity, cardiorespiratory endurance, muscular strength, and muscular endurance. METHOD: Data from 6- to 11-year-old participants (n = 499) in the 2012 National Youth Fitness Survey were analyzed. Parents/guardians reported children's PA levels and recess provision, categorized as no/minimal (9.0%), low (26.1%), medium (46.0%), or high (18.9%). Children wore a wrist-worn accelerometer for 7 days and completed anthropometric measurements. Fitness was assessed using grip strength and treadmill, pull-up, and plank tests. Cross-sectional linear and logistic regression compared outcomes across levels of recess provision adjusting for the survey's complex sampling design. RESULTS: Children with high provision of recess were 2.31 times more likely to meet PA guidelines according to parent report than those with no/minimal recess. Accelerometer-measured PA followed a more U-shaped pattern, wherein PA was higher in children with high, compared to low, recess provision but comparable to those with no/minimal recess provision. There were no associations with weight status, adiposity, or fitness. CONCLUSION: Current recess recommendations (20 min·d-1) may be insufficient as 30 minutes per day of recess was associated with a 2-fold greater likelihood of achieving recommended PA levels. Additional research on recess quantity and quality is needed.

Associations between Amount of Recess, Physical Activity, and Cardiometabolic Traits in U.S. Children.

Introduction/purpose: In the United States, it is recommended that schools provide at least 20 minutes of daily recess, but the optimal amount for health benefits is unknown. We examined associations between amount of recess and health indicators using National Health and Nutrition Examination Survey data (NHANES; 2013-2016). Methods: For this cross-sectional analysis, parents/guardians of 6-11 year olds (n=738) reported recess provision which was classified as low (22.8%; approximately 10-15 min, 5 days per week), medium (54.9%; approximately 16-30 min, 5 days per week), or high (22.3%; approximately >30 min, 5 days per week). Outcomes measured included parent/guardian-reported and accelerometer-measured physical activity (PA), blood pressure, cholesterol, grip strength, bone mineral content, weight status, percent body fat, vitamin D level, and C-reactive protein level. Linear and logistic regression compared outcomes by level of recess provision accounting for the NHANES complex survey design. Results: The odds of meeting PA guidelines according to parent/guardian reports were 1.70 and 2.05 times higher in those with medium and high (respectively) versus low recess provision. Accelerometer-measured weekday activity was highest in those with high recess provision while weekend activity was highest in those with low recess provision (Cohen's d = 0.40-0.45). There were no other significant associations. Conclusion: At least 30 minutes of daily recess is associated with two-fold greater odds of achieving recommended PA levels according to parent/guardian reports; accelerometer data suggest this is through increased weekday activity. This finding suggests current national recess recommendations are insufficient for PA promotion. More detailed data on the frequency and duration of recess are needed to quantify optimal provision more precisely.

Awareness of Alcohol and Cancer Risk and the California Proposition 65 Warning Sign Updates: A Natural Experiment.

In 1986, California enacted Proposition 65 (P65), requiring businesses to display warning signs informing consumers that specific chemicals and alcohol exposure increase the risk of cancer and reproductive harm. In 2018, the P65 alcohol warning signs were updated to include an informational P65 website link, and the update was associated with media coverage and increased enforcement of warning requirements. This study examines knowledge of the association between alcohol use and cancer risk in California compared to the rest of the US before and after the 2018 P65 update. We analyzed state-level data on alcohol and cancer knowledge from the Health Information National Trends Survey from 2017 (n = 3285), 2019 (n = 5438), and 2020 (n = 3865). We performed multinomial logistic regressions to examine knowledge levels by survey year and location (California vs. all other states) and reported the predicted marginals of knowledge by survey year and location. The adjusted prevalence of respondents who reported an association between alcohol and cancer risk was higher in California (41.6%) than the remaining states (34.1%) (p = 0.04). However, knowledge levels decreased significantly over survey years, and there was no evidence for an effect of the P65 update on knowledge in California compared to other states based on the testing of an interaction between state and year (p = 0.32). The 1986 warning signs may have had an enduring effect on awareness, though the update, so far, has not. Further efforts are needed to determine how to increase alcohol and cancer knowledge to address the burden of alcohol-attributable cancers.