Temporal patterns of physical activity and sedentary behavior in 10-14 year-old children on weekdays

Change in general and domain-specific physical activity during the transition from primary to secondary education: a systematic review

BACKGROUND

Knowledge of changes in the domains of physical activity (PA) during the transition period from primary to secondary education and the factors associated with these changes, are prerequisites for the design of effective PA promotion strategies. Therefore, the first aim of this study was to systematically review changes in general, leisure-time, school, transport, work, and home PA across the transition from primary to secondary education. The second aim was to systematically review the individual, social, and physical environmental factors that were associated with these changes.

METHODS

Records published up until September 2023 were retrieved from five electronic databases. We included longitudinal and cross-sectional studies that investigated general or domain-specific PA from 2 years before to 2 years after the transition from primary to secondary education. Information on source, study characteristics, sample characteristics, PA, and factors were extracted from the papers included. We reported the direction of change in general and domain-specific PA and the direction of association of the factors with change in general and domain-specific PA.

RESULTS

Forty-eight papers were included in the study. The evidence on changes in PA and associated factors was greatest for general PA. A limited number of the studies investigated the separate domains of leisure-time, school, and transport. Most studies on general and school PA reported a decline in PA, but there were no consistent results for the domains of leisure-time and transport. With respect to the associated factors, evidence was predominantly found for individual factors and to a lesser degree for physical environmental and social environmental factors. None of the factors were consistently associated with changes in general or domain-specific PA during the school transition.

CONCLUSIONS

For the design of targeted PA promotion strategies, further studies are warranted to explore changes in the specific domains of PA across the transition from primary to secondary education, especially in the domains of leisure-time, transport, home, and work PA. In addition, the interactions between factors at different socioecological levels to influence changes in PA need to be addressed more in the future.

TRIAL REGISTRATION

PROSPERO CRD42020190204.

Do girls wash dishes and boys play sports? Gender inequalities in physical activity and in the use of screen-based devices among schoolchildren from urban and rural areas in Brazil

OBJECTIVE

The aim of the study was to analyze gender inequalities in types of physical activity (PA) and in the use of screen-based devices among schoolchildren from both urban and rural areas in Brazil.

METHODS

Data from two population-based surveys conducted in 2019 (urban areas: n = 2,479; 52.6% girls; age = 9.2 ± 1.51 years) and 2022 (rural areas: n = 979; 42.6% girls; age = 9.4 ± 1.52 years) were used. PA (active play, nonactive play, home chores, and structured physical activities) and the use of screen-based devices (TV, cellphone, videogame, and computer) were self-reported in a previous-day-recall online questionnaire (Web-CAAFE). Absolute gender inequalities were evaluated and presented as equiplots. Relative gender inequalities were evaluated by the prevalence ratio (PR) and respective 95% confidence intervals (95% CI), which were estimated by Poisson regression, with adjustments for age and BMI z scores.

RESULTS

Girls from urban and rural areas presented a lower prevalence of active play and a higher prevalence of home chores. The prevalence of nonactive play among girls from urban areas was also lower; however, their prevalence of structured physical activities was higher, especially among girls aged seven to nine years. Girls in both urban and rural areas presented a higher prevalence of TV viewing and lower use of video games.

CONCLUSION

The gender inequalities observed in the types of physical activities and in the use of screen-based devices could be considered potential correlates of the likelihood of girls' and boys' compliance with the physical activity guidelines.

Temporal Patterns of Diet and Physical Activity and of Diet Alone Have More Numerous Relationships With Health and Disease Status Indicators Compared to Temporal Patterns of Physical Activity Alone

BACKGROUND

Daily temporal patterns of energy intake (temporal dietary patterns [TDPs]) and physical activity (temporal physical activity patterns [TPAPs]) have been independently and jointly (temporal dietary and physical activity patterns [TDPAPs]) associated with health and disease status indicators.

OBJECTIVE

The aim of this study was to compare the number and strength of association between clusters of daily TDPs, TPAPs, and TDPAPs and multiple health and disease status indicators.

DESIGN

This cross-sectional study used 1 reliable weekday dietary recall and 1 random weekday of accelerometer data to partition to create clusters of participants representing the 3 temporal patterns. Four clusters were created via kernel-k means clustering algorithm of the same constrained dynamic time warping distance computed over the time series for each temporal pattern.

PARTICIPANTS/SETTING

From the National Health and Nutrition Examination Survey (2003-2006), 1,836 US adults aged 20 through 65 years who were not pregnant and had valid diet, physical activity, sociodemographic, anthropometric, questionnaire, and health and disease status indicator data were included.

MAIN OUTCOME MEASURES

Health status indicators used as outcome measures were body mass index, waist circumference, fasting plasma glucose, hemoglobin A1c, triglycerides, high-density lipoprotein cholesterol, total cholesterol, and systolic and diastolic blood pressure; disease status indicators included obesity, type 2 diabetes mellitus, and metabolic syndrome.

STATISTICAL ANALYSES PERFORMED

Multivariate regression models determined associations between the clusters representing each pattern and health and disease status indicators, controlling for confounders and adjusting for multiple comparisons. The number of significant differences among clusters and adjusted R2 and Akaike information criterion compared the strength of associations between clusters of patterns and continuous and categorical health and disease status indicators.

RESULTS

TDPAPs showed 21 significant associations with health and disease status indicators, including body mass index, waist circumference, obesity, and type 2 diabetes; TDPs showed 19 significant associations; and TPAPs showed 8 significant associations.

CONCLUSIONS

TDPAPs and TDPs had stronger and more numerous associations with health and disease status indicators compared with TPAPs. Patterns representing the integration of daily dietary habits hold promise for early detection of obesity.

Cluster Analysis to Find Temporal Physical Activity Patterns Among US Adults

Physical activity (PA) is known to be a risk factor for obesity and chronic diseases such as diabetes and metabolic syndrome. Few attempts have been made to pattern the time of physical activity while incorporating intensity and duration in order to determine the relationship of this multi-faceted behavior with health. In this paper, we explore a distance-based approach for clustering daily physical activity time series to estimate temporal physical activity patterns among U.S. adults (ages 20-65) from the National Health and Nutrition Examination Survey 2003-2006 (NHANES). A number of distance measures and distance-based clustering methods were investigated and compared using various metrics. These metrics include the Silhouette and the Dunn Index (internal criteria), and the associations of the clusters with health status indicators (external criteria). Our experiments indicate that using a distance-based cluster analysis approach to estimate temporal physical activity patterns through the day, has the potential to describe the complexity of behavior rather than characterizing physical activity patterns solely by sums or labels of maximum activity levels.

How do previously inactive individuals restructure their time to ‘fit in’ morning or evening exercise: a randomized controlled trial

The objective of this study was to investigate changes in sedentary and active behaviors when previously inactive adults start exercising in the morning or evening. One-hundred adults with overweight or obesity (BMI ≥ 25 kg/m2) were recruited for a 12-week intervention and randomized to one of three groups: (i) morning exercise (AMEx; 0600–0900); (ii) evening exercise (PMEx; 1600–1900); or (iii) waitlist control. AMEx and PMEx were prescribed self-paced aerobic exercise to achieve a weekly total of 250 min via a combination of supervised and unsupervised training. Sedentary and active behavior times were measured at baseline, mid- and post-intervention using the multimedia activity recall for children and adults. Time spent engaging in physical activity was significantly increased from baseline at both mid- (+ 14–22 min·day−1) and post-intervention (+ 12–19 min·day−1), for AMEx and PMEx. At 12-weeks, participants in both morning and evening exercise groups reported increased time spent Sleeping (+ 36 and + 20 min·day−1, respecitively), and reduced time spent watching TV/playing videogames (− 32 and − 25 min·day−1, respectively). In response to an exercise stimulus, previously inactive adults make encouraging modifications in how they use their time, and the patterns of change are similar with morning and evening exercise.

Catch me if you can! How French adolescents seize social occasions and opportunities to be active

BACKGROUND

Following an ecological framework, the aim of this study was to highlight the way adolescents invested their time in opportunities to engage in moderate to vigorous physical activity (MVPA) according to whether they were profiled as more or less active. This study's innovation lies in the analysis of MVPA according to social occasions which are understood as opportunities to be active throughout the day (e.g. home, school, transport).

METHODS

PA data measured by accelerometry (ActiGraph GT3X) for seven consecutive days were compiled, with adolescents' social occasions during the week recorded in a daily digital diary (n = 135). The opportunity ratio of MVPA at each social time is the ratio between time spent in MVPA and the duration of a corresponding social occasion. Following the literature, participants were categorised into three profiles according to their reported amount of MVPA: HEPA active, minimally active and inactive. Non-parametric Wilcoxon signed rank and Kruskal Wallis tests were performed to determine the relative intensity of PA performed at different social occasions, and to investigate whether intensities differed between adolescents with various activity profiles.

RESULTS

Results showed that engagement in MVPA at different social occasions differed according to participant profiles. Mismatch was noticed between the opportunity ratio and the duration of the most and least favorable social occasions for MVPA. For all three profiles, the social occasion "physical education lesson" revealed an opportunity ratio of MVPA (23.6% vs 17.0% vs 13.8%) significantly higher than the overall opportunity ratio of the week (6.9% vs 2.9% vs 1.2%), but of lower duration. Conversely, "home" (5.3% vs 0.0% vs 0.0%) and "school" (outside of PE time) (2.4% vs 0.0% vs 0.0%) represented the two least opportune social occasions for PA in an adolescent's week.

CONCLUSIONS

Rethinking engagement with MVPA in the context of temporal opportunities would allow potential ways to intervene within an educational supervised setting to help young people adopt a physically active lifestyle at the end of the key period of adolescence. These results reinforced the importance of context in interventions for PA promotion, opening for "time education" in people.

Using Wearable Cameras to Categorize the Type and Context of Screen-Based Behaviors Among Adolescents: Observational Study

BACKGROUND

Automated wearable cameras present a new opportunity to accurately assess human behavior. However, this technology is seldom used in the study of adolescent's screen exposure, and the field is reliant on poor-quality self-report data.

OBJECTIVE

This study aimed to examine adolescents' screen exposure by categorizing the type and context of behaviors using automated wearable cameras.

METHODS

Adolescents (mean age 15.4 years, SD 1.6 years; n=10) wore a camera for 3 school evenings and 1 weekend day. The camera captured an image every 10 seconds. Fieldwork was completed between February and March 2020, and data were analyzed in August 2020. Images were date and time stamped, and coded for screen type, content, and context.

RESULTS

Data representing 71,396 images were analyzed. Overall, 74.0% (52,842/71,396) of images contained screens and 16.8% (11,976/71,396) of images contained multiple screens. Most screen exposures involved television sets (25,950/71,396, 36.3%), smartphones (20,851/71,396, 29.2%), and laptop computers (15,309/71,396, 21.4%). The context of screen use differed by device type, although most screen exposures occurred at home (62,455/64,856, 96.3%) and with solitary engagement (54,430/64,856, 83.9%). The immediate after-school period saw high laptop computer use (4785/15,950, 30.0%), while smartphone use (2059/5320, 38.7%) peaked during prebedtime hours. Weekend screen exposure was high, with smartphone use (1070/1927, 55.5%) peaking in the early morning period and fluctuating throughout the day.

CONCLUSIONS

There was evidence for high screen use during the after-school and weekend period, mostly through solitary engagement, and within the home environment. The findings may inform the basis of larger studies aimed at examining screen exposure in free-living conditions.

A 3-year longitudinal study of the association of physical activity and sedentary behaviours with childhood obesity in China: The childhood obesity study in China mega-cities

OBJECTIVES

Examine school children's physical activity (PA) and sedentary behaviours (SB) during 2015 to 2017 in China, and study their associations with children's weight status and relevant gender differences.

METHODS

This open cohort study included students from five major cities (Beijing, Shanghai, Xi'an, Nanjing, and Chengdu) across China. Data were collected from students in 2015, 2016, and 2017 (n = 5535) and from their parents and school personnel. Children's weight, height, and waist circumference were measured. SB and PA factors were evaluated using questionnaires. Mixed-effects models examined the relationship between weight status and PA-/SB-associated factors using this longitudinal data.

RESULTS

These children had high rates of obesity (12.4%, 95% CI 11.6%-13.3%) and central obesity (28.1%, 95% CI 26.9%-29.3%) during 2015 to 2017. Boys were more likely to have obesity than girls (16.5% vs 8.4%, respectively) as well as centrally obesity (36.3% vs 19.8%, respectively) and spent more time in screen viewing than girls (hours/week ± SD: 2015, 1.8 ± 2.5 vs 1.5 ± 2.0; 2016, 2.0 ± 2.4 vs 1.8 ± 2.5; 2017, 1.7 ± 2.3 vs 1.4 ± 2.1 hours/week). Those who walked <5 minutes on their average daily walk to school were more likely to have obesity (OR: 1.96, 95% CI 1.03-3.73) than those who spent ≥15 minutes on walking to school. When stratified by gender, this higher risk was only observed in girls (OR: 3.01, 95% CI 1.09-8.35). Children who spent more time in screen viewing were more likely to have obesity (OR: 1.13, 95% CI 1.06-1.21) and have central obesity (OR: 1.05, 95% CI 1.02-1.09). The association for obesity was consistent in boys and girls (boys, OR: 1.15, 95% CI 1.05-1.25; girls, OR: 1.12, 95% CI 1.00-1.24).

CONCLUSIONS

More screen time and less walking time were risk factors for developing obesity in urban Chinese children. The associations varied by gender.

Association between Tobacco Consumption and Problematic Internet Use and the Practice of Physical Activity in Spanish Adolescents

The practice of physical activity (PA) is a healthy habit that offers health benefits. In contrast, the lack thereof may be associated with an increase in diseases, even at an early age. The objective of this study was to analyze the association between unhealthy behaviors, such as tobacco consumption and problematic internet use, and the practice of PA in adolescents. Protective factors (physical activity and sport) and risk factors (leading a sedentary life, tobacco use, and problematic internet use) were evaluated. Other variables such as sex, the intensity of physical activity, and being a member of a sports federation were also evaluated. The sample consisted of a total of 1222 Spanish adolescents. Univariate descriptive analysis and multiple linear regression were used, and confirmatory factor analyses and structural models were also estimated. The results confirm a significant positive association between physical activity, intensity, and being a member of a sports federation, as well as between cigarette consumption and internet use. It is advisable to implement public policies that promote the practice of sports as a direct investment in health, preventing the consumption of tobacco and other habits that are harmful to the health of adolescents.

Acute after-school screen time in children decreases impulse control and activation toward high-calorie food stimuli in brain regions related to reward and attention

The purpose of this study was to examine the effects of after-school sedentary screen time on children's brain activation in reward and cognitive control regions in response to pictures of high- and low-calorie foods. Thirty-two children participated in a randomized crossover study with counterbalanced treatment conditions. Conditions took place on separate days after school and included three hours of active or sedentary play. After each condition, neural activation was assessed using functional magnetic resonance imaging (fMRI) while participants completed a go/no-go task involving pictures of high- and low-calorie foods. General response inhibition was also measured using the Stroop task. Hunger was measured upon arrival to the testing facility and just prior to fMRI scans. Mixed effects models were used to evaluate main effects and interactions. Significant stimulus by condition interactions were found in the right superior parietal cortex, and left anterior cingulate cortex (Ps ≤ 0.05). High-calorie pictures elicited significantly more activation bilaterally in the orbitofrontal cortex compared to low-calorie pictures (Ps ≤ 0.05). Stroop task performance diminished significantly following the sedentary condition compared to the active (P ≤ 0.05). Subjective feelings of hunger were not different between conditions at any point. Sedentary screen time was associated with significantly decreased response inhibition and a reversed brain activation pattern to pictures of high- and low-calorie foods compared to active play, in areas of the brain important to the modulation of food intake. Decreased attention, and impulse control following sedentary screen time may contribute to disinhibited eating that can lead to overweight and obesity.

Patterning of physical activity and sedentary behavior at and away from school in preadolescent children

Background

Understanding how and where children accumulate their physical activity (PA) and sedentary minutes throughout the day has important implications for behavioral interventions.

Purpose

The purpose of this study was to examine the duration and intensity of habitual PA and sedentary time (SED) at and away from school among preadolescent children.

Methods

Data from twenty-one children ages 7-11 (57% girls; 57% non-white; 24% overweight/obese) were included in this analysis. Proportion of time spent in PA, SED, and SED bouts were examined on school days (in-school and out-of-school) and non-school days via accelerometry.

Results

When comparing school time with non-school time on school days, children accumulated a higher proportion of light PA while in-school [49.3% (i.e. 5 minutes 18 seconds) vs. 39.6% (i.e. 3 hours 53 minutes), p=0.01]. While at school, the proportion of time spent in SED was less [46.3% (i.e. 3 hours 7 minutes) vs. 56.3% (i.e. 5 hours 32 minutes), p=0.01] and fewer children spent time engaged in prolonged sitting compared to out-of-school [uninterrupted SED for 30 minutes 52.4% (i.e. 11 children) vs. 85.7% (i.e. 18 children), p=0.02].

Discussion

These findings suggest children are proportionately most active and least sedentary when at school, yet children only accumulated approximately 18 minutes of moderate-to-vigorous PA in this environment.

Translation to Health Education Practice

These preliminary findings can help to inform physical activity programming designed to promote life-long physical activity behaviors in children.

Investigating longitudinal context-specific physical activity patterns in transition from primary to secondary school using accelerometers, GPS, and GIS

INTRODUCTION

Previous longitudinal studies indicate that physical activity (PA) significantly declines from primary-to secondary school, and report both changes in individual and environmental determinants of PA. In order to understand this transition and to prevent this negative trend, it is important to gather contextually rich data on possible mechanisms that drive this decline. Therefore, the aim of this study was to investigate changes of PA patterns in transition between primary and secondary school, and to add domain-specific insights of how, where, and when these changes occur.

METHODS

In total, 175 children participated in a 7-day accelerometer- and Global Positioning System (GPS) protocol at their last year of primary and their first year of secondary school. GPS data-points were overlaid with Geographical Information Systems (GIS) data using ArcGIS 10.1 software. Based on the GPS locations of individual data-points, we identified child's PA at home, school, local sports grounds, shopping centers, and other locations. Also, trips in active and passive transport were identified according to previously validated GPS speed-algorithms. Longitudinal multi-level linear mixed models were fitted adjusting for age, gender, meteorological circumstances, and the nested structure of days within children and children within schools. Outcome measures were minutes spent in light PA and moderate-to-vigorous PA, specified for the time-segments before school, during school, after school and weekend days.

RESULTS

Total PA significantly declined from primary to secondary school. Although transport-related PA increased before- and during school, decreases were found for especially afterschool time spent at sports grounds and transport-related PA during weekends.

CONCLUSIONS

This is the first study that demonstrated longitudinal changes of context- and domain-specific PA patterns in transition between primary and secondary school, based on device-assessed PA. Given the importance of this transition-period for the development of long-term PA patterns, results from this study warrant the development of evidence-based PA programs in this transition period, while acknowledging the integrative role of schools, parents, and afterschool sports providers. More specifically, the results underline the need to increase children's PA levels in primary schools, promote afterschool PA at secondary schools, and to prevent the drop-out in sports participation at secondary schools.

Feasibility and effect of a Pilates program on the clinical, physical and sleep parameters of adolescents with anorexia nervosa

BACKGROUND AND PURPOSE

Anorexia nervosa (AN) becomes chronic, with high physical, psychological and social morbidity and high mortality without early and effective treatment. The impact of physical exercise as a coadjutant to conventional treatment in this clinical population has been studied with favorable results. Although a Pilates program could be beneficial for patients with AN, no study has analyzed its feasibility and effects in adolescents with AN. Therefore, this study evaluated the safety of a Pilates program and investigated the feasibility and effect in adolescents with AN.

MATERIALS AND METHODS

In this prospective quasi-experimental study, body composition, blood analysis, sedentary time, physical activity and time of sleep, and physical fitness were measured objectively before and after a 10-week Pilates supervised program.

RESULTS

Twelve female adolescents with AN (14.6 ± 1.7 years old) completed the program, with a session attendance rate of 96%, a persistence rate of 100%. There were significant increases in height, plasma calcium and sleep efficiency. Significant decreases in plasma follitropin, sleep duration and, duration and number of night perturbations were observed.

CONCLUSION

A Pilates program is safe and feasible in adolescents with AN when they have a controlled and stable weight, and such a program could be a viable alternative among treatment programs to achieve better sleep quality.

Critical Hours and Important Environments: Relationships between Afterschool Physical Activity and the Physical Environment Using GPS, GIS and Accelerometers in 10-12-Year-Old Children

Introduction: The objective of this study was to assess relationships between children’s physical environment and afterschool leisure time physical activity (PA) and active transport. Methods: Children aged 10–12 years participated in a 7-day accelerometer and Global Positioning Systems (GPS) protocol. Afterschool leisure time PA and active transport were identified based on location- and speed-algorithms based on accelerometer, GPS and Geospatial Information Systems (GIS) data. We operationalized children’s exposure to the environment by combining home, school and the daily transport environment in individualized daily activity-spaces. Results: In total, 255 children from 20 Dutch primary schools from suburban areas provided valid data. This study showed that greenspaces and smaller distances from the children’s home to school were associated with afterschool leisure time PA and walking. Greater distances between home and school, as well as pedestrian infrastructure were associated with increased cycling. Conclusion: We demonstrated associations between environments and afterschool PA within several behavioral contexts. Future studies are encouraged to target specific behavioral domains and to develop natural experiments based on interactions between several types of the environment, child characteristics and potential socio-cognitive processes.

The Role of School in Helping Children and Adolescents Reach the Physical Activity Recommendations: The UP&DOWN Study

BACKGROUND

The aims were to: (1) examine the levels of physical activity (PA) during different time periods (ie, daily PA, school hour PA, recess PA, physical education classes [PEC] PA) in children and adolescents; and (2) identify the rate of compliance with the specific PA recommendations for these time periods.

METHODS

The participants were 1925 (940 girls) children and adolescents from 40 Spanish schools. Hip-worn accelerometers were used to assess PA during different time periods.

RESULTS

Boys and children were more physically active and had a greater percentage meeting the daily PA recommendation and the school-based PA recommendation than girls and adolescents, respectively. Compliance with daily PA recommendation was markedly higher than that with the school-based PA recommendation, regardless of sex and age groups (ie, 80.4% vs 24.1% for daily and school-based PA recommendations, respectively, in child boys). A very low percentage (ie, 9.7% and 1.2% of child boys with almost 50% of moderate-to-vigorous PA during recess and PEC, respectively) of students reached the recommended PA levels for recess and PEC.

CONCLUSIONS

Physical activity levels during school hours, recess, and PEC in children and adolescents are very low. Promoting PA in school settings is essential, especially in girls and adolescents.

Changes in objectively measured physical activity after a multidisciplinary lifestyle intervention in children with abdominal obesity: a randomized control trial

BACKGROUND

Physical activity (PA) is associated with changes in body composition that affect insulin sensitivity and leptin levels. Few studies have assessed the effect of lifestyle interventions on changes in objectively measured PA levels in obese children. To evaluate the effects of a multidisciplinary lifestyle intervention on anthropometric indices, biochemical parameters and accelerometer measured PA in abdominal obese children.

METHODS

A randomized control trial was performed in 106 children and adolescents with abdominal obesity. Participants were randomly assigned to usual or intensive care group for 8-week. PA was measured by accelerometry over four days including, at least, two weekdays in all participants. Both groups were encouraged to accumulate an extra time of 200 min per week in their PA.

RESULTS

At baseline, 75% of subjects do not fulfill the WHO recommendation of being more than 60 min/day on moderate-to-vigorous PA (MVPA). The intensive care group achieved a significant reduction in anthropometric indexes compared to the usual care but no significant change was found in biochemical or PA parameters. Both groups achieved a significant reduction in light PA. Interestingly, intensive care participants significantly increased MVPA in 5.5 min/day. Moreover, an inverse association between changes in MVPA and leptin levels was found.

CONCLUSION

The two lifestyle intervention reduced anthropometric indexes and lowered light PA in abdominal obese children. No significant differences were observed between intensive care and usual care in regard to PA. Intensive care participants significantly increase physical activity (MVPA) and, changes in MVPA were inversely associated with changes in leptin levels after the intervention.

TRIAL REGISTRATION

ClinicalTrials.gov , Identifier: NCT03147261 . Registered 10 May 2017. Retrospectively registered.

Imputing accelerometer nonwear time in children influences estimates of sedentary time and its associations with cardiometabolic risk

Background

A limitation of measuring sedentary time with an accelerometer is device removal. The resulting nonwear time is typically deleted from the data prior to calculating sedentary time. This could impact estimates of sedentary time and its associations with health indicators. We evaluated whether using multiple imputation to replace nonwear accelerometer epochs influences such estimates in children.

Methods

452 children (50% male) aged 10–13 were tasked with wearing an accelerometer (15 s epochs) for 7 days. On average, 8% of waking time was classified as nonwear time. Sedentary time was derived from a “nonimputed” dataset using the typical approach of deleting epochs that occurred during nonwear time, as well as from an “imputed” dataset. In the imputed dataset, each nonwear epoch was re-classified as being as sedentary or not using multiple imputation (5 iterations) which was informed by the likelihood of a wear time epoch being classified as sedentary or not using parameter estimates from a logistic regression model. Estimates of sedentary time and associations between sedentary time and health indicators (cardiometabolic risk factor and internalizing mental health symptoms Z-scores) were compared between the nonimputed and imputed datasets.

Results

On average, sedentary time was 33 min/day higher in the imputed dataset than in the nonimputed dataset (632 vs. 599 min/day). The association between sedentary time and the cardiometabolic risk factor Z-score was stronger in the imputed vs. the nonimputed dataset (β = 0.137 vs. β = 0.092 per 60 min/day change, respectively). These findings were more pronounced among children who had < 7 days with ≥10 h of wear time.

Conclusion

Researchers should consider using multiple imputation to address accelerometer nonwear time, rather than deleting it, in order to derive more unbiased estimates of sedentary time and its associations with health indicators.

Dietary intake and lifestyle behaviors of children in Mauritius

The purpose of the study was to explore the dietary intake, fruit, vegetable and energy intake and lifestyle behaviors among Mauritian children. A validated questionnaire was used, assessing dietary intake, mean energy intake, mean body mass index (BMI), lifestyle behaviors as well as nutritional knowledge (NK) among males and females. 336 children aged 6–12 years (165 males and 171 females) from 8 public primary schools were recruited. Statistical analyses revealed that children consumed less nutritious foods such as fruits, vegetables and whole grains and more of refined and calorie-laden foods, with no significant differences across genders. Mean energy intake of children was 1522 ± 282.4 kcal per day while mean BMI was 17.5 ± 4.03 kg/m². Majority of children had a low-to-moderate physical activity level (PAL), with males being more active than females on average (P = 0.021). 88.7% of children watched TV for more than an hour daily, with 84.8% of them reporting to be eating during the process. Females were more likely to be breakfast skippers (P = 0.003). Maximum frequency of snacking was twice daily (72.7%) while consumption of fast food was once or twice weekly (44.0%). Results indicate the need for intervention with aim of improving the dietary and life quality of children in Mauritius.

Novel patterns of physical activity in a large sample of preschool-aged children

Background

Moderate-to-vigorous physical activity (MVPA), shown to be associated with health benefits, is not well-characterized in preschool-aged children. MVPA is commonly described as a threshold amount to achieve. We examined a novel way to characterize MVPA patterns in preschool-aged children by gender and age.

Methods

Preschool-aged children from Nashville, TN and Minneapolis, MN wore triaxial accelerometers. Four distinct MVPA patterns were identified: isolated spurt (IS), isolated sustained activity (ISA), clustered spurt (CS), and clustered sustained activity (CSA). Multivariable linear regression models were used to test associations of gender and age with each pattern.

Results

One thousand one hundred thirty-one children (3.9 years old, 51% girls, 30% overweight, 11% obese, and 76% Hispanic) wore accelerometers for 12.9 (SD = 1.4) hours/day for 6.7 (SD = 0.7) days. Children spent 53% of wear time in sedentary behavior and 13% in MVPA. On average, boys and girls achieved > 90 min/day of MVPA (98.2 min, SD = 32.3). Most MVPA (80%) was obtained in spurt-like (IS and CS) MVPA; however, girls spent a higher proportion of MVPA in IS and CS, and lower proportion of time in CSA (all p < 0.001). Controlling for gender, an increase of 1-year in age corresponded to a 1.5% increase in CSA (p < 0.05).

Conclusions

How MVPA was obtained varied depending on the gender and age of the child. On average, boys spent more time in sustained MVPA than girls and MVPA was more sustained in older children. Utilizing these patterns could inform PA practice and policy guidelines.

Trial registration

NCT01316653, date of registration: March 3, 2011; NCT01606891, date of registration: May 23, 2012.

Substituting Sedentary Time With Light and Moderate to Vigorous Physical Activity is Associated With Better Cardiometabolic Health

BACKGROUND

The purpose of the current study was to apply a more novel approach to systematically examine (1) associations of clustered cardiometabolic risk and cardiometabolic risk factors and (2) theoretical substitution of sedentary time with either sleep, light physical activity (LPA), or moderate to vigorous physical activity (MVPA) and substituting LPA with MVPA.

METHODS

Physical activity and sleep were objectively measured in 410 Flemish adults [55.5 (9.6) y, 64% men] with a SenseWear Pro 3 Armband. Cardiometabolic risk factors (obesity, hyperglycemia, dyslipidemia, and hypertension) and cardiorespiratory fitness were objectively measured. Isotemporal substitution analyses were performed to assess the associations between substituting time from a potentially negative behavior into another potentially positive behavior.

RESULTS

Theoretical substitution of sedentary time with MVPA was associated with decreased clustered cardiometabolic risk, b = -0.06 (-0.08 to -0.04), and substituting LPA with MVPA was associated with a decrease in clustered cardiometabolic risk, b = -0.08 (-0.11 to -0.04). Substituting sedentary time with LPA or sleep improved high-density lipoprotein-cholesterol, systolic and diastolic blood pressures, and waist circumference.

CONCLUSION

Theoretical replacement of sedentary time with either sleep, LPA, or MVPA was positively associated with improved cardiometabolic risk factor status. Interventions for increasing cardiometabolic health can focus on replacing sedentary time with either sleep, LPA, or MVPA depending on the risk parameters that need to be targeted.

Using functional data analysis to understand daily activity levels and patterns in primary school-aged children: Cross-sectional analysis of a UK-wide study

Background

Temporal characterisation of physical activity in children is required for effective strategies to increase physical activity (PA). Evidence regarding determinants of physical activity in childhood and their time-dependent patterns remain inconclusive. We used functional data analysis (FDA) to model temporal profiles of daily activity, measured objectively using accelerometers, to identify diurnal and seasonal PA patterns in a nationally representative sample of primary school-aged UK children. We hypothesised that PA levels would be lower in girls than boys at play times and after school, higher in children participating in social forms of exercise (such as sport or play), and lower among those not walking to school.

Methods

Children participating in the UK-wide Millennium Cohort Study wore an Actigraph GT1M accelerometer for seven consecutive days during waking hours. We modelled 6,497 daily PA profiles from singleton children (3,176 boys; mean age: 7.5 years) by means of splines, and used functional analysis of variance to examine the cross-sectional relation of time and place of measurement, demographic and behavioural characteristics to smoothed PA profiles.

Results

Diurnal and time-specific patterns of activity showed significant variation by sex, ethnicity, UK country and season of measurement; girls were markedly less active than boys during school break times than boys, and children of Indian ethnicity were significantly less active during school hours (9:30–12:00). Social activities such as sport clubs, playing with friends were associated with higher level of PA in afternoon (15:00–17:30) and early evenings (17:30–19:30). Lower PA levels between 8:30–9:30 and 17:30–19:30 were associated with mode of travel to and from school, and number of cars in regular use in the household.

Conclusion

Diminished PA in primary school aged children is temporally patterned and related to modifiable behavioural factors. FDA can be used to inform and evaluate public health policies to promote childhood PA.

Imputing Accelerometer Nonwear Time When Assessing Moderate to Vigorous Physical Activity in Children

BACKGROUND

A limitation of accelerometer measures of moderate to vigorous physical activity (MVPA) is nonwear time. Nonwear-time data is typically deleted prior to estimating MVPA. In this study, we used an approach that used sociodemographic, health, and time data to guide the imputation of nonwear-time data. We determined whether imputing nonwear-time data influences estimates of MVPA and the association between MVPA, body mass index, and blood pressure.

METHODS

Seven days of accelerometer data were collected on 332 children aged 10-13 years. MVPA was estimated in a "nonimputed dataset," wherein nonwear-time data were deleted prior to estimating MVPA, and in an "imputed dataset," wherein nonwear-time data were imputed using sociodemographic and health characteristics of participants and time characteristics of the nonwear period prior to estimating MVPA.

RESULTS

Nonwear time represented 7% of waking hours. Average MVPA estimates did not differ in the nonimputed and imputed datasets (56.8 vs 58.4 min/d). The strength of the relationship between MVPA and the 2 health outcomes did not differ in the nonimputed and imputed datasets.

CONCLUSIONS

Studies achieving high accelerometer wear-time compliance can obtain MVPA estimates without substantial bias if they use the traditional approach of deleting nonwear-time data.

Changes in Physical Activity in the School, Afterschool, and Evening Periods During the Transition From Elementary to Middle School

BACKGROUND

We examined longitudinal changes in children's physical activity during the school day, afterschool, and evening across fifth, sixth, and seventh grades.

METHODS

The analytical sample included children who had valid accelerometer data in fifth grade and at least one other time-point, and provided complete sociodemographic information (N = 768, 751, and 612 for the 3 time-periods studied). Accelerometer-derived total physical activity (TPA) and moderate-to-vigorous physical activity (MVPA) were expressed in minutes per hour for the school day (∼7:45 am to 3:30 pm), afterschool (∼2:25 to 6:00 pm), and evening (6:00 to 10:00 pm) periods. We used growth curve analyses to examine changes in TPA and MVPA.

RESULTS

School day TPA and MVPA declined significantly; we observed a greater decrease from fifth to sixth grades than from sixth to seventh grades. Afterschool TPA declined significantly, but MVPA increased significantly among girls and remained stable for boys. Evening TPA decreased significantly and MVPA declined significantly in girls and remained stable among boys.

CONCLUSIONS

To inform the development of effective intervention strategies, research should focus on examining factors associated with the decline in physical activity during the transition from elementary to middle school, particularly during the hours when children are in school.

Parental Expectations and Child Screen and Academic Sedentary Behaviors in China

INTRODUCTION

This study examined sociodemographic patterns of parental expectations for academic performance, terminal degree, and future occupation for middle school students in China, and how these expectations influence students' screen-based and academic-related sedentary behaviors through parenting control practices.

METHODS

Based on data collected in 2013-2014 from 19,487 Chinese middle school students, bivariate logistic regressions tested associations between sociodemographic variables and parental expectations; structural equation models tested associations between parental expectations and students' self-reported daily time on TV/Internet/homework, with parental controls as potential mediators. Analyses were performed in October 2015.

RESULTS

Chinese students spent 0.96 (SD=1.44) hours/day on TV, 0.56 (SD=1.20) on Internet use, and 2.79 (SD=2.07) on homework. Girls spent more hours/day on homework (2.98 [SD=2.07] vs 2.62 [SD=2.04]) than boys but less on TV (0.90 [SD=1.37] vs 1.02 [SD=1.50]) and Internet (0.42 [SD=0.98] vs 0.69 [SD=1.36]). More than 30% of students were expected by parents to reach the top five of their class, almost 90% were expected to earn a college degree or higher, and >80% were expected to have a professional occupation. Students in rural areas, with siblings, and with lower parental SES tended to bear lower parental expectations. Children experiencing higher parental expectations spent more time on homework but less time on TV/Internet, partially explained by stricter parental homework and screen control.

CONCLUSIONS

High parental expectations suppress screen use but promote academic-related sedentary behaviors for Chinese children. Interventions should attend to academic-related sedentary behaviors and call for broader policies addressing sociocultural factors fueling high parental expectations.