Volume, patterns, and types of sedentary behavior and cardio-metabolic health in children and adolescents: a cross-sectional study

The association between device-measured sitting time and cardiometabolic health risk factors in children

BACKGROUND

There is limited evidence of the associations between postural-derived sitting time, waist-worn derived sedentary time and children's health and the moderation effect of physical activity (PA). This study examined associations of children's device-measured sitting time with cardiometabolic health risk factors, including moderation by physical activity.

METHODS

Cross-sectional baseline data from children (mean-age 8.2 ± 0.5 years) in Melbourne, Australia (2010) participating in the TransformUs program were used. Children simultaneously wore an activPAL to assess sitting time and an ActiGraph GT3X to assess sedentary time and physical activity intensity. Cardiometabolic health risk factors included: adiposity (body mass index [BMI], waist circumference [WC]), systolic and diastolic blood pressure (SBP, DBP), high-density lipoprotein (HDL), low-density lipoprotein (LDL), cholesterol, triglycerides, fasting plasma glucose (FPG), serum insulin, and 25-hydroxyvitaminD (25[OH]D). Linear regression models (n = 71-113) assessed associations between sitting time with each health risk factor, adjusted for different PA intensities (i.e. light [LIPA], moderate-vigorous intensities [MVPA], separately on each model), age, sex, adiposity, and clustering by school. Interaction terms examined moderation. The analyses were repeated using device-measured sedentary time (i.e. ActiGraph GT3X) for comparison.

RESULTS

Sitting time was positively associated with SBP (b = 0.015; 95%CI: 0.004, 0.026), DBP (b = 0.012; 95%CI:0.004, 0.020), and FPG (b = 0.001; 95%CI: 0.000, 0.000), after adjusting for higher PA intensities. The association between sitting time and insulin (b = 0.003; 95%CI: 0.000, 0.006) was attenuated after adjusting for higher PA intensities. When the models were adjusted for LIPA and MVPA, there was a negative association with LDL (b=-0.001; 95%CI: -0.002, -0.000 and b=-0.001; 95%CI: -0.003, -0.000, respectively). There was a negative association of sedentary time with WCz (b=-0.003; 95%CI: -0.005, 0.000) and BMIz (b=-0.003; 95%CI: -0.006, -0.000) when the models were adjusted by MVPA. Sedentary time was positively associated with triglycerides (b = 0.001; 95%CI: 0.000, 0.001) but attenuated after adjusting for MVPA. No evidence of moderation effects was found.

CONCLUSIONS

Higher volumes of sitting and sedentary time were associated with some adverse associations on some cardiometabolic health risk factors in children. These associations were more evident when sitting time was the predictor. This suggests that reducing time spent sitting may benefit some cardiometabolic health outcomes, but future experimental research is needed to confirm causal relationships and identify the biological mechanisms that might be involved.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry: ACTRN12609000715279.

Prolonged screen watching behavior is associated with high blood pressure among children and adolescents: a systematic review and dose-response meta-analysis

BACKGROUND

Numerous cardio-metabolic risk factors influence screen-related behaviors in children and adolescents. Numerous studies with inconsistent results revealed a relationship between blood pressure and screen time in the children and adolescents. This systematic review and meta-analysis summarized the data regarding the relationship between screen time and hypertension (HTN) in children and adolescents.

METHODS

We examined three electronic databases, including Scopus, PubMed, and Embase to find the recent research on the relationship between screen time and HTN up to 19 July 2022. Twenty papers were included in the final two-class and dose-response meta-analysis. We conducted subgrouping to identify the source of heterogeneity.

RESULTS

The highest category of screen time increased the odds of HTN by 8% [odds ratio (OR): 1.15; 95% confidence interval (CI): 1.08, 1.23; P < 0.001; I2 = 83.20%] and 1.9 mmHg increase in systolic blood pressure [weighted mean difference (WMD): 1.89; 95% CI: 0.18-3.62; P = 0.030; I2 = 83.4]. However, there was no significant difference in diastolic blood pressure. Moreover, screen time in hypertensive children and adolescents was 0.79 h (47.4 min) higher than normotensive subjects (WMD: 0.79; 95% CI: 0.02, 1.56; P = 0.046; I2 = 92.8). A departure from linearity was observed between increased screen time [digital video discs, personal computers, and video games and HTN (Pnonlinearity = 0.049).

CONCLUSION

This systematic meta-analysis review is the first to demonstrate a positive correlation between screen time and HTN in children and adolescents.

Sedentary Behavior and Lack of Physical Activity among Children in Indonesia

Sedentary behavior and lack of physical activity among children in Indonesia is an important issue that needs to be addressed. It is estimated that 57% of children in Indonesia have insufficient physical activity. Studies have shown that children who engage in sedentary behaviors are at an increased risk for various negative health outcomes, including obesity, type 2 diabetes, cardiovascular disease, and poor mental health, compared to physically active ones. This article aims to provide recommendations to increase physical activity and reduce passive behavior in children in Indonesia. This is a commentary article developed from observing the recent progress of sedentary behavior and lack of physical activity among children in Indonesia and the potential consequences. The level of inactive behavior in children in Indonesia is relatively high. Factors that contribute to sedentary behavior and lack of physical activity among children in Indonesia are the increasing use of electronic devices and screen time, the lack of safe and accessible places to be physically active, the COVID-19 pandemic, as well as cultural and social norms that prioritize academic achievement over physical activity. To address sedentary lifestyles among children, there is a need for a comprehensive approach that addresses both the individual and societal factors contributing to the problem. This might include increasing access to healthy food options, promoting physical activity, and implementing education programs to raise awareness about the importance of healthy eating and physical activity, as well as limiting screen time.

The influence of active video game play upon physical activity and screen-based activities in sedentary children

Background

Few children meet physical activity recommendations, partly due to the prevalence of screen-based sedentary activities. Active video game (AVG) play produces light to moderate physical activity. Yet, providing children access to AVG does not increase physical activity, possibly because children who play AVG may also tend towards sedentary screen-based activities. How multiple days of AVG play influences children’s choice of other activities is not yet known.

Purpose

To examine how AVG influences children’s physical activity, sedentary screen-based activities, and other alternative activities.

Methods

Sedentary children (N = 49) played AVG 3 times/week and sedentary video games (SVG) ad libitum for 6 weeks, followed by 4 weeks of ad libitum play of both AVG and SVG. Participants wore an activity monitor for 7 days and completed a 24-hour activity recall on 4 randomly selected days at baseline, week 6, and week 10.

Results

AVG play increased during the intervention (p < 0.01). Light activity and SVG play both decreased baseline to 10 weeks (p = 0.006) and 6 to 10 weeks (p = 0.017). Non-SVG sedentary behavior increased from baseline to 10 weeks (p = 0.005) and 6 to 10 weeks (p = 0.007). Changes over time were not observed in physical activity, or recall-measured active play, social activities, other hobbies, television or computer/phone use.

Conclusion

AVG play did not change children’s objectively-measured physical activity or subjectively measured active play. SVG time was substituted with other sedentary behaviors. AVG did not increase time engaged in SVG or screen-based devices.

Associations of physical activity, sedentary time, and diet quality with biomarkers of inflammation in children

We investigated the associations of physical activity (PA), sedentary time (ST), and diet quality with biomarkers of inflammation in 390 children (192 girls, 198 boys) aged 6-8 years. PA energy expenditure (PAEE), light PA, moderate PA (MPA), vigorous PA (VPA), moderate-to-vigorous PA (MVPA), and ST were assessed by combined movement and heart rate sensor. Finnish Children Healthy Eating Index was calculated using data from 4 d food records. Body fat percentage (BF%) was measured by dual-energy X-ray absorptiometry. High-sensitivity C-reactive protein (Hs-CRP), leptin, interleukin-6 (IL-6), adiponectin, tumour necrosis factor-α, and glycoprotein acetyls were measured from fasting blood samples. PAEE, MPA, VPA, and MVPA were inversely associated with hs-CRP (β=-191 to -139, 95% CI=-0.294 to -0.024), leptin (β=-0.409 to -0.301, 95% CI=-0.499 to -0.107), IL-6 (β=-0.136 to -0.104, 95% CI=-0.240 to -0.001) and PAEE, MPA, and MVPA were inversely associated with glycoprotein acetyls (β=-0.117 to -0.103, 95% CI=-0.213 to -0.001). ST was directly associated with hs-CRP (β=0.170, 95% CI=0.070-0.269), leptin (β=0.355, 95% CI=0.265-0.445), and IL-6 (β=0.105, 95% CI=0.005-0.205). VPA was inversely associated with hs-CRP, leptin, and IL-6 in children with higher BF% (β=-0.344 to -0.181, 95% CI=-0.477 to -0.033) but not among children with lower BF% (β=-0.007-0.033, 95% CI=-0.183-0.184). In conclusion, PA was inversely and ST directly associated with circulating levels of biomarkers of inflammation among children. Furthermore, we observed that PA was inversely associated with these biomarkers for inflammation in children with a higher BF%. HighlightsSystemic inflammation, as indicated by increased circulating concentrations of biomarkers for inflammation, may be important in causal pathways leading to insulin resistance, sub-clinical atherosclerosis, and eventually clinical manifestations of cardiovascular diseases.Higher levels of physical activity and lower levels of sedentary time were associated with more favourable inflammatory profile.Body fat percentage modified these associations and especially vigorous intensity physical activity was inversely associated with biomarkers of inflammation on children with higher body fat percentage but not in children with lower body fat percentage.

Consensus statement on Singapore integrated 24-hour activity guide for children and adolescents

INTRODUCTION

Lifestyle activities, such as regular physical activity, are important for good metabolic health and the prevention of non-communicable diseases. Epidemiological studies highlight an increase in the proportion of overweight children in Singapore. A workgroup was formed to develop recommendations to encourage children and adolescents (aged 7-17 years) to adopt a holistic approach towards integrating beneficial activities within a daily 24-hour period for good metabolic and general health.

METHODS

The Grading of Recommendations Assessment, Development and Evaluation (GRADE) Evidence to Decision framework was employed to formulate the public health question, assess the evidence and draw conclusions for the guide. The evidence for international 24-hour movement guidelines, and guidelines for physical activity, sedentary behaviour, and sleep and eating habits were reviewed. An update of the literature review from August 2018 to end of September 2020 was conducted through an electronic search of Medline and Cumulative Index to Nursing and Allied Health Literature (CINAHL) databases.

RESULTS

Ten consensus statements were developed. The statements focused on the overall aim of achieving good metabolic health through integration of these activities and initiatives: light and moderate- to vigorous-intensity physical activity on a regular basis; muscle- and bone-strengthening activities; limiting sedentary behaviour; regular and adequate sleep; good eating habits and choosing nutritionally balanced foods and drinks; practise safety in exercise; and aiming to achieve more or all aforementioned recommendations for the best results.

CONCLUSION

This set of recommendations provides guidance to encourage Singapore children and adolescents to adopt health-beneficial activities within a 24-hour period.

Investigating the influence of physical activity composition on arterial stiffness in youth

Physical activity is beneficial for arterial health in children but less is known about how all daily movement behaviours influence arterial stiffening. Compositional analysis can account for the co-dependent nature of these behaviours and therefore was employed to explore how the movement composition influences arterial health. Augmentation index (AIx) and pulse wave velocity were measured cross-sectionally in healthy children (n = 129; 12.4 ± 1.6 years). Time spent in sedentary, light physical activity (LPA), moderate-to-vigorous physical activity (MVPA) and asleep were derived from seven-day hip-worn accelerometry. The relative effects of individual behaviours and the overall movement composition on arterial stiffness were explored utilising compositional analysis, with predictive modelling used to predict effects of the substituting time between behaviours. Girls (n = 45, 12.1 ± 1.5yrs, 20.5 ± 3.6kg·m^-2) had a higher AIx (+ 3.94; p < 0.05) and accrued physical activity predominantly in LPA, whereas boys (n = 56, 12.6 ± 1.7yrs, 20.6 ± 4.0kg·m^-2) accrued physical activity predominantly in MVPA. Individual behaviours and the movement composition were not significant predictors of any measure of arterial stiffness (P > 0.05), and the reallocation of 20-minutes between behaviours did not elicit significant change in arterial stiffness, irrespective of sex (P > 0.05). The reallocation of time to MVPA from any other behaviour did not predict an improvement in arterial stiffness. This highlights the high potential dose of MVPA required to improve arterial health and the complex nature of the determinants of arterial stiffness. HighlightsMovement behaviours in isolation nor combination predicted arterial stiffness in youth.The reallocation of behaviours from any other behaviour to MVPA did not affect arterial stiffness in youth.Arterial stiffness is a complex, multidimensional health parameter that does not appear to be primarily determined by physical activity levels or intensity.

Asia-Pacific Consensus Statement on integrated 24-hour activity guidelines for children and adolescents

Non-communicable diseases (NCDs) constitute a significant public health challenge and pose a great burden on health and social systems throughout the world. The Asia-Pacific region is in a vulnerable position as the prevalence of NCDs will inevitably increase with rapid socioeconomic transitions; yet it is ill prepared for this public health challenge as Asian children are among the most physically inactive in the world. Aligned with the WHO's global strategy to control NCDs via preventive measures and health promotion policies, representatives from the Asia-Pacific region came together to develop consensus statement on integrated 24-hour activity guidelines for children and adolescents. These guidelines apply to children and adolescents, aged 5-18 years, in the Asia-Pacific region, regardless of gender, cultural background or socioeconomic status. These guidelines aim to provide the latest evidence-based recommendations, taking a holistic approach to lifestyle activities and adopting a practical perspective by framing these activities within a 24-hour period. Eating and dietary elements were incorporated as they closely influence the energy balance of the movement behaviours and vice versa. By investing in the younger generations through advocacy for healthier lifestyles, we aim to reduce the burden of NCDs in the Asia-Pacific region.

Changes in Families' Leisure, Educational/Work and Social Screen Time Behaviours before and during COVID-19 in Australia: Findings from the Our Life at Home Study

This study aimed to understand differences in leisure, educational/work and social screen time behaviours experienced by parents and children due to COVID-19 lockdown restrictions, which may inform behaviour change strategies and policy in the transition to a COVID-normal life. Participants in the "Our Life at Home" study (n = 218 parents from Australia, 43.4 ± 6.8 years, 88% female) completed a cross-sectional online survey in April/May 2020. Parents recalled their own and their child (8.7 ± 2.0 years, 42% female) or adolescents (15.0 ± 1.5 years, 50% female) participation in nine screen time behaviours in the past month (during lockdown) and retrospectively for February 2020 (pre-lockdown), providing data on 436 individuals. Screen time behaviours included leisure (computer/laptop and tablet/smartphone for leisure, TV/videos/DVDs and game consoles); education/work (computer/laptop and tablet/smartphone for work/education); and social screen time (computer/tablet/smartphone for social communication with friends, family and work (parents only)). Wilcoxon signed-rank tests and effect sizes (r) compared the time spent in each behaviour pre-lockdown and during lockdown. Large differences were observed in social (parents: r = 0.41-0.57; children: r = 0.55-0.65; adolescents: r = 0.28-0.43) and education (children: r = 0.50-0.65 and adolescents: r = 0.25-0.37) behaviours. There were small or no differences in leisure time screen use. COVID-19 lockdown restrictions have impacted parent's and children's screen time, and future research and policy should consider strategies to support families to manage screen time.

Media use trajectories and risk of metabolic syndrome in European children and adolescents: the IDEFICS/I.Family cohort

Background

Media use may influence metabolic syndrome (MetS) in children. Yet, longitudinal studies are scarce. This study aims to evaluate the longitudinal association of childhood digital media (DM) use trajectories with MetS and its components.

Methods

Children from Belgium, Cyprus, Estonia, Germany, Hungary, Italy, Spain and Sweden participating in the IDEFICS/I.Family cohort were examined at baseline (W1: 2007/2008) and then followed-up at two examination waves (W2: 2009/2010 and W3: 2013/2014). DM use (hours/day) was calculated as sum of television viewing, computer/game console and internet use. MetS z-score was calculated as sum of age- and sex-specific z-scores of four components: waist circumference, blood pressure, dyslipidemia (mean of triglycerides and HDL-cholesterol⁻¹) and homeostasis model assessment for insulin resistance (HOMA-IR). Unfavorable monitoring levels of MetS and its components were identified (cut-off: ≥ 90^th percentile of each score). Children aged 2–16 years with ≥ 2 observations (W1/W2; W1/W3; W2/W3; W1/W2/W3) were eligible for the analysis. A two-step procedure was conducted: first, individual age-dependent DM trajectories were calculated using linear mixed regressions based on random intercept (hours/day) and linear slopes (hours/day/year) and used as exposure measures in association with MetS at a second step. Trajectories were further dichotomized if children increased their DM duration over time above or below the mean.

Results

10,359 children and adolescents (20,075 total observations, 50.3% females, mean age = 7.9, SD = 2.7) were included. DM exposure increased as children grew older (from 2.2 h/day at 2 years to 4.2 h/day at 16 years). Estonian children showed the steepest DM increase; Spanish children the lowest. The prevalence of MetS at last follow-up was 5.5%. Increasing media use trajectories were positively associated with z-scores of MetS (slope: β = 0.54, 95%CI = 0.20–0.88; intercept: β = 0.07, 95%CI = 0.02–0.13), and its components after adjustment for puberty, diet and other confounders. Children with increasing DM trajectories above mean had a 30% higher risk of developing MetS (slope: OR = 1.30, 95%CI = 1.04–1.62). Boys developed steeper DM use trajectories and higher risk for MetS compared to girls.

Conclusions

Digital media use appears to be a risk factor for the development of MetS in children and adolescents. These results are of utmost importance for pediatricians and the development of health policies to prevent cardio-metabolic disorders later in life.

Trial registration

ISRCTN, ISRCTN62310987. Registered 23 February 2018- retrospectively registered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12966-021-01186-9.

Parental perception and guideline awareness of children's lifestyle behaviours at ages 5 to 14 in Singapore

INTRODUCTION

There are limited data on the descriptive lifestyle behaviour of school-age children in Singapore.

METHODS

A total of 100 parents of children ages 5 to 14 participated in a parents' proxy-reported survey. Frequency of moderate physical activity (PA) and vigorous PA was assessed, while t-tests or chi-square test was used to examine differences between weekdays and weekends for sleep, screen viewing time (SVT) and sedentary behaviour (SB).

RESULTS

Of the 100 children (68% of Chinese ethnicity, 59% boys, mean age 9.1±2.9 years), 31% were overweight or obese, with body mass index z-score of >1. For moderate and vigorous PA participation in a typical week, 32.0% and 43.0%, respectively, did not participate, while median (interquartile range) days of participation were 3 (2-3) days/week and 2 (1-3) days/week for a duration of 60 (interquartile range 30-120) minutes/session. When comparing weekends with weekdays, the means (standard deviation) of both SVT and sleep duration were higher on weekends (SVT: 4.1 [2.9] versus 3.3 [3.1] hours/day, P=0.07; sleep: 8.8 [1.5] vs 8.3 [1.3] hours/day, P=0.02), while there were no significant differences for SB. A higher proportion of children had SB of ≥10 hours/day and slept <8 hours/day on weekdays compared with on weekends (SB: 23.5% vs 20.6%, P>0.05; sleep:18.8% vs 2.1%, P<0.05), while the proportion exceeding SVT of 2 hours/day were higher on weekends than on weekdays (63.8% vs 45.4%, P=0.03). Overall, there was higher parental awareness of sleep guidelines (80.0%), but lower awareness of PA (51.0%) and SVT (59.0%) guidelines.

CONCLUSION

Lifestyle behaviours were suboptimal in Singapore children compared with existing overseas guidelines, indicating a need for an integrated guideline with greater dissemination.

Sedentary activity bout length was associated with BMI and waist circumference in Swedish children aged 5-7 years

AIM

This study examined the pattern of sedentary behaviour during the week and on weekends and associations with health outcomes among children aged 5-7 years in Sweden.

METHODS

This cross-sectional study used data from 342 children, many of whom had at least one parent born outside the Nordic region. Physical activity and sedentary time were measured by accelerometry. A sedentary bout was defined as 1-4 and 5-9 min. Diet, time in front of television or computer screen, sleep and physical activity behaviour were measured via parental reports, and anthropometric data by research staff.

RESULTS

The number of sedentary bouts was higher on weekends than on weekdays. Compared to girls, boys had more 1-4 min bouts on both weekdays and weekend days, and more 5-9 min bouts on weekends. A higher number of 5-9 min bouts was associated with a higher body mass index and waist circumference.

CONCLUSION

This study showed an association between sedentary activity and weight status in children as young as 5-7 years. Reducing time, especially longer bouts, spent in sedentary activities may encourage healthy weight development in children.

Relationship of Physical Activity and Sedentary Time with Metabolic Health in Children and Adolescents Measured by Accelerometer: A Narrative Review

The purpose of this study was to summarize the associations of physical activity (PA) and sedentary time (SED) with metabolic health and examine the effects of time reallocation on metabolic health in adolescents using accelerometer data. A literature search was conducted using PubMed, ScienceDirect, Web of Science, Cochran Library, and Google Scholar, and 27 articles were reviewed. Recent research generally confirms the associations of PA and SED with metabolic health. High PA levels and low SED levels had a positive relationship with metabolic health. Moreover, reallocating 10 min of daily SED to PA was associated with better metabolic health indicators. These results were stronger for moderate-to-vigorous physical activity than for light intensity PA. Thus, efforts to convert SED into PA of at least moderate intensity appear to be an effective strategy to prevent metabolic disease development in children and adolescents. However, some of the associations between PA and metabolic health indicators were inconsistent, depending on age, obesity degree, and PA intensity. Additionally, various accelerometer data collection and processing criteria impact the interpretation of the results. Therefore, consistent accelerometer data collection and analysis methods are needed in future studies. Further, intervention studies are required to verify the causality and effectiveness of the isotemporal substitution model.

The Association of Different Sedentary Patterns and Health-Related Physical Fitness in Pre-schoolers

Background: The results of sedentary time (ST) and health-related physical fitness (HPF) are not completely consistent and the studies concentrated on pre-schoolers are very limited. Methods: We measured ST and ST patterns (ST Bouts time, ST Breaks times) by accelerometer. The health-related physical fitness T-score (HPFT) was calculated by five indexes: height-weight standard score, 20 m shuttle-run test, grip strength, standing long jump and 2 × 10 m shuttle-run test. Results: We included 375 pre-schoolers (211 boys, 164 girls) in the final analysis. The total ST and ST Bouts times negatively correlated with HPFT in pre-schoolers. HPFT reduced by 1.69 and 0.70 points per 10 min increased in total ST and ST Bouts times, respectively. HPFT of the highest quartile group reduced by 9.85 points in total ST, and 10.54 points in ST Bouts time compared with the lowest quartile group. However, the HPFT increased by 0.09 points per 10 times increased in ST Breaks times; the HPFT increased by 16.21 and 15.59 points when moderate to vigorous physical activity (MVPA) replaced total ST and ST Bouts time. Conclusions: HPF negatively correlated with the Total ST and ST Bouts times, but positively correlated with ST Breaks times; and HPF significantly improved when MVPA replaced ST in pre-schoolers.

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.

Mediating role of disordered eating in the relationship between screen time and BMI in adolescents: longitudinal findings from the Research on Eating and Adolescent Lifestyles (REAL) study

OBJECTIVE

This study investigated whether the duration and type of screen time (ST) (TV viewing, recreational computer use, video gaming) is longitudinally associated with z-BMI and if these relationships are mediated by disordered eating (emotional, restrained).

DESIGN

At baseline, participants were n 1197 (T1; 60 % female) adolescents (mean age = 13·51 years) who completed surveys over 2 years. ST was assessed by a self-reported measure created by the investigative team, while emotional and restrained eating was measured by the Dutch Eating Behaviour Questionnaire (DEB-Q). Height and weight were objectively measured to quantify z-BMI.

SETTING

Thirty-one public and two private schools from the region of Ottawa, Canada.

PARTICIPANTS

Students in grades 7-12.

RESULTS

Parallel multiple mediation analyses revealed that more time spent watching TV at baseline is associated with higher z-BMI at T3 (total effect; B = 0·19, se = 0·07, P = 0·01, 95 % CI 0·05, 0·34), but no relationships were observed for total ST exposure or other types of ST and z-BMI. Disordered eating did not mediate the positive association between baseline TV viewing and z-BMI at T3.

CONCLUSIONS

TV viewing was longitudinally associated with higher z-BMI in a community-based sample of adolescents, but disordered eating behaviours did not mediate this relationship. However, other non-pathological eating behaviours may mediate the association between ST and obesity and warrant further investigation. Finding suggests that targeting reduction in youth's TV viewing may be an effective component in the prevention of childhood obesity.

Home-based screen time behaviors amongst youth and their parents: familial typologies and their modifiable correlates

Background

Excessive screen time behaviors performed by children and parents at home is a major public health concern. Identifying whether child and parent screen time behaviors cluster and understanding correlates of these familial clusters can help inform interventions for the whole family. This study characterized familial typologies of screen time behaviors and identified key modifiable correlates of these typologies.

Methods

Parents participating in the cross-sectional Sitting in the Home (SIT) study reported the duration (mins/day) they and their child (aged 11.2 ± 2.62 years) spent in six screen time behaviors at home (computer/laptop for home/work, computer/laptop for leisure, TV/videos/DVDs, tablet/smart phone for home/work, tablet/smart phone for leisure, and electronic games) and completed items related to 21 potential correlates framed by an adapted Social Cognitive Theory, Family Perspective. Latent Class Analysis was used to identify typologies based on parent and child data for the six behaviors. Multinomial logistic regression analysis assessed the relative risk of typology membership for each potential correlate, adjusting for child and parent age and sex.

Results

The sample comprised 542 parent-child dyads (parents: 40.7 ± 6.3 yrs., 94% female; children: 11.2 ± 2.6 yrs., 46% female). Three typologies were identified: 1) high computer/moderate TV (n = 197); 2) high TV/tablet/smartphone, low computer (n = 135); and 3) low-screen users (n = 210). ‘Low-screen users’ spent the least amount of time in all screen time behaviors (assigned as reference category). Greater child preference for screen time behaviors, parental support for screen time behaviors and frequency of homework requiring a tablet/laptop were associated with higher odds of being in the ‘high computer/moderate TV’ typology. The odds of being in the ‘high TV/tablet/smartphone, low computer’ typology were greater amongst children with a higher preference for screen time behaviors, and lower among more active parents.

Conclusions

Three familial typologies of screen time behaviors were identified. The findings highlight that screen time in the home can be influenced by the home environment, parental behaviours and role modelling, child preferences as well as school policies. Findings can inform the development of family screen time interventions, however more research exploring the influence of factors outside of the home is warranted.

Objectively measured sedentary behaviour in overweight and obese prepubertal children: challenging the school

Sedentary lifestyle is associated with unfavourable health outcomes; however, few studies have analysed the daily fluctuations of sedentary behaviour in children. The aim was to characterise sedentary behaviour in low active, overweight/obese prepubertal children and to examine whether there were daily, age- or gender-based differences. In this observational study free-living movement was measured by accelerometry for one week. Eighty-eight low active, overweight/obese children (8- to 12-year-olds) were included. Analysis was conducted for weekends, weekdays, school time and non-school time on weekdays. Participants spent half of their waking hours engaged in sedentary behaviour (48.1%). Short sedentary bouts (1-4 min) accounted for 86% of sedentary time. Sedentary time was similar on weekends and non-school time, while it was highest during school time. Interventions for the management of childhood obesity should include strategies for shifting sedentary time to physical activity on weekends and non-school time and implementing more activity-permissive classroom lessons.

Differences in adolescent activity and dietary behaviors across home, school, and other locations warrant location-specific intervention approaches

BACKGROUND

Investigation of physical activity and dietary behaviors across locations can inform "setting-specific" health behavior interventions and improve understanding of contextual vulnerabilities to poor health. This study examined how physical activity, sedentary time, and dietary behaviors differed across home, school, and other locations in young adolescents.

METHODS

Participants were adolescents aged 12-16 years from the Baltimore-Washington, DC and the Seattle areas from a larger cross-sectional study. Participants (n = 472) wore an accelerometer and Global Positioning Systems (GPS) tracker (Mean days = 5.12, SD = 1.62) to collect location-based physical activity and sedentary data. Participants (n = 789) completed 24-h dietary recalls to assess dietary behaviors and eating locations. Spatial analyses were performed to classify daily physical activity, sedentary time patterns, and dietary behaviors by location, categorized as home, school, and "other" locations.

RESULTS

Adolescents were least physically active at home (2.5 min/hour of wear time) and school (2.9 min/hour of wear time) compared to "other" locations (5.9 min/hour of wear time). Participants spent a slightly greater proportion of wear time in sedentary time when at school (41 min/hour of wear time) than at home (39 min/hour of wear time), and time in bouts lasting ≥30 min (10 min/hour of wear time) and mean sedentary bout duration (5 min) were highest at school. About 61% of daily energy intake occurred at home, 25% at school, and 14% at "other" locations. Proportionately to energy intake, daily added sugar intake (5 g/100 kcal), fruits and vegetables (0.16 servings/100 kcal), high calorie beverages (0.09 beverages/100 kcal), whole grains (0.04 servings/100 kcal), grams of fiber (0.65 g/100 kcal), and calories of fat (33 kcal/100 kcal) and saturated fat (12 kcal/100 kcal) consumed were nutritionally least favorable at "other" locations. Daily sweet and savory snacks consumed was highest at school (0.14 snacks/100 kcal).

CONCLUSIONS

Adolescents' health behaviors differed based on the location/environment they were in. Although dietary behaviors were generally more favorable in the home and school locations, physical activity was generally low and sedentary time was higher in these locations. Health behavior interventions that address the multiple locations in which adolescents spend time and use location-specific behavior change strategies should be explored to optimize health behaviors in each location.

Feasibility and applicability of Evenson sedentary behavior cut points applied to children with and without intellectual and developmental disabilities

AIM

Sedentary behavior (SB) is widely studied as it is associated with cardiometabolic health and obesity issues. However, children with Intellectual and Developmental Disabilities (IDD) have been understudied. Accelerometers are commonly used to measure SB in typically developing populations but may be inappropriate for IDD populations due to differences in body movement and physiologic responses to the activity. The use of Evenson sedentary cut-points, created based on typically developing children, has yet to be applied and/or examined in children with IDD.

PURPOSE

A descriptive cross-sectional study was conducted to (1) Assess the feasibility of applying Evenson sedentary cut-points in children with IDD (2) Describe SB over a two-week period between diagnosis groups.

METHODS

The SB of 22 participants (8 children with Down syndrome, 6 children with spina bifida, 8 children with no chronic illness) was assessed on two separate occasions: (1) during a 7-minute sedentary protocol, and (2) over a two-week period.

RESULTS

The study supports the preliminary efficacy of using Evenson cut-points for this population, with 100% of participants being within the Evenson counts per minute (0-100 cpm) during the 7-minute sedentary protocol. The total volume of SB over a two-week period was not significantly different between diagnosis groups (8.8 h, 8.6 h, and 7.1 h of SB for children with Down syndrome, spina bifida, or those with no chronic illness, respectively; p = 0.36).

CONCLUSIONS

Evenson sedentary cut-points can be used for children with IDD. Preliminary data suggest that children with IDD do not engage in significantly different SB than children without a chronic illness. Further study is warranted.Implications for rehabilitationObjective measures of physical activity and sedentary behavior for children with Down syndrome or spina bifida are rarely used due to potential differences in body movement (e.g., gait) during ambulation compared to typically developing peers that may influence the accuracy of cut-points.This study supports that Evenson sedentary cut-points can be used in children with Down syndrome or spina bifida to assess sedentary activity.Preliminary findings from this study demonstrate similarities in patterns of sedentary behaviors exhibited by our sample of children with Down syndrome, spina bifida, or no chronic illness.

Relationship between sleep duration and TV time with cardiometabolic risk in adolescents

Objective

To verify the association between sleep duration and television time with cardiometabolic risk and the moderating role of age, gender, and skin color/ethnicity in this relationship among adolescents.

Methods

Cross-sectional study with 1411 adolescents (800 girls) aged 10 to 17 years. Television time, sleep duration, age, gender, and skin color/ethnicity were obtained by self-reported questionnaire. Cardiometabolic risk was evaluated using the continuous metabolic risk score, by the sum of the standard z-score values for each risk factor: high-density lipoprotein cholesterol, triglycerides, glycemia, cardiorespiratory fitness, systolic blood pressure, and waist circumference. Generalized linear regression models were used.

Results

There was an association between television time and cardiometabolic risk (β, 0.002; 95% CI, 0.001; 0.003). Short sleep duration (β, 0.422; 95% CI, 0.012; 0.833) was positively associated with cardiometabolic risk. Additionally, age moderated the relationship between television time and cardiometabolic risk (β, − 0.009; 95% CI, − 0.002; − 0.001), suggesting that this relationship was stronger at ages 11 and 13 years (β, 0.004; 95% CI, 0.001; 0.006) compared to 13 to 15 years (β, 0.002; 95% CI, 0.001; 0.004). No association was found in older adolescents (β, 0.001; 95% CI, − 0.002; 0.002).

Conclusions

Television time and sleep duration are associated with cardiometabolic risk; adolescents with short sleep have higher cardiometabolic risk. In addition, age plays a moderating role in the relationship between TV time and cardiometabolic risk, indicating that in younger adolescents the relationship is stronger compared to older ones.

One size does not fit all: identifying clusters of physical activity, screen time, and sleep behaviour co-development from childhood to adolescence

Purpose

Canada was the first to adopt comprehensive 24-h movement guidelines that include recommendations for physical activity, screen time and sleep to promote health benefits. No studies have investigated the concurrent development of these behaviours in youth. The objectives were to assess adherence to the Canadian 24-h movement guidelines for children and youth and estimate co-development of self-reported moderate-to-vigorous intensity physical activity (MVPA), screen time and sleep during 8-years from childhood to adolescence.

Methods

Nine hundred and twenty three participants of the MATCH study self-reported their MVPA, screen time and sleep duration at least twice over 8 years. MVPA and screen time were measured three times per year (24 cycles), and sleep was measured once per year (8 cycles). Guideline adherence was dichotomised as meeting each specific health behaviour recommendation or not. Multi-group trajectory modeling was used to identify unique trajectories of behavioural co-development. Analyses were stratified by sex.

Results

Between 10 and 39% of youth did not meet any recommendation at the various cycles of data collection. More than half of youth met only one or two recommendation, and roughly 5% of participants met all three recommendations at one or more study cycle throughout the 8 years of follow-up. Four different trajectories of behavioural co-development were identified for boys and for girls. For boys and girls, a complier (good adherence to the guideline recommendations; 12% boys and 9% girls), a decliner (decreasing adherence to the guideline recommendations; 23% boys and 18% girls) and a non-complier group (low adherence to the guideline recommendations; 42% boys and 42% girls) were identified. In boys, a MVPA-complier group (high MVPA-low screen time; 23%) was identified, whereas in girls a screen-complier group (moderate screen time-low MVPA; 30%) was identified.

Conclusions

There is a need to recognise that variations from general trends of decreasing MVPA, increasing screen time and decreasing sleep exist. Specifically, we found that although it is uncommon for youth to adhere to the Canadian 24-h movement guidelines, some youth displayed a high likelihood of attaining one or multiple of the behavioural recommendations. Further, patterns of adherence to the guidelines can differ across different sub-groups of youth.

The Effects of Interrupting Sitting Time on Affect and State Anxiety in Children of Healthy Weight and Overweight: A Randomized Crossover Trial

PURPOSE

Sedentary time relates to higher anxiety and more negative affect in children. This study assessed whether interrupting sitting over 3 hours is sufficient to influence state anxiety, positive affect, or negative affect, and tested weight status as a moderator.

METHODS

Analyses were the second (preplanned) purpose of a larger study. Children (N = 61; age: mean [SD] = 9.5 [1.3]; 43% healthy weight) completed 2 experimental conditions: continuous sitting for 3 hours and sitting for 3 hours interrupted with walking for 3 minutes in every 30 minutes. State anxiety, positive affect, and negative affect were reported at pretest and posttest. Multilevel models for repeated measures assessed whether experimental condition predicted posttest scores.

RESULTS

Experimental condition was unrelated to posttest state anxiety or positive affect. Weight status moderated how experimental condition influenced posttest negative affect (P = .003). Negative affect was lower in the children of healthy weight after interrupted sitting (vs continuous sitting; β = -0.8; 95% confidence interval, -1.5 to 0.0, P = .05), but it was higher in the children with overweight/obesity after interrupted sitting (vs continuous sitting; β = 0.6; 95% confidence interval, 0.0 to 1.2, P = .06).

CONCLUSIONS

Interrupting sitting acutely reduced negative affect in children of healthy weight, but not in children with overweight. Further research is needed to better understand the potential emotional benefits of sitting interruptions in youth.

Tune out and turn in: the influence of television viewing and sleep on lipid profiles in children

BACKGROUND/OBJECTIVES

Physical activity is beneficial to lipid profiles; however, the association between sedentary behavior and sleep and pediatric dyslipidemia remains unclear. We aimed to investigate whether sedentary behavior or sleep predicted lipid profiles in children over a 2-year period.

SUBJECTS/METHODS

Six hundered and thirty children from the QUALITY cohort, with at least one obese parent, were assessed prospectively at ages 8-10 and 10-12 years. Measures of sedentary behavior included self-reported TV viewing and computer/video game use. Seven-day accelerometry was used to derive sedentary behavior and sleep duration. Adiposity was assessed using DEXA scans. Twenty-four-hour dietary recalls yielded estimates of carbohydrate and fat intake. Outcomes included fasting total cholesterol, triglycerides, HDL and LDL-cholesterol. Multivariable models were adjusted for adiposity and diet.

RESULTS

At both Visit 1 (median age 9.6 year) and Visit 2 (median age 11.6 year), children were of normal weight (55%), overweight (22%), or obese (22%). Every additional hour of TV viewing at Visit 1 was associated with a 7.0% triglyceride increase (95% CI: 3.5, 10.6; P < 0.01) and 2.6% HDL decrease (95% CI: -4.2, -0.9; P < 0.01) at Visit 2; findings remained significant after adjusting for adiposity and diet. Every additional hour of sleep at Visit 1 predicted a 4.8% LDL decrease (95% CI: -9.0, -0.5; P = 0.03) at Visit 2, after adjusting for fat intake; this association became nonsignificant once controlling for adiposity.

CONCLUSIONS

Longer screen time during childhood appears to deteriorate lipid profiles in early adolescence, even after accounting for other major lifestyle habits. There is preliminary evidence of a deleterious effect of shorter sleep duration, which should be considered in further studies.

Associations between accelerometry measured physical activity and sedentary time and the metabolic syndrome: A meta-analysis of more than 6000 children and adolescents

BACKGROUND

Metabolic syndrome is increasingly prevalent in the pediatric population. To prevent an early onset, knowledge about its association with modifiable lifestyle factors is needed.

OBJECTIVES

To estimate the prevalence of the metabolic syndrome and examine its cross-sectional associations with physical activity and sedentary time.

METHODS

Participants were 6009 children and adolescents from 8 studies of the International Children's Accelerometry Database. Physical activity and sedentary time were measured by accelerometer. Metabolic syndrome was defined based on International Diabetes Federation criteria. Logistic regression models adjusted for sex, age and monitor wear time were used to examine the associations between physical activity, sedentary time and the metabolic syndrome in each study and effect estimates were combined using random-effects meta-analysis.

RESULTS

The overall prevalence of the metabolic syndrome was 2.9%. In crude models, a 10 min increase in moderate-to-vigorous intensity physical activity and vigorous-intensity physical activity were inversely associated with the metabolic syndrome [OR 0.88, 95% CI 0.82-0.94, OR 0.80, 95% CI 0.70-0.92]. One hour increase in sedentary time was positively associated with the metabolic syndrome [OR 1.28, 95% CI 1.13-1.45]. After adjustment for sedentary time, the association between moderate-to-vigorous-intensity physical activity and the metabolic syndrome remained significant [OR 0.91, 95% CI 0.84-0.99]. Sedentary time was not associated with the metabolic syndrome after adjustment for moderate-to-vigorous intensity physical activity [OR 1.14 95% CI 0.96-1.36].

CONCLUSIONS

Physical activity of at least moderate intensity but not sedentary time is independently associated with the metabolic syndrome.

Substituting prolonged sedentary time and cardiovascular risk in children and youth: a meta-analysis within the International Children's Accelerometry database (ICAD)

BACKGROUND

Evidence on the association between sitting for extended periods (i.e. prolonged sedentary time (PST)) and cardio-metabolic health is inconsistent in children. We aimed to estimate the differences in cardio-metabolic health associated with substituting PST with non-prolonged sedentary time (non-PST), light (LIPA) or moderate-to-vigorous physical activity (MVPA) in children.

METHODS

Cross-sectional data from 14 studies (7 countries) in the International Children's Accelerometry Database (ICAD, 1998-2009) was included. Accelerometry in 19,502 participants aged 3-18 years, together with covariate and outcome data, was pooled and harmonized. Iso-temporal substitution in linear regression models provided beta coefficients (95%CI) for substitution of 1 h/day PST (sedentary time accumulated in bouts > 15 min) with non-PST, LIPA or MVPA, for each study, which were meta-analysed.

RESULTS

Modelling substitution of 1 h/day of PST with non-PST suggested reductions in standardized BMI, but estimates were > 7-fold greater for substitution with MVPA (- 0.44 (- 0.62; - 0.26) SD units). Only reallocation by MVPA was beneficial for waist circumference (- 3.07 (- 4.47; - 1.68) cm), systolic blood pressure (- 1.53 (- 2.42; - 0.65) mmHg) and clustered cardio-metabolic risk (- 0.18 (- 0.3; - 0.1) SD units). For HDL-cholesterol and diastolic blood pressure, substitution with LIPA was beneficial; however, substitution with MVPA showed 5-fold stronger effect estimates (HDL-cholesterol: 0.05 (0.01; 0.10) mmol/l); diastolic blood pressure: - 0.81 (- 1.38; - 0.24) mmHg).

CONCLUSIONS

Replacement of PST with MVPA may be the preferred scenario for behaviour change, given beneficial associations with a wide range of cardio-metabolic risk factors (including adiposity, HDL-cholesterol, blood pressure and clustered cardio-metabolic risk). Effect estimates are clinically relevant (e.g. an estimated reduction in waist circumference of ≈1.5 cm for 30 min/day replacement). Replacement with LIPA could be beneficial for some of these risk factors, however with substantially lower effect estimates.

Associations of accelerometer-measured sedentary time, sedentary bouts, and physical activity with adiposity and fitness in children

Sedentary time (ST) has been inconsistently associated with adiposity and cardiorespiratory fitness in children in previous studies. We studied cross-sectional associations of ST, light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA) with fat mass index (FMI) and cardiorespiratory fitness (estimated VO₂max). Associations were evaluated with and without considering pattern of ST by bout length. We measured ST and activity by a wrist-worn accelerometer, FMI by bioelectrical impedance, and VO₂max by Pacer test in 443 children (51.2% girls, 10.2 ± 0.6 years). Isotemporal substitution regression models estimated the effects of substituting ST, LPA, and MVPA on FMI and VO₂max. Further models repeated analyses separating ST into short (<10 min) and long (≥10 min) bouts. Only replacing ST or LPA with MVPA was consistently associated with lower FMI and greater VO₂max. When separated by bout length, only one unique association was found where replacing long ST bouts with short ST bouts was associated with lower FMI in girls only. In conclusion, activity pattern is associated with adiposity in girls and fitness in boys and girls. Separating ST into long and short ST bouts may be of minimal importance when assessing associations with adiposity and fitness using wrist-worn accelerometry in children.

Identifying characteristics of indicators of sedentary behavior using objective measurements

Objective

Recent attention has been focused on sedentary behavior (SB) affecting health outcomes, but the characteristics of indicators reflecting SB remain to be identified. This cross‐sectional study aims to identify the characteristics of indicators of SB, focusing on the examination of correlations, reliability, and validity of sedentary variables assessed by the smartphone app.

Method

Objectively measured data of SB of eligible 46 Japanese workers obtained from smartphones were used. We assessed the characteristics of current indicators being used with a 10‐minute or 30‐minute thresholds, in addition to the conventional indicators of total sedentary time, mean sedentary bout duration, and total number of sedentary bouts. They were evaluated from three perspectives: (a) association among the indicators, (b) reliability of the indicators, and (c) criterion validity.

Results

Total sedentary time under 10 minutes (U10) and U30 had negative associations with Total sedentary time (r = −.47 and −.21 respectively). The correlation between Mean sedentary bout duration and Total number of sedentary bouts was −.84, whereas between Mean sedentary bout duration 10, 30 and Total number of sedentary bouts were −.54 and −.21, respectively. The intraclass correlation coefficients of almost all indicators were around .80. Mean sedentary bout duration, Mean sedentary bout duration 10, Total number of sedentary bouts, Total sedentary time 30, U30 and U10 have significant differences between three BMI groups.

Conclusion

This study comprehensively revealed the rationale of advantage in the current indicator being used with a 10‐minute or 30‐minute threshold, rather than the conventional total amount of SB.

SEDENTARY BEHAVIOR AND CARDIOVASCULAR RISK IN CHILDREN: A SYSTEMATIC REVIEW

ABSTRACT In recognition of the increasing time spent in sedentary activities in modern life, an emerging area of study linking sedentary time to health has highlighted its role in the development of chronic diseases. Therefore, the objective of this systematic review was to investigate the indicators and characteristics of sedentary behavior associated with cardiovascular risk factors in children and adolescents. The databases SciVerse Scopus, MEDLINE®/PubMed and LILACS were selected as a source of reference, using the associated terms “sedentary lifestyle” or “sedentary behavior” or “sedentary” AND “cardiovascular diseases” AND “child or adolescent” to identify studies published from January 2006 to March 2019. The methodological quality of the studies was evaluated and a score was assigned. Fifty articles were included in this review at the end. Extensive sedentary time, especially greater screen and TV exposure time, were associated with cardiovascular risk factors. In addition, the accumulation of prolonged sedentary bouts with few breaks in sedentary time tended to compromise the cardiometabolic profile. These findings highlight the importance of differentiating and considering these various indicators and characteristics of sedentary behavior. Further studies are needed to elucidate the multiple and overlapping facets of sedentary behavior and their relationship with health, and to encourage the development of evidence-based recommendations for this population. Level of Evidence I; Systematic Review of Level I Studies.

Associations of Sitting Behavior Patterns With Cardiometabolic Risk in Children: The Sit Less for Health Cross-Sectional Study

BACKGROUND

The objective of this study was to investigate the associations between sedentary behavior patterns and cardiometabolic risk in children using a monitor that accurately distinguishes between different postures.

METHODS

In this cross-sectional study, 118 children (67 girls) aged 11-12 years had adiposity, blood pressure, lipids, and glucose measured, and then they wore an activPAL device to record sitting, standing, and stepping for 7 consecutive days. Data were analyzed using multiple linear regression.

RESULTS

After adjustment for potential confounders and moderate to vigorous physical activity, the number of breaks in sitting was significantly negatively associated with adiposity (standardized β ≥ -0.546; P ≤ .001) and significantly positively associated with high-density lipoprotein cholesterol (β = 0.415; P ≤ .01). Time in prolonged sitting bouts was significantly negatively associated with adiposity (β ≥ -0.577; P ≤ .001) and significantly positively associated with high-density lipoprotein cholesterol (β = 0.432; P ≤ .05). Standing time was significantly negatively associated with adiposity (β ≥ -0.270; P ≤ .05) and significantly positively associated with high-density lipoprotein cholesterol (β = 0.312; P ≤ .05).

CONCLUSIONS

This study suggests that increasing the number of breaks in sitting and increasing standing time are beneficially associated with cardiometabolic risk and should be considered in health promotion interventions in children.

Exploring when and how adolescents sit: cross-sectional analysis of activPAL-measured patterns of daily sitting time, bouts and breaks

BACKGROUND

This study describes patterns of adolescents' objectively-measured sitting volume, sitting bouts, and breaks in sitting during different days and periods of the day, and explored differences by sex and weekdays versus weekend days.

METHODS

ActivPAL™ data were collected in August 2014-December 2015 from adolescents attending secondary government schools in Melbourne Australia. Eight periods (early morning, mid-morning, morning break, late morning, lunch, early afternoon, late-afternoon and evening) were extracted for each day. School time, class time and out-of-school time were also extracted for weekdays. The percentage of time sitting, percentage of each hour in prolonged sitting (sitting bout ≥10 min), and number of sitting breaks/hour were calculated for each period. Differences by sex, and week and weekend days were determined using t-tests.

RESULTS

Participants (n = 297, 15.4 ± 1.6 years) spent 68% of their day sitting; ~ 30% of each hour in prolonged sitting and 3.1 sitting breaks/hour. Sitting time was greater during class time (75%) and school (70%) compared to out-of-school time (65%). Sitting patterns differed between week and weekend days for all periods except the evening period. Girls had higher proportion of sitting during class than boys (76% vs 72% respectively) and school hours (72% vs 67%), more prolonged sitting during school hours (27% vs 23%), and more sitting breaks per hour during out-of-school time (2.6 vs 2.4), but fewer during class (2.5 vs 3.3) and school hours (2.7 vs 3.3). Sitting patterns did not differ by sex on weekend days.

CONCLUSIONS

Adolescents spent two-thirds of their waking hours sitting, with distinct patterns on weekdays and weekend days. Even though boys and girls were exposed to the same school day routine, girls spent more time sitting and had fewer sitting breaks. Class times, school breaks and the evening period were identified as key intervention periods. Further research is needed to understand the behavioural differences, and guide future intervention design.

Metabolic Abnormalities in Normal Weight Children Are Associated with Increased Visceral Fat Accumulation, Elevated Plasma Endotoxin Levels and a Higher Monosaccharide Intake

Being overweight has been identified as the main risk factor for the development of metabolic disorders in adults and children. However, recent studies suggest that normal weight individuals are also frequently affected by metabolic abnormalities with underlying mechanisms not yet fully understood. The aim of the present study was to determine if dietary pattern and markers of intestinal permeability, as well as inflammation, differ between normal weight healthy children and normal weight children suffering from metabolic abnormalities. In total, 45 normal weight children aged 5–9 years were included in the study, of whom nine suffered from metabolic abnormalities. Anthropometric data, dietary intake and markers of inflammation, as well as intestinal permeability, were assessed in fasting blood samples. Neither BMI nor BMI-SDS differed between groups; however, children with metabolic abnormalities had a significantly larger waist circumference (+~5 cm) and a higher leptin to adiponectin ratio. While plasma leptin levels are significantly higher in normal weight children with metabolic abnormalities, neither TNF α nor sCD14, adiponectin, PAI-1 or IL-6 plasma levels differed between groups. Despite similar total calorie and macronutrient intake between groups, mean total fructose and total glucose intake (resulting mainly from sugar sweetened beverages, fruits and sweets) were higher in children with metabolic abnormalities than in healthy children. Time spent physically active was significantly higher in healthy normal weight children whereas time spent physically inactive was similar between groups. Furthermore, bacterial endotoxin levels were significantly higher in the peripheral plasma of normal weight children with metabolic abnormalities than in healthy normal weight children. Our results suggest that metabolic disorders in normal weight children are associated with a high monosaccharide intake and elevated bacterial endotoxin as well as leptin plasma levels, the latter also discussed as being indicative of visceral adiposity.

Reciprocal associations between screen time and emotional disorder symptoms during adolescence

Screen-based sedentary behaviors and emotional disorders are associated with one another in youth. Yet, the direction of the association is unclear, as is whether specific types of screen-based sedentary behaviors and emotional disorder symptoms are more closely linked. This study estimated the bi-directional associations between two types of screen-based sedentary behaviors and four types of self-reported emotional disorder symptoms, and tested whether physical activity buffered these associations in a Los Angeles high school student cohort (N = 2525, baseline Mage = 14.6 years). Participants completed baseline (9th Grade, 2013) and 12-month follow-up (10th grade, 2014) surveys reporting on: television viewing and computer/videogame use (≥4 h/day; yes/no), physical activity (≥60 min/day for ≥5 days/week), and Major Depressive Disorder (MDD), Generalized Anxiety Disorder (GAD), Panic Disorder (PD), and Social Phobia (SP) symptoms (meet/exceed [sub]clinical symptom threshold; yes/no). After adjusting for baseline screen-based sedentary behavior and covariates, students with (sub)clinical baseline MDD and GAD were at increased odds of high computer/videogame use one year later (OR = 1.36[95%CI, 1.07-1.73]; OR = 1.36[95%CI,1.09-1.71], respectively). Baseline SP was marginally related to increased computer/videogame use at follow-up (OR = 1.33[95%CI,1.04-1.69]). Greater baseline computer/videogame use was associated with increased odds of (sub)clinical GAD (OR = 1.54[95%CI,1.23-1.94]) and (sub)clinical SP (OR = 1.64[95%CI 1.27-2.12]) at follow-up; these associations were suppressed among baseline physically active students. Television viewing was unrelated to emotional disorder symptoms and PD was not associated with screen-based sedentary behaviors. Thus, only reciprocal associations between computer/videogame use, SP, and GAD during a one-year period of adolescence were observed. Interventions reducing computer/videogame use and increasing physical activity may improve adolescent emotional health.

Associations between self-reported physical activity and screen time with cardiometabolic risk factors in adolescents: Findings from the 1993 Pelotas (Brazil) Birth Cohort Study

The overall aim of this study was to examine the association of physical activity (PA) and screen time (ST) on indicators of cardio-metabolic risk during adolescence, by examining the combined association of PA and ST at ages 11, 15 and 18 on cardio-metabolic risk factors at 18 years. Data from the 1993 Pelotas (Brazil) Birth Cohort Study (N = 3613) were analysed in 2017. Self-reported PA and ST data were collected at 11, 15 and 18 years. Cardio-metabolic risk factors (fat mass index, waist circumference, triglycerides, blood glucose, non-HDL cholesterol and resting diastolic blood pressure) were examined at age 18. Multivariate linear regression was used to examine the associations between four mutually exclusive PA/ST groups: 1) active (≥1 h/day PA) and low ST (<5 h/day ST); 2) active (≥1 h/day PA) and high ST (≥5 h/day ST); 3) inactive (<1 h/day PA) and low ST (<5 h/day ST); 4) inactive (<1 h/day PA) and high ST (≥5 h/day ST) at each age, and outcomes at age 18. There were no significant associations between PA/ST at ages 11 and 15 with outcomes at 18 years. In the cross-sectional analyses, adolescents in the most active group had significantly better levels of all the outcomes, regardless of ST. Inactive participants with high ST had the highest levels of glucose and non-HDL-C. For diastolic blood pressure, values were higher among inactive participants. Overall, higher levels of physical activity appeared to be more important than low levels of ST for cardio-metabolic health in adolescents.

Association(s) Between Objectively Measured Sedentary Behavior Patterns and Obesity Among Brazilian Adolescents

PURPOSE

To investigate the association between patterns of sedentary behavior and obesity indicators among adolescents.

METHODS

This was a cross-sectional study conducted among 389 adolescents (186 boys) aged 10-14 years. Body mass index, body fat (skinfolds), and waist circumference were adopted as outcomes. Sedentary behavior patterns (total time, bouts, and breaks) measured through accelerometry (GT3X and GT3X+; ActiGraph, Pensacola, FL) were adopted as exposures. Peak height velocity, moderate to vigorous physical activity (accelerometer), cardiorespiratory fitness (Léger test), sex, and chronological age were adopted as covariates. Linear regression models adjusted for covariates were used to determine associations between outcome and exposure variables.

RESULTS

The mean age of adolescents was 11.8 (0.7) years. Boys were more active than girls (P < .001). Accumulating shorter bouts (1-4 min) of sedentary behavior was negatively associated with body mass index (β = -0.050; 95% confidence interval [CI], -0.098 to -0.003) and waist circumference (β = -0.133; 95% CI, -0.237 to -0.028). Similarly, a higher number of breaks in sedentary behavior were negatively associated with body mass index (β = -0.160; 95% CI, -0.319 to -0.001) and waist circumference (β = -0.412; 95% CI, -0.761 to -0.064).

CONCLUSION

Shorter bouts of sedentary behavior (1-4 min) and a higher number of breaks of sedentary behavior were associated with lower adiposity. Our findings also suggest that breaking up sedentary time to ensure bouts of sedentary behavior are short might contribute to the prevention of obesity in adolescents.

Establishing Raw Acceleration Thresholds to Classify Sedentary and Stationary Behaviour in Children

This study aimed to: (1) compare acceleration output between ActiGraph (AG) hip and wrist monitors and GENEActiv (GA) wrist monitors; (2) identify raw acceleration sedentary and stationary thresholds for the two brands and placements; and (3) validate the thresholds during a free-living period. Twenty-seven from 9- to 10-year-old children wore AG accelerometers on the right hip, dominant- and non-dominant wrists, GA accelerometers on both wrists, and an activPAL on the thigh, while completing seven sedentary and light-intensity physical activities, followed by 10 minutes of school recess. In a subsequent study, 21 children wore AG and GA wrist monitors and activPAL for two days of free-living. The main effects of activity and brand and a significant activity × brand × placement interaction were observed (all p < 0.0001). Output from the AG hip was lower than the AG wrist monitors (both p < 0.0001). Receiver operating characteristic (ROC) curves established AG sedentary thresholds of 32.6 mg for the hip, 55.6 mg and 48.1 mg for dominant and non-dominant wrists respectively. GA wrist thresholds were 56.5 mg (dominant) and 51.6 mg (non-dominant). Similar thresholds were observed for stationary behaviours. The AG non-dominant threshold came closest to achieving equivalency with activPAL during free-living.

Associations of Accumulated Time in Bouts of Sedentary Behavior and Moderate-to-Vigorous Physical Activity With Cardiometabolic Health in 10- to 13-Year-Old Boys

BACKGROUND

Little is known about the impact of sedentary and moderate-to-vigorous physical activity (MVPA) bouts on cardiometabolic health. The aim was to examine how the accumulation of bouts of sedentary time and MVPA associates to cardiometabolic health in children independently of total sedentary and MVPA time.

METHODS

In a cross-sectional study with 123 boys (10-13 y), sedentary and MVPA bouts were determined using 7-day accelerometry. Each bout was compared with cardiometabolic risk factors and with the risk score that was calculated using standardized values of body mass index, waist circumference, homeostasis model assessment for insulin resistance, triglycerides, and total cholesterol/high-density cholesterol ratio.

RESULTS

Time in 10- to 14-minute sedentary bouts was negatively associated with continuous cardiometabolic risk score in weekdays and weekend days and with triglycerides in a weekend (P < .05). Time accumulated in ≥30-minute sedentary bouts was associated with higher insulin and homeostasis model assessment for insulin resistance values in weekend (P < .05). Weekday total MVPA and time accumulated in ≥10-minute MVPA bouts were negatively associated with continuous cardiometabolic risk score and body mass index in weekdays (P < .05). No associations were found between total sedentary time and metabolic health.

CONCLUSION

Significant associations between sedentary and MVPA bouts with cardiometabolic risk factors suggest the need of the more detailed analysis for sedentary behavior and its effects on health risks.

Continuous cardiometabolic risk score definitions in early childhood: a scoping review

BACKGROUND

Cardiometabolic risk (CMR) in young children has been measured using various approaches, including a continuous summary score that incorporates components such as adiposity, lipids, metabolic factors and blood pressure.

OBJECTIVES

The objective of this study was to comprehensively review definitions of continuous CMR scores in children <10 years of age.

METHODS

A scoping review was conducted using a systematic search of four scientific databases up to June 2016. Inclusion criteria were children <10 years of age and report of a continuous CMR score.

RESULTS

Ninety-one articles were included. Most studies were published from 2007 to 2016 (96%). Nearly all continuous CMR scores (90%) were calculated using the sum or the mean of z-scores, and many articles age-standardized and sex-standardized components within their own population. The mean number of variables included in the risk scores was 5 with a range of 3-11. The most commonly included score components were waist circumference (52%), triglycerides (87%), high-density lipoprotein cholesterol (67%), glucose (43%) and systolic blood pressure (52%).

IMPORTANCE

Continuous CMR scores are emerging frequently in the child health literature and are calculated using numerous methods with diverse components. This heterogeneity limits comparability across studies. A harmonized definition of CMR in childhood is needed.

Indicators of Physical Activity Among Children and Youth in 9 Countries With Low to Medium Human Development Indices: A Global Matrix 3.0 Paper

BACKGROUND

This study compares results of physical activity report cards from 9 countries with low to medium human development indices, participating in the Global Matrix 3.0 initiative.

METHODS

Country-specific report cards were informed by relevant data and government policy documents, reporting on 10 core indicators of physical activity for children and youth. Data were synthesized by report card working groups following a harmonized process. Grade assignments for each indicator utilized a standard grading rubric. Indicators were grouped into one of 2 categories: daily behaviors and settings and sources of influence. Descriptive statistics (average grades) were computed after letter grades were converted into interval variables. Spearman's rank correlation coefficients were calculated for all correlation analyses.

RESULTS

Mean grades for daily behaviors were higher (C) than those for settings and sources of influence (D+). Twenty-nine out of the possible 90 grades were assigned an incomplete. There were moderate to strong positive and negative relationships between different global indices and overall physical activity, organized sport and physical activity, active play, family, community and environment, and government.

CONCLUSIONS

Findings demonstrate an urgent need for high-quality data at the country level in order to better characterize the physical activity levels of children and youth in countries with low to medium human development indices.

Movement behaviors and cardiometabolic risk in schoolchildren

Growing evidence has accumulated in recent years showing that movement behaviors have important implications for health in children, especially for cardiovascular health, whose risk factors could track from childhood to adulthood. However, these findings are mixed and inconsistent in children. The aim of this study was to examine the relationship between different movement behaviors (sedentary behavior, physical activity and sleep duration) and cardiometabolic risk in schoolchildren. The study shows cross-sectional results of baseline measurement from 146 Spanish schoolchildren, aged 8-to-11 years old, participating in the MOVI-2 study. Movement behaviors were determined using accelerometry combined with self-reported sleep time. Cardiometabolic risk was assessed using a validated metabolic syndrome index. Logistic regression analysis showed that higher levels of vigorous physical activity (OR = 0.110, p = 0.004) and sleeping more than 9 hours (OR = 0.269, p = 0.015) could be protective factors against metabolic syndrome risk in children. ANCOVA analysis showed associations between vigorous physical activity and waist circumference (p < 0.001), and sleep time with insulin resistance (p = 0.017) and lipid profile (p = 0.035). No association was observed between light and moderate physical activity, sedentary behavior and metabolic syndrome (index and components). No statistically significant differences were found for blood pressure and any of the movement behaviors. Our data suggest that both the amount of vigorous physical activity accumulated and sleep duration are independently associated with higher cardiometabolic risk in children.

Association between breaks in sitting time and adiposity in Australian toddlers: Results from the GET-UP! study

BACKGROUND

In youth, research on the health benefits of breaking up sitting time is inconsistent. Our aim was to explore the association between the number of breaks in sitting time and adiposity in Australian toddlers.

METHODS

This study comprised 266 toddlers (52% boys), aged 19.6 ± 4.2 months from the GET-UP! Study, Australia. Body mass index (BMI) was calculated and z-scores by age and sex were computed for waist circumference (WC). Participants were classified as overweight according to the WHO criteria for BMI. For WC, participants with a z-score≥1SD were considered overweight. Sitting time was assessed with activPALs during childcare hours and participants were classified by tertiles of the number of breaks/h in sitting time: <26 breaks/h; 26-39 breaks/h, and >39 breaks/h. Logistic regression assessed odds ratios for non-overweight (BMI or waist circumference categories) by number of breaks in sitting time/h, controlling for age, sex, and socioeconomic status.

RESULTS

The number of breaks in sitting time significantly predicted a lower weight status (non-overweight) according to WC values (P for trend = 0.032) after adjustments.

CONCLUSIONS

Breaking up sitting time was positively associated with toddlers' waist circumference. Future studies are needed to determine whether breaking up sitting time is a protective for cardiometabolic health in toddlers.

Longitudinal associations of physical activity and sedentary time with cardiometabolic risk factors in children

BACKGROUND

There are few prospective studies on the associations of changes in objectively measured vigorous physical activity (VPA_∆ ), moderate-to-vigorous physical activity (MVPA_∆ ), light physical activity (LPA_∆ ), and sedentary time (ST_∆ ) with changes in cardiometabolic risk factors (_∆ ) in children. We therefore investigated these relationships among children.

METHODS

The participants were a population sample of 258 children aged 6-8 years followed for 2 years. We assessed PA and ST by a combined heart rate and movement sensor; computed continuous age- and sex-adjusted z-scores for waist circumference, blood pressure, and fasting insulin, glucose, triglycerides, and high-density lipoprotein (HDL) cholesterol; and constructed a cardiometabolic risk score (CRS) of these risk factors. Data were analyzed using linear regression models adjusted for age, sex, the explanatory and outcome variables at baseline, and puberty.

RESULTS

VPA_∆ associated inversely with CRS_∆ (β = -0.209, P = 0.001), body fat percentage (BF%)_∆ (β = -0.244, P = 0.001), insulin_∆ (β = -0.220, P = 0.001), and triglycerides_∆ (β = -0.164, P = 0.012) and directly with HDL cholesterol_∆ (β = 0.159, P = 0.023). MVPA_∆ associated inversely with CRS_∆ (β = -0.178, P = 0.012), BF%_∆ (β = -0.298, P = <0.001), and insulin_∆ (β = -0.213, P = 0.006) and directly with HDL cholesterol_∆ (β = 0.184, P = 0.022). LPA_∆ only associated negatively with CRS_∆ (β = -0.163, P = 0.032). ST_∆ associated directly with CRS_∆ (β = 0.218, P = 0.003), BF%_∆ (β = 0.212, P = 0.016), and insulin_∆ (β = 0.159, P = 0.049).

CONCLUSIONS

Increased VPA and MVPA and decreased ST were associated with reduced overall cardiometabolic risk and major individual risk factors. Change in LPA had weaker associations with changes in these cardiometabolic risk factors. Our findings suggest that increasing at least moderate-intensity PA and decreasing ST decrease cardiometabolic risk in children.

Not all sedentary behaviour is equal: Children's adiposity and sedentary behaviour volumes, patterns and types

OBJECTIVE

The importance of different constructs of sedentary behaviours in relation to childhood obesity is uncertain. Thus, this study aimed to investigate relationships between volume, patterns and types of sedentary behaviour and adiposity in children.

METHODS

A case-control study was undertaken involving 234 children aged 10-13years who were either of a healthy-weight (74 boys, 56 girls) or classified as obese (56 boys, 48 girls). Percent body fat (by dual-energy X-ray absorptiometry) and waist-to-height ratio were assessed. Time, type (television, videogame, computer, eating, passive transport) and bout length of sedentary behaviours were measured using accelerometry and the Multimedia Activity Recall for Children and Adolescents. Time use (total daily energy expenditure, sleep, physical activity), age, household income and Tanner stage were covariates in sex-stratified partial least squares analyses.

RESULTS

Daily energy expenditure and income were negatively associated with adiposity for both sexes. Television time was consistently positively associated with adiposity. In boys only, prolonged bouts of sedentary behaviour and time spent playing video games/computer were positively linked with adiposity. Non-screen sedentary behaviour was negatively associated with adiposity in girls. Independent of total energy expenditure, total sedentary time was only inconsistently associated with fatness.

CONCLUSIONS

These data suggest that (1) characteristics of sedentary time other than duration are associated with adiposity in children, and (2) associations may be sex-specific.

Objectively Measured Sedentary Behavior, Physical Activity, and Cardiometabolic Risk in Hispanic Youth: Hispanic Community Health Study/Study of Latino Youth

Context

Time spent in moderate-to-vigorous physical activity (MVPA), but not in sedentary behavior (SB), is related to cardiometabolic risk among non-Hispanic white youth.

Objective

Examine associations of SB and MVPA with cardiometabolic risk factors among Hispanic/Latino youth.

Design

Cross-sectional analysis.

Setting

Four US communities.

Participants

Hispanic/Latino youth (N = 1,426) ages 8 to 16 years.

Measurements

Associations of MVPA and SB, measured using 7-day accelerometer data (independent variables), with markers of glucose and lipid metabolism, inflammation, and endothelial function (dependent variables), were assessed in multivariable linear regression models while adjusting for sociodemographic characteristics and accelerometer wear time. Additional models controlled for obesity measures.

Results

SB comprised a mean (SD) of 75% (13%) of accelerometer wear time; mean (SD) time of MVPA was 35 min/d (22 min/d). Deleterious levels of high-density lipoprotein-cholesterol (HDL-C), triglycerides, insulin resistance, C-reactive protein, and plasminogen activator inhibitor-1 were associated with lower levels of MVPA and higher levels of SB (all P < 0.05). Associations of MVPA with log-transformed triglyceride concentrations (β per 15-min/d increment, -0.039; SE, 0.018; P = 0.037) and SB with HDL-C (β per 30-min/d increment, -0.63; SE, 0.26; P = 0.018), but not those with other markers, remained significant after adjusting for MVPA or SB and further adjustment for body mass index and waist circumference. Higher SB tertiles were associated with lower soluble receptor for advanced glycation end products in fully adjusted models (P for trend = 0.037).

Conclusions

Physiological precursors of diabetes and cardiovascular disease were associated with MVPA and SB among US Hispanic/Latino youth, a group that bears a disproportionate burden of metabolic disorders.

Associations between activity patterns and cardio-metabolic risk factors in children and adolescents: A systematic review

INTRODUCTION

Total volumes of physical activity and sedentary behaviour have been associated with cardio-metabolic risk profiles; however, little research has examined whether patterns of activity (e.g., prolonged bouts, frequency of breaks in sitting) impact cardio-metabolic risk. The aim of this review was to synthesise the evidence concerning associations between activity patterns and cardio-metabolic risk factors in children and adolescents aged 5-19 years.

MATERIALS AND METHODS

A systematic search of seven databases was completed in October 2017. Included studies were required to report associations between objectively-measured activity patterns and cardio-metabolic risk factors in children and/or adolescents, and be published between 1980 and 2017. At least two researchers independently screened each study, extracted data, and undertook risk of bias assessments.

RESULTS

From the 15,947 articles identified, 29 were included in this review. Twenty-four studies were observational (cross-sectional and/or longitudinal); five were experimental. Ten studies examined physical activity patterns, whilst 19 studies examined sedentary patterns. Only one study examined both physical activity and sedentary time patterns. Considerable variation in definitions of activity patterns made it impossible to identify which activity patterns were most beneficial to children's and adolescents' cardio-metabolic health. However, potential insights and current research gaps were identified.

DISCUSSION AND CONCLUSION

A consensus on how to define activity patterns is needed in order to determine which activity patterns are associated with children's and adolescents' cardio-metabolic risk. This will inform future research on the impact of activity patterns on children's and adolescents' short- and longer-term health.

Learning "Math on the Move": Effectiveness of a Combined Numeracy and Physical Activity Program for Primary School Children

BACKGROUND

Physically active learning that combines physical activity with core curriculum areas is emerging in school-based health interventions. This study investigates the effectiveness of learning an important numeracy skill of times tables (TT) while concurrently engaging in aerobic activity compared with a seated classroom approach.

METHODS

Grade-4 primary school students were randomly allocated to physical activity (P) or classroom (C) groups and received the alternate condition in the following term. P group received moderate to vigorous exercise (20 min, 3 times per week, 6 wk) while simultaneously learning selected TT. C group received similar learning, but seated. Changes in TT accuracy, general numeracy, aerobic fitness, and body mass index were assessed. Data were expressed as mean (SEM) and between-condition effect size (ES; 95% confidence interval).

RESULTS

Participants [N = 85; 55% male, 9.8 (0.3) y, 36.4% overweight/obese] improved similarly on TT in both conditions [C group: 2.2% (1.1%); P group: 2.5% (1.3%); ES = 0.03; -0.30 to 0.36; P = .86]. Improvement in general numeracy was significantly greater for P group than C group [C group: 0.7% (1.2%); P group: 5.3% (1.4%); ES = 0.42; 0.08 to 0.75; P < .03]. An improvement in aerobic fitness for P group (P < .01) was not significantly greater than C group [C group: 0.8 (0.6); P group: 2.2 (0.5) mL·kg·min^-1; ES = 0.32; -0.01 to 0.66; P = .06]. Body mass index was unchanged.

CONCLUSION

Combined movement with learning TT was effective. Physically active learning paradigms may contribute to meeting daily physical activity guidelines while supporting or even boosting learning.

A comparison of 10 accelerometer non-wear time criteria and logbooks in children

BACKGROUND

There are many unresolved issues regarding data reduction algorithms for accelerometry. The choice of criterion for removal of non-wear time might have a profound influence on physical activity (PA) and sedentary time (SED) estimates. The aim of the present study was to compare 10 different non-wear criteria and a log of non-wear periods in 11-year-old children.

METHODS

Children from the Active Smarter Kids study performed 7-days of hip-worn accelerometer monitoring (Actigraph GT3X+) and logged the number of non-wear periods each day, along with the approximate duration and reason for non-wear. Accelerometers were analyzed using 10 different non-wear criteria: ≥ 10, 20, 30, 45, 60, and 90 min of consecutive zero counts without allowance for interruptions, and ≥60 and 90 min with allowance for 1 and 2 min of interruptions.

RESULTS

891 children provided 5203 measurement days, and reported 1232 non-wear periods ranging from 0 to 3 periods per day: on most days children reported no non-wear periods (77.1% of days). The maximum number of non-wear periods per day was 2 for the 90-min criterion, 3 to 5 for most criteria, 7 for the 20-min criterion, and 20 for the 10-min criterion. The non-wear criteria influenced overall PA (mean values across all criteria: 591 to 649 cpm; 10% difference) and SED time (461 to 539 min/day; 17% difference) estimates, especially for the most prolonged SED bouts. Estimates were similar for time spent in intensity-specific (light, moderate, vigorous, and moderate-to-vigorous) PA, but varied 6-9% among the non-wear criteria for proportions of time spent in intensity-specific PA (% of total wear time).

CONCLUSIONS

Population level estimates of PA and SED differed between different accelerometer non-wear criteria, meaning that non-wear time algorithms should be standardized across studies to reduce confusion and improve comparability of children's PA level. Based on the numbers and reasons for non-wear periods, we suggest a 45 or 60-min consecutive zero count-criterion not allowing any interruptions to be applied in future pediatric studies, at least for children older than 10 years.

TRIAL REGISTRATION

The study is registered in Clinicaltrials.gov with identification number NCT02132494 . Registered 7 April 2014.

The Effect of the Presence of an Internet-Connected Mobile Tablet Computer on Physical Activity Behavior in Children

BACKGROUND

Mobile Internet-connected electronic devices provide access to activities that have traditionally been associated with sedentary behavior. Because they are portable, these devices can be utilized in any environment. Therefore, providing children with access to these devices in environments that typically promote physical activity may result in a reduction in physical activity behavior.

PURPOSE

To assess children's physical and sedentary (ie, sitting) activity with and without the presence of a mobile Internet-connected tablet computer.

METHODS

A total of 20 children [6.7 (1.9) y old] participated in 2 simulated recess conditions in a gymnasium on separate days. During each condition, children had free-choice access physical activity options and a table of sedentary activities for 40 minutes. During 1 session, the iPad was present, and in the other session, it was not. Physical activity was monitored via an accelerometer, and sedentary time was monitored via a stopwatch.

RESULTS

Children significantly (P ≤ .03) reduced average physical activity intensity and increased their sedentary behavior with the iPad present [4.4 (4.0) metabolic equivalents/min and 20.9 (12.4) min sitting] versus the condition without the iPad present [5.3 (4.0) metabolic equivalents/min and 13.6 (13.2) min sitting].

CONCLUSION

Introducing an mobile Internet-connected tablet computer into a gymnasium reduced children's physical activity intensity by 17% and increased sedentary behavior by 54%.