The association between accelerometer-measured patterns of sedentary time and health risk in children and youth: results from the Canadian Health Measures Survey

Patterns of objectively measured sedentary time in 10- to 12-year-old Belgian children: an observational study within the ENERGY-project

BACKGROUND

This study examined the frequency of and differences in sedentary bouts of different durations and the total time spent in sedentary bouts on a weekday, a weekend day, during school hours, during after-school hours and in the evening period in a sample of 10- to 12-year-old Belgian children.

METHODS

Accelerometer data were collected as part of the ENERGY-project in Belgium (n = 577, 10.9 ± 0.7 years, 53% girls) in 2011. Differences in total sedentary time, sedentary bouts of 2-5, 5-10, 10-20, 20-30 and ≥30 min and total time accumulated in those bouts were examined on a weekday, a weekend day, during school hours, during after-school hours and in the evening period, using multilevel analyses in MLwiN 2.22.

RESULTS

More than 60% of the participants' waking time was spent sedentary. Children typically engaged in short sedentary bouts of 2-5 and 5-10 min, which contributed almost 50% towards their total daily sedentary time. Although the differences were very small, children engaged in significantly fewer sedentary bouts of nearly all durations during after-school hours compared to during school hours and in the evening period. Children also engaged in significantly fewer sedentary bouts of 5-10, 10-20, and 20-30 min per hour on a weekend day than on a weekday.

CONCLUSIONS

Although primary school children spend more than 60% of their waking time sedentary, they generally engaged in short sedentary bouts. Children's sedentary bouts were slightly longer on weekdays, particularly during school hours and in the evening period, although the differences were very small. These results suggest that in this age group, interventions focusing on reducing total sedentary time rather than interrupting prolonged sedentary time are needed.

The Association of Physical Activity and Academic Behavior: A Systematic Review

BACKGROUND

In this systematic review, we assessed the existing research describing the effects of physical activity (PA) on academic behavior, with a special focus on the effectiveness of the treatments applied, study designs, outcome measures, and results.

METHODS

We obtained data from various journal search engines and 218 journal articles were downloaded that were relevant to PA and academic performance topics. The abstracts of all the articles were independently peer reviewed to assess whether they met the inclusion criteria for further analysis. The literature search was ongoing. Of the reviewed articles, 9 were chosen on the topic of PA effects on academic behavior. Each article was analyzed and summarized using a standard summary template.

RESULTS

Overall, PA interventions commonly found positive effects on academic behavior, with few exceptions. There were additional unique findings regarding differences in outcome measures and PA treatments.

CONCLUSIONS

The findings from these studies are significant and support the implementation or continuation of PA in schools to improve academic behavior and associated performance. More research needs to be conducted using the effective aspects of the treatments from this review with consistent outcome measures.

Sedentary patterns, physical activity and health-related physical fitness in youth: a cross-sectional study

Background

Strong evidence indicates that moderate-vigorous physical activity (MVPA) is positively associated with fitness in youth, independent of total sedentary-time. Sedentary-time appears negatively associated with fitness only when it replaces MVPA. However, whether different sedentary-patterns affect health-related fitness is unknown.

Methods

The associations between MVPA and sedentary-patterns with physical fitness were examined in 2698 youths (1262 boys) aged 13.4 ± 2.28 years. Sedentary-time (counts · minute⁻¹ < 100) and PA were objectively measured by accelerometry. Each break (≥100 counts · min⁻¹ < 2295) in sedentary-time and the frequency of daily bouts in non-prolonged (<30 min) and prolonged (≥30 min) sedentary-time were determined. The FITNESSGRAM® test battery was used to assess fitness. A standardized fitness composite-score (z-score) was calculated by summing the individual z-scores of the five tests adjusted to age and sex.

Results

Positive associations between MVPA and fitness were observed in both boys (β = 0.013, 95% CI: 0.005; 0.021) and girls (β = 0.014, 95% CI: 0.006; 0.022), independent of sedentary-patterns. Modest associations were found for the breaks in sedentary-time with fitness (β = 0.026, 95% CI: 0.009; 0.042), independent of total sedentary-time and MVPA in boys. In girls, non-prolonged sedentary bouts were positively associated with fitness (β = 0.014, 95% CI: 0.003; 0.024), independent of total sedentary-time and MVPA.

Conclusions

These results reinforce that, independent of the time and patterns of sedentary behavior, MVPA is consistently associated with fitness in youth. Modest and inconsistent associations were found for sedentary behaviors. Breaking-up sedentary-time in boys and non-prolonged sedentary bouts in girls were positively associated with fitness, independent of total sedentary-time and MVPA. In order to enhance youth’s fitness, public health recommendations should primarily target MVPA, still, suggestion to reduce and break-up sedentary-time may also be considered.

Does diet mediate associations of volume and bouts of sedentary time with cardiometabolic health indicators in adolescents?

OBJECTIVE

Examine the mediating role of diet in the relationship between volume and duration of sedentary time with cardiometabolic health in adolescents.

METHODS

Adolescents (12-19 years) participating in the 2003/04 and 2005/06 U.S. National Health and Nutrition Examination Survey (NHANES) were examined. Cardiometabolic health indicators were body mass index z-scores (zBMI) (n = 1,797) and metabolic syndrome (MetS) (n = 812). An ActiGraph hip-worn accelerometer was used to derive total sedentary time and usual sedentary bout duration. Dietary intake was assessed using two 24-hour dietary recalls. Mediation analyses were conducted to examine five dietary mediators [total energy intake, discretionary foods, sugar-sweetened beverages (SSB), fruits and vegetables, and dietary quality] of the relationship between total sedentary time and usual sedentary bout duration with zBMI and MetS.

RESULTS

Total sedentary time was inversely associated with zBMI (β = -1.33; 95% CI -2.53 to -0.13) but attenuated after adjusting for moderate-to-vigorous physical activity. No significant associations were observed between usual sedentary bout duration with zBMI or either sedentary measure with MetS. None of the five dietary variables mediated any of the relationships examined.

CONCLUSIONS

Further studies are needed to explore associations of specific time periods (e.g., after school) and bout durations with both cardiometabolic health indicators and dietary behaviors.

Objectively measured sedentary behaviour and moderate and vigorous physical activity in different school subjects: a cross-sectional study

BACKGROUND

Evidence shows the positive influence of moderate and vigorous physical activity (MVPA) and negative influence of sedentary time on health and academic achievement. Although schools can significantly contribute to overall physical activity, little is known about MVPA and sedentary behaviour in different school subjects in different grades.

METHODS

Physical activity of 646 students from 18 schools (94 classes) and from three school stages (grades 1-9, aged 7-16) was measured with accelerometry for 5 school days. Time and proportion of MVPA and sedentary time, also average sedentary bout length was calculated for native language (Estonian), mathematics, science, foreign language, music and crafts lessons.

RESULTS

A total of 6363 lessons were measured, with lesson duration of 45 min. The average lesson time MVPA remained below 2.2 min in all school stages and in all subjects. Students in grades 4-6 had greatest decline in the proportion of lesson time MVPA in science (β = -1.9, 95%CI -3.1- -0.6) and music (-1.2, -2.1- -0.4) and in grades 7-9 in music (-1.7, -3.1- -0.3) lessons compared to grades 1-3. In grades 1-3 students spent on average 76% of lesson time (34.0 ± 7.0 min) as sedentary, whereas in grades 7-9 the average proportion of sedentary time was 87% (38.9 ± 5.7 min). An average sedentary bout length increased from 13 min in grades 1-3 to 20 min in grades 7-9. An increase in sedentary bout length from grades 1-3 compared to grades 7-9 was present in most subjects, except crafts, with smallest increase in foreign language (6 min, 3.5-8.9) and greatest in music lessons (16.6 min, 11.9-21.3). Lessons with prolonged sedentary bouts formed a maximum 36% of all lessons in grades 1-3 and 73% in grades 7-9.

CONCLUSION

The long sedentary time, bout length and low MVPA in most subjects were unfavourable in respect of both health and academic achievement. Significantly increasing sedentary time and sedentary bout length in older school stages highlights the need for interventions in all subjects and especially in older grades in order to combat the inactivity of children.

Impact of an 8-Month Trial Using Height-Adjustable Desks on Children's Classroom Sitting Patterns and Markers of Cardio-Metabolic and Musculoskeletal Health

During school hours, children can sit for prolonged and unbroken periods of time. This study investigated the impact of an 8-month classroom-based intervention focusing on reducing and breaking-up sitting time on children’s cardio-metabolic risk factors (i.e., body mass index, waist circumference, blood pressure) and perceptions of musculoskeletal discomfort. Two Year-6 classes (24 students per class) in one primary school were assigned to either an intervention or control classroom. The intervention classroom was equipped with height-adjustable desks and the teacher was instructed in the delivery of pedagogical strategies to reduce and break-up sitting in class. The control classroom followed standard practice using traditional furniture. At baseline, and after 8-months, time spent sitting, standing, stepping, and sitting-bouts (occasions of continuous sitting) as well as the frequency of sit-to-stand transitions were obtained from activPAL inclinometers and the time spent in light-intensity physical activity was obtained from ActiGraph accelerometers. Demographics and musculoskeletal characteristics were obtained from a self-report survey. Hierarchical linear mixed models found that during class-time, children’s overall time spent sitting in long bouts (>10 min) were lower and the number of sit-to-stand transitions were higher in the intervention group compared to the control group, while no changes were observed for musculoskeletal pain/discomfort. No significant intervention effects were found for the anthropometrics measures and blood pressure. Height-adjustable desks and pedagogical strategies to reduce/break-up sitting can positively modify classroom sitting patterns in children. Longer interventions, larger and varied sample size may be needed to show health impacts; however, these desks did not increase musculoskeletal pain/discomfort.

Heterogeneous effects of old age on human muscle oxidative capacity in vivo: a systematic review and meta-analysis

Despite intensive efforts to understand the extent to which skeletal muscle mitochondrial capacity changes in older humans, the answer to this important question remains unclear. To determine what the preponderance of evidence from in vivo studies suggests, we conducted a systematic review and meta-analysis of the effects of age on muscle oxidative capacity as measured noninvasively by magnetic resonance spectroscopy. A secondary aim was to examine potential moderators contributing to differences in results across studies, including muscle group, physical activity status, and sex. Candidate papers were identified from PubMed searches (n = 3561 papers) and the reference lists of relevant papers. Standardized effects (Hedges’ g) were calculated for age and each moderator using data from the 22 studies that met the inclusion criteria (n = 28 effects). Effects were coded as positive when older (age, ≥55 years) adults had higher muscle oxidative capacity than younger (age, 20–45 years) adults. The overall effect of age on oxidative capacity was positive (g = 0.171, p < 0.001), indicating modestly greater oxidative capacity in old. Notably, there was significant heterogeneity in this result (Q = 245.8, p < 0.001; I2 = ∼70%–90%). Muscle group, physical activity, and sex were all significant moderators of oxidative capacity (p ≤ 0.029). This analysis indicates that the current body of literature does not support a de facto decrease of in vivo muscle oxidative capacity in old age. The heterogeneity of study results and identification of significant moderators provide clarity regarding apparent discrepancies in the literature, and indicate the importance of accounting for these variables when examining purported age-related differences in muscle oxidative capacity.

Relationship between Healthy Lifestyle and Sociodemographic Factors in Adolescents in Catalonia: Application of VISA-TEEN Questionnaire

Introduction

There is a clear relationship between the way of life and the health of individuals, and therefore, we can speak of healthy and unhealthy lifestyles. There are different surveys and questionnaires that evaluate the lifestyles of adolescents, but none of them offers a final score that can quantify the healthfulness of an adolescent’s lifestyle. It was with this goal that the VISA-TEEN questionnaire is developed and validated. The objective of this study is to apply the questionnaire to a sample of adolescents who attend school in Catalonia to evaluate the healthfulness of their lifestyles and to relate the scores obtained to different sociodemographic variables.

Methods

Cross-sectional study. A total of 2,832 students from 25 schools in Catalonia responded to the questionnaire. A descriptive analysis was performed, calculating the mean (Standard deviation), median (p₂₅, p₇₅), and confidence interval. The results were calculated for the total population, factoring according to gender, age, urban/rural population, origin (native/immigrant), and family wealth, which was based on the Family Affluence Scale (FAS II). The significance of the difference was calculated for each factor with the appropriate statistical test.

Results

For the total score of healthy lifestyle, the youngest students and those with the highest family wealth obtained higher scores. With respect to eating habits, girls scored higher than boys, and higher scores were observed in natives and those with high family wealth. For physical activity, boys scored higher, as well as younger individuals, natives, and those from rural areas. With respect to substance abuse, the worst scores were found in older individuals, students from rural areas, and natives. The rational use of leisure technology was only associated with age (worsening scores with older age). Lastly, hygiene was better with girls, decreased with age, and was worse with natives than immigrants.

An institutional pilot study to investigate physical activity patterns in boys with haemophilia

INTRODUCTION

Haemophilia is a bleeding disorder characterized by musculoskeletal bleeding. Trauma-induced bleeding into joints and muscles may be associated with participation in physical activities. Recognizing this, persons with haemophilia may limit physical activities to avoid bleeding. The characterization of physical activity profiles (type, intensity, frequency and duration) in children with differing severities of haemophilia has not been well documented. This is required to better understand the relationship between physical activity and bleeding in children with haemophilia.

AIM

This study was a prospective, cross-sectional, observational study to compare the quantity, type and intensity of physical activity as measured by accelerometry in boys with different haemophilia severities.

METHODS

Subjects wore an accelerometer daily for 1 week and completed validated self-report PedHAL and 3DPAR questionnaires. Accelerometer activity levels were classified as sedentary, light, moderate or vigorous.

RESULTS

A total of 66 males were enrolled, 24 had mild/moderate and 42 had severe haemophilia. Subjects average age was 11.52 years (±3.99) and their average BMI was 20.74 kg m(2) (±5.68). Boys with severe haemophilia reported significantly more time per day spent in sedentary activities compared to those with mild/moderate haemophilia. Furthermore, the amount of time engaged in sedentary activities increased with age in those boys with severe haemophilia, whereas the opposite was true in those with mild/moderate haemophilia.

CONCLUSION

We speculate that prophylaxis in children with severe haemophilia permitted them to engage in similar amounts of moderate to vigorous physical activity (MVPA) as children with mild/moderate haemophilia. Increasing sedentary time in the severe cohort with age may be attributed to increasing arthropathy among other psychosocial factors.

Canadian 24-Hour Movement Guidelines for Children and Youth: Exploring the perceptions of stakeholders regarding their acceptability, barriers to uptake, and dissemination

Engaging stakeholders in the development of guidelines and plans for implementation is vital. The purpose of this study was to examine stakeholders’ (parents, teachers, exercise professionals, paediatricians, and youth) perceptions of the Canadian 24-Hour Movement Behaviour Guidelines for Children and Youth (“Movement Guidelines”). Stakeholders (n = 104) engaged in semi-structured focus groups or interviews to discuss the perceived acceptability of the guidelines, potential barriers to implementation, and preferred methods and messengers of dissemination. A thematic analysis was conducted. Overall, there was consistent support across all stakeholder groups, with the exception of youth participants, for the Movement Guidelines. Stakeholders identified a range of barriers to the uptake of the guidelines including concerns with accurately defining key terms such as “recreational” screen time; everyday challenges such as financial and time constraints; and the possibility of the Movement Guidelines becoming just another source of stress and guilt for already busy and overwhelmed parents. Participants identified a range of recommended methods and messengers for future dissemination. School and medical settings were the most commonly recommended settings through which dissemination efforts should be delivered. Overall, participants representing a range of stakeholder groups were receptive to the new Movement Guidelines and endorsed their value. In complementing the Movement Guidelines, messaging and resources will need to be developed that address common concerns participants had regarding their dissemination and implementation.

Systematic review of sedentary behaviour and health indicators in school-aged children and youth: an update

This systematic review is an update examining the relationships between objectively and subjectively measured sedentary behaviour and health indicators in children and youth aged 5–17 years. EMBASE, PsycINFO, and Medline were searched in December 2014, and date limits were imposed (≥February 2010). Included studies were peer-reviewed and met the a priori-determined population (apparently healthy children and youth, mean age: 5–17 years), intervention (durations, patterns, and types of sedentary behaviours), comparator (various durations, patterns, and types of sedentary behaviours), and outcome (critical: body composition, metabolic syndrome/cardiovascular disease risk factors, behavioural conduct/pro-social behaviour, academic achievement; important: fitness, self-esteem) study criteria. Quality of evidence by outcome was assessed using the Grading of Recommendations Assessment, Development, and Evaluation framework. Due to heterogeneity, a narrative analysis was conducted. A total of 235 studies (194 unique samples) were included representing 1 657 064 unique participants from 71 different countries. Higher durations/frequencies of screen time and television (TV) viewing were associated with unfavourable body composition. Higher duration/frequency of TV viewing was also associated with higher clustered cardiometabolic risk scores. Higher durations of TV viewing and video game use were associated with unfavourable behavioural conduct/pro-social behaviour. Higher durations of reading and doing homework were associated with higher academic achievement. Higher duration of screen time was associated with lower fitness. Higher durations of screen time and computer use were associated with lower self-esteem. Evidence ranged from “very low” to “moderate” quality. Higher quality studies using reliable and valid sedentary behaviour measures should confirm this largely observational evidence.

Comparison of ActiGraph GT3X+ and Actical accelerometer data in 9-11-year-old Canadian children

Accelerometry is the gold standard for field-based physical activity assessment in children; however, the plethora of devices, data reduction procedures, and cut-points available limits comparability between studies. This study aimed to compare physical activity variables from the ActiGraph GT3X+ and Actical accelerometers in children under free-living conditions. A cross-sectional study of 379 children aged 9-11 years from Ottawa (Canada) was conducted. Children wore the ActiGraph GT3X+ and Actical accelerometers on the hip simultaneously for 7 consecutive days (24-h protocol). Moderate-to-vigorous (MVPA), vigorous (VPA), moderate (MPA), and light (LPA) physical activity, as well as sedentary time, (SED) were derived using established data reduction protocols. Excellent agreement between devices was observed for MVPA (ICC = 0.73-0.80), with fair to good agreement for MPA, LPA and SED, and poor agreement for VPA. Bland-Altman plots showed excellent agreement for MVPA, LPA, and SED, adequate agreement for MPA, and poor agreement for VPA. MVPA derived from the Actical was 11.7% lower than the ActiGraph GT3X+. The ActiGraph GT3X+ and Actical are comparable for measuring children's MVPA. However, comparison between devices for VPA, MPA, LPA, and SED are highly dependent on data reduction procedures and cut-points, and should be interpreted with caution.

Objectively measured sedentary behaviour and health and development in children and adolescents: systematic review and meta-analysis

Sedentary behaviour has emerged as a unique determinant of health in adults. Studies in children and adolescents have been less consistent. We reviewed the evidence to determine if the total volume and patterns (i.e. breaks and bouts) of objectively measured sedentary behaviour were associated with adverse health outcomes in young people, independent of moderate-intensity to vigorous-intensity physical activity. Four electronic databases (EMBASE MEDLINE, Ovid EMBASE, PubMed and Scopus) were searched (up to 12 November 2015) to retrieve studies among 2- to 18-year-olds, which used cross-sectional, longitudinal or experimental designs, and examined associations with health outcomes (adiposity, cardio-metabolic, fitness, respiratory, bone/musculoskeletal, psychosocial, cognition/academic achievement, gross motor development and other outcomes). Based on 88 eligible observational studies, level of evidence grading and quantitative meta-analyses indicated that there is limited available evidence that the total volume or patterns of sedentary behaviour are associated with health in children and adolescents when accounting for moderate-intensity to vigorous-intensity physical activity or focusing on studies with low risk of bias. Quality evidence from studies with robust designs and methods, objective measures of sitting, examining associations for various health outcomes, is needed to better understand if the overall volume or patterns of sedentary behaviour are independent determinants of health in children and adolescents.

Are temporal patterns of sitting associated with obesity among blue-collar workers? A cross sectional study using accelerometers

Background

Little is known about associations of temporal patterns of sitting (i.e., distribution of sitting across time) with obesity. We aimed investigating the association between temporal patterns of sitting (long, moderate and brief uninterrupted bouts) and obesity indicators (body mass index (BMI), waist circumference and fat percentage), independently from moderate-vigorous physical activity (MVPA) and total sitting time among blue-collar workers.

Methods

Workers (n = 205) wore Actigraph GT3X+ accelerometers on the thigh and trunk for 1–4 working days. Using the validated Acti4 software, the total sitting time and time spent sitting in brief (≤5 mins), moderate (>5 and ≤30 mins), and long (>30mins) bouts on working days were determined for the whole day, and for leisure and work separately. BMI (kg/m²), waist circumference (cm) and fat percentage were objectively measured.

Results

Results of linear regression analysis adjusted for multiple confounders indicated that brief bouts of sitting was negatively associated with obesity for the whole day (BMI, P < 0.01; fat percentage, P < 0.01; waist circumference, P < 0.01) and work (BMI, P < 0.01; fat percentage, P < 0.01; waist circumference, P < 0.01), but not for leisure. Sitting time in long bouts was positively associated with obesity indicators for the whole day (waist circumference, P = 0.05) and work (waist circumference, P = 0.01; BMI, P = 0.04), but not leisure.

Conclusions

For the whole day as well as for work, brief bouts and long bouts of sitting showed opposite associations with obesity even after adjusting for MVPA and total sitting time, while sitting during leisure did not show these associations. Thus, the temporal distribution of sitting seems to influence the relationship between sitting and obesity.

The association between time spent in sedentary behaviors and blood pressure: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Sedentary behaviors, defined as waking behaviors with low energy expenditure while sitting, are positively associated with several adverse health outcomes. However, the association between sedentary behaviors and blood pressure (BP) is inconclusive. This study aimed to conduct a systematic review and meta-analysis on the association between time spent in sedentary behaviors and BP.

METHODS

We searched PubMed, MEDLINE, and Web of Science for papers published before August 2014 that assessed the association between time spent in sedentary behaviors and BP. Studies on both adults and children were included. Only good quality studies were included. The pooled estimates of systolic BP (SBP) and diastolic BP (DBP) increase per hour of time spent in sedentary behaviors a day were computed using a fixed-effects model and a random-effects model, respectively. Another pooled estimate of odds ratio per hour of time spent in sedentary behaviors a day on having high BP was computed using a fixed-effects model. A sub-group analysis was conducted for studies using self-reported and objectively assessed time spent in sedentary behaviors separately.

RESULTS

A total of 31 papers of good quality were included in the systematic review, 18 of which found no association between time spent in sedentary behaviors and BP (58.1%). A total of 28 papers were included in the meta-analysis. Pooled effects showed that an additional hour of time spent in sedentary behaviors per day was associated with an increase of 0.06 mmHg (108,228 participants, 95% CI 0.01-0.11, p = 0.01) of SBP and 0.20 mmHg (107,791 participants, 95% CI 0.10-0.29, p < 0.001) of DBP. Accelerometer-assessed time spent in sedentary behaviors was not associated with either SBP (p = 0.06) or DBP (p = 0.33). The odds ratio (OR) of having high BP with an additional hour of time spent in sedentary behaviors per day was 1.02 (98,798 participants, 95% CI 1.003-1.03, p = 0.02).

CONCLUSIONS

Self-reported but not accelerometer-assessed time spent in sedentary behaviors was associated with BP. Further studies are warranted to determine the preventive effect of reducing sedentary behaviors on high BP.

Comparison of three activity monitors for estimating sedentary time among children

Background

Time spent sedentary appears to be associated with several health outcomes in adults, but findings are inconsistent in children. Further, the assessment of sedentary time represents a major challenge. The objectives of the present study were to determine whether 1) ActiGraph GT3X+, ActivPAL and SenseWear Armband Pro3 (SWA) provide comparable estimates of sedentary time in 9–12-year-old children, 2) these devices are valid compared with direct observation, and 3) ActivPAL discriminates between sitting and standing behavior.

Methods

The sample was 67 children. Data were collected during three consecutive days in November 2012. To test the activity monitors in contexts related to physical and sedentary activities commonly performed by children, the children participated in sessions of activity while sitting (watching television, playing video games and tossing a ball while sitting) and standing (musical chairs, active video gaming and tossing a ball) while wearing three different activity monitors at the same time. All activity sessions were observed by two researchers. Differences between monitors were determined using Friedman’s two-way analysis of variance by rank order.

Results

Minutes of estimated sedentary time differed across device brands during combined sitting activities: SWA vs. ActiGraph GT3X+ (P = 0.048), SWA vs. ActivPAL, (P < 0.001) and ActiGraph GT3X+ vs. ActivPAL (P = 0.002). Out of 12 min in total of combined recorded sitting activity, SWA reported a median of 6 min (95 % Confidence Interval [CI] = 5.0, 7.0), ActiGraph GT3X+ 7 min (7.0, 8.0) and ActivPAL 10 min (8.6, 10.8) as sedentary time. ActivPAL recorded 3.7 (2.4, 4.0) minutes of the non-sitting activities ‘musical chairs’, 4.0 (4.0, 4.0) minutes in ‘standing ball toss’; and 4.0 (2.7, 4.0) minutes in ‘active video gaming’ as sitting time.

Conclusion

Recorded sedentary time varied among the monitors GT3X+, SWA and ActivPAL, and misclassification of standing activities as sitting activities were apparent for ActivPAL in certain activities.

Impact of prolonged sitting on vascular function in young girls

NEW FINDINGS

What is the central question of this study? Children are spending more than 60% of their waking day sedentary. The consequences of excessive sedentary behaviour are not well understood in the child, but there is growing evidence that with increasing sedentary time, cardiovascular risk in childhood also increases. What is the main finding and its importance? Our findings show that a 3 h period of uninterrupted sitting causes a profound (33%) reduction in vascular function in young girls. Importantly, we also demonstrate that breaking up sitting with regular exercise breaks can prevent this. Excessive sedentary behaviour has serious clinical and public health implications; however, the physiological changes that accompany prolonged sitting in the child are not completely understood. Herein, we examined the acute effect a prolonged period of sitting has upon superficial femoral artery function in 7- to 10-year-old girls and the impact of interrupting prolonged sitting with exercise breaks. Superficial femoral artery endothelium-dependent flow-mediated dilatation, total shear rate, anterograde and retrograde shear rates and oscillatory shear index were assessed before and after two experimental conditions: a 3 h uninterrupted period of sitting (SIT) and a 3 h period of sitting interrupted each hour with 10 min of moderate-intensity exercise (EX). A mixed-model analysis of variance was used to compare between-condition and within-condition main effects, controlling for the within-subject nature of the experiment by including random effects for participant. Superficial femoral artery endothelium-dependent flow-mediated dilatation decreased significantly from pre- to post-SIT (mean difference 2.2% flow-mediated dilatation; 95% confidence interval = 0.60-2.94%, P < 0.001). This relative decline of 33% was abolished in the EX intervention. Shear rates were not significantly different within conditions. Our data demonstrate the effectiveness of short but regular exercise breaks in offsetting the detrimental effects of uninterrupted sitting in young girls.

Objectively measured physical activity and sedentary time in youth: the International children's accelerometry database (ICAD)

Background

Physical activity and sedentary behaviour in youth have been reported to vary by sex, age, weight status and country. However, supporting data are often self-reported and/or do not encompass a wide range of ages or geographical locations. This study aimed to describe objectively-measured physical activity and sedentary time patterns in youth.

Methods

The International Children’s Accelerometry Database (ICAD) consists of ActiGraph accelerometer data from 20 studies in ten countries, processed using common data reduction procedures. Analyses were conducted on 27,637 participants (2.8–18.4 years) who provided at least three days of valid accelerometer data. Linear regression was used to examine associations between age, sex, weight status, country and physical activity outcomes.

Results

Boys were less sedentary and more active than girls at all ages. After 5 years of age there was an average cross-sectional decrease of 4.2 % in total physical activity with each additional year of age, due mainly to lower levels of light-intensity physical activity and greater time spent sedentary. Physical activity did not differ by weight status in the youngest children, but from age seven onwards, overweight/obese participants were less active than their normal weight counterparts. Physical activity varied between samples from different countries, with a 15–20 % difference between the highest and lowest countries at age 9–10 and a 26–28 % difference at age 12–13.

Conclusions

Physical activity differed between samples from different countries, but the associations between demographic characteristics and physical activity were consistently observed. Further research is needed to explore environmental and sociocultural explanations for these differences.

Electronic supplementary material

The online version of this article (doi:10.1186/s12966-015-0274-5) contains supplementary material, which is available to authorized users.

Bouts and breaks in children's sedentary time: currently used operational definitions and recommendations for future research

Increasing attention is paid to the potential health effects of children's sedentary bouts and breaks, rather than total sedentary time. This paper discusses currently used operational definitions of sedentary bouts and breaks in studies among children. Remarkably, these studies applied different operational definitions, complicating comparison between studies. To advance the field of sedentary behaviour epidemiology, we need a clear and 'evidence-based' operationalization for such sedentary bouts and breaks.

Quantitative physical activity assessment of children and adolescents in a rural population from Eastern Nepal

OBJECTIVES

We report cross-sectional, objectively measured physical activity data for 399 children and adolescents aged 6 to 18 years. We evaluated physical activity of children and adolescents, considered time spent in each activity intensity category, and explored the impact of growth disruption (stunting and wasting) on physical activity patterns.

METHODS

Participants wore an Actical (Mini-Mitter, Bend, OR) omnidirectional accelerometer for one week as part of their annual visit to the Jiri Growth Study. The percentage of time spent in standard activity intensities were computed using standard metabolic equivalents (METS) cutpoints and compared by chronological age, sex, and school versus non-school days.

RESULTS

Primary findings include (1) children are more active on non-school days and adolescents are more active during the school week; (2) Jirel children do not exhibit the reduction in physical activity that most Western populations experience during the transition from childhood to adolescence; and (3) Jirel children and adolescents routinely meet the suggested one hour/day MVPA threshold; (4) Stunting is prevalent and factors leading to this growth disruption may contribute to the amount of time in sedentary or light physical activity.

CONCLUSIONS

We report child and adolescent physical activity patterns from the Jirel population of eastern Nepal. In this rural context, children and adolescents are more active than populations reported from Western contexts. This key finding has important biomedical implications for the maintenance of healthy body composition, skeletal health, and other health traits.

Correlates of Total Sedentary Time and Screen Time in 9-11 Year-Old Children around the World: The International Study of Childhood Obesity, Lifestyle and the Environment

Purpose

Previously, studies examining correlates of sedentary behavior have been limited by small sample size, restricted geographic area, and little socio-cultural variability. Further, few studies have examined correlates of total sedentary time (SED) and screen time (ST) in the same population. This study aimed to investigate correlates of SED and ST in children around the world.

Methods

The sample included 5,844 children (45.6% boys, mean age = 10.4 years) from study sites in Australia, Brazil, Canada, China, Colombia, Finland, India, Kenya, Portugal, South Africa, the United Kingdom, and the United States. Child- and parent-reported behavioral, household, and neighborhood characteristics and directly measured anthropometric and accelerometer data were obtained. Twenty-one potential correlates of SED and ST were examined using multilevel models, adjusting for sex, age, and highest parental education, with school and study site as random effects. Variables that were moderately associated with SED and/or ST in univariate analyses (p<0.10) were included in the final models. Variables that remained significant in the final models (p<0.05) were considered correlates of SED and/or ST.

Results

Children averaged 8.6 hours of daily SED, and 54.2% of children failed to meet ST guidelines. In all study sites, boys reported higher ST, were less likely to meet ST guidelines, and had higher BMI z-scores than girls. In 9 of 12 sites, girls engaged in significantly more SED than boys. Common correlates of higher SED and ST included poor weight status, not meeting physical activity guidelines, and having a TV or a computer in the bedroom.

Conclusions

In this global sample many common correlates of SED and ST were identified, some of which are easily modifiable (e.g., removing TV from the bedroom), and others that may require more intense behavioral interventions (e.g., increasing physical activity). Future work should incorporate these findings into the development of culturally meaningful public health messages.

Examining communication- and media-based recreational sedentary behaviors among Canadian youth: results from the COMPASS study

OBJECTIVES

To examine the prevalence of different communication- and media-based sedentary behaviors and examine how they are associated with modifiable risk behaviors and key demographic correlates among a large sample of youth.

METHODS

Data from 23,031 grade 9 to grade 12 students in Year 1 (2012-2013) of the COMPASS study (Canada) were used to examine the prevalence of sedentary behaviors by gender and by grade. The between-school variance in sedentary behaviors was calculated and models were developed to examine how modifiable risk factors and demographic correlates were associated with sedentary behaviors.

RESULTS

Youth averaged 494 (± 313) min/day of sedentary behavior and 96.7% of the sample exceeded the sedentary behavior guidelines of no more than 2h per day. Significant between-school random variation in the sedentary behaviors was identified. Substance use, weight status, ethnicity, and gender were the main predictors of the sedentary behaviors examined.

CONCLUSIONS

The vast majority of youth in the COMPASS sample are considered highly sedentary. The evidence clearly suggests we need to develop more effective methods of intervening, that school-based programming is warranted, and that gender-specific programming may be required.

Correlates of objectively measured sedentary time and self-reported screen time in Canadian children

BACKGROUND

Demographic, family, and home characteristics play an important role in determining childhood sedentary behaviour. The objective of this paper was to identify correlates of total sedentary time (SED) and correlates of self-reported screen time (ST) in Canadian children.

METHODS

Child- and parent-reported household, socio-demographic, behavioural, and diet related data were collected; directly measured anthropometric and accelerometer data were also collected for each child. Participants with complete demographic, anthropometric, and either SED (n=524, 41% boys) or ST (n=567, 42% boys) data from the Canadian site of the International Study of Childhood Obesity Lifestyle and the Environment (ISCOLE) were included in analysis. Sixteen potential correlates of SED and ST were examined using multilevel general linear models, adjusting for sex, ethnicity, number of siblings, and socio-economic status. All explanatory variables moderately associated (p<0.10) with SED and/or ST in univariate analyses were included in the final, fully-adjusted models. Variables that remained significant in the final models (p<0.05) were considered correlates of SED and/or ST.

RESULTS

Children averaged 8.5 hours of daily SED; no differences in total SED, or total ST were seen between girls and boys, but boys reported significantly more video game/computer usage than girls. Boys also had higher waist circumference and BMI z-scores than girls. In the final models, waist circumference and number of TVs in the home were the only common correlates of both SED and ST. SED was also negatively associated with sleep duration. ST was also positively associated with mother's weight status, father's education, and unhealthy eating pattern score and negatively associated with healthy eating pattern score, and weekend breakfast consumption. Few common correlates existed between boys and girls.

CONCLUSION

Several factors were identified as correlates of SED and/or of ST in Canadian children; however, few correlates were common for both SED and ST, and for both boys and girls. This suggests that a single strategy to reduce SED and ST is unlikely to be effective. Future work should examine a variety of other, non-screen based sedentary behaviours and their potential correlates in the hopes of creating tailored public health messages to reduce SED and ST in both boys, and girls.

Extracting objective estimates of sedentary behavior from accelerometer data: measurement considerations for surveillance and research applications

BACKGROUND

Accelerometer-based activity monitors are widely used in research and surveillance applications for quantifying sedentary behavior (SB) and physical activity (PA). Considerable research has been done to refine methods for assessing PA, but relatively little attention has been given to operationalizing SB parameters (i.e., sedentary time and breaks) from accelerometer data - particularly in relation to health outcomes. This study investigated: (a) the accrued patterns of sedentary time and breaks; and (b) the associations of sedentary time and breaks in different bout durations with cardiovascular risk factors.

METHODS

Accelerometer data on 5,917 adults from the National Health Examination and Nutrition Survey (NHANES) 2003-2006 were used. Sedentary time and breaks at different bout durations (i.e., 1, 2-4, 5-9, 10-14, 15-19, 20-24, 25-29, and ≥ 30-min) were obtained using a threshold of < 100 counts per minute. Sedentary time and breaks were regressed on cardiovascular risk factors (waist circumference, triglyceride, and high-density lipoprotein cholesterol) and body mass index across bout durations.

RESULTS

The results revealed that the majority of sedentary time occurred within relatively short bout durations (≈ 70% and ≈ 85% for < 5-min and < 10-min, respectively). The associations of sedentary time and breaks with health outcomes varied depending on how bout time was defined. Estimates of SB parameters based on bout durations of 5 min or shorter were associated with reduced cardiovascular risk factors while durations longer than 10-min were generally associated with increased risk factors.

CONCLUSIONS

The present study demonstrates that the duration of sedentary bouts should be further considered when operationalizing the SB parameters from accelerometer data. The threshold of 5 minutes to define a bout is defensible, but a 10 minute threshold would provide a more conservative estimate to clearly capture the prolonged nature of sedentary behavior. Additional research is needed to determine the relative sensitivity and specificity of these thresholds.

Occurrence and duration of various operational definitions of sedentary bouts and cross-sectional associations with cardiometabolic health indicators: the ENERGY-project

OBJECTIVE

This study examined the occurrence and duration of sedentary bouts and explored the cross-sectional association with health indicators in children applying various operational definitions of sedentary bouts.

METHODS

Accelerometer data of 647 children (10-13 years old) were collected in five European countries. We analyzed sedentary time (<100 cpm) accumulated in bouts of at least 5, 10, 20 or 30 min based on four operational definitions, allowing 0, 30 or 60s ≥100 cpm within bouts. Health indicators included anthropometrics (i.e. waist circumference and body mass index (BMI)) and in a subsample from two European countries (n=112) fasting capillary blood levels of glucose, C-peptide, high-density- and low-density cholesterol, and triglycerides. Data collection took place from March to July 2010. Associations were adjusted for age, gender, moderate-to-vigorous physical activity, total wear time and country.

RESULTS

Occurrence of sedentary bouts varied largely between the various definitions. Children spent most of their sedentary time in bouts of ≥5 min while bouts of ≥20 min were rare. Linear regression analysis revealed few significant associations of sedentary time accumulated in bouts of ≥5-30 min with health indicators. Moreover, we found that more associations became significant when allowing no tolerance time within sedentary bouts.

CONCLUSION

Despite a few significant associations, we found no convincing evidence for an association between sedentary time accumulated in bouts and health indicators in 10-13 year old children.

The Dynamic Family Home: a qualitative exploration of physical environmental influences on children's sedentary behaviour and physical activity within the home space

Background

Recent changes in home physical environments, such as decreasing outdoor space and increasing electronic media, may negatively affect health by facilitating sedentariness and reducing physical activity. As children spend much of their time at home they are particularly vulnerable. This study qualitatively explored family perceptions of physical environmental influences on sedentary behaviour and physical activity within the home space.

Methods

Home based interviews were conducted with 28 families with children aged 9–13 years (total n = 74 individuals), living in Perth, Australia. Families were stratified by socioeconomic status and selected to provide variation in housing. Qualitative methods included a family interview, observation and home tour where families guided the researcher through their home, enabling discussion while in the physical home space. Audio recordings were transcribed verbatim and thematically analysed.

Results

Emergent themes related to children’s sedentariness and physical activity included overall size, space and design of the home; allocation of home space; equipment within the home space; perceived safety of the home space; and the changing nature of the home space. Families reported that children’s activity options were limited when houses and yards were small. In larger homes, multiple indoor living rooms usually housed additional sedentary entertainment options, although parents reported that open plan home layouts could facilitate monitoring of children’s electronic media use. Most families reported changing the allocation and contents of their home space in response to changing priorities and circumstances.

Conclusions

The physical home environment can enhance or limit opportunities for children’s sedentary behaviour and physical activity. However, the home space is a dynamic ecological setting that is amenable to change and is largely shaped by the family living within it, thus differentiating it from other settings. While size and space were considered important, how families prioritise the use of their home space and overcome the challenges posed by the physical environment may be of equal or greater importance in establishing supportive home environments. Further research is required to tease out how physical, social and individual factors interact within the family home space to influence children’s sedentary behaviour and physical activity at home.

Electronic supplementary material

The online version of this article (doi:10.1186/s12966-014-0157-1) contains supplementary material, which is available to authorized users.

Daily physical activity and screen time, but not other sedentary activities, are associated with measures of obesity during childhood

Childhood obesity is related to low physical activity level and a sedentary lifestyle. The aim of this study was to assess the physical activity level and sedentary behaviour of Malaysian children aged 7 to 12 years and to examine their association with body mass index (BMI), BMI-for-age Z-score (BAZ), body fatness (%BF) and waist circumference (WC). A total of 1736 children, representing all ethnic groups were recruited from six regions of Malaysia. Anthropometric measurements included body weight, height and waist circumference. Body fat percentage (%BF) was assessed using bioelectrical impedance. Physical activity was assessed by a physical activity questionnaire (PAQ) in all children and by pedometers in a subsample (n = 514). PAQ score and pedometer step counts were negatively associated with BMI, BAZ, %BF and WC after adjusting for covariates. Screen time was positively associated with BAZ and WC. However, other sedentary activities were not significantly related with any anthropometric indicators. Strategies to promote active living among children in Malaysia should focus not only on increasing physical activity but also emphasise reduction in sedentary behaviours.

From sedentary time to sedentary patterns: accelerometer data reduction decisions in youth

Aim

This study aims to establish evidence-based accelerometer data reduction criteria to accurately assess total sedentary time and sedentary patterns in children.

Methods

Participants (n = 1057 European children; 9–13 yrs) were invited to wear an accelerometer for at least 6 consecutive days. We explored 1) non-wear time criteria; 2) minimum daily valid wear time; 3) differences between weekday and weekend day; and 4) minimum number of days of accelerometer wear by comparing the effects of commonly used data reduction decisions on total sedentary time, and duration and number of prolonged sedentary bouts.

Results

More than 60 consecutive minutes of zero counts was the optimal criterion for non-wear time. Increasing the definition of a valid day from 8 to 10 hours wear time hardly influenced the sedentary outcomes, while the sample size of children with more than 4 valid days increased from 69 to 81%. On weekdays, children had on average 1 hour more wear time, 50 minutes more total sedentary time, 26 minutes more sedentary time accumulated in bouts, and 1 more sedentary bout. At least 6 days of accelerometer data were needed to accurately represent weekly sedentary time and patterns.

Conclusions

Based on our results we recommend 1) a minimum of 60 minutes of consecutive zeros as the most realistic criterion for non-wear time; and 2) including at least six days with minimum eight valid hours to characterize children's usual total sedentary time and patterns, preferably including one weekend day.

Associations between aspects of friendship networks, physical activity, and sedentary behaviour among adolescents

BACKGROUND

Adolescent friendships have been linked to physical activity levels; however, network characteristics have not been broadly examined.

METHOD

In a cross-sectional analysis of 1061 adolescents (11-15 years), achieving 60 minutes/day of moderate-to-vigorous physical activity (MVPA) and participating in over 2 hours/day of sedentary behaviour were determined based on friendship network characteristics (density; proportion of active/sedentary friends; betweenness centrality; popularity; clique membership) and perceived social support.

RESULTS

Adolescents with no friendship nominations participated in less MVPA. For boys and girls, a ten percent point increase in active friends was positively associated with achievement of 60 minutes/day of MVPA (OR 1.11; 95% CI 1.02-1.21, OR 1.14; 95% CI 1.02-1.27, resp.). For boys, higher social support from friends was negatively associated with achieving 60 minutes/day of MVPA (OR 0.63; 95% CI 0.42-0.96). Compared with low density networks, boys in higher density networks were more likely to participate in over 2 hours/day of sedentary behaviour (OR 2.93; 95% CI 1.32-6.49). Social support from friends also modified associations between network characteristics and MVPA and sedentary behaviour.

CONCLUSION

Different network characteristics appeared to have different consequences. The proportion of active close friends was associated with MVPA, while network density was associated with sedentary behaviour. This poses challenges for intervention design.

Distance to School is Associated with Sedentary Time in Children: Findings from the URBAN Study

Sedentary behavior is associated with overweight and obesity in children, and distance to school has been negatively associated with active commuting to school. It is not known how distance to school relates to sedentary behavior in children. The aim of this study was to investigate the association between distance to school and children's sedentary behavior during weekdays at times where children interact with the neighborhood environment. Children (5-13 years, n = 295) who participated in the understanding relationships between activity and neighborhoods study (2008-2010) across four New Zealand cities wore a hip-mounted accelerometer for 7 days. Minutes spent sedentary (accelerometer count <100 min(-1)) were derived for the school travel periods (0800-0859 and 1500-1559) and after school discretionary time (1600-1759). Shortest street network distance to school was calculated from residential addresses using geographical information systems and parsed into tertiles for analysis. Children completed a daily travel log including mode of transport to and from school, which was dichotomized into active (walking and cycling) and passive (motorized) modes. Children living in the second tertile of distance from school were the least sedentary during the school traveling periods (42 ± 10%, mean ± true between-child SD) compared to those living in the first or third distance tertiles (47 ± 10 and 49 ± 10%, respectively); the differences were clear and likely substantial (90% confidence limits ± 6%). Children who traveled by motorized transport were more sedentary for each of the distance tertiles (50 versus 44%, 46 versus 39%, and 54 versus 27% for first, second, and third tertiles, respectively; 90% confidence limits ± 7%). In the period of 1600-1759, girls in the third distance tertile were the most sedentary. The combined effects of 1-2 km distance from school and active commuting to school contributed to least sedentary time in children.

Low physical activity level and short sleep duration are associated with an increased cardio-metabolic risk profile: a longitudinal study in 8-11 year old Danish children

Background

As cardio-metabolic risk tracks from childhood to adulthood, a better understanding of the relationship between movement behaviors (physical activity, sedentary behavior and sleep) and cardio-metabolic risk in childhood may aid in preventing metabolic syndrome (MetS) in adulthood.

Objective

To examine independent and combined cross-sectional and longitudinal associations between movement behaviors and the MetS score in 8-11 year old Danish children.

Design

Physical activity, sedentary time and sleep duration (seven days and eight nights) were assessed by accelerometer and fat mass index (fat mass/height²) was assessed using Dual-energy X-ray absorptiometry. The MetS-score was based on z-scores of waist circumference, mean arterial blood pressure, homeostatic model assessment of insulin resistance, triglycerides and high density lipoprotein cholesterol. All measurements were taken at three time points separated by 100 days. Average of the three measurements was used as habitual behavior in the cross-sectional analysis and changes from first to third measurement was used in the longitudinal analysis.

Results

723 children were included. In the cross-sectional analysis, physical activity was negatively associated with the MetS-score (P<0.03). In the longitudinal analysis, low physical activity and high sedentary time were associated with an increased MetS-score (all P<0.005); however, after mutual adjustments for movement behaviors, physical activity and sleep duration, but not sedentary time, were associated with the MetS-score (all P<0.03). Further adjusting for fat mass index while removing waist circumference from the MetS-score rendered the associations no longer statistically significant (all P>0.17). Children in the most favorable tertiles of changes in moderate-to-vigorous physical activity, sleep duration and sedentary time during the 200-day follow-up period had an improved MetS-score relative to children in the opposite tertiles (P = 0.005).

Conclusion

The present findings indicate that physical activity, sedentary time and sleep duration should all be targeted to improve cardio-metabolic risk markers in childhood; this is possibly mediated by adiposity.

Objectively measured sedentary behaviour and cardio-metabolic risk in youth: a review of evidence

The aim of this paper was to review studies that examine the association between volume and pattern of objectively measured sedentary behaviour and markers of cardio-metabolic risk in youth. A search for relevant articles was conducted in PubMed and SportDiscus, and the following inclusion criteria were applied: (i) youth participants (age range 6-19); (ii) accelerometer-measured volume and/or pattern of sedentary behaviour and its association with ≥1 cardio-metabolic outcome; and (iii) published, in press or accepted in an English language peer-reviewed journal between January 2000 and October 2013. A total of 45 articles met the a priori criteria and, thus, were considered eligible for inclusion. Although youth accumulate approximately 6 to 8 h of daily sedentary behaviour, little evidence supports an association with individual and clustered cardio-metabolic risk when adjusted for moderate-to-vigorous physical activity (MVPA).

CONCLUSION

We suggest that youth should be encouraged to engage in recommended levels of MVPA and reduce excessive time spent in screen-based sedentary behaviour. Future studies should examine the association between volume and pattern of objectively measured sedentary behaviour and cardio-metabolic risk independent of time spent in MVPA.

Sedentary behaviour as an emerging risk factor for cardiometabolic diseases in children and youth

Sedentary behaviour (e.g. TV viewing, seated video game playing, prolonged sitting) has recently emerged as a distinct risk factor for cardiometabolic diseases in children and youth. This narrative review provides an overview of recent evidence in this area and highlights research gaps. Current evidence suggests that North American children and youth spend between 40% and 60% of their waking hours engaging in sedentary pursuits. Although data are lacking concerning temporal trends of objectively measured sedentary time, self-reported sedentary behaviours have increased over the past half century, with a rapid increase since the late 1990s. Excessive sedentary behaviour has been found to have independent and deleterious associations with markers of adiposity and cardiometabolic disease risk. These associations are especially consistent for screen-based sedentary behaviours (TV viewing, computer games, etc), with more conflicting findings observed for overall sedentary time. The above associations are possibly mediated by the influence of screen-based sedentary behaviours on energy intake. Although excessive sitting has been reported to have adverse acute and chronic metabolic impacts in adults, research on children is lacking. Research is particularly needed to investigate the impact of characteristics of sedentary behaviour (i.e. type/context, sedentary bout length, breaks in sedentary time, etc), as well as interventions that examine the health and behavioural impacts of sitting per se.

A comparison of physical activity and sedentary behaviour in 9-11 year old British Pakistani and White British girls: a mixed methods study

BACKGROUND

Previous studies suggest that British children of South Asian origin are less active and more sedentary than White British children. However, little is known about the behaviours underlying low activity levels, nor the familial contexts of active and sedentary behaviours in these groups. Our aim was to test hypotheses about differences between British Pakistani and White British girls using accelerometry and self-reports of key active and sedentary behaviours, and to obtain an understanding of factors affecting these behaviours using parental interviews.

METHODS

Participants were 145 girls (70 White British and 75 British Pakistani) aged 9-11 years and parents of 19 of the girls. Accelerometry data were collected over 4 days and girls provided 24-hour physical activity interviews on 3 of these days. Multilevel linear regression models and generalised linear mixed models tested for ethnic differences in activity, sedentary time, and behaviours. Semi-structured interviews were conducted with parents.

RESULTS

Compared to White British girls, British Pakistani girls accumulated 102 (95% CI 59, 145) fewer counts per minute and 14 minutes (95% CI 8, 20) less time in moderate to vigorous physical activity per day. British Pakistani girls spent more time (28 minutes per day, 95% CI 14, 42) sedentary. Fewer British Pakistani than White British girls reported participation in organised sports and exercise (OR 0.22 95% CI 0.08, 0.64) or in outdoor play (OR 0.42 95% CI 0.20, 0.91). Fewer British Pakistani girls travelled actively to school (OR 0.26 95% CI 0.10, 0.71). There was no significant difference in reported screen time (OR 0.88 95% CI 0.45, 1.73). Parental interviews suggested that structural constraints (e.g. busy family schedules) and parental concerns about safety were important influences on activity levels.

CONCLUSIONS

British Pakistani girls were less active than White British girls and were less likely to participate in key active behaviours. Sedentary time was higher in British Pakistani girls but reported screen-time did not differ, suggesting that British Pakistani girls engaged more than White British girls in other sedentary behaviours. Interviews highlighted some differences between the groups in structural constraints on activity, as well as many shared constraints.

Volumes and bouts of sedentary behavior and physical activity: associations with cardiometabolic health in obese children

OBJECTIVE

To examine associations of volumes and bouts of sedentary behavior (SED) and moderate-to-vigorous physical activity (MVPA) with individual and clustered cardio-metabolic outcomes in overweight/obese children.

METHODS

Cross-sectional data from 120 overweight/obese children (8.3 ± 1.1 years, 62% girls, 74% obese) with SED and MVPA assessed using accelerometry. Children were categorized into quartiles of mean bouts per day of SED (10, 20, and 30 min) and MVPA (5, 10, and 15 min). Associations with triglycerides, HDL cholesterol, glucose, insulin, systolic/diastolic blood pressure, and clustered cardio-metabolic risk (cMet) were examined using linear regression, adjusted for confounders.

RESULTS

Independent of MVPA, SED volume was inversely associated with HDL cholesterol (β [95% CI] = -0.29 [-0.52, -0.05]). MVPA volume was inversely associated with diastolic blood pressure, independent of SED (β = -0.22 [-0.44, -0.001]), and cMet (β = -0.19 [-0.36, -0.01]) although not after adjustment for SED (β = -0.14 [-0.33, 0.06]). Independent of MVPA and SED volumes, participants in the highest quartile of 30 min bouts per day of SED had 12% lower HDL cholesterol than those in the lowest quartile (d = 0.53, P = 0.046, Ptrend = 0.11).

CONCLUSIONS

In addition to increasing MVPA, targeting reduced SED and limiting bouts of SED to <30 min may contribute to improved HDL cholesterol levels and cardio-metabolic health in overweight/obese children.

Independent and combined associations of total sedentary time and television viewing time with food intake patterns of 9- to 11-year-old Canadian children

The relationships among sedentary time, television viewing time, and dietary patterns in children are not fully understood. The aim of this paper was to determine which of self-reported television viewing time or objectively measured sedentary time is a better correlate of the frequency of consumption of healthy and unhealthy foods. A cross-sectional study was conducted of 9- to 11-year-old children (n = 523; 57.1% female) from Ottawa, Ontario, Canada. Accelerometers were used to determine total sedentary time, and questionnaires were used to determine the number of hours of television watching and the frequency of consumption of foods per week. Television viewing was negatively associated with the frequency of consumption of fruits, vegetables, and green vegetables, and positively associated with the frequency of consumption of sweets, soft drinks, diet soft drinks, pastries, potato chips, French fries, fruit juices, ice cream, fried foods, and fast food. Except for diet soft drinks and fruit juices, these associations were independent of covariates, including sedentary time. Total sedentary time was negatively associated with the frequency of consumption of sports drinks, independent of covariates, including television viewing. In combined sedentary time and television viewing analyses, children watching >2 h of television per day consumed several unhealthy food items more frequently than did children watching ≤2 h of television, regardless of sedentary time. In conclusion, this paper provides evidence to suggest that television viewing time is more strongly associated with unhealthy dietary patterns than is total sedentary time. Future research should focus on reducing television viewing time, as a means of improving dietary patterns and potentially reducing childhood obesity.

Insulin secretion and its association with physical activity, fitness and screen time in children

OBJECTIVES

To determine the independent associations of moderate to vigorous physical activity (MVPA), fitness, screen time, and adiposity with insulin secretion in children.

DESIGN AND METHODS

Caucasian youth (n = 423/630), 8-10 years old, with at least one obese biological parent, were studied (QUALITY cohort). Insulin secretion was measured using HOMA2-%B, area under the curve (AUC) of insulin to glucose over the first 30 minutes (AUC I/G(t30min)) of the OGTT and AUC I/G(t120min) over 2 hours. Fitness was measured by VO₂peak ; percent fat mass (PFM) by DXA; 7-day MVPA by accelerometry; self-reported screen time included television, video game, or computer use. Models were adjusted for age, sex, season, puberty, PFM, and insulin sensitivity [IS] (HOMA2-IS, Matsuda-ISI).

RESULTS

PFM was strongly associated with insulin secretion, even after adjustment for IS: for every 1% increase in PFM, insulin secretion increased from 0.3% to 0.8% across indices. MVPA was negatively associated with HOMA2-%B (P < 0.05), but not with OGTT-derived measures. Fitness was negatively associated with AUC I/G(t120min) (P < 0.05). Screen time showed a trend toward higher HOMA2-%B in girls (P = 0.060).

CONCLUSIONS

In children with an obese parent, lower insulin secretion is associated with lower adiposity, higher MVPA, better fitness, and possibly reduced screen time.

Evaluating the Responsiveness of Accelerometry to Detect Change in Physical Activity

The responsiveness to change of the Actical and ActiGraph accelerometers was assessed in children and adolescents. Participants (n=208) aged 6-16 years completed two simulated free-living protocols, one with primarily light-to-moderate physical activities (PA) and one with mostly moderate-to-vigorous PA. Time in sedentary, light, moderate, and vigorous PA was estimated using 8 previously developed cut-points (4 for Actical and 4 for ActiGraph) and 15-s and 30-s epochs. Accelerometer responsiveness for detecting differences in PA between protocols was assessed using standardized response means (SRM). SRM values ≥0.8 represented high responsiveness to change. Both accelerometers showed high responsiveness for all PA intensities (SRMs = 1.2-4.7 for Actical and 1.1-3.3 for ActiGraph). All cut-points and epoch lengths yielded high responsiveness, and choice of cut-points and epoch length had little effect on responsiveness. Thus, both the Actical and ActiGraph can detect change in PA in a simulated free-living setting, irrespective of cut-point selection or epoch length.

Associations of sedentary behavior, sedentary bouts and breaks in sedentary time with cardiometabolic risk in children with a family history of obesity

BACKGROUND

Although reports in adults suggest that breaks in sedentary time are associated with reduced cardiometabolic risk, these findings have yet to be replicated in children.

PURPOSE

To investigate whether objectively measured sedentary behavior, sedentary bouts or breaks in sedentary time are independently associated with cardiometabolic risk in a cohort of Canadian children aged 8-11 years with a family history of obesity.

METHODS

Data from 286 boys and 236 girls living in Quebec, Canada, with at least one biological parent with obesity (QUALITY cohort) were collected from 2005-2008, and analyzed in 2013. Sedentary behavior, light and moderate-to-vigorous physical activity were measured over 7 days using accelerometry. Leisure time computer/video game use and TV viewing over the past 7 days were self-reported. Outcomes included waist circumference, body mass index Z-score, fasting insulin, fasting glucose, triglycerides, HDL-cholesterol, C-reactive protein and a continuous cardiometabolic risk score.

RESULTS

After adjustment for confounders, breaks in sedentary time and the number of sedentary bouts lasting 1-4 minutes were associated with reduced cardiometabolic risk score and lower BMI Z-score in both sexes (all p<0.05). The number of sedentary bouts lasting 5-9 minutes was negatively associated with waist circumference in girls only, while the number of bouts lasting 10-14 minutes was positively associated with fasting glucose in girls, and with BMI Z-score in boys (all p<0.05). Leisure time computer/video game use was associated with increased cardiometabolic risk score and waist circumference in boys, while TV viewing was associated with increased cardiometabolic risk, waist circumference, and BMI Z-score in girls (all p<0.05).

CONCLUSIONS

These results suggest that frequent interruptions in sedentary time are associated with a favourable cardiometabolic risk profile and highlight the deleterious relationship between screen time and cardiometabolic risk among children with a family history of obesity.