Longitudinal patterns of physical activity in children aged 8 to 12 years: the LOOK study

Comparison of physical activity and physical fitness in children and adolescents of Chinese Han and Tibet ethnicity

Background

Physical activity (PA) and physical fitness (PF) are important markers of health status in children and adolescents in different ethnicities. In this study, we aimed to compare the PA and PF indicators between Tibetan and Han children and adolescents.

Methods

Children and adolescents of 4-9 grades were recruited in Shigatse (n = 963) and Shanghai (n = 2,525) respectively. The information related to demographic, PA, and PF was collected via a self-reported questionnaire. PA was assessed through the participation of moderate to vigorous PA (MVPA), muscle-strengthening exercise (MSE) and organized sport participation (OSP). PF was estimated using the International Fitness Scale containing components of overall fitness, cardiorespiratory fitness, speed and agility, muscular strength and flexibility.

Results

Han (mean age = 13.45 ± 3.3 years; 49.7% girls) and Tibet (mean age = 13.8 ± 2.5 years; 48.3% girls) children and adolescents from Shanghai and Shigatse completed the questionnaire survey. It was revealed that Tibetan students had higher MVPA, MSE and OSP than children and adolescents of Han ethnicity (p < 0.01, small to medium effect size). A relatively higher percentage of student in Shanghai did not participate in any form of PA. On the other hand, less Tibetan students thought their PF indicators including overall fitness, cardiorespiratory fitness, speed and agility, muscular strength and flexibility were poor or very poor than their counterparts of Han ethnicity (p < 0.01, small to medium effect size).

Conclusion

Tibetan children and adolescents have higher levels of PA and PF in comparison to their Han counterparts. More children and adolescents of Han ethnicity engage in no PA and think their PF indicators were poor.

Adherence to 24-h movement behaviour guidelines in families with multiple children

BACKGROUND

In 2019, the World Health Organization (WHO) launched the first global movement guidelines for children that combined sleep, physical activity and screen time. Our previous research showed that adherence to age-specific guidelines for screen time was challenging for families with children in different age groups. We aimed to determine whether families with children in different age-based movement guideline categories have poorer adherence to the broader 24-h movement guidelines than those with all children in the same age category.

METHODS

Data were from the 1973-1978 cohort of the Australian Longitudinal Study on Women's Health (seventh survey, 2015) and the women's three youngest children (aged ≤12) (Mothers and their Children's Health sub-study, 2016/2017). The sample was 1787 women (families) with 4064 children (mean age 7.2 [SD 2.9]). Whether children in the family were in the same or different age-based category was determined by matching children's ages in a family against age-based guideline categories for the 24-h movement behaviours. The association between children in the family being in the same or different age-based guideline category on adherence to 24-h movement guidelines, both collectively and individually, was analysed by adjusted logistic regression (binary and multinomial).

RESULTS

Families with children in the same age guideline categories had double the odds of having all children meet 24-h movement guidelines (adjusted odds ratio [OR] 1.95 [95% confidence interval, CI: 1.32, 2.86]). Families with children in the same age categories on the screen guideline had higher odds of all children meeting (2.25 [1.73, 2.93]) and lower odds of some meeting/some failing the screen guideline (0.18 [0.14, 0.25]), than families with all children in different age categories. Families with children in the same age categories on the physical activity guideline had lower odds of all children meeting (0.57 [0.43, 0.75]) or some meeting/some failing the physical activity guideline (0.08 [0.06, 0.12]). No associations were found for sleep guidelines.

CONCLUSIONS

Families with multiple children may need practical advice and strategies on how to adhere to guidelines when children span age categories. This could form part of public health strategies that raise awareness of the guidelines and may improve guideline adherence.

Is Measuring Physical Literacy in School-Aged Children With Cystic Fibrosis or Congenital Heart Disease Needed?

PURPOSE

To explore the association between cardiorespiratory fitness and other physical literacy domains in children with cystic fibrosis (CF) or congenital heart disease (CHD).

METHODS

In 28 children with CF (n = 10) or CHD (n = 18), aged 7 to 11 years, cardiorespiratory fitness and the following physical literacy domains were measured: ( a ) physical competence, ( b ) motivation and confidence, ( c ) knowledge and understanding, and ( d ) daily behavior (ie, self-perceived moderate-to-vigorous physical activity [MVPA]).

RESULTS

Cardiorespiratory fitness was significantly associated with motivation and confidence and self-perceived MVPA. There were no other significant associations.

CONCLUSIONS

Cardiorespiratory fitness is associated with self-perceived MVPA, motivation, and confidence in children with CF or CHD.

Physical activity correlates in children and adolescents with autism spectrum disorder: a systematic review

PURPOSE

This systematic review examined correlates of physical activity (PA) at all levels of the socio-ecological model (i.e., intrapersonal, interpersonal, environmental and policy level) in children and adolescents with autism spectrum disorder (ASD).

MATERIALS AND METHODS

Major electronic databases were searched from inception until March 23^rd, 2021. A summary coding was used to analyze the data for children (3-12 years) and adolescents (13-18 years) with ASD separately.

RESULTS

Out of the 79 potential PA correlates, retrieved from 32 studies (991 657 children; 3857 adolescents), only five correlates were consistently examined as a PA correlate (i.e., examined in four or more studies) in children and adolescents with ASD. Only age was inversely associated with PA in children and adolescents with ASD. Data on gender, body mass index, autism severity level and day of the week being physically active in children with ASD were mixed.

CONCLUSIONS

We only found consistent evidence for age being inversely related to PA. Our review indicates that more research is needed to explore intrapersonal, interpersonal, environmental and policy-related correlates of PA in children and adolescents with ASD.IMPLICATIONS FOR REHABILITATIONRehabilitation programs should take into account that in particular older children and adolescents with autism spectrum disorder are at risk for physical inactivity.Boys and girls with autism spectrum disorder need the same care when motivating them to be more physically active.

Using compositional data analysis to explore accumulation of sedentary behavior, physical activity and youth health

PURPOSE

The study aimed to describe youth time-use compositions, focusing on time spent in shorter and longer bouts of sedentary behavior and physical activity (PA), and to examine associations of these time-use compositions with cardiometabolic biomarkers.

METHODS

Accelerometer and cardiometabolic biomarker data from 2 Australian studies involving youths 7-13 years old were pooled (complete cases with accelerometry and adiposity marker data, n = 782). A 9-component time-use composition was formed using compositional data analysis: time in shorter and longer bouts of sedentary behavior; time in shorter and longer bouts of light-, moderate-, or vigorous-intensity PA; and "other time" (i.e., non-wear/sleep). Shorter and longer bouts of sedentary time were defined as <5 min and ≥5 min, respectively. Shorter bouts of light-, moderate-, and vigorous-intensity PA were defined as <1 min; longer bouts were defined as ≥1 min. Regression models examined associations between overall time-use composition and cardiometabolic biomarkers. Then, associations were derived between ratios of longer activity patterns relative to shorter activity patterns, and of each intensity level relative to the other intensity levels and "other time", and cardiometabolic biomarkers.

RESULTS

Confounder-adjusted models showed that the overall time-use composition was associated with adiposity, blood pressure, lipids, and the summary score. Specifically, more time in longer bouts of light-intensity PA relative to shorter bouts of light-intensity PA was significantly associated with greater body mass index z-score (zBMI) (β = 1.79; SE = 0.68) and waist circumference (β = 18.35, SE = 4.78). When each activity intensity was considered relative to all higher intensities and "other time", more time in light- and vigorous-intensity PA, and less time in sedentary behavior and moderate-intensity PA, were associated with lower waist circumference.

CONCLUSION

Accumulating PA, particularly light-intensity PA, in frequent short bursts may be more beneficial for limiting adiposity compared to accumulating the same amount of PA at these intensities in longer bouts.

Using compositional analysis to explore the relationship between physical activity and cardiovascular health in children and adolescents with and without type 1 diabetes

OBJECTIVE

The aim of this study was to use a compositional analysis approach to account for the inherent co-dependencies between behaviors and to explore how daily movement behaviors influence cardiovascular health in children with and without T1D.

RESEARCH DESIGN AND METHODS

Augmentation index, pulse wave velocity (PWV) and heart rate variability were measured in 20 children with (11.9 ± 1.6 years) and 17 children without T1D (11.6 ± 2.2 years). Subsequently, physical activity and sleep were assessed at 20 Hz for 28 consecutive days using a wrist-worn accelerometer. Compositional analyses were utilized to explore the relative effects of each movement behavior and the overall movement complex on cardiovascular parameters, with predictive modeling used to explore the effects of reallocating 20 min between behaviors.

RESULTS

Arterial stiffness markers were most influenced by the total movement composition, whereas autonomic function was most influenced by sedentary time and sleep relative to all other behaviors. Reallocation of time from moderate-to-vigorous physical activity (MVPA) to any other behavior was predicted to negatively affect all cardiovascular measures, independent of disease status, whereas reallocating time to MVPA was consistently predicted to improve all outcome measures. Additionally, the same intensity of physical activity appeared to be more potent for cardiovascular health in T1D children compared to nondiabetic peers.

CONCLUSIONS

Intensity, rather than volume, of physical activity may be key in reducing risk of premature adverse changes in cardiovascular health, whereas increasing time in MVPA could potentially the slow progression of cardiovascular aging in children with diabetes.

Changes in 24-Hour Physical Activity Patterns and Walking Gait Biomechanics After Primary Total Hip Arthroplasty: A 2-Year Follow-up Study

BACKGROUND

Despite marked improvements in self-reported pain, perceived functional ability, and gait function following primary total hip arthroplasty (THA), it remains unclear whether these improvements translate into improved physical activity and sleep behaviors. The aim of this study was to determine the change in 24-hour activity profile (waking activities and sleep) and laboratory-based gait function from preoperatively to 2 years following the THA.

METHODS

Fifty-one patients undergoing primary THA at a single public hospital were recruited. All THAs were performed using a posterior surgical approach with the same prosthesis type. A wrist-worn accelerometer was used to capture 24-hour activity profiles preoperatively and at 1 and 2 years postoperatively. Three-dimensional gait analysis was performed to determine changes in temporospatial and kinematic parameters of the hip and pelvis.

RESULTS

Patients showed improvements in all temporospatial and kinematic parameters with time. Preoperatively, patients were sedentary or asleep for a mean time (and standard deviation) of 19.5 ± 2.2 hours per day. This remained unchanged up to 2 years postoperatively (19.6 ± 1.3 hours per day). Sleep efficiency remained suboptimal (<85%) at all time points and was worse at 2 years (77% ± 10%) compared with preoperatively (84% ± 5%). More than one-quarter of the sample were sedentary for >11 hours per day at 1 year (32%) and 2 years (41%), which was greater than the preoperative percentage (21%). Patients accumulated their activity performing light activities; however, patients performed less light activity at 2 years compared with preoperative levels. No significant differences (p = 0.935) were observed for moderate or vigorous activity across time.

CONCLUSIONS

Together with improvements in self-reported pain and perceived physical function, patients had significantly improved gait function postoperatively. However, despite the opportunity for patients to be more physically active postoperatively, patients were more sedentary, slept worse, and performed less physical activity at 2 years compared with preoperative levels.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Children's moderate-to-vigorous physical activity on weekdays versus weekend days: a multi-country analysis

Purpose

The Structured Days Hypothesis (SDH) posits that children’s behaviors associated with obesity – such as physical activity – are more favorable on days that contain more ‘structure’ (i.e., a pre-planned, segmented, and adult-supervised environment) such as school weekdays, compared to days with less structure, such as weekend days. The purpose of this study was to compare children’s moderate-to-vigorous physical activity (MVPA) levels on weekdays versus weekend days using a large, multi-country, accelerometer-measured physical activity dataset.

Methods

Data were received from the International Children’s Accelerometer Database (ICAD) July 2019. The ICAD inclusion criteria for a valid day of wear, only non-intervention data (e.g., baseline intervention data), children with at least 1 weekday and 1 weekend day, and ICAD studies with data collected exclusively during school months, were included for analyses. Mixed effects models accounting for the nested nature of the data (i.e., days within children) assessed MVPA minutes per day (min/day MVPA) differences between weekdays and weekend days by region/country, adjusted for age, sex, and total wear time. Separate meta-analytical models explored differences by age and country/region for sex and child weight-status.

Results/findings

Valid data from 15 studies representing 5794 children (61% female, 10.7 ± 2.1 yrs., 24% with overweight/obesity) and 35,263 days of valid accelerometer data from 5 distinct countries/regions were used. Boys and girls accumulated 12.6 min/day (95% CI: 9.0, 16.2) and 9.4 min/day (95% CI: 7.2, 11.6) more MVPA on weekdays versus weekend days, respectively. Children from mainland Europe had the largest differences (17.1 min/day more MVPA on weekdays versus weekend days, 95% CI: 15.3, 19.0) compared to the other countries/regions. Children who were classified as overweight/obese or normal weight/underweight accumulated 9.5 min/day (95% CI: 6.9, 12.2) and 10.9 min/day (95% CI: 8.3, 13.5) of additional MVPA on weekdays versus weekend days, respectively.

Conclusions

Children from multiple countries/regions accumulated significantly more MVPA on weekdays versus weekend days during school months. This finding aligns with the SDH and warrants future intervention studies to prioritize less-structured days, such as weekend days, and to consider providing opportunities for all children to access additional opportunities to be active.

Associations between in-school-hours physical activity and child health-related quality of life: A cross-sectional study in a sample of Australian primary school children

The aim of the current study was to examine the association between Australian primary school children's objectively measured in-school-hours weekly physical activity (PA) and their health-related quality of life (HRQoL). A cross-sectional study of 1128 Grade 2 and 3 children, aged 7-9 years, from 62 primary schools was conducted in New South Wales, Australia between October 2017 and April 2018. Children's PA was assessed via an accelerometer worn for five days during school hours. Their parents completed a telephone interview, answering demographic, child HRQoL and out-of-school-hours PA questions. Children's in-school-hours PA was classified as total PA and moderate-to-vigorous PA (MVPA). HRQoL scores were aggregated and reported at the high construct level domains (Total Quality of Life (Total HRQoL), Physical and Psychosocial Health Summary Scores). Multiple linear mixed regression analyses accounting for clustering were conducted to evaluate the association between children's in-school-hours weekly PA and their HRQoL. After adjusting for potential confounders, significant positive associations were found between children's in-school-hours weekly total PA and Total HRQoL (0.62 units, 95% CI: 0.29; 0.94, p < 0.001), Physical (0.71 units, 95% CI: 0.38; 1.04, p ≤ 0.001) and Psychosocial (0.58 units, 95% CI: 0.19; 0.97, p = 0.004) scores, with a stronger association observed between average weekly MVPA than average weekly total PA. There were also positive associations between PA and HRQoL for each sex when analysed separately. Our findings demonstrate a positive association between children's objectively-measured in-school-hours PA and parent-reported child HRQoL, strengthening evidence supporting the continued implementation of school-based PA programs for broader health outcomes.

Sleep is Inversely Associated with Sedentary Time among Youth with Obesity

Objective: Pathways underlying the sleep-obesity relationship in youth are poorly understood. In this study, we examined associations of sleep with sedentary time and moderate-to-vigorous physical activity (MVPA) among youth, stratified by weight category (obesity versus no obesity). A sub-aim examined whether controlling for screen time changed the sleep-sedentary time association. Methods: Methods entailed secondary analysis of baseline data collected June-August 2014-2017 during a school-based healthy weight management trial in Minneapolis/St. Paul, Minnesota. Participants (N = 114) were 8-to-12 years old with BMI ≥ 75th percentile, most of whom were members of racial/ethnic minority groups (57%) or from households receiving economic assistance (55%). Mean nightly sleep duration and daily screen time were measured by survey, MVPA and sedentary time by accelerometer, and height and weight by research staff. Multivariate linear regression examined associations of sleep with sedentary time and MVPA. Results: Sleep was inversely associated with hours of sedentary time (β = -1.34 [-2.11, -0.58] p = .001) and percent of time spent sedentary (β = -2.92 [-4.83, -1.01], p = .004), for youth with obesity only. The association was unchanged by screen time. Sleep was not significantly associated with MVPA in total sample or stratified models. Conclusions: Associations among sleep, activity levels, and obesity may differ based upon movement type (sedentary time vs MVPA) and weight category (obesity vs no obesity).

Australian Primary School Principals', Teachers', and Parents' Attitudes and Barriers to Changing School Uniform Policies From Traditional Uniforms to Sports Uniforms

BACKGROUND

To determine Australian primary school principals', teachers', and parents' attitudes to changing school uniform policies to allow students to wear sports uniforms every day and to assess associations between participant characteristics and their attitudes. A secondary aim was to identify principals' and teachers' perceived barriers to uniform changes.

METHODS

Cross-sectional surveys of principals, teachers, and parents of children in grades 2 to 3 (age 7-10 y) from 62 Australian primary schools (Oct 2017-Mar 2018) were undertaken. Mixed logistic regression analyses assessed the associations between participant characteristics and attitudes toward uniform changes.

RESULTS

In total, 73% of the principals (38/52) who responded reported that their school only allowed children to wear a sports uniform on sports days. Overall, 38% of the principals (18/47), 63% of the teachers (334/579), and 78% of the parents (965/1231) reported they would support a policy that allowed children to wear daily sports uniforms. The most commonly reported barrier was the perception that sports uniforms were not appropriate for formal occasions.

CONCLUSIONS

Although the majority of the principals were not supportive of a change to a daily sports uniform, the majority of the teachers and parents were. Strategies to improve principal support may be required if broader adoption of physical activity-supporting uniforms is to be achieved.

A Sex/Gender Perspective on Interventions to Reduce Sedentary Behaviour in Girls and Boys: Results of the genEffects Systematic Review

This systematic review aims to evaluate the extent of sex/gender consideration and effectiveness of interventions designed to reduce sedentary behaviour (SB). We searched for randomised or non-randomised controlled trials with the outcome SB and a sex/gender analysis in eleven electronic databases. Sixty-seven studies were included. Sex/gender considerations were qualitatively rated. Sex/gender was reported separately in 44.8% of studies, 14.9% of studies conducted a sex/gender interaction analysis, and 19.4% enrolled either girls or boys. SB was significantly reduced for girls in 16.4%, for boys in 11.9% and for both in 13.4%. No sex/gender intervention effect was found in 38.8%. According to the qualitative rating, studies without significant sex/gender effects reached "detailed" rating twice as often as studies finding a significant intervention effect for either girls or boys, or both. Overall, no clear pattern according to the qualitative rating and in terms of intervention effectiveness can be drawn. The results reveal a lack of sufficient sex/gender information in intervention planning and delivery. Further research should consider analysing sex/gender intervention effects as well as consider sex/gender inclusive intervention planning and delivery.

Cross-Sectional Associations of Total Daily Volume and Activity Patterns across the Activity Spectrum with Cardiometabolic Risk Factors in Children and Adolescents

Sedentary and physical activity patterns (bouts/breaks) may be important for cardiometabolic health in early life. This study aimed to examine cross-sectional associations of total daily volume and patterns across the activity spectrum with cardiometabolic risk factors in youth aged 7-13 years. Objectively measured accelerometer and cardiometabolic risk factor data were pooled from two studies (n = 1219; 69% valid accelerometry). Total daily volume of sedentary time and light-, moderate-, and vigorous-intensity physical activity was determined. Time in sustained bouts and median bout lengths of all intensities and breaks in sedentary time were also calculated. Outcomes included body mass index, waist circumference, blood pressure, blood lipids, and a cardiometabolic summary score. Regression models revealed beneficial associations between total daily volumes of moderate- and vigorous-intensity physical activity and cardiometabolic risk. Time spent in ≥1 min vigorous-intensity physical activity bouts was beneficially associated with cardiometabolic risk, yet this disappeared after adjusting for total vigorous-intensity physical activity and confounders. Time accumulated in light- (≥1 min; ≥5 min) and moderate-intensity (≥1 min) physical activity bouts was detrimentally associated with cardiometabolic risk. Total daily volume and activity patterns may have implications for cardiometabolic risk early in life. Sporadic physical activity may be more beneficial for health than sustained physical activity.

Objectively Assessed Physical Activity of Preschool-Aged Children from Urban Areas

Little is known about physical activity (PA) of preschool-age children in Poland through the course of the day. PA monitoring using an accelerometer increases the reliability of measuring daily PA levels and offers a reasonable compromise between accuracy and feasibility of measurement. The aim of the study was to determine the level of physical activity of preschool children (aged 5-6) on the basis of moderate to vigorous physical activity (MVPA) index and the number of steps. The physical activity of preschool children was assessed using accelerometery (ActiGraph) in 371 children for up to seven days. The normality of distribution was assessed using the Shapiro-Wilk test. The Mann-Whitney U-test and Kruskal-Wallis test were used to assess the significance of differences. The study group children had an average age of 5.4 years (± 0.6). Boys and girls showed a different level of MVPA index. The results significantly improve the current knowledge of PA in Europe. Promoting active lifestyles in children should be one of the health priorities in developed countries.

Longitudinal changes in moderate-to-vigorous-intensity physical activity in children and adolescents: A systematic review and meta-analysis

Moderate-to-vigorous-intensity physical activity (MVPA) is important for childhood obesity prevention and treatment, yet declines with age. Timing and magnitude of the decline in MVPA in children and adolescents are unclear but important for informing effective obesity intervention development. This systematic review aimed to determine and compare the year-to-year changes in MVPA among children and adolescents. Longitudinal studies were identified by searching 10 relevant databases up to December 2018. Studies were eligible for inclusion if they reported accelerometer-assessed MVPA (min day^-1 ) separately for boys and girls and had follow-up duration of at least 1 year. After screening 9,232 studies, 52 were included representing 22,091 aged 3 to 18 year olds (boys=8,857; girls=13,234). Pooled-analysis of the relative change in MVPA per year showed a decline of -3.4% (95% CI, -5.9 to -0.9) in boys and -5.3% (95% CI, -7.6 to -3.1) in girls, across all age groups. There were notable declines in MVPA at age 9 for both boys (-7.8%, 95% CI, -11.2 to -4.4) and girls (-10.2%, 95% CI, -14.2 to -6.3). The relative decline in MVPA affects both sexes from an early age; however, it is greater among girls. Interventions to promote MVPA should start before adolescence.

Self-Efficacy, Not Peer or Parent Support, Is Associated With More Physical Activity and Less Sedentary Time Among 8- to 12-Year-Old Youth With Elevated Body Mass Index

BACKGROUND

Youth experience a decrease in physical activity (PA) and an increase in sedentary time during adolescence. Better understanding of factors associated with activity levels during preadolescence may inform interventions to minimize decline. This study compared the association of self-efficacy for PA, parent support for PA, and peer support for PA with moderate-to-vigorous PA (MVPA) and sedentary time among 8- to 12-year-old children with body mass index ≥75th percentile.

METHODS

This study analyzed baseline data from a school-based healthy weight management intervention trial, conducted in metropolitan Minnesota. Self-efficacy for PA, parent support for PA, and peer support for PA were measured by child survey using reliable tools. MVPA and sedentary time were measured using accelerometer.

RESULTS

Participants included 114 children; mean age was 9.4 (0.9) years, 51% were females, 55% received public assistance, and 57% were racial/ethnic minorities. Self-efficacy for PA was positively associated with moderate to vigorous PA for girls (β = 1.83, P < .01) and inversely with sedentary time for the total sample (β = -7.00, P = .03). Parent support for PA was positively associated with sedentary time for girls (β = 9.89, P = .04) and the total sample (β = 7.83, P = .04).

CONCLUSIONS

Interventions for preadolescents with elevated body mass index may improve activity levels by increasing self-efficacy for PA.

Disentangling Physical Activity and Sedentary Behavior Patterns in Children with Low Motor Competence

Children with low motor competence (MC) are at high-risk for physical inactivity, yet little is known about their physical activity (PA) and sedentary behavior (SB) patterns throughout the day. The purpose of this study is to disentangle PA and SB patterns among children with low MC across segmented day periods taking into account differences in gender and age. Data collection took place between May and July 2017. The Athletic Skills Track was used to measure MC. PA levels were objectively measured using accelerometers (ActiGraph, GT3X+) on school days. Data were segmented for (1) time before school, (2) time during school (based on school schedules), and (3) time after school. In total, data from 117 7-to-11 years-old children with low MC were eligible for analyses (N = 58 girls; N = 59 boys). Differences in moderate-to-vigorous PA (MVPA) and SB between segmented periods, gender, and grade were analyzed by ANOVAs with post hoc tests (Tukey) and Independent Sample T-tests respectively. Time spent at school is the major contributor of time spent in SB in children with low MC. Low MC is equally distributed among gender, but large differences exist among boys and girls in both MVPA and SB, indicating low-MC girls as most inactive group. This pattern is found in all segmented periods of the school day, i.e., before, during, and after school. This study stresses the negative contribution of current school curricula on PA and SB in children with low MC, indicating the most efficient period of the day to intervene. Future school-based PA and SB interventions should particularly focus on specific high-risk populations, i.e., children with low MC, and girls in particular.

Physical activity and sedentary activity: population epidemiology and concordance in Australian children aged 11-12 years and their parents

OBJECTIVES

To describe the epidemiology and parent-child concordance of objectively measured physical activity in a population-based sample of Australian parent-child dyads.

DESIGN

Cross-sectional study (Child Health CheckPoint) nested within the Longitudinal Study of Australian Children.

SETTING

Assessment centres in seven Australian cities and eight regional towns or home visits; February 2015-March 2016.

PARTICIPANTS

Of all CheckPoint families (n=1874), 1261 children (50% girls) and 1358 parent (88% mothers) provided objectively measured activity data, comprising 1077 parent-child dyads.

OUTCOME MEASURES

Activity behaviour was assessed by GENEActiv accelerometer. Duration of moderate-to-vigorous physical activity (MVPA) and vigorous physical activity and sedentary behaviour (SB) were derived using Cobra custom software, along with MVPA/SB fragmentation and mean daily activity. Pearson's correlation coefficients and linear regression estimated parent-child concordance. Survey weights and methods accounted for the complex sample design and clustering.

RESULTS

Although parents had average lower accelerometry counts than children (mean [SD] 209 [46] vs 284 [71] g.min), 93% of parents met MVPA daily duration guidelines on published cutpoints (mean [SD] 125 [63] min/day MVPA), compared with only 15% of children (mean 32 [27] min). Parents showed less daily SB duration (parents: 540 [101], children: 681 [69] minutes) and less fragmented accumulation of MVPA (parents: α=1.85, children: α=2.00). Parent-child correlation coefficients were 0.16 (95% CI 0.11 to 0.22) for MVPA duration, 0.10 (95% CI 0.04 to 0.16) for MVPA fragmentation, 0.16 (95% CI 0.11 to 0.22) for SB duration and 0.18 (95% CI 0.12 to 0.23) for SB fragmentation.

CONCLUSIONS

Standardised cutpoints are needed for objective activity measures to inform activity guidelines across the lifecourse. This may reflect large amounts of time in non-shared environments (school and work).

Accelerometer-Measured Physical Activity in Children and Adolescents at Altitudes over 3500 Meters: A Cross-Sectional Study in Tibet

There is a scarcity of studies on the physical activity (PA) of children and adolescents who live at high altitudes. This study aimed to objectively assess PA of children and adolescents living in the Tibet at altitudes over 3500 m and to examine its difference by ethnicity, gender, age/grade, and body weight status groups. A sample of 397 students aged 9–18 years were recruited from 7 schools in Lhasa, Tibet. PA was measured using accelerometers (ActiGraph GT3X) for seven consecutive days and moderate to vigorous PA (MVPA) was identified using the Evenson (2008) cut-points. Participant MVPA was 62.3 min/day, with 65.5 min/day during weekdays and 54.1 min/day on weekends. Indigenous Tibetans were more active than Hans, and boys had more MVPA than girls. Age had a significantly weak negative correlation with MVPA. There was no significant difference in MVPA between the non-overweight and overweight/obese groups. Overall, only 9.1% (13.8% in boys and 4.5% in girls) accumulated at least 60 min of MVPA per day. Compared to their counterparts in other regions, the daily MVPA of children and adolescents living on the Tibetan Plateau at altitudes over 3500 m was relatively high. However, the proportion of meeting the WHO’s PA recommendations was extremely low.

Pedometer-determined physical activity among primary schoolchildren in Kuala Lumpur

Objective:

The aim of this study was to objectively measure physical activity and its association with sociodemographic factors among Malaysian primary school-age children.

Methods:

A total of 111 primary school children in Kuala Lumpur were selected through random sampling. Activity pattern was determined using pedometers and differences by sex, ethnicity and body mass index categories were analysed. The relationship between pedometer-determined physical activity and sociodemographic factors were also studied.

Results:

Overall, boys attained significantly higher daily step counts than girls (9573 ± 4145 vs 7313 ± 2697). Significant difference in daily step counts between boys and girls were observed during weekdays ( p<0.01), weekends ( p<0.05) and total mean step counts ( p<0.01). Malay ethnicity showed higher daily step counts during weekdays than weekends ( p<0.05). Compared with boys, girls had higher odds (OR=5.58; 95% CI 1.12, 27.77) of not meeting the recommended daily step counts. Those who had low physical activity levels had higher odds (OR=15.75; 95% CI 1.78, 139.33) of not meeting recommended daily step counts than children who had moderate physical activity level.

Conclusion:

Boys were significantly more active than girls and physical activity was greater during weekdays than on weekends. The primary schoolchildren in Kuala Lumpur were sedentary, with minimum physical activity being observed. Differences in sexes and physical activity levels influenced pedometer step counts in children.

Determinants of Physical Activity for Latino and White Middle School-Aged Children

BACKGROUND

Physical activity (PA) has long been acknowledged to contribute health benefits among children. However, research has consistently shown that PA declines as children grow older. Thus, this study examined the factors which are associated to children's PA in order to identify potential barriers to PA.

METHODS

Using data from the KidQuest Program, we conducted bivariate and multivariate analyses on survey data collected from fifth to seventh grade students in a small Midwestern city.

RESULTS

We found that food knowledge, eating breakfast, and talking with family about eating healthy foods, are positively related to PA. On the other hand, screen time is negatively related to PA. In addition, our results evinced differences between ethnicities and found that Latino children's screen time affects their PA levels more than their white counterpart.

CONCLUSIONS

There are different factors which can be tapped to increase PA among middle school-aged children. Given the differences between the Latino and white samples especially in screen time, schools should consider individualized intervention, rather than a "one size fits all" program, to increase PA participation.

Patterns of Physical Activity Adherence by Adolescents With Diabetes or Obesity Enrolled in a Personalized Community-Based Intervention

PURPOSE

The purpose of this study was to determine the feasibility of a personalized, 16-week community-based physical activity intervention for adolescents with diabetes or obesity and examine the weekly patterns of adherence to the intervention.

METHODS

Physical activity adherence was evaluated throughout the intervention using accelerometers in 46 adolescents with type 1 diabetes (N = 22), type 2 diabetes (N = 12), or obesity (N = 12) (age, 14.4 ± 1.5 years; 56.5% female; 61% Hispanic). Of these, 39 completed the intervention, and 7 did not.

RESULTS

There were no differences in baseline anthropometric characteristics or fitness between the completers versus noncompleters. Completers began above 1060 metabolic equivalent (MET) min/wk-1and stayed above 900 MET min/wk-1 for ~4 weeks and declined 39 MET min/wk-1 until end of study. Noncompleters began at 924 MET min/wk-1 yet dropped below 800 MET min/wk-1 by end of week 1 and declined an average of 151 MET min/wk-1. Interestingly, self-report of barriers to activity were higher in completers versus noncompleters.

CONCLUSIONS

Findings highlight that adolescents completing the intervention could sustain a prescribed level of personalized activity for at least 1 month but had steadfast declines in weekly activity. Even with individualized programs, factors other than barriers to activity need to be considered when designing approaches to physical activity adherence for adolescents with diabetes or obesity.

Investigating Motor Competence in Association with Sedentary Behavior and Physical Activity in 7- to 11-Year-Old Children

Children's motor competence (MC) has declined in the past decades, while sedentary behavior (SB) has increased. This study examined the association between MC and physical activity (PA) levels among primary schoolchildren. Demographics, body height and weight, MC (Athletic Skills Track), and PA levels (ActiGraph, GT3X+) were assessed among 595 children (291 boys, mean age = 9.1 years, SD = 1.1). MC was standardized into five categories: from very low to very high. PA levels were classified into SB, light PA (LPA), and moderate-to-vigorous PA (MVPA). Mixed-model analyses were conducted with PA levels as dependent variables and MC as the independent variable, while adjusting for age, gender, and body mass index (BMI) z-score on the individual level. A negative association between MC and SB and a positive association between MC and MVPA were found. The strength of both associations increased as children expressed lower or higher levels of MC. MC is an important correlate of both SB and MVPA, particularly for children with very high or low MC. Developing and improving children's MC may contribute to spending less time in SB and more time in MVPA, particularly for high-risk groups, i.e., children with low MC. Moreover, addressing MC development and PA promotion simultaneously might create positive feedback loops for both children's MC and PA levels.

Bone health, activity and sedentariness at age 11-12 years: Cross-sectional Australian population-derived study

AIM

To examine cross-sectional associations of children's bone health (size, density, strength) with moderate-vigorous physical activity (MVPA) and sedentary behaviour by considering: (1) duration of activity, (2) fragmentation, and (3) duration/fragmentation combined.

METHODS

Design: Population-based cross-sectional study.

PARTICIPANTS

11-12 year-olds in the Longitudinal Study of Australian Children's Child Health CheckPoint. Exposures: MVPA and sedentary behaviour (7-day accelerometry), yielding (1) daily average durations (min/day) and (2) fragmentations (the parameter alpha, representing the relationship between activity bout frequency and bout length).

OUTCOMES

Tibial peripheral quantitative computed tomography (bone density, geometry, strength).

ANALYSIS

Multivariable regression models including activity durations and fragmentations separately and combined.

RESULTS

Of 1357 children attending the CheckPoint, 864 (64%) provided both bone and accelerometry data (mean age 11.4 years (standard deviation (SD) 0.5); 49% male). Mean daily MVPA and sedentary behaviour durations were 34.4 min/day (SD 28.3) and 667.9 min/day (SD 71.9) respectively for boys and girls combined. Each additional daily hour of MVPA was associated with small bone health benefits comprising greater periosteal and endosteal circumference (standardised effect sizes 0.25, 95% CI 0.10 to 0.40 and 0.21, 95% CI 0.03 to 0.39, respectively) and bone strength (0.26, 95% CI 0.14 to 0.38). Sedentary duration and fragmentation of either MVPA or sedentary behaviour showed little association with bone health.

CONCLUSIONS

In early adolescence, MVPA duration showed associations with better bone health that, while modest, could be of population-level importance. MVPA fragmentation and sedentary behaviour duration and fragmentation seemed less important.

Sedentary Behaviour in Swiss Children and Adolescents: Disentangling Associations with the Perceived and Objectively Measured Environment

Identifying correlates of sedentary behaviour across all levels of the ecological model and understanding their interrelations is a promising method to plan effective interventions. The present study examined whether the objectively assessed and the perceived neighbourhood are associated with children’s sedentary behaviour time (SBT). A comprehensive set of factors at different levels of influence across the ecological model were taken into account and analysed for mediating and modifying effects. Analyses were based on 1306 children and adolescents (6⁻16 years) participating in the population-based SOPHYA-study. Accelerometers were used to assess SBT, the perceived environment was examined by a validated parental questionnaire, and objective environmental data were allocated using GIS (ArcMap 10.2, Esri, Redlands, CA, USA) for each family’s residential address. A high perceived safety was associated with less SBT. Boys, those whose residential neighbourhood was characterized by dead ends in urban areas, a low main street density in the neighbourhood of children and greenness were less likely to exhibit SBT. The association of the objective environment with the respective parental perceptions was low and no significant mediating effect was found for the perceived environment. We conclude for land-use planning to reduce sedentary behaviour objective environments should be complemented with efforts to increase parental sense of security.

Regular Physical Activity and Educational Outcomes in Youth: A Longitudinal Study

PURPOSE

The objectives of this study were to determine whether longitudinal changes in accelerometer-assessed moderate-to-vigorous physical activity (MVPA) were associated with changes in educational outcomes (i.e., academic performance and mathematics engagement) and to examine whether the association was nonlinear.

METHODS

Longitudinal data were collected from 2,194 Australian adolescents (mean age = 13.40 years, standard deviation = .73) at two time points (Term 1, 2014, and Term 2, 2015). To measure the total MVPA, the adolescents wore an accelerometer for seven consecutive days. The participants responded to a questionnaire to measure mathematics engagement and completed a nationally administered numeracy test to assess academic performance.

RESULTS

Latent change score models indicated that increases in MVPA had a positive quadratic association with National Assessment Program-Literacy and Numeracy (NAPLAN) scores in girls (β = .39, p < .001) but not boys. In comparison, cross-sectional regression analyses indicated that MVPA had a positive quadratic association with NAPLAN scores in grade 7 (β = .92, p = .04) boys and in grade 9 boys (β = .60, p = .06), but not in girls. There was also a positive quadratic association between MVPA and school engagement in grade 9 boys (β = .77, p = .03).

CONCLUSIONS

Cross-sectional evidence indicated that boys who were more physically active had better educational outcomes than their less active peers, and girls who increased their regular physical activity showed improvements in academic performance. All students need to increase their physical activity levels for health and educational benefits, without compromising the time spent on study and homework.

Correlates of compliance with recommended levels of physical activity in children

The purpose of this study was to describe children’s daily compliance with moderate-to-vigorous physical activity (MVPA) recommendations across a week in different parts of the world, and to identify individual- and school-level correlates that may explain differences in daily MVPA compliance. The sample included 6553 children aged 9–11 years from 12 countries, and multilevel statistical analyses were used, including both child- and school-level variables. Most children did not comply with the MVPA guidelines on a daily basis: Chinese children complied the least, whereas Finnish, Australian, Colombian, UK, and Kenyan children complied the most. Boys (rate ratio [RR] = 1.47) and children with higher unhealthy diet scores (RR = 1.08) complied more, but overweight/obese children (RR = 0.81), earlier maturing children (RR = 0.93), and those who spent more time in screen activities (RR = 0.98) and sleeping (RR = 0.96) had the lowest compliance. At the school level, children with access to playground or sport equipment (RR = 0.88, for both) tended to comply less, whereas those with access to a gymnasium outside the school hours complied more with the MVPA guidelines (RR = 1.14). Significant between-country differences in children’s daily MVPA compliance were observed, reflecting not only site characteristics, but also the importance of individual traits and local school contexts.

Parental Support and Objectively Measured Physical Activity in Children: A Yearlong Cluster-Randomized Controlled Efficacy Trial

PURPOSE

We studied whether physical activity (PA) counseling for parents influenced the level of parental support of children's PA and leisure-time PA in children of different levels of initial parental support. We hypothesized that the initial level of parental support would moderate the intervention efficacy.

METHOD

Children (n = 44, M_age = 6.09 ± 1.17 years) and their parents (n = 61) randomly assigned to an intervention group received counseling for 6 months. Children in the control group (n = 47, M_age = 6.12 ± 1.11 years) and their parents (n = 63) did not receive any counseling. Parental support was assessed using the Family Physical Activity Environment Questionnaire, and children's leisure-time PA was recorded using triaxial accelerometers at baseline, at 6 months, and at 12 months. The efficacy of the intervention was tested by linear mixed-effects modeling adjusted for confounding variables (Model 1) and additionally for children's participation in organized PA or sports (Model 2).

RESULTS

Parents within the lowest initial parental support intervention tertile significantly increased their support, and their children's mean level of leisure-time PA significantly improved compared with the corresponding controls during the counseling period. On the other hand, intervention was found to have an unfavorable influence especially in the PA of children of initially highly supportive parents.

CONCLUSION

Targeting PA counseling for parents with low support of their children's PA could contribute to better family-based PA counseling efficacy.

Longitudinal community walking activity in Duchenne muscular dystrophy

INTRODUCTION

Natural history studies for Duchenne muscular dystrophy (DMD) have not included measures of community ambulation.

METHODS

Step activity (SA) monitors quantified community ambulation in 42 boys (ages 4-16 years) with DMD with serial enrollment up to 5 years by using a repeated-measures mixed model. Additionally, data were compared with 10-meter walk/run (10mWR) speed to determine validity and sensitivity.

RESULTS

There were significant declines in average strides/day and percent strides at moderate, high and pediatric high rates as a function of age (P < 0.05). Significant correlations for 10mWR versus high and low stride rates were found at baseline (P < 0.05). SA outcomes were sensitive to change over 1 year, but the direction and parameter differed by age group (younger vs. older). Changes in strides/day and percentages of high frequency and low frequency strides correlated significantly with changes in 10mWR speed (P < 0.05).

DISCUSSION

Community ambulation data provide valid and sensitive real-world measures that may inform clinical trials. Muscle Nerve 57: 401-406, 2018.

Dyslipidemia management in overweight or obese adolescents: A mixed-methods clinical trial of motivational interviewing

Background:

Lifestyle management for dyslipidemic adolescents often occurs in the context of family-centered care, which necessitates adaptation of counseling strategies.

Objective:

To determine the effectiveness of motivational interviewing for lifestyle behavior change for dyslipidemic adolescents in a dyad with a parent versus alone.

Methods:

A total number of 32 adolescents were randomized 1:1 to receive a series of motivational interviewing sessions either together with a parent or alone for a 6-month intervention, with both quantitative and qualitative assessment of outcomes.

Results:

Both groups were similar at baseline. Following the intervention, there were no significant differences between groups in physical, laboratory, lifestyle or psychosocial measures, except for a reduction in dietary fats/sugars (p = 0.02) and in screen time (p = 0.02) in the alone group. When both groups were combined, significant reductions at 6 months were noted for body mass index (p < 0.001), waist circumference (p < 0.001), total cholesterol (p < 0.001), low-density lipoprotein cholesterol (p < 0.001), triglycerides (p = 0.01), non–high-density lipoprotein cholesterol (p < 0.001), fasting insulin (p = 0.01), and homeostatic model (p = 0.02). Reduced screen time and increased fruit and vegetable intake were also noted for both groups combined. These changes were also reflected in self-efficacy (p = 0.004), self-esteem (p = 0.03), and improvement in quality of life measures. Interview data provided insights into the utility and acceptability of the motivational interviewing intervention.

Conclusion:

Motivational interviewing was an efficient strategy for inspiring healthy lifestyle and physiological changes among adolescents in both groups. Family centered pediatric approaches should consider the autonomy and individual preferences of the adolescent prior to counseling.

Association between daily step counts and physical activity level among Korean elementary schoolchildren

[Purpose]

The purpose of the current study was to investigate steps per day (steps/d) and physical activity level (PAL) in Korean elementary school children having normal weight (normal-weight). We also clarified whether a gender difference exited between steps/d and PAL.

[Methods]

Children aged 9 to 12 y were recruited from two elementary schools located in different urban districts in Korea. The present study included 33 Korean children, of which 18 were normal-weight boys and 15 were normal-weight girls. During the same 1 week study period under free-living conditions the total energy expenditure (TEE) and step counts were estimated using the doubly labeled water (DLW) method and an accelerometer, respectively. We calculated PAL as the TEE/ resting metabolic rate.

[Results]

The range of PAL was 1.25 – 1.93 with a mean value of 1.57. None of the variables of energy expenditure was significantly different by sex. However, steps/d were significantly higher in boys than in girls. When adjusting regression analysis by gender, steps/ d were positively associated with PAL among all subjects (r = 0.56, P < 0.01). Furthermore, steps/d were positively associated with PAL in boys (r = 0.68, P < 0.01), but not in girls (r = 0.27, P = 0.34).

[Conclusion]

Our results suggest that locomotive activity may be the main contributor to the individual PAL differences for elementary school boys, while non-locomotive activity may be the main contributor for elementary school girls.

Outcomes of a four-year specialist-taught physical education program on physical activity: a cluster randomized controlled trial, the LOOK study

BACKGROUND

The objective of this study was to investigate the effect of a 4-year specialist-taught Physical Education (PE) program on physical activity (PA) among primary school children.

METHODS

A 4-year cluster randomised controlled trial was conducted in children (initially aged 8 years) from 29 primary schools (13 Intervention, 16 Control). Intervention students (N = 457) received 2 × 45 min PE lessons per week from specialist-trained PE teachers (68 lessons per year, 272 lessons over 4 years). Control group students (N = 396) received usual practice PE from generalist classroom teachers. PA during PE lessons was examined using the System for Observing Fitness Instruction Time (SOFIT). Pedometers (steps/day) were worn for 7 days each year, and accelerometers were worn concurrently in the final two years to assess moderate to vigorous (MVPA) and sedentary activity. Linear and generalized mixed models were used to determine differences in Intervention and Control student PA and the proportion of students meeting PA guidelines.

RESULTS

The intervention increased SOFIT-observed student MVPA during PE lessons by 6.5 mins (16.7 v 10.2, p < 0.001). Within intervention schools, participants increased their whole-day step counts (boys = 449 [CI,140 to 756]; girls = 424 [CI,222 to 626]) and minutes of MVPA (boys = 8.0 [CI,6.8 to 9.2]; girls = 3.5 [CI,1.7 to 5.4]) on PE days. However, compared to the Control group the Intervention did not: increase habitual steps/day or MVPA when averaged over 7 days; elicit greater improvements in these measures over time; or increase the odds of meeting step/day or MVPA recommendations. At age 11 years Intervention group boys were 20 mins less sedentary per day (380 [CI,369 to 391] vs 360 [CI,350 to 369]) and this effect was sustained at age 12 years.

CONCLUSIONS

Well-designed specialist-taught PE can improve student PA during PE lessons. However for PE to be a significant contributor to improving habitual PA in pre-adolescent children, daily classes are likely to be required, and even this would need to be supplemented with a wider multicomponent strategy. Our finding of a reduction in sedentary time among Intervention boys warrants further investigation into the potential role PE could play in influencing sedentary behaviour.

Write, draw, show, and tell: a child-centred dual methodology to explore perceptions of out-of-school physical activity

BACKGROUND

Research to increase children's physical activity and inform intervention design has, to date, largely underrepresented children's voices. Further, research has been limited to singular qualitative methods that overlook children's varied linguistic ability and interaction preference. The aim of this study was to use a novel combination of qualitative techniques to explore children's current views, experiences and perceptions of out-of-school physical activity as well as offering formative opinion about future intervention design.

METHODS

Write, draw, show and tell (WDST) groups were conducted with 35 children aged 10-11 years from 7 primary schools. Data were analysed through a deductive and inductive process, firstly using the Youth Physical Activity Promotion Model as a thematic framework, and then inductively to enable emergent themes to be further explored. Pen profiles were constructed representing key emergent themes.

RESULTS

The WDST combination of qualitative techniques generated complimentary interconnected data which both confirmed and uncovered new insights into factors relevant to children's out-of-school physical activity. Physical activity was most frequently associated with organised sports. Fun, enjoyment, competence, and physical activity provision were all important predictors of children's out-of-school physical activity. Paradoxically, parents served as both significant enablers (i.e. encouragement) and barriers (i.e. restricting participation) to physical activity participation. Some of these key findings would have otherwise remained hidden when compared to more traditional singular methods based approaches.

CONCLUSIONS

Parents are in a unique position to promote health promoting behaviours serving as role models, physical activity gatekeepers and choice architects. Given the strong socialising effect parents have on children's physical activity, family-based physical activity intervention may offer a promising alternative compared to traditional school-based approaches. Parents' qualitative input is important to supplement children's voices and inform future family-based intervention design. The WDST method developed here is an inclusive, interactive and child-centred methodology which facilitates the exploration of a wide range of topics and enhances data credibility.

Disparities in moderate-to-vigorous physical activity among girls and overweight and obese schoolchildren during school- and out-of-school time

BACKGROUND

Increasing physical activity (PA) during the school day and out-of-school time are critical strategies for preventing childhood obesity and improving overall health. The purpose of the present investigation was to examine schoolchildren's volume and type of PA during school-time and out-of-school, compared to national recommendations and differences by sex and weight status.

METHODS

This cross-sectional analysis included 517 3(rd)-5(th) grade schoolchildren from 13 New England elementary schools (October 2013-January 2014). Demographics were collected by parent questionnaire. Measured height and weight were used to categorize child weight status. Accelerometer data were collected over 7 days. PA was coded as total activity counts and minutes of sedentary, light, and moderate-to-vigorous physical activity (SED, LPA, MVPA) during 1) school, 2) weekday out-of-school, 3) weekend, and 4) total daily time. Multivariable mixed models were used to examine associations between sex and weight status and total counts, SED, LPA, and MVPA, controlling for demographics, wear-time, and clustering within schools.

RESULTS

453 participants (60.5% girls; mean age 9.1 years; 30.5% overweight/obese) had valid accelerometer wear time (≥3 days, ≥ 10 h/day). Few children achieved 60 min total daily (15.0%) or school-time (8.0 %) MVPA recommendations. For all time-of-day categories, girls achieved fewer MVPA minutes than boys (p < .0001), and overweight/obese participants achieved fewer MVPA minutes than normal/underweight participants (p = 0.05). Minutes of LPA declined by grade-level (p < .05) and were lower in girls than boys during school-time only (p < .05).

CONCLUSION

Disparities in MVPA by sex and weight status across school and out-of-school time highlight the need for programs with equitable reach.

Correlates of children's compliance with moderate-to-vigorous physical activity recommendations: a multilevel analysis

This study aimed to investigate the association between individual and school characteristics associated with the number of school days children comply with moderate-to-vigorous physical activity (MVPA) recommendations. Sample comprises 612 Portuguese children, aged 9-11 years, from 23 schools. Time spent in MVPA was measured by accelerometry, while individual-level correlates were obtained by anthropometry and questionnaires. School-level variables were collected by questionnaire, and accelerometer wear time and season were also considered. Maximum likelihood estimates of model parameters were obtained via a multilevel analysis with children as level-1, and school as level-2. Children who spent more time in sedentary activities and girls were less likely to comply with MVPA/daily. More mature children and those who use active transportation to school were more likely to attain the PA recommendation. Furthermore, greater accelerometer wear time and spring season increased the chance to achieve the recommended MVPA. In terms of school-level correlates, a greater number of available facilities was negatively associated with children MVPA compliance. Given the set of variables, our results showed that individual characteristics seem to be more relevant for children's compliance rates with PA/day than school context variables, which should be taken into account in the implementation of school policies and practices.

Why Are Girls Less Physically Active than Boys? Findings from the LOOK Longitudinal Study

Background

A gender-based disparity in physical activity (PA) among youth, whereby girls are less active than boys is a persistent finding in the literature. A greater understanding of the mechanisms underlying this difference has potential to guide PA intervention strategies.

Methods

Data were collected at age 8 and 12 years (276 boys, 279 girls) from 29 schools as part of the LOOK study. Multilevel linear models were fitted separately for boys and girls to examine effects of individual, family and environmental level correlates on pedometer measured PA. Cardio-respiratory fitness (multi-stage run), percent fat (DEXA), eye-hand coordination (throw and catch test) and perceived competence in physical education (questionnaire) were used as individual level correlates. At the family level, parent’s support and education (questionnaire) were used. School attended and extracurricular sport participation were included as environmental level correlates.

Results

Girls were 19% less active than boys (9420 vs 11360 steps/day, p<0.001, 95%CI [1844, 2626]). Lower PA among girls was associated with weaker influences at the school and family levels and through lower participation in extracurricular sport. School attended explained some of the variation in boys PA (8.4%) but not girls. Girls compared to boys had less favourable individual attributes associated with PA at age 8 years, including 18% lower cardio-respiratory fitness (3.5 vs 4.2, p<0.001, CI [0.5,0.9]), 44% lower eye-hand coordination (11.0 vs 17.3, p<0.001, CI [5.1,9.0]), higher percent body fat (28% vs 23%, p<0.001, CI [3.5,5.7]) and 9% lower perceived competence in physical education (7.7 vs 8.4, p<0.001, CI [0.2,0.9]). Participation in extracurricular sport at either age 8 or 12 years was protective against declines in PA over time among boys but not girls.

Conclusion

Girls PA was less favourably influenced by socio-ecological factors at the individual, family, school and environmental levels. These factors are potentially modifiable suggesting the gap in PA between boys and girls can be reduced. Strategies aiming to increase PA should be multicomponent and take into consideration that pathways to increasing PA are likely to differ among boys and girls.

Sensitivity of blood lipids to changes in adiposity, exercise, and diet in children

PURPOSE

This study aims to determine whether blood lipids in healthy preadolescent children are sensitive to normally occurring changes in percent body fat, physical activity (PA), cardiorespiratory fitness (CRF), and macronutrient intake.

METHODS

Repeated measurements of fasting serum LDL cholesterol, HDL cholesterol, and triglycerides (TG); percent body fat (dual-energy x-ray absorptiometry); PA (pedometers); CRF (multistage run); and carbohydrate, sugar, and fat intake (dietary recall and record) were carried out in 469 children (51% girls) age 8, 10, and 12 yr.

RESULTS

Longitudinal relationships in boys showed that, for every one-unit increase in percent body fat, there was a 1.3% (95% CI, 0.9-1.8; P < 0.001) increase in LDL cholesterol; among girls, the increase was 0.8% (95% CI, 0.3-1.2; P = 0.003). In addition, we found a positive longitudinal relationship between TG and percent body fat (P < 0.001) in girls, and a negative longitudinal relationship between HDL cholesterol and percent body fat (P = 0.03) in boys. There were also longitudinal relationships between TG and CRF in both sexes (P < 0.05), but these were not sustained upon adjustment for percent body fat. Although cross-sectional relationships occurred in girls for both HDL cholesterol and TG with PA (P < 0.05), we found no evidence of any relationships between lipids and fat or sugar intake. By age 12 yr, LDL cholesterol was elevated (>3.36 mmol·L) in 16% and 20% of girls and boys, respectively.

CONCLUSIONS

Blood lipids in preadolescent children appear sensitive to normal changes occurring in their percent body fat and, thus, fitness. Our data support early attention to body composition in community strategies designed to prevent cardiovascular disease in later life.

Estimates of the energy deficit required to reverse the trend in childhood obesity in Australian schoolchildren

OBJECTIVES

To estimate: 1) daily energy deficit required to reduce the weight of overweight children to within normal range; 2) time required to reach normal weight for a proposed achievable (small) target energy deficit of 0.42 MJ/day; 3) impact that such an effect may have on prevalence of childhood overweight.

METHODS

Body mass index and fitness were measured in 31,424 Australian school children aged between 4.5 and 15 years. The daily energy deficit required to reduce weight to within normal range for the 7,747 (24.7%) overweight children was estimated. Further, for a proposed achievable target energy deficit of 0.42 MJ/day, the time required to reach normal weight was estimated.

RESULTS

About 18% of children were overweight and 6.6% obese; 69% were either sedentary or light active. If an energy deficit of 0.42 MJ/day could be achieved, 60% of overweight children would reach normal weight and the current prevalence of overweight of 24.7% (24.2%-25.1%) would be reduced to 9.2% (8.9%-9.6%) within about 15 months.

CONCLUSIONS

The prevalence of overweight in Australian school children could be reduced significantly within one year if even a small daily energy deficit could be achieved by children currently classified as overweight or obese.

Effects of a Specialist-Led, School Physical Education Program on Bone Mass, Structure, and Strength in Primary School Children: A 4-Year Cluster Randomized Controlled Trial

This 4-year cluster randomized controlled trial of 365 boys and 362 girls (mean age 8.1 ± 0.3 years) from grade 2 in 29 primary schools investigated the effects of a specialist-taught physical education (PE) program on bone strength and body composition. All children received 150 min/week of common practice (CP) PE from general classroom teachers but in 13 schools 100 min/week of CP PE was replaced by specialized-led PE (SPE) by teachers who emphasized more vigorous exercise/games combined with static and dynamic postural activities involving muscle strength. Outcome measures assessed in grades 2, 4, and 6 included: total body bone mineral content (BMC), lean mass (LM), and fat mass (FM) by DXA, and radius and tibia (4% and 66% sites) bone structure, volumetric density and strength, and muscle cross-sectional area (CSA) by pQCT. After 4-years, gains in total body BMC, FM, and muscle CSA were similar between the groups in both sexes, but girls in the SPE group experienced a greater gain in total body LM (mean 1.0 kg; 95% CI, 0.2 to 1.9 kg). Compared to CP, girls in the SPE group also had greater gains in cortical area (CoA) and cortical thickness (CoTh) at the mid-tibia (CoA, 5.0% [95% CI, 0.2% to 1.9%]; CoTh, 7.5% [95% CI, 2.4% to 12.6%]) and mid-radius (CoA, 9.3% [95% CI, 3.5% to 15.1%]; CoTh, 14.4% [95% CI, 6.1% to 22.7%]), whereas SPE boys had a 5.2% (95% CI, 0.4% to 10.0%) greater gain in mid-tibia CoTh. These benefits were due to reduced endocortical expansion. There were no significant benefits of SPE on total bone area, cortical density or bone strength at the mid-shaft sites, nor any appreciable effects at the distal skeletal sites. This study indicates that a specialist-led school-based PE program improves cortical bone structure, due to reduced endocortical expansion. This finding challenges the notion that periosteal apposition is the predominant response of bone to loading during the prepubertal and early-pubertal period.

A systematic review of determinants of sedentary behaviour in youth: a DEDIPAC-study

Sedentary behaviour (SB) has emerged as a potential risk factor for metabolic health in youth. Knowledge on the determinants of SB in youth is necessary to inform future intervention development to reduce SB. A systematic review was conducted to identify predictors and determinants of SB in youth. Pubmed, Embase, CINAHL, PsycINFO and Web of Science were searched, limiting to articles in English, published between January 2000 and May 2014. The search strategy was based on four key elements and their synonyms: (a) sedentary behaviour, (b) determinants, (c) types of sedentary behaviours, (d) types of determinants. The full protocol is available from PROSPERO (PROSPERO 2014:CRD42014009823). Cross-sectional studies were excluded. The analysis was guided by the socio-ecological model. 37 studies were selected out of 2654 identified papers from the systematic literature search. Most studies were conducted in Europe (n = 13), USA (n = 11), and Australia (n = 10). The study quality, using the Qualsyst tool, was high with a median of 82 % (IQR: 74–91 %). Multiple potential determinants were studied in only one or two studies. Determinants were found at the individual, interpersonal, environmental and policy level but few studies examined a comprehensive set of factors at different levels of influences. Evidence was found for age being positively associated with total SB, and weight status and baseline assessment of screen time being positively associated with screen time (at follow-up). A higher playground density and a higher availability of play and sports equipment at school were consistently related to an increased total SB, although these consistent findings come from single studies. Evidence was also reported for the presence of safe places to cross roads and lengthening morning and lunch breaks being associated with less total SB. Future interventions to decrease SB levels should especially target children with overweight or obesity and should start at a young age. However, since the relationship of many determinants with SB remains inconsistent, there is still a need for more longitudinal research on determinants of SB in youth.

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.

Prevalence of Youth Fitness in the United States: Baseline Results from the NFL PLAY 60 FITNESSGRAM Partnership Project

OBJECTIVE

To assess age- and sex-specific patterns of 6 health-related fitness components in youth, baseline data from the NFL PLAY 60 FITNESSGRAM Partnership Project were analyzed.

STUDY DESIGN

A total of 192,848 students from 1st through 12th grade in 725 schools completed the standard FITNESSGRAM testing in 2010-2014, including assessments of aerobic capacity (AC), body mass index (BMI), upper body strength and endurance, trunk extensor strength and flexibility, abdominal strength and endurance, and flexibility. Individual data were aggregated by grade and sex. Age- and sex-specific health-related criterion-referenced standards were used to classify fitness results into the healthy fitness zone (HFZ), needs improvement zone, or needs improvement health risk.

RESULTS

The proportion of youth meeting the HFZ for AC varied considerably by grade for both boys (62.1%-37.6%) and girls (49.1%-26.1%) among 1st-12th grade. There was less variability by age and sex for achievement of the BMI HFZ (ranged from 52.7%-65.0%). The prevalence of achievement was similar for the remaining fitness components. Significantly lower achievement was found in the middle school years for BMI HFZ in both sexes and for AC HFZ achievement in boys. Continuous age-related lower HFZ achievement was evident in girls for AC.

CONCLUSIONS

The results provide updated health-related fitness profiles for US youth and identify the critical ages when youth fitness levels start to decline.

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

Background

An important but often ignored aspect of physical activity (PA) and sedentary behavior (SB) is the chronological succession of activities, or temporal pattern. The main purposes of this study were (1) to investigate when certain types of PA and SB compete against each other during the course of the day and (2) compare intensity- and domain-specific activity levels during different day-segments.

Methods

The study sample consists of 211 children aged 10–14, recruited from 15 primary and 15 secondary schools. PA was assessed combining the SenseWear Mini Armband (SWM) with an electronic activity diary. The intensity- and domain-specific temporal patterns were plotted and PA differences between different day-segments (i.e., morning, school, early evening and late evening) were examined using repeated-measures ANCOVA models.

Results

Physical activity level (PAL) was highest during the early evening (2.51 MET_SWM) and school hours (2.49 MET_SWM); the late evening segment was significantly less active (2.21 MET_SWM) and showed the highest proportion of sedentary time (54 % of total time-use). Throughout the different day-segments, several domains of PA and SB competed with each other. During the critical early-evening segment, screentime (12 % of time-use) and homework (10 %) were dominant compared to activity domains of sports (4 %) and active leisure (3 %). The domain of active travel competed directly with motor travel during the morning (5 % and 6 % respectively) and early-evening segment (both 8 %).

Conclusions

Throughout the day, different aspects of PA and SB go in competition with each other, especially during the time period immediately after school. Detailed information on the temporal patterns of PA and SB of children could help health professionals to develop more effective PA interventions and promotion strategies. By making adaptations to the typical day schedule of children (e.g., through the introduction of extra-curricular PA after school hours), their daily activity levels might improve.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-015-2093-7) contains supplementary material, which is available to authorized users.

Variability and Stability in Daily Moderate-to-Vigorous Physical Activity among 10 Year Old Children

Day-to-day variability and stability of children's physical activity levels across days of the week are not well understood. Our aims were to examine the day-to-day variability of moderate-to-vigorous physical activity (MVPA), to determine factors influencing the day-to-day variability of MVPA and to estimate stability of MVPA in children. The sample comprises 686 Portuguese children (10 years of age). MVPA was assessed with an accelerometer, and BMI was computed from measured height and weight. Daily changes in MVPA and their correlates (gender, BMI, and maturity) were modeled with a multilevel approach, and tracking was calculated using Foulkes &amp; Davies γ. A total of 51.3% of boys and 26.2% of girls achieved 60 min/day of MVPA on average. Daily MVPA was lower during the weekend (23.6% of boys and 13.6% of girls comply with the recommended 60 min/day of MVPA) compared to weekdays (60.8% and 35.4%, boys and girls, respectively). Normal weight children were more active than obese children and no effect was found for biological maturation. Tracking is low in both boys (γ = 0.59 ± 0.01) and girls (γ = 0.56 ± 0.01). Children's MVPA levels during a week are highly unstable. In summary, boys are more active than girls, maturation does not affect their MVPA, and obese children are less likely to meet 60 min/day of MVPA. These results highlight the importance of providing opportunities for increasing children's daily MVPA on all days of week, especially on the weekend.