Physical activity patterns measured by accelerometry in 6- to 10-yr-old children

Objectively measured 24-h movement behaviours of child-guardian pairs in low-to-middle income households in Nairobi City County, Kenya

Background

The decreasing prevalence of physical activity (PA) among urban children in Sub-Saharan Africa is a growing public health concern. More emphasis should focus on examining the influence of parental PA behaviour on the children's PA patterns. We explored associations of 24 ​hour (h) accelerometer-measured movement behaviours of guardian-child pairs in Nairobi City County, Kenya.

Methods

This cross-sectional study assessed 80 pairs consisting of children aged 9-14 years and their guardians in one area of low and one area of middle socioeconomic status (SES) (Embakasi Sub-County and Lang'ata Sub-County), in Nairobi City County, Kenya. The study used waist worn Tri-axial Actigraph (GT3X+ and ActiSleep+) accelerometers to quantify PA and sedentary time (SED). Association between guardians' and children's PA was examined using linear regression, adjusting for guardians' educational attainment and household wealth.

Results

Of the children, 42 (52.5%) and 76 (96.2%) of the guardians were women. Children in low SES areas spent more time (p ​< ​0.001) in moderate-to-vigorous physical activity compared to children from middle SES area. The guardians in low SES area were younger and spent more time in light PA (p ​= ​0.036) while their counterparts had higher daily SED (p ​= ​0.049). Guardian's SED associated with higher children's SED (p ​= ​0.033) even after adjusting for guardians' educational attainment (p ​= ​0.032) and wealth (p ​= ​0.05). There was no association between guardians' and children's MVPA.

Conclusion

Considered alongside the extant literature, these results suggest that health promotion strategies should aim to reduce parental SED time while also planning to increase children's PA.

Differences in the activity intensity distribution over the day between boys and girls aged 3 to 17 years

Physical activity (PA) decreases from childhood to adolescence, with girls being less active than boys. The timing of these differences remains unknown. Using accelerometer data from three cross-sectional studies in Norway and Belgium (n = 2507, age = 3-17years), we assessed sex differences in sedentary behaviour (SB) and PA levels (light, moderate, vigorous) throughout the day and across the full spectrum of activity intensity distribution on weekdays and weekend days, using linear regression and functional data analyses. Across all age groups (preschoolers (3-5y), children (6-10y), adolescents (11-17y)), girls were less active than boys, particularly on weekdays (e.g., vigorous PA (> 1111 counts/15s) difference:-16.9 min/day (95% Confidence interval:-19.3,-14.4; p-value < 0.001) in children). It was the case throughout the day, particularly during school hours (8h30-15h29) in all age groups. Analysis of the full spectrum of activity intensity distribution (0 to 3000 counts) added to these findings that on weekend days, girls spent less time in zero-count SB than boys (difference=-21.0 min/day (-28.7,-13.4; p-value < 0.001) in children), but higher (17.3 min/day (13.2,21.4; p-value < 0.001)) in the "other SB", 1-180 counts/15s. The sex differences in PA during school hours suggest the need for targeted interventions promoting activities engaging girls. Additionally, the time spent in zero-count, particularly evident in boys on weekend days, deserves further investigation.

Rationale and design of Healthy Kids Beyond the Bell: a 2x2 full factorial study evaluating the impact of summer and after-school programming on children's body mass index and health behaviors

BACKGROUND

The Structured Days Hypothesis posits that structure protects children against obesogenic behaviors (e.g., physical inactivity, unhealthy dietary intake) and, ultimately, prevents the occurrence of excessive weight gain. The hours following school (i.e., 3-6 pm school days) and summer vacation are two "windows of vulnerability" when children may experience less structure. Programs that provide a healthy structured environment and may prevent BMI gain exist for both time periods (i.e., after-school programs and summer day camps). Unfortunately, these programs are cost prohibitive for children from low-income families to attend. This study will test the impact of providing vouchers to access existing, community-operated after-school and summer programs on BMI z-score, body composition, and obesogenic behaviors (i.e., physical activity, screen use, diet, and sleep) of children (5-12 years) from schools that primarily serve families with low income.

METHODS

The study will employ a 2x2 factorial design. Participants (N = 480) attending 4 elementary schools in one school district will be randomly assigned to a no treatment control, after-school program voucher only, summer day camp voucher only, or after-school and summer day camp vouchers. Vouchers will cover the full cost of attending a pre-existing community-based after-school or summer camp program. The primary outcome (BMI z-score) will be measured at baseline (before end of school year, ~ May), 3-month follow-up (after summer, ~ August), and 12-month follow-up (end the following school year, ~ May). Secondary outcomes include body composition (i.e., whole-body fat mass, fat free mass, and percent body fat) and obesogenic behaviors (i.e., physical activity, sedentary time, sleep, screen-time, and diet). The study will also employ a rigorous process evaluation which will consider after-school and summer camp program attendance and content. Analyses will examine differences between the four groups in BMI z-score, body composition, and obesogenic behaviors. Incremental cost effectiveness ratios will determine the cost effectiveness of the intervention.

DISCUSSION

The current study will provide critical information for researchers, practitioners, and policy makers seeking to combat the childhood obesity epidemic in children from families with low-income during the school year and summer.

TRIAL REGISTRATION

NCT05880901 . Registered 27 May 2023.

Effects of Universal School-Based Parental Support for Children's Healthy Diet and Physical Activity-the Healthy School Start Plus Cluster-Randomised Controlled Trial

Health promotion from an early age is key to preventing unhealthy weight development in childhood, and parental involvement is essential. The school-based Healthy School Start intervention aims to promote healthy dietary and activity habits in the home environment and prevent child obesity through parental support. This study evaluated the effectiveness of the third iteration of the programme on children's dietary and activity behaviours, and body composition through a cluster-randomised controlled trial. The trial included 17 schools (8 intervention) in disadvantaged areas in mid-Sweden with 353 families with 5- to 7-year-old children. The primary outcomes were intake of selected healthy and unhealthy foods and beverages measured using photography. Secondary outcomes were physical activity and sedentary time measured by accelerometry, and measured weight and height. All outcomes were assessed at baseline and post-intervention (8 months). Linear multi-level regression showed significant favourable effects of the intervention for intake of sweet beverages (b =  - 0.17, p = 0.04), intake of healthy foods (b = 0.11, p = 0.04), and more time in moderate to vigorous physical activity during weekdays (b = 5.68, p = 0.02). An unfavourable sub-group effect of the intervention was found for children from families with low education regarding sedentary time on weekends (b = 23.04, p = 0.05). The results align with the previous two trials of the programme, indicating that school-based parental support is a useful approach for health promotion in young children in disadvantaged areas. Trial registration: ClinicalTrials.gov: No. NCT03390725, retrospectively registered on January 4, 2018, https://clinicaltrials.gov/ct2/show/NCT03390725 .

Mediating Effects of the COVID-19 Pandemic on the Associations between Physical Activity and Physical Fitness; Cross-Sectional Study among High School Adolescents

The COVID-19 pandemic and the imposed social distancing measures caused negative changes in physical activity levels (PALs) and physical fitness (PF) among adolescents, but the potential mediating effect of the pandemic on the association between PAL and PF is unknown. This study aimed to evaluate gender-specific associations between objectively measured PAL and indices of PF among high school adolescents during the period of the COVID-19 pandemic. The participants were 150 adolescents (101 females) aged 14-18 years; their anthropometrics were evaluated, and they were tested on PF (cardiorespiratory fitness (CRF; beep test), power (broad jump), flexibility (sit-and-reach test), and abdominal strength (sit-ups)) and PAL (using a pedometer for 7 days) during the pandemic period. A T-test was calculated to determine differences between genders. Associations between variables were evaluated using Pearson correlations. Additionally, multivariate taxonomic classification was used to sort participants into homogenous groups (clusters) according to their PF, and then analysis of variance (ANOVA) was performed to differentiate them according to PAL. For the total sample, PAL was correlated with CRF only (R = 0.25, p < 0.05), while gender-stratified correlations showed that PAL was significantly associated with CRF among girls only (R = 0.29, p < 0.05), which was additionally confirmed with multivariate cluster analysis and subsequent ANOVA. No association between PAL and PF was found for boys. The relatively low association between PAL and PF is most likely related to the mediating effect of the change in life circumstances during the COVID-19 pandemic, and limited applicability of pedometers in evaluating high-intensity PAL. Further studies in other age groups and environments are warranted.

Physical activity in early childhood: a five-year longitudinal analysis of patterns and correlates

Background

Knowledge on longitudinal patterns and related factors of young children’s physical activity (PA) is still scarce. Therefore, the aim of this study was to examine patterns and changes of accelerometer-measured PA over time in two to six-year-old children. Furthermore, the aim was to investigate if parental PA, socioeconomic status, sex, weight status, and motor skills are related to child PA over time, using prospective cohort data from a clustered randomized controlled trial.

Methods

One hundred and six children (52% girls) and their parents had PA measured yearly from age two to six with an Actigraph GT3X. The actigraph was worn on the non-dominant wrist for one week; anthropometric data and motor skills, as well as background information, was collected simultaneously. The outcome was counts per minute from the vector magnitude, and linear mixed-effect models were used to answer the research questions.

Results

Among the children, accelerometer-measured PA increased on average by 11% per year from two years of age (mean 3170 cpm (3007-3334 95% CI)) onwards to six years of age (mean 4369 cpm (4207-4533 95% CI)). From three years of age, children were more active on weekdays than on weekend days. The rate of difference varied across low, medium, and highly active children (based on tertiles). No significant differences in weekdays/weekend PA among the lowest active children was found. Despite this, they were still significantly less active on weekend days than the most active children. Maternal, but not paternal PA was found to be significantly positively related to child PA over time, with a medium to large effect size. But no significant relationships were found between child PA and sex, weight status, or socioeconomic status.

Conclusions

PA increased on average with 11% per year, similarly for boys and girls. From three years of age children were more active during weekdays than weekend days. These results indicate that child PA benefits from active stimulation by parents and care takers already from early ages. It is important to identify attributes of possible intervention designs for weekend days for families with young children as well as characterize the least active children.

Trial registration

Early STOPP was prospectively registered in the clinical trials registry: clinicaltrials.gov, ID NCT01198847

Supplementary Information

The online version contains supplementary material available at 10.1186/s12966-022-01289-x.

Relationship Between Parent and Child Physical Activity Using Novel Acceleration Metrics

Background: Raw acceleration data lend themselves to innovative metrics in which comparisons can be made across populations. This study examined whether the intensity gradient (IG) or average acceleration (AvAcc) was associated with body mass index (BMI) in children and adults and explored parent-child associations between time spent in physical activity intensities and BMI. Methods: Parent-child dyads (n = 90) wore a wrist-mounted ActiGraph GT3X+ monitor for ≥ 3 valid days (i.e., ≥ 16 hrs each day). Participants' BMI was calculated. Results: Girls' BMI-z scores were positively associated with parent BMI and inactive time. Parent BMI was negatively associated with boys' inactive time. Parental inactive time predicted girls' BMI-z scores. The metrics were not associated with parent BMI, and no independent effects were observed between the metrics. Associations between boys' IG and BMI z-score were observed. No independent effects were observed between the metrics and no significant associations were observed between boys' BMI z-score and AvAcc. Girls' AvAcc and IG were not associated with BMI z-score and no independent effects were observed between the metrics. Conclusion: Findings support previous research which suggests that parent's activity does not influence their child's activity.

Subjective Health, Physical Activity, Body Image and School Wellbeing among Adolescents in South of Sweden

This study aimed to investigate subjective health and its associations with perceived body image (body appearance and body functioning), physical activity, perceived wellbeing in school, perceived family financial situation, and body mass index among 13- to 15-year-old boys and girls. The study was a cross-sectional study performed in four municipalities in Southern Sweden. Data were obtained from questionnaires completed by adolescents (median age 14; range: 13–15) in Sweden (n = 1518, 51% girls), with a participation rate of 73%. Body weight and body height were measured by school nurses and body mass index was calculated. Logistic regression analyses were carried out with subjective health as the dependent variable. Independent variables included in the model were perceived wellbeing in school, perceived family financial situation, perceived body image, physical activity, body mass index, sex, and residency. Variables significantly associated with good subjective health were good wellbeing in school, a perceived good family financial situation, perceived positive body appearance, perceived positive body functioning, being a boy, and high physical activity. Residency and body mass index were not associated with subjective health. Good subjective health is associated with good wellbeing in school, good family financial situation, positive body image, and high physical activity levels. The results highlight the importance of good school climates, the promotion of positive body image, and increased physical activity for adolescents.

COVID-19 Leads to Accelerated Increases in Children's BMI z-Score Gain: An Interrupted Time-Series Study

INTRODUCTION

The COVID-19 pandemic may have negatively impacted children's weight status owing to the closure of schools, increased food insecurity and reliance on ultraprocessed foods, and reduced opportunities for outdoor activity.

METHODS

In this interrupted time-series study, height and weight were collected from children (n=1,770 children, mean age=8.7 years, 55.3% male, 64.6% Black) and were transformed into BMI z-score in each August/September from 2017 to 2020. Mixed-effects linear regression estimated yearly BMI z-score change before the COVID-19 pandemic year (i.e., 2017-2019) and during the COVID-19 pandemic year (i.e., 2019-2020). Subgroup analyses by sex, race (i.e., Black, White, other race), weight status (overweight or obese and normal weight), and grade (i.e., lower=kindergarten-2nd grade and upper=3rd-6th grade) were conducted.

RESULTS

Before the COVID-19 pandemic, children's yearly BMI z-score change was +0.03 (95% CI= -0.10, 0.15). Change during the COVID-19 pandemic was +0.34 (95% CI=0.21, 0.47), an acceleration in BMI z-score change of +0.31 (95% CI=0.19, 0.44). For girls and boys, BMI z-score change accelerated by +0.33 (95% CI=0.16, 0.50) and +0.29 (95% CI=0.12, 0.46), respectively, during the pandemic year. Acceleration in BMI z-score change during the pandemic year was observed for children who were Black (+0.41, 95% CI=0.21, 0.61) and White (+0.22, 95% CI=0.06, 0.39). For children classified as normal weight, BMI z-score change accelerated by +0.58 (95% CI=0.40, 0.76). Yearly BMI z-score change accelerated for lower elementary/primary (+0.23, 95% CI=0.08, 0.37) and upper elementary/primary (+0.42, 95% CI=0.42, 0.63) children.

CONCLUSIONS

If similar BMI z-score accelerations occurred for children across the world, public health interventions to address this rapid unhealthy BMI gain will be urgently needed.

Changes in Physical Fitness during Summer Months and the School Year in Austrian Elementary School Children-A 4-Year Longitudinal Study

Even though physical fitness is an important component in children's health and well-being, there has been a decline in physical fitness over the last several decades. The present study examined potential differences in the development of physical fitness during the academic year and summer vacation in Austrian elementary-school children. A total of 214 children (52.3% boys) completed the German motor test in the fall (after summer vacation) and spring (prior to summer vacation) of every grade throughout their elementary school years. This resulted in eight assessments of cardio-respiratory endurance, muscular fitness, flexibility, speed, agility, and balance over a 4-year period. As expected, physical fitness increased with age but the improvement in cardio-respiratory endurance and muscular fitness was more pronounced during summer vacation (p < 0.01), while the improvement in speed was more pronounced during the academic year (p < 0.01). These results indicate an influence of weather conditions on health-enhancing physical activity in addition to structural and social support. Particularly in geographical regions with cold winters and shorter days, health-enhancing physical activity may be limited. Accordingly, schools need to provide additional opportunities to ensure an adequate amount of physical activity that stimulates the development of physical fitness.

Cross-Sectional and Longitudinal Associations between Non-School Time Physical Activity, Sedentary Time, and Adiposity among Boys and Girls: An Isotemporal Substitution Approach

This study investigated the cross-sectional and longitudinal associations of the substitution of non-school time light physical activity (LPA), moderate-to-vigorous physical activity (MVPA), and sedentary time (ST) with adiposity in boys and girls. Boys (n = 65, baseline Mage= 9.93 ± 0.86 years) and girls (n = 77, baseline Mage = 10.17 ± 0.95 years) wore waist-worn accelerometers (ActiGraph GT3X) at baseline and at a 30-month follow-up, from which non-school time LPA, MVPA, ST, and total device wear were quantified. Body mass index (BMI) and waist-to-height-ratio (WHR) were measured at baseline and follow-up. Body fat percent (BF%) was obtained at follow-up only. Isotemporal substitution models assessed the cross-sectional and longitudinal associations of reallocating non-school time activity with BMI, WHR and BF%. In boys, replacing 30 min/day of LPA with MVPA was cross-sectionally (β = -8.26, p < 0.05) associated with a lower BF%. Replacing 30 min/day of ST with MVPA was cross-sectionally (β = -6.02, p < 0.05) associated with a lower BF% in boys. Longitudinally in boys, replacing 30 min of change in LPA with MVPA (β = -7.42, p < 0.10) and replacing 30 min of change in MVPA with ST (β = 5.78, p < 0.10) over 30 months was marginally associated with less BF%. Associations were null in girls (p > 0.05). These results may support targeting activity reallocation during non-school time for the purposes of adiposity improvement in boys. A multi-behavioral approach may be more appropriate for girls, as non-school time activity may not be driving adiposity status.

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 gender, school socioeconomic status, and cardiorespiratory fitness among elementary and middle school students

Background

Schools play an important role in providing access to physical activity opportunities for children. There are common economic and gender disparities in physical activity and health-related fitness among children, which may inform a school’s programming needs. The purpose of this study is to gain a better understanding about gender, school-level socioeconomic status, and children’s cardiorespiratory fitness.

Methods

This observational study used 2017–2018 school year data from schools in the Dallas Metropolitan area participating in the Healthy Zone School (HZS) program. Three data sources were integrated: 1) FitnessGram® data, 2) school-level data from the Texas Education Agency, and 3) HZS survey data. Being in the Healthy Fitness Zone (HFZ) for aerobic capacity was the dependent variable, and gender and the percentage of economically disadvantaged students (at the school-level) were key independent variables. Mixed-effects logistic regression models examined associations between dependent and independent variables. Final models were adjusted for age and type of aerobic test.

Results

There were 67 schools and 15,052 students included in the analysis. When testing main effects, girls had lower odds for being in the HFZ for aerobic capacity than boys (OR = 0.54, CI = 0.47–0.62). Additionally, having a greater percentage of students who were economically disadvantaged was associated with lower odds for being in the HFZ for aerobic capacity (0.98, CI = 0.98–0.99). There was a significant interaction between gender and the percentage of economically disadvantaged students. Results indicated girls had even lower odds (than boys) for being in the HFZ in schools with 90% economically disadvantaged students (OR = 0.44, CI = 0.35–0.55) versus in schools with 15% economically disadvantage students (OR = 0.62, CI = 0.51–0.76).

Conclusions

Results suggest girls in Healthy Zone Schools have lower odds to meet aerobic capacity fitness standards than boys. Additionally, boys and girls in schools serving a greater percentage of economically disadvantaged students have lower odds to meet aerobic capacity fitness standards. Last, girls have even lower odds of meeting HFZ standard when attending a school serving a greater percentage of economically disadvantaged students. Thus, schools need to provide more programs for girls targeting aerobic physical activity. This is especially important for schools serving a high percentage of low-income students.

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

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

A Systematic Review of Children's Physical Activity Patterns: Concept, Operational Definitions, Instruments, Statistical Analyses, and Health Implications

Despite the widespread use of the expression “physical activity pattern” (PAP), there apparently is no general consensus regarding its definition. This systematic review aimed to examine available research focussing on (1) definitions of PAP, (2) instruments/techniques used to describe PAP, (3) statistical approaches used to analyse PAP, and (4) implications of PAP on children’s health. A systematic review of the available literature was done to identify studies published up to October 2019, and 76 studies were eligible. None of the studies presented a formal definition of PAP; a wide range of instruments were used to investigate children’s PAP, and most of the revised studies did not explicitly present a formal statistical model to define PAP. Twenty-four papers purported to examine associations between PAP and health indicators. The review highlights no consensus on a clear PAP definition whatever the instrument used to capture it, and we did not find any agreement regarding how best to analyse PAP. We suggest that PAP should be used when targeting the investigation of similarities/dissimilarities, as well as stabilities and/or changes in children’s PA at an intra-personal level. In sum, PAP should be used to best describe individual streams of behaviours, and not exclusively PA levels/intensities.

Effectiveness of a Family Intervention to Increase Physical Activity in Disadvantaged Areas-A Healthy Generation, a Controlled Pilot Study

There are large social inequalities in health. The purpose of this study was to evaluate the effects of a family intervention on physical activity (PA) and sedentary time (ST) in children and their parents. In this controlled pilot study, all 8–9-year-old children from four schools from a socioeconomically disadvantaged area in Sweden were invited and 67 children and 94 parents were included. The intervention was run by a foundation in co-operation with the municipality. The 9-month program included: (1) activity sessions, (2) healthy meals, (3) health information and (4) parental support groups. PA was primary outcome and ST was secondary outcome, measured by accelerometry. In total, 40 of the children (60%) and 45 of the adults (50%) had at least one day of valid accelerometer data at both baseline and follow-up. Significant intervention effects for the whole group were found in total PA (p = 0.048, mean difference (MD) intervention/control 150 counts per minute) and in vigorous PA (p = 0.02, MD 8 min/day) during the weekends. There were no differences between groups in the other PA variables or ST. This pilot study shows that it is possible to influence PA in families from a disadvantaged area through a family program.

Patterns and correlates of objectively measured physical activity in 3-year-old children

Background

To increase the knowledge about physical activity (PA) patterns and correlates among children under the age of 4, there is a need for study’s using objective measurements. The aim of this study was therefore to investigate if objectively measured PA among 3-year-old children differed between day of week and time of day and whether it correlated to child weight status and sex as well as parental weight status and education.

Methods

Totally 61 children (51% girls) aged 3, participating in Early Stockholm Obesity Prevention Project were included. PA was measured with a tri-axial accelerometer (ActiGraph GT3X+) worn on the non-dominant wrist for one week. The main outcome was average PA expressed as counts per minute from the vector magnitude. PA and demographics/family-related factors were collected at baseline and at age 3. To analyze the results simple linear regression, ANOVA and paired t-tests were performed.

Results

The mean number of valid days was 6.7 per child. The children were more active on weekdays than weekends (p < 0.01) and the hourly pattern differed over the day with children being most active midmorning and midafternoon (p = 0.0001). Children to parents with low education were more active (p = 0.01) than those with highly educated parents. No differences in PA by child weight status, sex nor parental weight status were found.

Conclusions

PA in 3-year-old children was lower during weekends than weekdays and varied over the day. Boys and girls had similar PA patterns, these patterns were independent of child or parental weight status. Children to parents with low education were more active than their counterparts. The fact that PA differed between weekdays and weekends indicates that PA might be affectable in 3-year-old children.

Group-based physical activity trajectories in children transitioning from elementary to high school

Background

Physical activity has been observed repeatedly to decline as children transition into adolescence; however, few studies have explored the possibility that sub-groups of children experience unique patterns of change during this transition. The purpose of this longitudinal study was to examine the physical activity trajectories in clusters of youth transitioning from 5th to 11th grade.

Methods

Participants (n = 652) were recruited as 5th graders (ages 10–12 years) from elementary schools (n = 21) in two school districts. Demographic, anthropometric, and physical activity data were collected once per year when children were in 5th, 6th, 7th, 9th, and 11th grades. Children wore accelerometers for 7 consecutive days. Group-based trajectory modeling statistical techniques were applied to identify patterns of physical activity trajectories. Posterior probabilities confirmed participants’ membership in their respective group.

Results

Three distinct physical activity trajectories were identified. Group 1 (n = 27) remained highly active over time, and physical activity increased from ages 14 to 16 years. Group 2 (n = 365) was active at baseline, but activity declined and remained low as group members aged. Group 3 (n = 260) had the lowest levels of physical activity at all ages, and activity declined from ages 10 to 16 years.

Conclusions

While most children experienced a decline in physical activity as they transitioned into high school, some remained highly active and increased their level of physical activity. Future studies should test physical activity interventions for youth that are tailored for age-related trajectory groups.

Physical Activity and Sedentary Behavior From 6 to 11 Years

: media-1vid110.1542/5849572910001PEDS-VA_2018-0994Video Abstract OBJECTIVES: Physical activity (PA) is presumed to decline during childhood and adolescence, but only few long-term studies about PA development during this period of life exist. We assessed PA and sedentary behavior (SB) over a 5-year period to gain a better understanding of the extent of change in activity and potential influencing factors.

METHODS

PA and SB of 600 children from the Childhood Obesity Project were objectively measured with the SenseWear Armband 2 at the ages of 6, 8, and 11 years, resulting in 1254 observations. Longitudinal changes of total PA, moderate-to-vigorous physical activity (MVPA), light physical activity (LPA), and SB were modeled with mixed-effects models.

RESULTS

Total PA revealed a significant quadratic decline with age (P < .001), resulting in a change of total PA by -75.3 minutes per day from 6 to 11 years. LPA linearly declined (P < .001) by 44.6 minutes per day, MVPA quadratically declined (P < .001) by an overall 30.7 minutes, whereas SB increased significantly (+107 minutes; P = .001). Boys showed a steeper decline in LPA (P = .003) and MVPA (P < .001) than did girls. Higher fat mass index and BMI z scores were associated with lower levels of total PA and MVPA and higher levels of SB (all P < .001).

CONCLUSIONS

We showed that PA decreased, and SB increased in earlier years than previously thought. MVPA remained relatively stable until 8 years, but revealed a drop-off at 11 years, identifying this period as a crucial time for intervention.

Omega-3 fatty acids does not affect physical activity and body weight in primary school children - a double-blind randomized placebo-controlled trial

It was hypothesized that supplementation of omega-3 fatty acids could increase physical activity (PA) levels, where traditional interventions often fail. The aim of this double-blind, randomized, placebo-controlled trail was to evaluate the effects of 15-week administration of omega-3 fatty acids on objectively measured PA and relative body weight in 8–9 year-old children. The children were randomly assigned to supplementation of omega-3 fatty acids or placebo. Primary outcome was change in PA counts per minute (cpm), and secondly change in body mass index standard deviation score (BMI SDS). Covariance models were applied adjusting for age, gender, weight status, PA and intervention season. Compliance was controlled for by analyzing fatty acid composition in plasma. The intention to treat population consisted of 362 children (omega-3 n = 177, placebo n = 185). No significant effects of omega-3 fatty acids on PA or relative body weight were observed. In covariance models no effects were observed by gender, weight status or change in PA (all p > 0.05), but inactive children increased their PA more than children classified as active at baseline (p < 0.05).

A Healthy School Start Plus for prevention of childhood overweight and obesity in disadvantaged areas through parental support in the school setting - study protocol for a parallel group cluster randomised trial

Background

Systematic reviews conclude that interventions to prevent overweight and obesity in children obtain stronger effects when parents are involved. Parenting practices and parent-child interactions shape children’s health-related behaviours. The Healthy School Start Plus intervention aims to promote healthy dietary habits and physical activity and prevent obesity in children through parental support in disadvantaged areas with increased health needs, delivered by teachers and school nurses. This protocol describes the design, outcome and process evaluation of the study.

Methods

Effectiveness of the intervention is compared to standard care within school health services. The 6-month programme, based on Social Cognitive Theory, consists of four components: 1) Health information to parents regarding the child; 2) Motivational Interviewing with the parents by the school nurse concerning the child; 3) classroom activities for the children by teachers; and 4) a web-based self-test of type-2 diabetes risk by parents. Effects will be studied in a cluster randomised trial including 17 schools and 352 six-year old children. The primary outcome is dietary intake of indicator foods, and secondary outcomes are physical activity, sedentary behaviour and BMI. Outcomes will be measured at baseline, at 6 months directly after the intervention, and at follow-up 18 months post baseline. Statistical analysis will be by mixed-effect regression analysis according to intention to treat and per protocol. Mediation analysis will be performed with parental self-efficacy and parenting practices. Quantitative and qualitative methods will be used to study implementation in terms of dose, fidelity, feasibility and acceptability. The hypothesis is that the programme will be more effective than standard care and feasible to perform in the school context.

Discussion

The programme is in line with the cumulated evidence regarding the prevention of childhood obesity: That schools should be a focal point of prevention efforts, interventions should involve multiple components, and include the home environment. If effective, it will fill a knowledge gap concerning evidence-based health promotion practice within school health services to prevent obesity, and in the long term reduce social inequalities in health.

Trial registration

The trial was retrospectively registered on January 4, 2018 and available online at ClinicalTrials.gov: No. NCT03390725.

Summer Weight Gain and Fitness Loss: Causes and Potential Solutions

Over the past 3 decades, public health professionals have worked to stem the rising childhood obesity epidemic. Despite the field's best efforts, no progress has been made in reducing child obesity. One reason for this failure may be that obesity prevention and treatment efforts have predominately been delivered during the 9-month school year. However, recent evidence suggests that the summer, not the school year, is when unhealthy changes in body composition (ie, accelerated increases in percent body fat) and fitness losses occur. This unhealthy change in body composition and fitness loss during the summer could be explained by the "Structured Days Hypothesis," which posits that children engage in a greater number of unhealthy obesogenic behaviors on unstructured days when compared with structured days. Furthermore, the summer may be contributing to a widening "health gap" between children from low-income and middle- to upper-income families. During summer, fewer opportunities exist for children from low-income households to access healthy structured programs that do not require fees for participation. Moving forward, public health professionals should prioritize efforts to mitigate unhealthy changes in body composition and fitness loss during the summer by identifying ways to provide access to structured programming during this timeframe for children from low-income households.

Breakfast habits, dairy product consumption, physical activity, and their associations with body mass index in children aged 6-18

The purpose of this study was to determine breakfast habits, dairy product consumption, and physical activity and their relations with body mass index (BMI) in schoolchildren and adolescents. This cross-sectional, school-based study was performed with children aged 6-18 years. Height and weight were measured, and a BMI z-score was calculated for each child. Breakfast consumption frequency, intake of milk and other dairy products, physical activity habits, and mothers' employment status were assessed via a self-report questionnaire. Multiple linear regression analysis was used to estimate the association between these habits and BMI z-scores. Seven thousand one hundred sixteen children were included, 3445 (48.4%) female, with a mean age of 11.7 ± 2.7 years (5.8-18.9). Of these, 62.6% had breakfast every day. Boys ate breakfast daily significantly more often than girls (64.5 and 60.7%, respectively; p < 0.001). The percentage of children eating breakfast daily decreased with age (79.1% at 6-11 vs. 52.1% at 12-18 years, p < 0.001). Sixty-four (0.9%) children consumed no dairy products. Milk intake was negatively and significantly associated with BMI z-score (β = - 0.103, p < 0.001). Cheese consumption and the mother being employed were positively and significantly associated with BMI z-score (β = 0.517, p < 0.001, and β = 0.172, p < 0.001, respectively). Children engaging in physical activity had higher BMI z-score values than others (0.22 ± 0.01 vs. 0.12 ± 0.02, p < 0.001). Prevalence of overweight/obese was higher among children of working mothers compared to those of unemployed mothers (respectively, 29.3, 23.3%, p < 0.001).

CONCLUSIONS

Skipping breakfast was associated with overweight/obesity in schoolchildren and adolescents, while milk consumption exhibited a protective effect. What is known? • Dietary interventions should be incorporated into a multidisciplinary strategy for obesity prevention. • Most studies of habitual physical activity in children suggest that the overweight and obese children are less active. What is new? • Milk consumption seems to have a protective effect against overweight/obesity, irrespective of yogurt or cheese consumption. • Children engaging in greater physical activity had higher body mass index values than others.

Understanding differences between summer vs. school obesogenic behaviors of children: the structured days hypothesis

BACKGROUND

Although the scientific community has acknowledged modest improvements can be made to weight status and obesogenic behaviors (i.e., physical activity, sedentary/screen time, diet, and sleep) during the school year, studies suggests improvements are erased as elementary-age children are released to summer vacation. Emerging evidence shows children return to school after summer vacation displaying accelerated weight gain compared to the weight gained occurring during the school year. Understanding how summer days differ from when children are in school is, therefore, essential.

DISCUSSION

There is limited evidence on the etiology of accelerated weight gain during summer, with few studies comparing obesogenic behaviors on the same children during school and summer. For many children, summer days may be analogous to weekend days throughout the school year. Weekend days are often limited in consistent and formal structure, and thus differ from school days where segmented, pre-planned, restrictive, and compulsory components exist that shape obesogenic behaviors. The authors hypothesize that obesogenic behaviors are beneficially regulated when children are exposed to a structured day (i.e., school weekday) compared to what commonly occurs during summer. This is referred to as the 'Structured Days Hypothesis' (SDH). To illustrate how the SDH operates, this study examines empirical data that compares weekend day (less-structured) versus weekday (structured) obesogenic behaviors in U.S. elementary school-aged children. From 190 studies, 155 (~80%) demonstrate elementary-aged children's obesogenic behaviors are more unfavorable during weekend days compared to weekdays.

CONCLUSION

In light of the SDH, consistent evidence demonstrates the structured environment of weekdays may help to protect children by regulating obesogenic behaviors, most likely through compulsory physical activity opportunities, restricting caloric intake, reducing screen time occasions, and regulating sleep schedules. Summer is emerging as the critical period where childhood obesity prevention efforts need to be focused. The SDH can help researchers understand the drivers of obesogenic behaviors during summer and lead to innovative intervention development.

Physical activity outside of organised sports is associated with functional performance

AIM

The purpose of this study was to determine whether high levels of strenuous physical activity outside of organised sports are associated with better functional test performance.

METHODS

Youth athletes (n = 445, mean = 14.2 ± 2.5 years) reported their frequency of strenuous physical activity outside of organised sports. The functional performance tests: vertical jump height, pro agility test time, estimated maximal oxygen uptake (VO₂ max), front plank time and postural stability were measured and compared between groups.

RESULTS

Athletes in the five or more times a week group demonstrated faster pro agility times (5.37 ± 0.43 seconds) than the never group (5.59 ± 0.56 seconds; p = 0.002) and the 1-4 times a week group (5.52 ± 0.47 seconds; p = 0.005). The five or more times a week group demonstrated higher mean vertical jump height (42.9 ± 13.3 vs. 40.3 ± 10.8 cm; p = 0.009) and higher estimated VO₂ max (48.1 vs. 45.6 mL/kg/minute; p = 0.001) than the 1-4 times a week group.

CONCLUSION

Youth athletes who engaged in strenuous physical activity outside of organised sports five or more times a week performed best on functional performance tests.

School-time physical activity among Arab elementary school children in Qatar

Background

Recent data from a self-administered questionnaire show that approximately 75% of school children in Qatar do not meet the daily recommended levels of physical activity (PA). Since children spend half of their waking hours in school, it is important to understand when and how much PA children accumulate during the school day. This study aimed to objectively assess school-time PA among elementary school children in Qatar and to determine association of PA with age, gender, body mass index (BMI) status, or day of the week.

Methods

A cross-sectional epidemiological study was conducted in four randomly selected elementary schools in Qatar. Two classes representing grade 1 children (age 5) and grade 4 children (age 9) were randomly selected within each school. A total of 183 elementary school children (86 boys and 97 girls) ages 6–12 years participated in this study. PA was assessed using a three-axial accelerometer (ActiGraph® wGT3X-BT). Participants wore accelerometers on their non-dominant wrist at school (7:00 a.m. to 1:00 p.m.) for five consecutive school days during the week. A cutoff points of 818 counts per 5 s was classified as moderate-to-vigorous physical activity (MVPA).

Results

The average duration of MVPA in our study was 28.2 ± 13.5 min per day. Only 39% of participated children reach the recommended school-based MVPA of 30 min or more per day. Students spent on average 58.1 ± 8.4% of school time on sedentary activities. MVPA of boys and girls was similar in age 5 while girls age 9 were less active (23.7 ± 1.5 min/day) than boys of the same age (42.7 ± 1.8 min/day), ES = 0.269, P < 0.001. Neither overweight children nor children at risk for being overweight showed any differences in physical activity parameters when compared to children of normal weight. Our results showed, percentage of MVPA on the first (7.7 ± 5.1%) and last (7.1 ± 4.1%) day of the week was generally lower compared to other weekdays (P < 0.001).

Conclusion

This was the first study to objectively assess PA during school hours among elementary school-children in Qatar. This study found that many of school children do not perform sufficient time being physically active at school. All students in two age categories (age 5 and age 9) spend the majority of school time engaged in sedentary activities. The low participation of girls age 9 in MVPA is a cause for concern and need to be addressed.

levels and sociodemographic correlates of accelerometer-based physical activity in Irish children: a cross-sectional study

BACKGROUND

The aim of this study was to explore levels and sociodemographic correlates of physical activity (PA) over 1 week using accelerometer data.

METHODS

Accelerometer data was collected over 1 week from 1075 8-11-year-old children in the cross-sectional Cork Children's Lifestyle Study. Threshold values were used to categorise activity intensity as sedentary, light, moderate or vigorous. Questionnaires collected data on demographic factors. Smoothed curves were used to display minute by minute variations. Binomial regression was used to identify factors correlated with the probability of meeting WHO 60 min moderate to vigorous PA guidelines.

RESULTS

Overall, 830 children (mean (SD) age: 9.9(0.7) years, 56.3% boys) were included. From the binomial multiple regression analysis, boys were found more likely to meet guidelines (probability ratio 1.17, 95% CI 1.06 to 1.28) than girls. Older children were less likely to meet guidelines than younger children (probability ratio 0.91, CI 0.87 to 0.95). Normal weight children were more likely than overweight and obese children to meet guidelines (probability ratio 1.25, CI 1.16 to 1.34). Children in urban areas were more likely to meet guidelines than those in rural areas (probability ratio 1.19, CI 1.07 to 1.33). Longer daylight length days were associated with greater probability of meeting guidelines compared to shorter daylight length days.

CONCLUSIONS

PA levels differed by individual factors including age, gender and weight status as well as by environmental factors including residence and daylight length. Less than one-quarter of children (26.8% boys, 16.2% girls) meet guidelines. Effective intervention policies are urgently needed to increase PA.

Wear Compliance and Activity in Children Wearing Wrist- and Hip-Mounted Accelerometers

PURPOSE

This study aimed to 1) explore children's compliance to wearing wrist- and hip-mounted accelerometers, 2) compare children's physical activity (PA) derived from raw accelerations of wrist and hip, and 3) examine differences in raw and counts PA measured by hip-worn accelerometry.

METHODS

One hundred and twenty-nine 9- to 10-yr-old children wore a wrist-mounted GENEActiv accelerometer (GAwrist) and a hip-mounted ActiGraph GT3X+ accelerometer (AGhip) for 7 d. Both devices measured raw accelerations, and the AGhip also provided count-based data.

RESULTS

More children wore the GAwrist than those from the AGhip regardless of wear time criteria applied (P < 0.001-0.035). Raw data signal vector magnitude (r = 0.68), moderate PA (MPA) (r = 0.81), vigorous PA (VPA) (r = 0.85), and moderate-to-vigorous PA (MVPA) (r = 0.83) were strongly associated between devices (P < 0.001). GAwrist signal vector magnitude (P = 0.001), MPA (P = 0.037), VPA (P = 0.002), and MVPA (P = 0.016) were significantly greater than those from the AGhip. According to GAwrist raw data, 86.9% of children engaged in at least 60 min · d(-1) of MVPA, compared with 19% for AGhip. ActiGraph MPA (raw) was 42.00 ± 1.61 min · d(-1) compared with 35.05 ± 0.99 min · d(-1) (counts) (P = 0.02). ActiGraph VPA was 7.59 ± 0.46 min · d(-1) (raw) and 37.06 ± 1.85 min · d(-1) (counts; P = 0.19).

CONCLUSIONS

In children, accelerometer wrist placement promotes superior compliance than the hip. Raw accelerations were significantly higher for GAwrist compared with those for AGhip possibly because of placement location and technical differences between devices. AGhip PA calculated from raw accelerations and counts differed substantially, demonstrating that PA outcomes derived from cut points for raw output and counts cannot be directly compared.

Physical Activity Levels in Chinese One-Year-Old Children and Their Parents, an Early STOPP China Study

BACKGROUND

Physical activity (PA) is associated with health benefits, already in childhood. However, little is known about actual levels, patterns and gender differences in PA level in very young children. This study examines Chinese one-year-old children and their parents' PA levels and patterns, and assesses the correlations between children's PA level and gender, body mass index standard deviation score (BMI SDS), parental BMI and parental PA level.

METHODS

Data from 123 families participating in the Early STOPP China study were used. Families were recruited based on parental BMI and were classified as either high-risk or low-risk of obesity. Parents and children wore an ActiGraph GT3X+ to assess the average PA levels. PA levels and hourly patterns during weekdays and weekends were examined as were correlations with gender, BMI SDS, parental BMI and parental PA levels.

RESULTS

There were no significant differences in children's averaged PA between risk groups, genders, or between weekdays and weekends. Children's peak average activity level was at 7 pm and they were least active at 3 pm (p<0.001). Both mothers and fathers demonstrated a similar PA pattern as their children, although paternal PA level was consistently lower than that of mothers and children. No significant association was found between children's PA and their gender, BMI SDS, parental BMI or paternal PA levels. Maternal PA was found positively associated with child PA (p<0.05).

CONCLUSION

PA in one-year-old Chinese children vary over the day but weekdays and weekends are similar. At this age, children's PA is not related to gender, BMI SDS, parental BMI or paternal PA. Larger scale studies with more contextual information are needed to improve the understanding of our findings.

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.

Relationships of physical activity and sedentary time in obese parent-child dyads: a cross-sectional study

BACKGROUND

Research suggests physical activity is linked to obesity. Further, the physical activity of healthy parents and their children is associated with each other. However, this relationship has not been examined in obese parents and their obese children.

METHODS

The purpose of this study was to compare the physical activity and sedentary time of obese, low-income, ethnic minority parents and their children on weekdays and weekend days using accelerometry. Data were obtained from eight rural sites in the middle and eastern part of North Carolina (N.C.), United States (U.S.) from 2007-2010 using a rolling enrollment. One hundred and ninety-nine obese parents (94 % female) and their obese children (54 % female) wore accelerometers simultaneously for three weekdays and one weekend day. Total physical activity, moderate-to-vigorous physical activity (MVPA) and sedentary time and proportions were determined.

RESULTS

Parents' and children's total physical activity and MVPA levels were lower on weekend days than weekdays. Total counts per minute for children on weekdays and weekend days were greater than for parents (p < 0.001). Total counts per minute were more highly correlated on weekend days than weekdays (r = 0.352, p < 0.0002 versus r = 0.165, p < 0.025). Parents' performed MVPA for 14 (SD = ±25) and 9 (SD = ±16) minutes/day on weekdays and weekend days, respectively; children performed MVPA for 37 (SD = ±25) and 31(SD = ±38) minutes/day for weekdays and weekend days, respectively. Correlations between parents and children for MVPA were higher on weekend days versus weekdays (r = 0.253 and 0.177, respectively; p < 0.015). Associations for sedentary time followed a similar trend, with r = 0.33 (p < 0.0002) for weekend days and r = 0.016 (p < 0.026) for weekdays. Associations between obese parent-child dyads on sedentary time were stronger for girls, while associations between dyads on MVPA were stronger for boys. However, formal interaction analyses were not significant (p > 0.13).

DISCUSSION

Since physical activity levels of obese parents and their obese child are somewhat related, especially on weekend days, combined parent-child obesity programs focused on reducing sedentary time could be beneficial, particularly for the child.

CONCLUSION

In conclusion, this study of the physical activity levels of obese parents and their obese children found some relationships between the parents' and children's physical activity and sedentary behavior patterns, especially on weekend days.

TRIAL REGISTRATION

NCT01378806 .

Age group comparability of raw accelerometer output from wrist- and hip-worn monitors

PURPOSE

The study aims were to compare raw triaxial accelerometer output from ActiGraph GT3X+ (AG) and GENEActiv (GA) placed on the hip and the wrist and to develop regression equations for estimating energy expenditure.

METHODS

Thirty children (7-11 yr) and 30 adults (18-65 yr) completed eight activities (ranging from lying to running) while wearing one AG and one GA on the hip and the wrist. Oxygen consumption (V˙O2) was measured with indirect calorimetry. Analysis involved the use of ANOVA to examine the effect of activity, brand, and placement on the acceleration values, intraclass correlation coefficient to evaluate the agreement between the two brands and placements, and linear regression to establish intensity thresholds.

RESULTS

A significant difference in acceleration values between the hip and the wrist placement was found (P < 0.001). The output from the wrist placement was, in general, higher compared with that from the hip. There was no main effect of monitor brand in adults (P < 0.12) and children (P < 0.73), and the intraclass correlation coefficient showed a strong agreement (0.96-0.99). However, a three-way interaction and systematic error between the brands was found in children. Acceleration from both brands and placements showed a strong correlation with V˙O2. The intensity classification accuracy of the developed thresholds for both brands and placements was, in general, higher for adults compared with that for children and was greater for sedentary/light (93%-97%), and vigorous activities (68%-92%) than that for moderate activities (33%-59%).

CONCLUSIONS

Accelerometer outputs from AG and GA seem comparable when attached to the same body location in adults, whereas inconsistent differences are apparent between the two brands and placements in children, hence limiting the comparability between brands in this age group.

Effectiveness of a universal parental support programme to promote healthy dietary habits and physical activity and to prevent overweight and obesity in 6-year-old children: the Healthy School Start Study, a cluster-randomised controlled trial

Objective

To develop and evaluate the effectiveness of a parental support programme to promote healthy dietary and physical activity habits and to prevent overweight and obesity in Swedish children.

Methods

A cluster-randomised controlled trial was carried out in areas with low to medium socio-economic status. Participants were six-year-old children (n = 243) and their parents. Fourteen pre-school classes were randomly assigned to intervention (n = 7) and control groups (n = 7). The intervention lasted for 6 months and included: 1) Health information for parents, 2) Motivational Interviewing with parents and 3) Teacher-led classroom activities with children. Physical activity was measured by accelerometry, dietary and physical activity habits and parental self-efficacy through a questionnaire. Body weight and height were measured and BMI standard deviation score was calculated. Measurements were conducted at baseline, post-intervention and at 6-months follow-up. Group differences were examined using analysis of covariance and Poisson regression, adjusted for gender and baseline values.

Results

There was no significant intervention effect in the primary outcome physical activity. Sub-group analyses showed a significant gender-group interaction in total physical activity (TPA), with girls in the intervention group demonstrating higher TPA during weekends (p = 0.04), as well as in sedentary time, with boys showing more sedentary time in the intervention group (p = 0.03). There was a significantly higher vegetable intake (0.26 servings) in the intervention group compared to the control group (p = 0.003). At follow-up, sub-group analyses showed a sustained effect for boys. The intervention did not affect the prevalence of overweight or obesity.

Conclusions

It is possible to influence vegetable intake in children and girls’ physical activity through a parental support programme. The programme needs to be intensified in order to increase effectiveness and sustain the effects long-term. These findings are an important contribution to the further development of evidence-based parental support programmes to prevent overweight and obesity in children.

Trial Registration

Controlled-trials.com ISRCTN32750699

Calibration and cross-validation of a wrist-worn Actigraph in young preschoolers

OBJECTIVE

To calibrate the Actigraph GT3X+ accelerometer for wrist-worn placement in young preschoolers by developing intensity thresholds for sedentary, low- and high-intensity physical activity. Furthermore, to cross-validate the developed thresholds in young preschoolers.

METHODS

Actigraph GT3X+ was used to measure physical activity during structured activities and free play in 38 children (15-36 months). Activity was video recorded and scored into sedentary, low- and high-intensity physical activity based on Children's Activity Rating Scale (CARS) and combined with accelerometer data using a 5 s epoch. Receiver operating characteristic analysis was used to develop intensity thresholds in 26 randomly selected children. The remaining 12 children were used for cross-validation.

RESULTS

Intensity thresholds for sedentary were ≤89 vertical counts (Y) and ≤221 vector magnitude (VM) counts per 5 s and ≥440 Y counts and ≥730 VM counts per 5 s for high-intensity physical activity. Sensitivity and specificity were 60-100% for the developed intensity thresholds. Strong correlations (Spearman rank correlation 0.69-0.91) were found in the cross-validation sample between the developed thresholds for the accelerometer and CARS scoring time in all intensity categories.

CONCLUSION

The developed intensity thresholds appear valid to categorize sedentary behaviour and physical activity intensity categories in children 2 years of age.

Objectively measured physical activity in two-year-old children - levels, patterns and correlates

Background

The aim was to describe levels, patterns and correlates of physical activity and sedentary behavior in a sample of Swedish children, two years of age, with normal weight, overweight and obese parents.

Methods

Data from 123 children, 37 with normal-weight parents and 86 with overweight/obese parents, enrolled in the Early Stockholm Obesity Prevention Project study was used. Children wore an Actigraph GT3X+ accelerometer for seven days. Average activity (counts per minute), number of steps and time spent in low and high-intensity physical activity and in sedentary was assessed. Differences between weekdays and weekend days were examined as were correlations with sex, body mass index (BMI), motor skills and family-related factors.

Results

Children were active at high intensity 11% of the day. On average 55% of the day was spent being sedentary. Number of steps and time in low-intensity physical activity differed between weekdays and weekend days: on weekdays, 363 more steps (p = 0.01) and six more minutes in low physical activity (p = 0.04). No differences were found for any physical activity or sedentary behavior variable by sex, BMI, motor skills or any family-related variable (p = 0.07 – 0.95).

Conclusions

Two-year-old children have an intermittent activity pattern, that is almost similar on weekdays and they spend about half of the daytime active. The absence of any association with sex, BMI, motor skills or parental factors indicates that the individual variation in this age group is primarily due to endogenous factors.

Trial registration

Clinicaltrials.gov: NCT01198847.

Association between socioeconomic vulnerability and height with obesity in low-income Chilean children in the transition from preschool to first grade

This study determined the percentage of obesity among lower-income Chilean children 4-6 years of age, by socioeconomic vulnerability (family score assessing the children's risk of becoming poor) and height. The sample included 17,080 children with anthropometry at 4, 5, and 6 years of age, and three categories of socioeconomic vulnerability. Body mass index Z-score (BMI Z), % obesity, height/age Z-score (HAZ) by socioeconomic vulnerability/sex, the effect of socioeconomic vulnerability on BMI Z and HAZ by age/sex, and BMI Z and % obesity at 4-6 years, according to initial height, were determined. Between 4-6 years, % obesity is very high, especially among the less-vulnerable and taller children. Preventive measures should prioritize this group.

Physical activity and motor skills in children attending 43 preschools: a cross-sectional study

BACKGROUND

Little is known about health characteristics and the physical activity (PA) patterns in children attending preschools. The objective of this study was to describe the gender differences in relation to body mass index (BMI), motor skills (MS) and PA, including PA patterns by the day type and time of day. Additionally, the between-preschool variation in mean PA was estimated using the intraclass correlation.

METHODS

We invited 627 children 5-6 years of age attending 43 randomly selected preschools in Odense, Denmark. Aiming and catching MS was assessed using subtests of the Movement Assessment Battery for Children (Second Edition) and motor coordination MS was assessed by the Kiphard-Schilling body coordination test, Körperkoordination Test für Kinder. PA was measured using accelerometry. The PA patterns were analysed using mixed models.

RESULTS

No gender differences in the BMI or norm-referenced MS risk classification, or the average weekly PA level or patterns of PA were observed. However, boys performed better in the aiming and catching score (p < 0.01) and in the motor coordination score (p < 0.05) on average. Girls performed better in the balance subtest (p < 0.001). Relative to the norm-referenced classification of MS, the Danish sample distribution was significantly well for aiming and catching but poorer for the motor coordination test.The total sample and the least active children were most active on weekdays, during preschool time and in the late afternoon at the weekend. However, a relatively larger decrease in PA from preschool to weekday leisure time was observed in children in the lowest PA quartile compared to children in the highest PA quartile. Finally, the preschool accounted for 19% of the total variance in PA, with significant gender differences.

CONCLUSIONS

Results of this study could provide a valuable reference material for studies monitoring future trends in obesity, MS and PA behaviour in Denmark and other countries.Knowledge about sources of variation in PA among preschool children is scarce and our findings need to be replicated in future studies. A potentially important finding is the large between-preschool variation in PA, indicating that especially girls are very susceptible to the environment offered for PA during preschool attendance.

Top 10 research questions related to exercise deficit disorder (EDD) in youth

Exercise deficit disorder (EDD) is a pediatric medical condition characterized by reduced levels of moderate-to-vigorous physical activity (MVPA) that are below current recommendations and inconsistent with positive health outcomes. At present, a majority of children and adolescents meet the diagnostic criteria for EDD because they are not accumulating minimum thresholds of daily MVPA. The purpose of this article is to highlight 10 important research questions related to EDD in youth. The critical research needs to better define the clinical spectrum of EDD to include an assessment of physical activity behaviors to determine the age or stage of maturation at which EDD first emerges; an examination of the kinesiogenesis of movement skills and physical abilities; and an evaluation of lifestyle factors that can influence the MVPA trajectory in youth. Research questions about interventions and policies to treat EDD include evaluating the education and training of health care providers on the importance of exercise medicine; determining the effectiveness of strategies to identify and treat youth with EDD in clinical practice; developing sensitive, specific, and cost-effective methods to diagnose youth with EDD; and assessing methods to promote health care reimbursement for the treatment of this condition. Without future research to optimize identification, treatment, and management strategies for youth with EDD, new health care concerns with significant biomedical, psychosocial, economic, and political ramifications will continue to emerge.

Longitudinal changes in health behaviours and body weight among Swedish school children--associations with age, gender and parental education--the SCIP school cohort

Background

In order to develop health promotion initiatives it is important to identify at what age gender and socioeconomic inequalities in health-related behaviours emerge. The aim of this longitudinal study was to analyse how health-related behaviours and weight status differed by age-group, gender, family socio-economic status and over time in three cohorts of school children.

Methods

All children in grades 2, 4 and 7 in a Swedish semi-urban municipality were invited to participate (n = 1,359) of which 813 (60%) consented. At baseline and after 2 years a health questionnaire was answered by all children. Height and weight was measured. Fourteen outcomes were analysed. The main and interaction effects of time, gender and parental educational level on the health-related behaviours, weight status and body mass index standard deviation score (BMIsds) were analysed by the Weighted Least Squares method for categorical repeated measures and Analysis of Variance.

Results

Nine of 12 health behaviours deteriorated over the two years: consumption of breakfast and lunch, vegetables and fruit, intake of sweetened drinks, TV viewing, club membership, being outdoors, and school recess activity; two behaviours were unchanged: intake of sweets, and active transport. Only sports participation increased with time. Girls consumed more vegetables, less sweetened drinks, performed less sports, were less physically active during recess, and had lower BMIsds, compared to boys. Those with more highly educated parents had more favourable or similar behaviours compared to those with less educated parents in 10 out of 12 health behaviours, the only exception being intake of sweets and being outdoors, and had lower BMIsds.

Conclusions

This study adds to our knowledge regarding the temporal development of health behaviours and weight status in school children. Differences with regard to gender and socioeconomic status were seen already at a young age. These results contribute to our understanding of several important determinants of obesity and chronic diseases and may inform future interventions regarding how to decrease gender and social inequalities in health.

Weekday and weekend sedentary time and physical activity in differentially active children

OBJECTIVES

To investigate whether weekday-weekend differences in sedentary time and specific intensities of physical activity exist among children categorised by physical activity levels.

DESIGN

Cross-sectional observational study.

METHODS

Seven-day accelerometer data were obtained from 810 English children (n=420 girls) aged 10-11 years. Daily average minday(-1) spent in moderate to vigorous physical activity were calculated for each child. Sex-specific moderate to vigorous physical activity quartile cut-off values categorised boys and girls separately into four graded groups representing the least (Q1) through to the most active (Q4) children. Sex- and activity quartile-specific multilevel linear regression analyses analysed differences in sedentary time, light physical activity, moderate physical activity, vigorous physical activity, and moderate to vigorous physical activity between weekdays and weekends.

RESULTS

On weekdays Q2 boys spent longer in light physical activity (p<0.05), Q1 (p<0.001), Q2 boys (p<0.01) did significantly more moderate physical activity, and Q1-Q3 boys accumulated significantly more vigorous physical activity and moderate to vigorous physical activity than at weekends. There were no significant differences in weekday and weekend sedentary time or physical activity for Q4 boys. On weekdays Q2 and Q3 girls accumulated more sedentary time (p<0.05), Q1 and Q2 girls did significantly more moderate physical activity (p<0.05), and Q1-Q3 girls engaged in more vigorous physical activity (p<0.05) and more moderate to vigorous physical activity (p<0.01) than at weekends. Q4 girls' sedentary time and physical activity varied little between weekdays and weekends.

CONCLUSIONS

The most active children maintained their sedentary time and physical activity levels at weekends, while among less active peers weekend sedentary time and physical activity at all intensities was lower. Low active children may benefit most from weekend intervention strategies.

The importance of parental beliefs and support for pedometer-measured physical activity on school days and weekend days among Canadian children

BACKGROUND

Parental influences are essential to the behaviours and physical activity of their children. Our study aimed to determine if parental beliefs and support are associated with children's pedometer measured physical activity levels on school days and weekend days.

METHODS

In the spring of 2009 and 2011, we analyzed cross-sectional data from 1,355 grade five students and parents in 30 schools in Alberta, Canada. Parents reported how much they care about exercising, how much they encourage their child to be physically active, and how frequently they engage in physical activities with their child. Physical activity was assessed from step counts obtained from time-stamped pedometers collected over nine consecutive days.

RESULTS

Increased parental encouragement was positively associated with boys' and girls' physical activity on school days (Boys: beta = 1373, 95% CI: 606, 2139; Girls: beta = 632, 95% CI: 108, 1155) and girls' physical activity on weekend days (beta = 997, 95% CI: 130, 1864). Increased parental care was positively associated with boys' physical activity on weekend days (beta = 1381, 95% CI: 85, 2676). Increased parental support and engagement was associated with an additional 632-1381 steps/day for children in this study.

CONCLUSIONS

Parental care, encouragement and engagement are associated with physical activity levels of children 10-11 years of age. Policy makers and researchers should consider the importance of targeting parents when designing strategies to promote physical activity in children. This is particularly relevant to weekends and holidays when children's activity levels are low.

Effects of a playground marking intervention on school recess physical activity in French children

OBJECTIVE

Playground interventions offer an opportunity to enhance school recess physical activity. We aimed to assess the effects of playground marking on objectively measured school recess physical activity in French children.

METHODS

Participants were four hundred and twenty children (6-11years old) from 4 primary schools in Nord-Pas de Calais, France. Children's physical activity (PA) was measured with a uniaxial accelerometer twice a day (morning and afternoon recess) during a 4-day school week in April and May 2009. Two experimental schools (EG) received a recess-based intervention (playground markings) and two others served as controls (CG). Percentage of time spent on the following intensities of physical activity during school recess was measured before and after intervention: sedentary (SED), light physical activity (LPA), moderate physical activity (MPA), vigorous physical activity (VPA), very high physical activity (VHPA) and moderate-to-vigorous physical activity (MVPA).

RESULTS

At baseline, school recess PA among children from CG was significantly (p<0.001) higher than that among EG children. No interaction was observed between the recess-based intervention and gender. After the intervention, the EG spent significantly (p<0.05) more time in MPA, VPA and MVPA with a concomitant significant decrease in SED (p<0.05) compared to baseline, while the PA in CG remained unchanged.

CONCLUSION

Painted playground markings had a positive short-term effect on school recess physical activity levels.

Sleep, physical activity and BMI in six to ten-year-old children measured by accelerometry: a cross-sectional study

Background

The aim of this study is to describe the relationship between objective measures of sleep, physical activity and BMI in Swedish pre-adolescents. The day-to-day association between physical activity and sleep quality as well as week-day and weekend pattern of sleep is also described.

Method

We conducted a cross sectional study consisted of a cohort of 1.231 children aged six to ten years within the Stockholm county area. Sleep and physical activity were measured by accelerometry during seven consecutive days. Outcome measures are total sleep time, sleep efficiency, sleep start and sleep end; physical activity intensity divided into: sedentary (<1.5 METS), light (1.5 to 3 METS) and moderate-to-vigorous (> 3 METS); and Body Mass Index standard deviations score, BMIsds.

Results

Total sleep time decreased with increasing age, and was shorter in boys than girls on both weekdays and weekends. Late bedtime but consistent wake-up time during weekends made total sleep time shorter on weekends than on weekdays. Day-to-day within-subject analysis revealed that moderate-to-vigorous intense physical activity promoted an increased sleep efficiency the following night (CI < 0.001 to 0.047), while total sleep time was not affected (CI -0.003 to 0.043). Neither sleep duration (CI -0.024 to 0.022) nor sleep efficiency (CI -0.019 to 0.028) affected mean physical activity level the subsequent day. The between-subject analysis indicates that the sleep of children characterized by high moderate-to-vigorous physical activity during the day was frequently interrupted (SE = -.23, P < .01). A negative association between BMIsds and sleep duration was found (-.10, p < .01).

Conclusions

Short sleep duration was associated with high BMI in six to ten year old children. This study underscores the importance of consistent bedtimes throughout the week for promoting sleep duration in preadolescents. Furthermore, this study suggests that a large proportion of intensive physical activity during the day might promote good sleep quality.

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

BACKGROUND

Data on longitudinal monitoring of daily physical activity (PA) patterns in youth over successive years is scarce but may provide valuable information for intervention strategies aiming to promote PA.

METHODS

Participants were 853 children (starting age ~8 years) recruited from 29 Australian elementary schools. Pedometers were worn for a 7-day period each year over 5 consecutive years to assess PA volume (steps per day) and accelerometers were worn concurrently in the final 2 years to assess PA volume (accelerometer counts (AC) per day), moderate and vigorous PA (MVPA), light PA (LPA) and sedentary time (SED). A general linear mixed model was used to examine daily and yearly patterns.

RESULTS

A consistent daily pattern of pedometer step counts, AC, MVPA and LPA emerged during each year, characterised by increases on school days from Monday to Friday followed by a decrease on the weekend. Friday was the most active and Sunday the least active day. The percentage of girls and boys meeting international recommendations of 11,000 and 13,000 steps/day respectively on a Monday, Friday and Sunday were 36%, 50%, 21% for boys and 35%, 45%, 18% for girls. The equivalent percentages meeting the recommended MVPA of >60 min/day on these days were 29%, 39%, 16% for boys and 15%, 21%, 10% for girls. Over the 5 years, boys were more active than girls (mean steps/day of 10,506 vs 8,750; p<0.001) and spent more time in MVPA (mean of 42.8 vs 31.1 min/day; p<0.001). Although there was little evidence of any upward or downward trend in steps/day from age 8 to 12 years, there was a trend toward lower MVPA, LPA and a corresponding increase in SED from age 11 to 12 years.

CONCLUSION

A weekly pattern of PA occurred in children as young as age 8 on a day by day basis; these patterns persisting through to age 12. In addition to supporting previous evidence of insufficient PA in children, our data, in identifying the level and incidence of insufficiency on each day of the week, may assist in the development of more specific strategies to increase PA in community based children.

Physical activity in 3-6 year old children measured by SenseWear Pro®: direct accelerometry in the course of the week and relation to weight status, media consumption, and socioeconomic factors

BACKGROUND

Data on objectively measured physical activity (PA) in preschoolers are controversial. Direct accelerometry was performed in children aged 3-6 years, and differences in PA patterns over the course of the week were evaluated. Data were analyzed with gender, BMI, lifestyle, and socioeconomic parameters as covariates.

METHODS

PA was measured in 119 children by the SensewearPro® accelerometer and analyzed in the 92 (40 girls) that wore it for at least 4 days including one day of the weekend. Median measuring time in this group was 7 consecutive days (median/mean daily measuring time: 23.5 h/d and 21.8 h/d, respectively), corresponding to 834,000 analyzed minutes. PA questionnaires were completed by 103 parents and 87 preschool teachers to collect anthropometric, lifestyle, and socioeconomic data.

RESULTS

Median daily PA (MET>3) was 4.3 hours (mean: 4.4 hours). Boys spent an estimated 52 min/week more being very active (MET>6) than girls (95% CI [6, 96] min/week, p = 0.02). PA was lower during the weekend (3.7 h/d) compared to weekdays (4.5 h/d), p = 3 × 10(-6)), where a 95% CI for the difference is [0.5, 1.0] h/d. PA levels did not differ between overweight/obese children (median 4.7 h/d) and normal-weight peers (median 4.2 h/d). Daily media consumption increased with decreasing social class on weekdays (p = 0.05) and during the weekend (p = 0.01), but was not related to the amount of daily PA. A multivariate regression with BMI-SDS as independent variable and gender, age, amount of PA>6 MET, parental BMI, media time and socioeconomic status as explanatory variables revealed that only SES had a significant contribution.

CONCLUSION

The negative impact of obesity-promoting factors in older children is rather low for preschoolers, but there is evidently a gradient in PA between weekdays and weekends already in this age group. Weight status of preschoolers is already considerably influenced by SES, but not physical activity levels.

After-school setting, physical activity, and sedentary behavior in 5th grade boys and girls

After-school hours are considered critical for children's physical activity (PA) and sedentary behaviors (SB); however, whether the after-school setting influences children's activity patterns is unknown. This study examined the influence of after-school setting (i.e., parent report of the child's usual after-school setting) on 5th grade children's PA and SB, and differences by race/ethnicity. Boys whose parents reported they usually attended an after-school program had higher PA than boys who usually went home after school. A significant interaction between race/ethnicity and after-school setting showed that minority girls whose parents reported they usually attended an after-school program had higher PA and engaged in less SB compared with those who usually went home, whereas the activity patterns of white girls did not differ by after-school setting. Children's usual after-school setting affects their activity patterns; after-school programs may potentially increase PA in boys and minority girls.