In-school and out-of-school physical activity in primary and secondary school children

Schooltime's contribution to pupils' physical activity levels: A longitudinal study

Introduction

Pupils spend a significant portion of their time at school. As a result, the school serves as an important setting for both learning and the formation of healthy behaviors. Many children, and even fewer young people, do not fulfill the (inter)national health recommendations of 60 minutes of moderate to vigorous physical activity (MVPA) per day. The aim of this study was to examine pupils' MVPA during schooltime in a longitudinal perspective, including the transition from primary to secondary school.

Methods

The MVPA of 234 pupils' was measured objectively using accelerometer monitors for seven consecutive days, in the spring of 2017, 2018, and 2019. Statistical analyses by Friedman, Wilcoxon and Mann-Whitney U-test were used to answer the research questions.

Results

The results showed a significant decrease in the pupils' MVPA and fulfilment of health recommendations during schooltime, from 7^th to 8^th grade. The analyses also showed that MVPA during schooltime was higher among boys than girls, and also contributed more to boys' fulfilment of the health recommendations at all three time periods.

Discussion

The results indicate that the transition between primary and secondary school is vulnerable concerning pupils' MVPA during schooltime. As schooltime accounted for significantly more MVPA for boys than for girls at all three time periods, we question whether physical activity is sufficiently facilitated for girls in school.

Compensation of overall physical activity in (pre)adolescent girls - the CReActivity project

BACKGROUND

According to the ActivityStat hypothesis more physical activity (PA) in one timespan is compensated by increased sedentary time (ST) in the following timespan and vice versa to maintain an overall stable PA level. Until now, existing literature revealed inconsistent results regarding compensatory behaviour across children and adolescents. Thus, the aim of the present study is (1) to investigate whether ST in the morning is compensated by active behaviour in the afternoon and (2) whether ST during the week is compensated by active behaviour during the weekend in (pre)adolescent girls. Additionally, we aimed to differentiate between positive and negative compensatory behaviour and examine whether it is moderated by socioeconomic status (SES), age or weight status.

METHODS

The participants were 370 sixth grade school girls (mean age 11.6 years) from Munich that participated in the CReActivity study, a school based intervention study aiming to identify the mechanisms of behavioural changes in PA among girls. ST and PA were measured over seven consecutive days using accelerometery. Descriptive determination of compensatory behaviour, as well as Bayesian multivariate multilevel analysis were conducted with data clustered on the individual (ID), class and school level.

RESULTS

Descriptive analysis revealed rather constant compensatory behaviour of about 60% for after-school days and weekends over all observation points. However, regarding all girls, compensation was predominantly negative. Differentiated analysis indicated that all girls with low ST levels in the morning or on weekdays, compensated for this behaviour with lower PA levels in the afternoon or on weekends. Multilevel covariate analysis indicated great variability between the participants. Furthermore, differences in compensatory behaviour can also be seen on class and school levels. Interestingly, PA compensatory behaviour is not associated with age, weight status or SES.

CONCLUSION

Our findings could neither confirm nor reject the ActivityStat Hypothesis. Overall, due to the great variability across the girls, it seems that compensation depends on individual factors. In the future, to prevent negative compensation, school-based interventions that have the potential to provide opportunities to be physically active, should not neglect (pre)adolescents' leisure time behaviour.

TRIAL REGISTRATION

DRKS00015723 (date of registration: 2018/10/22 retrospectively registered).

The gendered playing field: Family socioeconomic status and national gender inequality in adolescents' out-of-school physical activity

Research has shown that both gender and family socioeconomic status (SES) are important determinants of adolescents' physical activity (PA). This study expands our current knowledge by exploring the moderating role of family SES on gender differences in adolescents' out-of-school PA. We also examine whether this moderating effect varies across countries with different levels of gender inequality. Based on existing empirical studies and theoretical framework, it is hypothesized that 1) gender differences in out-of-school PA would be smaller among adolescents from higher SES families due to them being more likely to share egalitarian gender norms, and 2) this SES gradient in gender differences in adolescents' out-of-school PA would be more salient in countries with lower levels of gender inequality. A total of 316,657 15-year-old adolescents in 50 countries from the 2015 Programme for International Student Assessment (PISA) survey were analyzed. Our multilevel negative binomial regression models show that the gender gap in out-of-school PA is mitigated among families with higher SES, but this moderating role of family SES is less noticeable in countries with higher levels of national gender inequality. Our findings suggest the importance of egalitarian gender culture at both individual and macro-level in understanding gender disparities in adolescents' PA.

Equalisation of Children's Various Levels of Physical Activity Using Increased Physical Activity at School Among Ninth Graders

The purpose of this study was to examine whether 60 min of physical activity implemented during school hours, would have an impact on 15-year-olds' MVPA (moderate to vigorous physical activity) throughout the school day, and what effect it would have on low-, average-, and high- physically-active students. The intervention study included a sample of every 93 students in the ninth grade from a school in Trøndelag, Norway. Data on the students' physical activity levels during schooltime were measured using accelerometers and analyzed using the Actilife program. A significant higher change in MVPA was found in the intervention group compared to the control group, with an average increase of 25 min in MVPA in the pre-test to 42 min in post-test. Further analyses showed that the that both the low-active and the high-active had a significant increase in MVPA, taking the results of the control group into consideration. However, the low-active participants had the largest increase, with a 123% increase in MVPA during schooltime. The implication of the study is that PA interventions in school have the largest percentage effect among the low-active students in the study, which indicates that school-based interventions can be important in bridging social differences in MVPA among adolescents.

Compensation or Displacement of Physical Activity in Children and Adolescents: A Systematic Review of Empirical Studies

Regular physical activity during childhood and adolescence is associated with health benefits. Consequently, numerous health promotion programs for children and adolescents emphasize the enhancement of physical activity. However, the ActivityStat hypothesis states that increases in physical activity in one domain are compensated for by decreasing physical activity in another domain. Currently, little is known about how physical activity varies in children and adolescents within intervals of one day or multiple days. This systematic review provides an overview of studies that analyzed changes in (overall) physical activity, which were assessed with objective measurements, or compensatory mechanisms caused by increases or decreases in physical activity in a specific domain in children and adolescents. A systematic search of electronic databases (PubMed, Scopus, Web of Science, SportDiscus) was performed with a priori defined inclusion criteria. Two independent researchers screened the literature and identified and rated the methodological quality of the studies. A total of 77 peer-reviewed articles were included that analyzed changes in overall physical activity with multiple methodological approaches resulting in compensation or displacement. Of 40,829 participants, 16,265 indicated compensation associated with physical activity. Subgroup analyses separated by study design, participants, measurement instrument, physical activity context, and intervention duration also showed mixed results toward an indication of compensation. Quality assessment of the included studies revealed that they were of high quality (mean = 0.866). This review provides inconclusive results about compensation in relation to physical activity. A trend toward increased compensation in interventional studies and in interventions of longer duration have been observed.

Estimating the health and economic burden of shipping related air pollution in the Iberian Peninsula

Air pollution is the leading cause of the global burden of disease from the environment, entailing substantial economic consequences. International shipping is a significant source of NO_x, SO₂, CO and PM, which can cause known negative health impacts. Thus, this study aimed to estimate the health impacts and the associated external costs of ship-related air pollution in the Iberian Peninsula for 2015. Moreover, the impact of CAP2020 regulations on 2015 emissions was studied. Log-linear functions based on WHO-HRAPIE relative risks for PM_2.5 and NO₂ all-cause mortality and morbidity health end-points, and integrated exposure-response functions for PM_2.5 cause-specific mortality, were used to calculate the excess burden of disease. The number of deaths and years of life lost (YLL) due to NO₂ ship-related emissions was similar to those of PM_2.5 ship-related emissions. Estimated all-cause premature deaths attributable to PM_2.5 ship-related emissions represented an average increase of 7.7% for the Iberian Peninsula when compared to the scenario without shipping contribution. Costs of around 9 100 million € yr-1 (for value of statistical life approach - VSL) and 1 825 million € yr^-1 (for value of life year approach - VOLY) were estimated for PM and NO₂ all-cause burden of disease. For PM_2.5 cause-specific mortality, a cost of around 3 475 million € yr^-1 (for VSL approach) and 851 million € yr^-1 (for VOLY approach) were estimated. Costs due to PM and NO₂ all-cause burden represented around 0.72% and 0.15% of the Iberian Peninsula gross domestic product in 2015, respectively for VSL and VOLY approaches. For PM_2.5 cause-specific mortality, costs represented around 0.28% and 0.06%, respectively, for VSL and VOLY approaches. If CAP2020 regulations had been applied in 2015, around 50% and 30% respectively of PM_2.5 and NO₂ ship-related mortality would been avoided. These results show that air pollution from ships has a considerable impact on health and associated costs affecting the Iberian Peninsula.

Levels of Physical Activity during School Hours in Children and Adolescents: A Systematic Review

BACKGROUND

This systematic review determines the levels of physical activity (PA) during school hours in children and adolescents.

METHODS

Studies carried out from January 1987 to December 2019 were retrieved from four databases (Web of Science, Pubmed, Scopus and SportDiscus). The 29 selected studies were cross-sectional, long-term and case studies.

RESULTS

Most of them used accelerometers and showed that male and female children accumulated a mean of between 14 and 68 min of moderate-to-vigorous PA (MVPA) during school hours (3%-22% of this daily segment), and male and female adolescents accumulated a mean of between 13 and 28 min of MVPA during this daily segment (3%-8% of the school hours). Less than a quarter of children and adolescents reached the recommended 30 min of MVPA during school hours, with notable differences between sexes.

CONCLUSIONS

These results suggest that the levels of PA during school hours are not enough, and consequently, schools should develop strategies for helping children and adolescents reach the school PA recommendation.

Ecological study of playground space and physical activity among primary school children

OBJECTIVES

To examine the relationship between school playground size and total physical activity (PA), fitness and fundamental movement skills (FMS) of primary school students.

DESIGN

Cross-sectional ecological analysis.

SETTING

43 primary schools in New South Wales, Australia.

PARTICIPANTS

Data were from 5238 students, aged 5 to 12 years, participating in the Schools Physical Activity and Nutrition Survey.

OUTCOME MEASURES

Self (for age ≥11 years) and parent (for age <11 years) report of PA (meeting PA recommendations and number of days meeting recommendations), objectively measured FMS and cardiorespiratory and muscular fitness.

RESULTS

Associations between playground space and measures of PA and fitness were mostly non-linear and moderated by loose equipment. Students in schools with no loose equipment showed a weak association between space and meeting PA recommendations (self-report). In schools with equipment, students' predicted probability of meeting PA recommendations increased sharply between 15 m² and 25 m² per student from 0.04 (95% CI: 0.01 to 0.08) to 0.30 (95% CI: 0.14 to 0.46), but at 30 m² returned to levels comparable to students in schools with no equipment (0.18, 95% CI: 0.07 to 0.28). For cardiorespiratory fitness, in schools with no loose equipment, probabilities for being in the healthy cardiovascular fitness zone varied between 0.66 and 0.77, showing no consistent trend. Students in schools with loose equipment had a predicted probability of being in the healthy fitness zone of 0.56 (95% CI: 0.41 to 0.71) at 15 m² per student, which rose to 0.75 (95% CI: 0.63 to 0.86) at 20 m² per student. There was no relationship between space and FMS.

CONCLUSIONS

School space guidelines need to incorporate sufficient playground space for students. Our study provides evidence supporting better PA outcomes with increasing space up to 25 m² per student, and access to loose equipment, however further research is required to determine precise thresholds for minimum space. Intersectoral planning and cooperation is required to meet the needs of growing school populations.

Physical Activity in 15-17-Year-Old Adolescents as Compensation for Sedentary Behavior in School

The traditional concept of education and school settings significantly contribute to the sedentary behavior of adolescents at secondary schools. The aim of this study is to identify the volume and intensity of physical activity (PA) that adolescent boys and girls engage in during recesses, after school, and during the day to compensate for sedentary behavior in lessons. The study was conducted at 29 Czech and 9 Polish schools. The study involved 868 girls and 409 boys aged 15-17 years. An ActiTrainerTM accelerometer was used to monitor PA and heart rate. Participants were divided into four quartile groups. Most sedentary boys and girls had less PA and showed a worse ratio of physical inactivity (PI)/PA than non-sedentary participants during recesses. In the after-school period, there were no significant differences. On school days, most sedentary boys and girls showed lower PA, a worse ratio of PI/PA, fewer steps·hour-1, and lower energy expenditure than their non-sedentary counterparts. Vigorous PA of ≥8 METs was reached by 48% of most sedentary boys (75% non-sedentary) and 47% of most sedentary girls (54% non-sedentary). Most sedentary adolescents do not compensate for their sedentary behavior in lessons with higher PA intensity or volume during recesses, after-school, or in overall daily PA.

Understanding physical activity and sedentary behaviour among preschool-aged children in Singapore: a mixed-methods approach

OBJECTIVES

This study investigated physical activity (PA) and sedentary behaviour (SB) among preschool-aged children in Singapore and potential correlates at multiple levels of the socioecological model from in-school and out-of-school settings.

DESIGN

A cross-sectional study using a mixed-methods approach.

PARTICIPANTS

Parent-child dyads from six preschools in Singapore.

METHODS

PA and SB of children (n=72) were quantified using wrist-worn accelerometers for seven consecutive days. Three focus group discussions (FGDs) among 12 teachers explored diverse influences on children's activities, and System for Observing Play and Leisure Activity in Youth (SOPLAY) assessed PA environment and children's activity levels at preschools. Seventy-three parents completed questionnaires on home and neighbourhood factors influencing children's PA and SB. Descriptive analyses of quantitative data and thematic analysis of FGDs were performed.

RESULTS

Based on accelerometry, children (4.4±1.1 years) spent a median of 7.8 (IQR 6.4-9.0) hours/day in SB, and 0.5 (0.3-0.8) hours/day in moderate-to-vigorous physical activity (MVPA). MVPA was similar throughout the week, and SB was slightly higher on non-school days. In preschools, SOPLAY showed more children engaging in MVPA outdoors (34.0%) than indoors (7.7%), and absence of portable active play equipment. FGDs revealed issues that could restrict active time at preschool, including academic requirements of the central curriculum and its local implementation. The teachers had varying knowledge about PA guidelines and perceived that the children were sufficiently active. In out-of-school settings, parents reported that their children rarely used outdoor facilities for active play and spent little time in active travel. Few children (23.5%) participated in extracurricular sports, but most (94.5%) reported watching screens for 1.5 (0.5-3.0) hours/day.

CONCLUSION

MVPA was low and SB was high in preschool-aged children in an urban Asian setting. We identified diverse in-school and out-of-school correlates of PA and SB that should be taken into account in health promotion strategies.

International Comparison of the Levels and Potential Correlates of Objectively Measured Sedentary Time and Physical Activity among Three-to-Four-Year-Old Children

Physical activity (PA) patterns track from childhood through to adulthood. The study aimed to determine the levels and correlates of sedentary time (ST), total PA (TPA), and moderate-to-vigorous PA (MVPA) in preschool-aged children. We conducted cross-sectional analyses of 1052 children aged three-to-four-years-old from six studies included in the International Children’s Accelerometry Database. Multilevel linear regression models adjusting for age, gender, season, minutes of wear time, and study clustering effects were used to estimate associations between age, gender, country, season, ethnicity, parental education, day of the week, time of sunrise, time of sunset, and hours of daylight and the daily minutes spent in ST, TPA, and MVPA. Across the UK, Switzerland, Belgium, and the USA, children in our analysis sample spent 490 min in ST per day and 30.0% and 21.2% of children did not engage in recommended daily TPA (≥180 min) and MVPA (≥60 min) guidelines. There was evidence for an association between all 10 potential correlates analyzed and at least one of the outcome variables; average daily minutes spent in ST, TPA and/or MVPA. These correlates can inform the design of public health interventions internationally to decrease ST and increase PA in preschoolers.

Kindergarten: Producer or Reducer of Inequality Regarding Physical Activity Levels of Preschool Children

Several studies have shown that children have sub-optimal physical activity levels. Since preschool children (4-6 years-old) spend most of their time awake in kindergarten on weekdays, physical activity level at kindergarten is crucial. The study examines preschool children's physical activity level at kindergarten. Preschool children's activity level at kindergarten is also investigated related to activity level at leisure, gender, and mothers' education level, income, and age. Two hundred and forty four children (125 boys and 119 girls) supplied valid accelerometer data, and mothers' education level, income, and age were measured using a questionnaire. One-way ANOVA and linear regression were utilized as statistical analyses. The results demonstrated that physical activity level during kindergarten is the main contributor to preschool children's physical activity level on weekdays. Furthermore, boys were more active than girls, and preschool children's physical activity level at both leisure and at kindergarten were not associated with mothers' age, education level, or income. However, a positive association was found between physical activity level at leisure and physical activity level at kindergarten, in which physical activity level at kindergarten increases when physical activity level at leisure increases. Physical activity level was also significantly different between kindergartens. The study indicated that kindergartens increase inequality according to physical activity level among preschool children-contributing to creating differences according to low-active and high-active children.

Off-Training Levels of Physical Activity and Sedentary Behavior in Young Athletes: Preliminary Results during a Typical Week

The level of physical activity (PA) and sedentary behavior (SED) off-training of young athletes may reveal the quality of recovery from training and highlight health related issues. Thus, the aim was to identify and describe young athletes' PA and SED off-training, according to daily life activities. Eight athletes (15.7 ± 2 years, 1.72 ± 0.6 m height, 62.9 ± 10.2 kg) of a sport talent program wore on their waist a tri-axial accelerometer (ActiGraph^® wGT9X-link, Shalimar, FL, USA) at 30 Hz for 15 consecutive days, and reported their schedule. A two-step cluster analysis classified three groups according to sedentary PA and MVPA. The Sedentary (56.9%), presented the highest sedentary PA (mean [CI], 37.37 [36.45⁻38.29] min/hour); The Hazardous (19.4%) had the lowest values of sedentary and MVPA (10.07 [9.41⁻10.36] min/hour and 8.67 [7.64⁻9.70] min/hour, respectively). Balanced (23.7%) had the highest MVPA (28.61 [27.16⁻30.07] min/hour). Sedentary had the lowest count of home time associated (20%) and higher school (26%) time when compared to the Hazardous (13%). The Balanced showed the highest count of school (61%) and home time (47%). Different profiles for young athletes revealed alarming behavior in the associations with sedentary PA, sitting and SED breaks, which may influence performance and health.

Physical activity intensity, bout-duration, and cardiometabolic risk markers in children and adolescents

OBJECTIVES

To determine the role of physical activity intensity and bout-duration in modulating associations between physical activity and cardiometabolic risk markers.

METHODS

A cross-sectional study using the International Children's Accelerometry Database (ICAD) including 38,306 observations (in 29,734 individuals aged 4-18 years). Accelerometry data was summarized as time accumulated in 16 combinations of intensity thresholds (≥500 to ≥3000 counts/min) and bout-durations (≥1 to ≥10 min). Outcomes were body mass index (BMI, kg/m2), waist circumference, biochemical markers, blood pressure, and a composite score of these metabolic markers. A second composite score excluded the adiposity component. Linear mixed models were applied to elucidate the associations and expressed per 10 min difference in daily activity above the intensity/bout-duration combination. Estimates (and variance) from each of the 16 combinations of intensity and bout-duration examined in the linear mixed models were analyzed in meta-regression to investigate trends in the association.

RESULTS

Each 10 min positive difference in physical activity was significantly and inversely associated with the risk factors irrespective of the combination of intensity and bout-duration. In meta-regression, each 1000 counts/min increase in intensity threshold was associated with a -0.027 (95% CI: -0.039 to -0.014) standard deviations lower composite risk score, and a -0.064 (95% CI: -0.09 to -0.038) kg/m2 lower BMI. Conversely, meta-regression suggested bout-duration was not significantly associated with effect-sizes (per 1 min increase in bout-duration: -0.002 (95% CI: -0.005 to 0.0005) standard deviations for the composite risk score, and -0.005 (95% CI: -0.012 to 0.002) kg/m2 for BMI).

CONCLUSIONS

Time spent at higher intensity physical activity was the main determinant of variation in cardiometabolic risk factors, not bout-duration. Greater magnitude of associations was consistently observed with higher intensities. These results suggest that, in children and adolescents, physical activity, preferably at higher intensities, of any bout-duration should be promoted.

Effect of Sex and Body Mass Index on Children's Physical Activity Intensity during Free Play at an Indoor Soft Play Center: An Exploratory Study

Background: Indoor soft play can provide a safe but exciting physical activity opportunity regardless of environmental conditions. Relatively little is known about the quality or quantity of physical activity engaged in by children during indoor free soft play. The aim of this study was to evaluate the contribution indoor free soft play can make in enabling children to meet physical activity guidelines and to evaluate the effects of sex and body mass index category. Methods: Seventy-two boys and girls aged five to 10 years engaged in un-controlled indoor free soft play with a mean duration of 120.7 (27.1) min, during which physical activity was monitored using Actigraph accelerometers. Results: Children spent an average of 61.7 (24.2) min engaging in moderate to vigorous physical activity (MVPA) and 51.4% (n = 37) achieved the recommended 60 min of MVPA through the single visit to the indoor soft play center. Boys (68.3 (25.7) min) engaged in significantly (p < 0.05) more MVPA than girls (55.8 (21.4) min). Normal weight (65.7 (23.3) min) children engaged in significantly more MVPA than overweight children (48.0 (18.9) min). Conclusions: Attendance at a soft play indoor center has the potential to support children to engage in sufficient MVPA and overcome environmental factors that can restrict physical activity opportunities.

Physical Education Increases Daily Moderate to Vigorous Physical Activity and Reduces Sedentary Time

BACKGROUND

Physical activity (PA) is important to mental and physical health. Physical education (PE) lessons have the potential to increase daily moderate to vigorous PA (MVPA) and reduce sedentary time (SED). We measured MVPA and SED in primary school PE, determined the contribution of PE to daily MVPA and SED, and compared PA on days with and without PE.

METHODS

PA was measured in 504 first (ages 7-9) and second (ages 10-12) school level children for 1 school week, with inclusion criteria of at least 10 hours of valid data. Linear mixed methods were used for data analysis.

RESULTS

In PE, students spent 28.6 ± 16.5% in MVPA and 29.3 ± 19.8% in SED. Each additional MVPA minute in PE was associated with 1.4 more daily MVPA minutes. On days with PE, students had 12.8 (95% CI 10.5; 15.0) minutes more MVPA and 9.7 (95% CI 16.3; 3.1) minutes less SED compared with days without PE.

CONCLUSIONS

Although MVPA in PE was relatively low and SED high, PE significantly increased daily MVPA and reduced SED, confirming the important role of PE in supporting the healthy development of children.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Age-related patterns of vigorous-intensity physical activity in youth: The International Children's Accelerometry Database

Physical activity declines during youth but most evidence reports on combined moderate and vigorous-intensity physical activity. We investigated how vigorous-intensity activity varies with age. Cross-sectional data from 24,025 participants (5.0-18.0 y; from 20 studies in 10 countries obtained 2008-2010) providing ≥ 1 day accelerometer data (International Children's Accelerometry Database (ICAD)). Linear regression was used to investigate age-related patterns in vigorous-intensity activity; models included age (exposure), adjustments for monitor wear-time and study. Moderate-intensity activity was examined for comparison. Interactions were used to investigate whether the age/vigorous-activity association differed by sex, weight status, ethnicity, maternal education and region. A 6.9% (95% CI 6.2, 7.5) relative reduction in mean vigorous-intensity activity with every year of age was observed; for moderate activity the relative reduction was 6.0% (5.6%, 6.4%). The age-related decrease in vigorous-intensity activity remained after adjustment for moderate activity. A larger age-related decrease in vigorous activity was observed for girls (- 10.7%) versus boys (- 2.9%), non-white (- 12.9% to - 9.4%) versus white individuals (- 6.1%), lowest maternal education (high school (- 2.0%)) versus college/university (ns) and for overweight/obese (- 6.1%) versus healthy-weight participants (- 8.1%). In addition to larger annual decreases in vigorous-intensity activity, overweight/obese individuals, girls and North Americans had comparatively lower average vigorous-intensity activity at 5.0-5.9 y. Age-related declines in vigorous-intensity activity during youth appear relatively greater than those of moderate activity. However, due to a higher baseline, absolute moderate-intensity activity decreases more than vigorous. Overweight/obese individuals, girls, and North Americans appear especially in need of vigorous-intensity activity promotion due to low levels at 5.0-5.9 y and larger negative annual differences.

Physical activity of German children during different segments of the school day

AIM

This study objectively investigated the amount and intensity of German primary school children's physical activity (PA) during different segments of the school day and explored the contribution of physical education (PE) and break times to daily moderate to vigorous PA (MVPA).

SUBJECT AND METHODS

PA of 294 children (7.1 ± 0.7 years, 48 % male) was objectively measured for 6 days using Actiheart®. Based on children's timetables, break times and PE periods were determined and PA was calculated individually and subsequently classified in light (1.5-3 MET), moderate (3-6 MET) and vigorous (>6 MET) intensities. Weight status was determined during a school visit.

RESULTS

Children spent 133 ± 61 min in MVPA; on weekdays, this amount increased significantly (141 ± 66 min, p ≤ 0.01). 45.9 % of children reached physical activity guidelines of 60 min of MVPA daily, with boys achieving this goal significantly more often than girls (65.6 vs. 28.7 %, respectively; p ≤ 0.01). PE lessons and break times accounted for 15 ± 13 min (12.7 %) and 7 ± 6 min (5.8 %) of daily MVPA, respectively. On days with PE, children spent 144 ± 68 min in MVPA, whereas on days without PE, this time decreased significantly to 122 ± 63 min (p ≤ 0.01).

CONCLUSION

The findings suggest that segments such as PE lessons and morning breaks are important sources for MVPA for boys and girls. This should therefore be considered for policies, timetables and curriculums in order to offer sufficient opportunities for children to be physically active during the school day.

Reliability and Validity of the Physical Education Activities Scale

BACKGROUND

Measuring adolescent perceptions of physical education (PE) activities is necessary in understanding determinants of school PE activity participation. This study assessed reliability and validity of the Physical Education Activities Scale (PEAS), a 41-item visual analog scale measuring high school adolescent perceptions of school PE activity participation.

METHODS

Adolescents (N = 529) from the Pacific Northwest aged 15-19 in grades 9-12 participated in the study. Construct validity was assessed using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). Measurement invariance across sex groups was tested by multiple-group CFA. Internal consistency reliability was analyzed using Cronbach's alpha. Inter-subscale correlations (Pearson's r) were calculated for latent factors and observed subscale scores.

RESULTS

Exploratory factor analysis suggested a 3-factor solution explaining 43.4% of the total variance. Confirmatory factor analysis showed the 3-factor model fit the data adequately (comparative fit index [CFI] = 0.90, Tucker-Lewis index [TLI] = 0.89, root mean squared error of approximation [RMSEA] = 0.063). Factorial invariance was supported. Cronbach's alpha of the total PEAS was α = 0.92, and for subscales α ranged from 0.65 to 0.92. Independent t-tests showed significantly higher mean scores for boys than girls on the total scale and all subscales.

CONCLUSION

Findings provide psychometric support for using the PEAS for examining adolescent's psychosocial and environmental perceptions to participating in PE activities.

Different Methods Yielded Two-Fold Difference in Compliance with Physical Activity Guidelines on School Days

Introduction

The aim was to compare the average and the days method in exploring the compliance of children with physical activity guidelines and describe their physical activity patterns in different school day segments.

Methods

Physical activity was objectively measured in 472 children aged 6–13 for one school week. Children were compliant when fulfilling PA recommendations 1) on average over all measured days (average method) or 2) on at least four measured days (days method). To explore the difference in moderate to vigorous physical activity (MVPA) minutes between compliant and non-complaint children (using both the average and days method) in various day segments, linear mixed models was used.

Results

Compliance with physical activity guidelines was significantly higher with the average compared to the days method (51.7% and 23.7%, respectively). In segmented-day analysis, compliant children accrued more MVPA minutes in all day segments, especially during after-school. Gender differences appeared only during the in-school segments, where girls spent less time in MVPA (average method: -4.39 min, 95% CI = -5.36,-3.42, days method: -4.45 min, 95%CI = -5.46,-3.44). Older children accrued more MVPA minutes during physical education classes, but less during breaks, compared to younger children.

Conclusions

The used methods yielded remarkably different prevalence estimates for compliance to physical activity recommendations. To ensure comparability between studies, interventions and reports, there is a need for internationally agreed operationalization and assessment methods of physical activity guidelines. As non-compliant children had lower MVPA during all day segments, greater efforts should be made to provide physical activity opportunities both during and after school.

The Role of Physical Education Lessons and Recesses in School Lifestyle of Adolescents

BACKGROUND

This study investigates school lifestyle among adolescents in terms of physical activity (PA) structure: (1) adolescents participating in a physical education lesson (PEL) versus (2) aggregate recess time exceeding 60 minutes.

METHODS

The research was conducted in 24 secondary schools in the Czech Republic (boys N = 208, girls N = 433). For the whole day (1-3 days) participants wore the ActiTrainer accelerometer, which monitored PA, and heart rate. A total of 1122 school days were recorded.

RESULTS

Both boys and girls participating in a PEL reported significantly better results compared with nonparticipating individuals regarding all indicators of volume and intensity of school PA (SPA). In most SPA indicators, longer aggregate recess time (>60 minutes) had a statistically significant effect, particularly on the volume of SPA. The recommended 500 steps/hours for SPA was achieved by 83% of boys participating in PEL and 69% of girls. In contrast just 32% of nonparticipating boys and 31% of girls reached this level. With longer recess time the recommendation was met by 43% of boys (42% of girls) compared with 26% of boys (23% of girls) with shorter recess time.

CONCLUSIONS

An increase in SPA and an improved lifestyle in adolescents on school days are significantly supported more by PELs than by longer recess time.

A systematic literature review with meta-analyses of within- and between-day differences in objectively measured physical activity in school-aged children

Background

Targeting specific time periods of the day or week may enhance physical activity (PA) interventions in youth. The most prudent time segments to target are currently unclear.

Objectives

To systematically review the literature describing differences in young people’s objectively measured PA on weekdays vs. weekends, in school vs. out of school, weekends vs. out of school and lesson time vs. break time.

Methods

Electronic databases were searched for English-language, cross-sectional studies of school-aged children (4–18 years) reporting time-segment-specific accelerometer-measured PA from 01/1990 to 01/2013. We meta-analysed standardised mean differences (SMD) between time segments for mean accelerometer counts per minute (TPA) and minutes in moderate-to-vigorous PA (MVPA). SMD is reported in units of standard deviation; 0.2, 0.5 and 0.8 represent small, moderate and large effects. Heterogeneity was explored using meta-regression (potential effect modifiers: age, sex and study setting).

Results

Of the 54 included studies, 37 were eligible for meta-analyses. Children were more active on weekdays than weekends [pooled SMD (95 % CI) TPA 0.14 (0.08; 0.20), MVPA 0.42 (0.35; 0.49)]. On school days, TPA was lower in school than out of school; however, marginally more MVPA was accumulated in school [TPA −0.24 (−0.40; −0.08), MVPA 0.17 (−0.03; 0.38)]. TPA was slightly lower on weekends than out of school on school days, but a greater absolute volume of MVPA was performed on weekends [TPA −0.10 (−0.19; −0.01), MVPA 1.02 (0.82; 1.23)]. Heterogeneity between studies was high (I² 73.3–96.3 %), with 20.3–53.1 % of variance between studies attributable to potential moderating factors.

Conclusions

School-aged children are more active on weekdays than weekend days. The outcome measure influences the conclusions for other comparisons. Findings support the tailoring of intervention strategies to specific time periods.

Electronic supplementary material

The online version of this article (doi:10.1007/s40279-014-0215-5) contains supplementary material, which is available to authorized users.

Longitudinal changes in sedentary time and physical activity during adolescence

BACKGROUND

Low levels of physical activity and high time spent in sedentary activities have been associated with unfavourable health outcomes in adolescents. During adolescence, physical activity declines and sedentary time increases, however little is known about whether the magnitude of these changes differs within or between school-time, after-school time, or at weekends.

METHODS

Adolescents (n = 363) participating in the PEACH (Personal and Environmental Associations with Children's Health) project provided accelerometer data at 12 and 15 years of age. Data were collected in 2008/2009 and 2012/2013. Time spent sedentary (<100 cpm), in light physical activity (LPA (100-2295 cpm) and in moderate to vigorous physical activity (MVPA: ≥ 2296 cpm) were generated for school-time, after-school time and for weekends using school-specific start and finish times. All data were analysed in 2014.

RESULTS

The proportion of time spent sedentary significantly increased during school (+8.23%, 95% CI = 7.35 to 9.13), after-school (+6.99%, 95% CI = 5.91 to 8.07) and at weekends (+6.86%, 95% CI = 5.10 to 8.62). A parallel decrease was found in the proportion of time spent in LPA during school (-7.62%, 95% CI = -8.26 to -6.98), after-school (-7.01%, 95% CI = -7.74 to -6.28) and at weekends (-6.72%, 95% CI = -7.80 to -5.65). The proportion of time spent in MVPA remained relatively stable during school (-0.64, 95% CI = -1.11 to -0.18), after-school (0.04%, 95% CI = -0.58 to 0.67) and at weekends (-0.14%, 95% CI = -1.18 to 0.90).

CONCLUSIONS

Objectively measured sedentary time increased between 12 and 15 years of age during-school, after-school, and at weekends, suggesting that interventions aiming to reduce the age-associated changes in sedentary time are needed in all three time contexts. Future work should identify which sedentary activities change more than others to inform interventions which aim to minimise the increase in time spent sedentary during adolescence.

Do extra compulsory physical education lessons mean more physically active children--findings from the childhood health, activity, and motor performance school study Denmark (The CHAMPS-study DK)

BACKGROUND

Primarily, this study aims to examine whether children attending sports schools are more active than their counterpart attending normal schools. Secondary, the study aims to examine if physical activity (PA) levels in specific domains differ across school types. Finally, potential modifications by status of overweight/obesity and poor cardio-respiratory fitness are examined.

METHODS

Participants were from the first part of the CHAMPS-study DK, which included approximately 1200 children attending the 0th - 6th grade. At the sports schools, the mandatory physical education (PE) program was increased from 2 to 6 weekly lessons over a 3-year period. Children attending normal schools were offered the standard 2 PE lessons. PA was assessed at two different occasions with the GT3X ActiGraph accelerometer, once during winter in 2009/10 and once during summer/fall in 2010. Leisure time organized sports participation was quantified by SMS track. Based on baseline values in 2008, we generated a high-BMI and a low-cardio-respiratory fitness for age and sex group variable.

RESULTS

There were no significant differences in PA levels during total time, PE, or recess between children attending sports schools and normal schools, respectively. However, children, especially boys, attending sports schools were more active during school time than children attending normal schools (girls: β=51, p=0.065; boys: β=113, p<0.001). However, in the leisure time during weekdays children who attended sports schools were less active (girls: β=-41, p=0.004; boys: β=-72, p<0.001) and less involved in leisure time organized sports participation (girls: β=-0.4, p=0.016; boys: β=-0.2, p=0.236) than children who attended normal schools. Examination of modification by baseline status of overweight/obesity and low cardio-respiratory fitness indicated that during PE low fit girls in particular were more active at sports schools.

CONCLUSION

No differences were revealed in overall PA levels between children attending sports schools and normal schools. Sports schools children were more active than normal schools children during school time, but less active during leisure time. In girls, less organized sports participation at least partly explained the observed differences in PA levels during leisure time across school types. Baseline status of cardio-respiratory fitness modified school type differences in PA levels during PE in girls.

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.

Patterns of physical activity outside of school time among Japanese junior high school students

BACKGROUND

Physical activity is beneficial for adolescent health. The physical activity patterns of Japanese adolescents are relatively unknown. Therefore, this study aimed to describe the current patterns of physical activity and to identify sex and grade differences among them.

METHODS

The participants comprised 714 Japanese adolescents aged 12 to 15 years old (boys N = 372, girls N = 342) from a public junior high school in Okayama, Japan. Physical activity at school, outside of school after hours, and during lunch recess as well as the total leisure time in a usual week was assessed with a 5-item questionnaire. To assess the differences in the physical activity patterns by sex and grade, independent t tests and analysis of variance (ANOVA) were conducted, respectively.

RESULTS

Boys spent significantly more time in physical activity both inside and outside of school settings than girls (p < .05). Higher grade students were significantly less active than lower grade students (p < .05). Furthermore, the physical activity patterns across the grades differed between settings (at school, outside of school during the after-school period, lunchtime recess, and at home).

CONCLUSION

To increase physical activity levels among Japanese adolescents, implementation of after-school programs or environmental modifications developed within the school setting could be effective strategies.

Weekday and weekend patterns of physical activity and sedentary time among Liverpool and Madrid youth

Levels of physical inactivity and sedentary behaviour among English and Spanish youth are high and vary within different regions of each country. Little though is known about these during specific periods of the day. The purpose of this study was to describe physical activity (PA) and sedentary time during segments of the day and week, and compare these critical contexts between youth in the Liverpool and Madrid areas of England and Spain, respectively. PA was objectively assessed in 235 Liverpool- and 241 Madrid youth (aged 10-14 years) who wore accelerometers for seven consecutive days. Minutes of sedentary time, moderate PA, vigorous PA and moderate-to-vigorous physical activity (MVPA) were calculated for weekdays, weekend days, school time, non-school time and after-school. Between-country differences were analysed using analysis of covariance (ANCOVA). Madrid youth spent significantly more time in sedentary activities than their Liverpool counterparts. Madrid youth engaged in more minutes of moderate intensity physical activity (MPA) than Liverpool youth during weekdays, school time and non-school time (P<0.01). Liverpool children recorded more time in vigorous physical activity (VPA) than Madrid peers during week days and weekend days (P<0.01) and during school time and after-school periods (P<0.01). The MVPA was significantly higher among Madrid youth during non-school time (P<0.01). Around 25% of all youth achieved recommended levels of MVPA. Low levels of MVPA and systematic differences in sedentary time, MPA and VPA exist between Liverpool and Madrid youth. Interventions targeted at the least-active children during weekends, after-school and non-school periods within the cultural contexts common to each city are required.

Weekday and weekend physical activity patterns of French and Spanish adolescents

Adolescents' objectively assessed physical activity (PA) patterns during specific segments of the day remain unclear. In order to develop a clearer understanding this study examined country and gender differences in moderate to vigorous physical activity (MVPA) levels during specific segments of weekdays and weekend days, and explored the contribution of each segment to PA guidelines. Morpho-demographic, socio-economic and PA data were collected from a sample of 829 French and Spanish adolescents (45.0% Spanish; 55.2% females; 14.33±.73 years). Actigraph GT3X accelerometers were worn for seven days to assess adolescents' MVPA for three segments of weekdays (school-travel-time, school-time, and non-school-time), and weekend days (morning-time, afternoon-time and night-time). Data were analysed using multilevel modelling. The most active segments were non-school-time (29.2±17.5 min) and school-time (25.8±14.2 min) during weekdays, and morning-time (28.2±25.8 min) on weekend days. Except for school-time, Spanish adolescents were more significantly active than French adolescents during all segments. Significant gender differences were found in all segments. Country differences highlight the need to recognise cultural contexts that influence adolescents' PA. Common European-wide strategies may be insufficient to increase MVPA levels if cultural variability is not considered. Spanish and French PA intervention programmes should target girls and low-active boys during non-school-time and weekends.

How active are our children? Findings from the Millennium Cohort Study

OBJECTIVE

To describe levels of physical activity, sedentary time and adherence to Chief Medical Officers (CMO) physical activity guidelines among primary school-aged children across the UK using objective accelerometer-based measurements.

DESIGN

Nationally representative prospective cohort study.

SETTING

Children born across the UK, between 2000 and 2002.

PARTICIPANTS

6497 7-year-old to 8-year-old singleton children for whom reliable accelerometer data were available for at least 10 h a day for at least 2 days.

MAIN OUTCOME MEASURES

Physical activity in counts per minute (cpm); time spent in sedentary and moderate-to-vigorous intensity physical activity (MVPA); proportion of children meeting CMO guidelines (≥60 min/day MVPA); average daily steps.

EXPLANATORY MEASURES

Gender, ethnicity, maternal current/most recent occupation, lone parenthood status, number of children in the household and country/region of residence.

RESULTS

The median daily physical activity level was 595 cpm (IQR 507, 697). Children spent a median of 60 min (IQR 47-76) in MVPA/day and were sedentary for a median of 6.4 h/day (IQR 6-7). Only 51% met CMO guidelines, with girls (38%) less active than boys (63%). Children took an average of 10 229 (95% CI (8777 to 11 775)) steps each day. Children of Indian ethnicity were significantly less active overall than all other ethnic groups. Children of Bangladeshi origin and those living in Northern Ireland were least likely to meet CMO guidelines.

CONCLUSIONS

Only half of 7-year-old children in the UK achieve recommended levels of physical activity, with significant gender, ethnic and geographic variations. Longitudinal studies are needed to better understand the relevance of these (in)activity patterns for long-term health and well-being. In the meantime population-wide efforts to boost physical activity among young people are needed which are likely to require a broad range of policy interventions.

Schoolyard physical activity of 6-11 year old children assessed by GPS and accelerometry

BACKGROUND

Children's current physical activity levels are disturbingly low when compared to recommended levels. This may be changed by intervening in the school environment. However, at present, it is unclear to what extent schoolyard physical activity contributes towards reaching the daily physical activity guideline. The aim of this study was to examine how long and at what intensity children are physically active at the schoolyard during different time segments of the day. Moreover, the contribution of schoolyard physical activity towards achieving the recommended guideline for daily physical activity was investigated.

METHODS

Children (n=76) between the age of 6-11 years were recruited in six different schools in five cities (>70.000 residents) in the Netherlands. During the weekdays of a regular school week, childrens' physical activity and location were measured with ActiGraph accelerometers and Travelrecorder GPS receivers. Data was collected from December 2008 to April 2009. From the data, the amount of moderate to vigorous physical activity (MVPA) on and outside the schoolyard was established. Moreover, the percentage of MVPA on the schoolyard was compared between the following segments of the day: pre-school, school, school recess, lunch break and post-school. Differences between boys and girls were compared using linear and logistic mixed-effects models.

RESULTS

On average, children spent 40.1 minutes/day on the schoolyard. During this time, boys were more active on the schoolyard, with 27.3% of their time spent as MVPA compared to 16.7% among girls (OR=2.11 [95% CI 1.54 - 2.90]). The children were most active on the schoolyard during school recess, during which boys recorded 39.5% and girls recorded 23.4% of the time as MVPA (OR=2.55 [95% CI: 1.69 - 3.85]). Although children were only present at the schoolyard for 6.1% of the total reported time, this time contributed towards 17.5% and 16.8% of boys' and girls' minutes of MVPA.

CONCLUSIONS

On the schoolyard, children's physical activity levels are higher than on average over the whole day. Physical activity levels are particularly high during school recess. The school environment seems to be an important setting for improving children's physical activity levels. Further research on the facilitators of these high activity levels may provide targets for further promotion of physical activity among children.

Objectively measured patterns of physical activity in primary school children in Coventry: the influence of ethnicity

AIMS

The aetiology of increased metabolic risk in South Asians is incompletely understood, but may include modifiable factors such as physical activity. This study assessed patterns of physical activity in UK primary school children and examined the influence of ethnicity.

METHODS

We studied a community sample of children aged 8-9 years attending primary schools in Coventry, UK. One hundred and sixty-one children wore combined physical activity and heart rate monitors for 7 days. Levels of activity and energy expenditure were compared between White European (n = 96) and South Asian children (n = 65). Patterns of physical activity during the school week were also described.

RESULTS

Seventy-three per cent of White Europeans compared with only 35% of South Asians achieved international recommendations of 60 minutes of moderate to vigorous physical activity daily (P < 0.0000). South Asians were less active during the week (106 ± 28 vs. 120 ± 32 counts/min, respectively, P = 0.0054) and at weekends (92 ± 34 vs. 108 ± 54 counts/min, P = 0.0118) compared with White Europeans. There were differences in energy expenditure with lower physical activity levels in South Asians (daily average 1.68 ± 0.13 vs. 1.76 ± 0.17, P < 0.0001). Differences were attributable to less activity after school in South Asians (97 ± 29 vs. 120 ± 43 counts/min, P < 0.0000) as daytime activity was comparable between groups (120 ± 41 vs. 124 ± 39 counts/min, P > 0.05).

CONCLUSION

South Asian children in Coventry do significantly less physical activity than White Europeans, mainly attributable to differences in after-school activity. Ethnically tailored interventions should explore whether physical activity can be increased in South Asian children and, if so, whether this increased physical activity improves metabolic health.

Quality control methods in accelerometer data processing: defining minimum wear time

BACKGROUND

When using accelerometers to measure physical activity, researchers need to determine whether subjects have worn their device for a sufficient period to be included in analyses. We propose a minimum wear criterion using population-based accelerometer data, and explore the influence of gender and the purposeful inclusion of children with weekend data on reliability.

METHODS

Accelerometer data obtained during the age seven sweep of the UK Millennium Cohort Study were analysed. Children were asked to wear an ActiGraph GT1M accelerometer for seven days. Reliability coefficients(r) of mean daily counts/minute were calculated using the Spearman-Brown formula based on the intraclass correlation coefficient. An r of 1.0 indicates that all the variation is between- rather than within-children and that measurement is 100% reliable. An r of 0.8 is often regarded as acceptable reliability. Analyses were repeated on data from children who met different minimum daily wear times (one to 10 hours) and wear days (one to seven days). Analyses were conducted for all children, separately for boys and girls, and separately for children with and without weekend data.

RESULTS

At least one hour of wear time data was obtained from 7,704 singletons. Reliability increased as the minimum number of days and the daily wear time increased. A high reliability (r = 0.86) and sample size (n = 6,528) was achieved when children with ≥ two days lasting ≥10 hours/day were included in analyses. Reliability coefficients were similar for both genders. Purposeful sampling of children with weekend data resulted in comparable reliabilities to those calculated independent of weekend wear.

CONCLUSION

Quality control procedures should be undertaken before analysing accelerometer data in large-scale studies. Using data from children with ≥ two days lasting ≥10 hours/day should provide reliable estimates of physical activity. It's unnecessary to include only children with accelerometer data collected during weekends in analyses.

Predictors of non-response in a UK-wide cohort study of children's accelerometer-determined physical activity using postal methods

OBJECTIVES

To investigate the biological, social, behavioural and environmental factors associated with non-consent, and non-return of reliable accelerometer data (≥2 days lasting ≥10 h/day), in a UK-wide postal study of children's activity.

DESIGN

Nationally representative prospective cohort study.

SETTING

Children born across the UK, between 2000 and 2002.

PARTICIPANTS

13 681 7 to 8-year-old singleton children who were invited to wear an accelerometer on their right hip for 7 consecutive days. Consenting families were posted an Actigraph GT1M accelerometer and asked to return it by post.

PRIMARY OUTCOME MEASURES

Study consent and reliable accelerometer data acquisition.

RESULTS

Consent was obtained for 12 872 (94.5%) interviewed singletons, of whom 6497 (50.5%) returned reliable accelerometer data. Consent was less likely for children with a limiting illness or disability, children who did not have people smoking near them, children who had access to a garden, and those who lived in Northern Ireland. From those who consented, reliable accelerometer data were less likely to be acquired from children who: were boys; overweight/obese; of white, mixed or 'other' ethnicity; had an illness or disability limiting daily activity; whose mothers did not have a degree; who lived in rented accommodation; who exercised once a week or less; who had been breastfed; were from disadvantaged wards; had younger mothers or lone mothers; or were from households with just one, or more than three children.

CONCLUSIONS

Studies need to encourage consent and reliable data return in the wide range of groups we have identified to improve response and reduce non-response bias. Additional efforts targeted at such children should increase study consent and data acquisition while also reducing non-response bias. Adjustment must be made for missing data that account for missing data as a non-random event.

State policies about physical activity minutes in physical education or during school

BACKGROUND

School policies can change practices on a relatively permanent basis. This study investigated adoption and implementation of state-level policies specifying minutes (or percent) of physical activity in physical education (PE) or during school.

METHODS

Policies were identified from existing databases and rated as having weak, moderate, or strong wording. Interviews with state-level PE coordinators were conducted to investigate the level of implementation, monitoring, and enforcement of the identified policies.

RESULTS

Sixteen states had a policy that met inclusion criteria (19 policies total); 11 states had a policy addressing minutes of physical activity during school, 2 had a policy addressing percent of PE time to be spent in physical activity, and 3 had policies addressing both. None of the 19 policies were rated as having strong wording and 5 were rated as having moderate wording. The range in minutes of physical activity per week addressed in the policies was 60 to 300. Four of the 5 (elementary) and 5 of 5 (middle) policies addressing percent of PE spent physically active specified 50%. The only monitoring efforts reported consisted of schools self-reporting progress to the state.

CONCLUSIONS

More states need to adopt school physical activity policies and policy language needs to be more specific to prevent potential loopholes. Monitoring and evaluation strategies, beyond school self-report, are likely needed for these policies to lead to increases in physical activity.

Social network analysis of childhood and youth physical activity: a systematic review

CONTEXT

Social network analysis has been used to better understand the influence of friends and peer groups in a wide range of health behaviors. This systematic review synthesizes findings from various social network analyses of child and adolescent physical activity, to determine the extent to which social network structure is associated with physical activity behaviors.

EVIDENCE ACQUISITION

Medical and social science databases were searched and screened between September and November 2011. Eligible studies collected a measure of physical activity and a measure of an individual's social network, either through friendship nominations or social ratings, and reported analyses investigating the association between physical activity and the social network measure.

EVIDENCE SYNTHESIS

A total of 1767 articles yielded nine publications from seven eligible studies, which were synthesized and analyzed in December 2011. Three research themes were identified: (1) friendship similarities in physical activity; (2) peer group influences on physical activity; and (3) social preference (i.e., popularity) and physical activity. Synthesis of findings across studies found strong evidence for similarities in physical activity levels between an individual and their friends and within peer groups. There was mixed evidence for an association between social preference and physical activity levels.

CONCLUSIONS

Friendship plays an important role in shaping physical activity behaviors. Physical activity interventions targeted at peer groups and that account for the influence of friendship groups might have utility as a means of increasing youth physical activity.

Accelerometry-assessed sedentary behaviour and physical activity levels during the segmented school day in 10-14-year-old children: the HAPPY study

The school day offers several different time periods that provide varying opportunities for sedentary time (SED) and engagement in physical activity (PA), yet little is known about the PA and sedentary behaviour patterns of boys and girls during these times. The volume, intensity and temporal distributions of SED and PA undertaken by 135 schoolchildren aged 10-14 years, during different segments of the school day: (a) school transport, (b) morning recess, (c) lunch break, (d) class time and (e) after school, were explored using triaxial accelerometry. PA was categorised into SED, light PA (LPA), moderate PA (MPA) and vigorous PA (VPA). Girls engaged in significantly more SED and LPA than boys during recess and lunch break (p < 0.05), while boys engaged in significantly higher levels of VPA during recess (p < 0.001) and MPA and VPA during lunch break (p < 0.001). PA engagement was similar between sexes during other segments of the day.

CONCLUSION

PA patterns appear more beneficial for health in boys during less structured school-based time periods and interventions may therefore target opportunities for girls to be physically active during these times to overcome this observed sex deficit.

Patterns of physical activity and sedentary behaviour in preschool children

BACKGROUND

Little is known about patterns of sedentary behavior (SB) and physical activity among preschoolers. Therefore, in this observational study patterns of SB and moderate-to-vigorous physical activity (MVPA) were examined in detail throughout the week in preschool-aged boys and girls.

METHODS

A sample of 703 Melbourne preschool children (387 boys; 4.6 ± 0.7 y) were included in data analysis. SB and MVPA data were collected using accelerometry over an eight-day period. Percentage of time per hour in SB and in MVPA between 08:00 h and 20:00 h was calculated. Multi-level logistic regression models were created to examine the hour-by-hour variability in SB and MVPA for boys and girls across weekdays and weekend days. Odds ratios (OR) were calculated to interpret differences in hour-by-hour SB and MVPA levels between boys and girls, and between weekdays and weekend days.

RESULTS

The highest SB levels co-occurred with the lowest MVPA levels from the morning till the early afternoon on weekdays, and during the morning and around midday on weekends. Besides, participation in SB was the lowest and participation in MVPA was the highest from the mid afternoon till the evening on weekdays and weekend days. The variability across the hours in SB and, especially, in MVPA was rather small throughout weekdays and weekends. These patterns were found in both boys and girls. During some hours, girls were found to be more likely than boys to demonstrate higher SB levels (OR from 1.08 to 1.16; all p < 0.05) and lower MVPA levels (OR from 0.75 to 0.88; all p < 0.05), but differences were small. During weekends, hour-by-hour SB levels were more likely to be lower (OR from 0.74 to 0.98; all p < 0.05) and hour-by-hour MVPA levels were more likely to be higher (OR from 1.15 to 1.50; all p < 0.05), than during weekdays, in boys and girls.

CONCLUSION

Entire weekdays, especially from the morning till the early afternoon, and entire weekend days are opportunities to reduce SB and to promote MVPA in preschool-aged boys and girls. Particularly weekdays hold the greatest promise for improving SB and MVPA. No particular time of the week was found where one sex should be targeted.

Physical activity and BMI: evidence from the Panel Study of Income Dynamics Child Development Supplement

BACKGROUND

This study assessed the association between amount of physical activity and body mass index (BMI) percentile among middle and high school children. Total daily physical activity needs to include both in and out of school physical activity.

METHODS

A secondary data analysis was performed on 1306 children drawn from the Panel Study of Income Dynamics Child Development Supplement (CDS III, 2007). The dependent variable in this study was BMI percentile, while the independent variable was physical activity. The multinomial logistic regression model was used to assess the associations between physical activity and BMI percentile controlling for age, gender, race/ethnicity, parental income, and neighborhood safety.

RESULTS

Children who engaged in low daily physical activity levels had 1.8 times the odds of being obese versus normal weight than those who engaged in moderate levels [odds ratio (OR) = 1.80, confidence interval (CI) = 1.31, 2.48]. African-American children had 1.6 times the odds of being obese than normal weight (OR = 1.55, CI = 0.99, 2.43) and Hispanic children had approximately 1.8 times the odds of being obese than normal weight in comparison to non-Hispanic white children (OR = 1.79, CI = 1.00, 3.21). Females had about 1.5 times the odds of being overweight than normal weight than males (OR = 1.49, CI = 1.04, 2.13).

CONCLUSIONS

This study suggests that the accumulation of 30 minutes or more of daily physical activity may be effective in decreasing obesity prevalence among middle and high school-aged children.

After-school physical activity and eating behaviors of middle school students in relation to adult supervision

OBJECTIVE

Examine after-school activity patterns, eating behaviors, and social environment of overweight and normal weight middle school students.

DESIGN

Eating and physical activity behaviors of 141 students, ages 10-14, were monitored. Students completed a diary documenting type of activity, location, adult supervision, accompanying participants, and eating habits from 3:00 pm-12:00 am.

SETTING

Three middle schools, grades 6-8.

MAIN OUTCOME MEASURES

Body mass index, estimated energy expenditure, eating behavior, active time, sedentary time, supervised time.

ANALYSIS

t tests, ANOVA, chi-square, correlation coefficients. Significance set at P < .05.

RESULTS

Children spent 76% of time sedentary, and 85% of sedentary time was under adult supervision (r = 0.76). Active time related to time with friends (r = 0.64) and family (r = 0.46). Children spent 40% of eating time consuming unhealthful food, and adults supervised 86% of children's eating. Overweight and normal weight children were similarly active (335 ± 156 vs 373 ± 194 counts per minute). Overweight girls spent more eating time (77%) eating healthfully than overweight boys (57%).

CONCLUSIONS AND IMPLICATIONS

Children should be given access to healthful food and encouraged to eat healthfully when alone and with friends. Adults should be more physically engaged with children. Children should be encouraged to eat under adult supervision and with their families.

Accelerometer use with children, older adults, and adults with functional limitations

Accurately assessing physical activity behavior in children, older adults, and adults with functional limitations is essential to further our understanding of determinants of physical activity behavior in these populations and to design, implement, and evaluate interventions designed to increase physical activity participation. Objective methods to assess physical activity behavior, owing to improvements in accuracy and precision over self-report measures, have become common in research and practice settings. This article reviews the current use of objective methods to assess physical activity in observational, determinant, and intervention studies for children, older adults, and adults with functional limitations. Important considerations are presented when adopting prediction algorithms developed on one population, and using in another population that is markedly different in age, health, and functional status. Best practices are presented, along with future recommendations for research to advance this area of scientific inquiry.

Physical activity correlates for children with autism spectrum disorders in middle school physical education

This study examined potential correlates that might influence physical activity (PA) of adolescents with autism spectrum disorders (ASD) in physical education. Students with (n = 19) and without (n = 76) ASD wore an accelerometer during physical education. Data were collected in 38 physical education lessons. The results showed that (a) students with ASD were less physically active than their peers, (b) their PA was related positively to their social interaction with peers, and (c) their moderate to vigorous PA depended on PA content, physical environment, and instructor-related characteristics. The findings suggest a need for additional studies on the relationship between the needs of adolescents with ASD and the content offered in physical education so as to inform school policies and help to remove barriers to promoting PA among this population.

Differences in physical activity during school recess

BACKGROUND

School recess provides a daily opportunity for physical activity engagement. The purpose of this study was to examine physical activity levels during recess by gender, ethnicity, and grade, and establish the contribution of recess to daily school physical activity levels.

METHODS

Two hundred and ten children (45% boys) from grades 3 to 6 in 4 elementary schools had their physical activity during school quantified using uni-axial accelerometry every 5 seconds for 5 consecutive school days. Data were collected in fall 2009. The proportion of time spent engaged in physical activity during daily school recess was determined using existing age-appropriate cutpoints. The relative contribution of recess to school day physical activity was also determined.

RESULTS

Boys were more active than girls during recess. Girls engaged in more sedentary activity than boys. No main effects for ethnicity were observed. Children in grades 3 and 5 were more active than children in grades 4 and 6. Recess contributed 17.9% and 15.5% toward boys' and girls' school day moderate-to-vigorous physical activity, respectively.

CONCLUSION

Children engaged in physical activity during recess, though interventions may be needed to increase the intensity of activity in this context.

International children's accelerometry database (ICAD): design and methods

Background

Over the past decade, accelerometers have increased in popularity as an objective measure of physical activity in free-living individuals. Evidence suggests that objective measures, rather than subjective tools such as questionnaires, are more likely to detect associations between physical activity and health in children. To date, a number of studies of children and adolescents across diverse cultures around the globe have collected accelerometer measures of physical activity accompanied by a broad range of predictor variables and associated health outcomes. The International Children's Accelerometry Database (ICAD) project pooled and reduced raw accelerometer data using standardized methods to create comparable outcome variables across studies. Such data pooling has the potential to improve our knowledge regarding the strength of relationships between physical activity and health. This manuscript describes the contributing studies, outlines the standardized methods used to process the accelerometer data and provides the initial questions which will be addressed using this novel data repository.

Methods

Between September 2008 and May 2010 46,131 raw Actigraph data files and accompanying anthropometric, demographic and health data collected on children (aged 3-18 years) were obtained from 20 studies worldwide and data was reduced using standardized analytical methods.

Results

When using ≥ 8, ≥ 10 and ≥ 12 hrs of wear per day as a criterion, 96%, 93.5% and 86.2% of the males, respectively, and 96.3%, 93.7% and 86% of the females, respectively, had at least one valid day of data.

Conclusions

Pooling raw accelerometer data and accompanying phenotypic data from a number of studies has the potential to: a) increase statistical power due to a large sample size, b) create a more heterogeneous and potentially more representative sample, c) standardize and optimize the analytical methods used in the generation of outcome variables, and d) provide a means to study the causes of inter-study variability in physical activity. Methodological challenges include inflated variability in accelerometry measurements and the wide variation in tools and methods used to collect non-accelerometer data.