Reactivity to accelerometer measurement of children and adolescents

Network Interventions for Changing Physical Activity Behaviour in Preadolescents

Network interventions can help achieve behavioural change by inducing peer-pressure in the network. However, inducing peer-pressure without considering the structure of the existing social network may render the intervention ineffective or weaker. In a 7-week school-based field experiment using preadolescents' physical activity (PA) as a proxy for estimating behavioural change, we test the hypothesis that boys' and girls' distinct networks are susceptible to different social incentives. We run three different social-rewards schemes, in which classmates' rewards depend on the PA of two friends either reciprocally (directly or indirectly) or collectively. Compared to a random-rewards control, social-rewards schemes had an overall significantly positive effect on PA (51.8% increase), with females being more receptive to the direct reciprocity scheme (76.4%) and males to team (collective) rewards (131.5%). Differences in the sex-specific sub-networks can explain these findings. Network interventions adapted to the network-specific characteristics may constitute a powerful tool for behavioural change.

Effect of a School-Based Activity Tracker, Companion Social Website, and Text Messaging Intervention on Exercise, Fitness, and Physical Activity Self-Efficacy of Middle School Students

This study examined the effect of a 10-week activity tracker, companion social website, and text messaging intervention on body mass index (BMI), body fat percentage, physical fitness, and physical activity (PA) self-efficacy of children. Children (n = 98) were assigned to one of three groups: activity tracker group, text messaging group, and activity tracker + text messaging group. Pre-/posttest fitness, BMI, PA self-efficacy, and body fat percentage were measured. The activity tracker group had a significant increase in fitness, no significant difference in PA self-efficacy, and an increase in body fat percentage and BMI (p < .05). The text messaging group had a significant increase in BMI (p < .05). The activity tracker + text messaging group had no significant differences in fitness, BMI, PA self-efficacy, or body fat percentage. This study gives no clear support to the hypothesis that use of activity trackers and a text messaging intervention have a positive effect on fitness, PA self-efficacy, or body fat percentage.

Relationship between Physical Activity, Screen Time and Weight Status among Young Adolescents

It is well established that lack of physical activity and high bouts of sedentary behaviour are now associated with all-cause and cardiovascular mortality. The purpose of this study was to investigate the relationship between physical activity participation, overall screen time and weight status amongst early Irish adolescent youth. Participants were a sample of 169 students: 113 boys (mean age = 12.89 ± 0.34 years) and 56 girls (mean age = 12.87 ± 0.61 years). The data gathered in the present study included physical activity (accelerometry), screen time (self-report) and anthropometric measurements. Overweight and obese participants accumulated significantly more minutes of overall screen time daily compared to their normal-weight counterparts. A correlation between physical activity and daily television viewing was evident among girls. No significant interaction was apparent when examining daily physical activity and overall screen time in the prediction of early adolescents’ body mass index. Results suggest the importance of reducing screen time in the contribution towards a healthier weight status among adolescents. Furthermore, physical activity appears largely unrelated to overall screen time in predicting adolescent weight status, suggesting that these variables may be independent markers of health in youth. The existing relationship for girls between moderate-to-vigorous physical activity and time spent television viewing may be a potential area to consider for future intervention design with adolescent youth.

Does school physical education really contribute to accelerometer-measured daily physical activity and non sedentary behaviour in high school students?

Physical education has been highlighted as an important environment for physical activity promotion, however, to our knowledge there are no previous studies examining the contribution of physical education to daily accelerometer-measured physical activity and non sedentary behaviour. The purpose was to compare the accelerometer-measured physical activity and sedentary behaviour between physical education, non-physical education and weekend days in adolescents. Of the 394 students from a Spanish high school that were invited to participate, 158 students (83 boys and 75 girls) aged 13-16 years were analyzed (wear time ≥ 600 min). Participants' physical activity and sedentary behaviour were objectively-measured by GT3X+ accelerometers during physical education (one session), non-physical education and weekend days. Results indicated that overall adolescents had statistically significant greater physical activity levels and lower values of sedentary behaviour on physical education days than on non-physical education and weekend days (e.g., moderate-to-vigorous physical activity = 71, 54 and 57 min; sedentary = 710, 740 and 723 min) (p < 0.05). Physical education contributes significantly to reducing students' daily physical inactivity and sedentary behaviour. Increasing the number of physical education classes seems to be an effective strategy to reduce the high current prevalence of physical inactivity and sedentary behaviour in adolescence.

The epigenetic clock and objectively measured sedentary and walking behavior in older adults: the Lothian Birth Cohort 1936

Background

Estimates of biological age derived from DNA-methylation patterns-known as the epigenetic clock-are associated with mortality, physical and cognitive function, and frailty, but little is known about their relationship with sedentary behavior or physical activity. We investigated the cross-sectional relationship between two such estimates of biological age and objectively measured sedentary and walking behavior in older people.

Methods

Participants were 248 members of the Lothian Birth Cohort 1936. At age 79 years, sedentary behavior and physical activity were measured over 7 days using an activPAL activity monitor. Biological age was estimated using two measures of DNA methylation-based age acceleration-i.e., extrinsic and intrinsic epigenetic age acceleration. We used linear regression to assess the relationship between these two estimates of biological age and average daily time spent sedentary, number of sit-to-stand transitions, and step count.

Results

Of the six associations examined, only two were statistically significant in initial models adjusted for age and sex alone. Greater extrinsic age acceleration was associated with taking fewer steps (regression coefficient (95% CI) - 0.100 (- 0.008, - 0.001), and greater intrinsic age acceleration was associated with making more sit-to-stand transitions (regression coefficient (95% CI) 0.006 (0.0001, 0.012). When we controlled for multiple statistical testing, neither of these associations survived correction (both P ≥ 0.17).

Conclusion

In this cross-sectional study of 79-year-olds, we found no convincing evidence that biological age, as indexed by extrinsic or intrinsic epigenetic age acceleration, was associated with objectively measured sedentary or walking behavior.

A Multicomponent Schoolyard Intervention Targeting Children's Recess Physical Activity and Sedentary Behavior: Effects After 1 Year

BACKGROUND

The aim of the study was to test the 12-month effects of a multicomponent physical activity (PA) intervention at schoolyards on morning recess PA levels of sixth- and seventh-grade children in primary schools, using accelerometry and additional global positioning system data.

METHODS

A quasi-experimental study design was used with 20 paired intervention and control schools. Global positioning system confirmatory analyses were applied to validate attendance at schoolyards during recess. Accelerometer data from 376 children from 7 pairs of schools were included in the final analyses. Pooled intervention effectiveness was tested by multilevel linear regression analyses, whereas effectiveness of intervention components was tested by multivariate linear regression analyses.

RESULTS

Children exposed to the multicomponent intervention increased their time spent in light PA (+5.9%) during recess. No pooled effects on moderate to vigorous PA were found. In-depth analyses of intervention components showed that physical schoolyard interventions particularly predicted a decrease in time spent in sedentary behavior during recess at follow-up. Intervention intensity and the school's commitment to the project strengthened this effect.

CONCLUSIONS

The multicomponent schoolyard PA intervention was effective in making children spend a larger proportion of recess time in light PA, which was most likely the result of a shift from sedentary behavior to light PA.

Pitfalls in accelerometer-based measurement of physical activity: The presence of reactivity in an adult population

When a behavior is monitored, it is likely to change, even if no change may be intended. This phenomenon is known as measurement reactivity. We investigated systematic changes in accelerometer-based measures over the days of monitoring as an indicator of measurement reactivity in an adult population. One hundred seventy-one participants from the general population (65% women; mean age = 55 years, range: 42-65 years) wore accelerometers for 7 consecutive days to measure sedentary behavior and physical activity (PA). Latent growth models were used (a) to investigate changes in accelerometer wear time over the measurement days and (b) to identify measurement reactivity indicated by systematic changes in sedentary time (ST), light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA). Over the measurement days, participants reduced accelerometer wear time by trend (rate of change [b] = -4.7 min/d, P = .051, Cohen's d = .38), increased ST (b = 2.4 min/d, P = .018, d = .39), and reduced LPA (b = -2.4 min/d, P = .015, d = .38). Participants did not significantly reduce MVPA (P = .537). Our data indicated that accelerometry might generate reactivity. Small effects on ST and LPA were found. Thus, the validity of accelerometer-based data on ST and LPA may be compromised. Systematic changes observed in accelerometer wear time may further bias accelerometer-based measures. MVPA seems to be less altered due to the presence of an accelerometer.

Adolescents' technology and face-to-face time use predict objective sleep outcomes

OBJECTIVES

The present study examined both within- and between-person associations between adolescents' time use (technology-based activities and face-to-face interactions with friends and family) and sleep behaviors. We also assessed whether age moderated associations between adolescents' time use with friends and family and sleep.

DESIGN

Adolescents wore an actigraph monitor and completed brief evening surveys daily for 3 consecutive days.

PARTICIPANTS

Adolescents (N=71; mean age=14.50 years old, SD=1.84; 43.7% female) were recruited from 3 public high schools in the Midwest.

MEASURES

We assessed 8 technology-based activities (eg, texting, working on a computer), as well as time spent engaged in face-to-face interactions with friends and family, via questions on adolescents' evening surveys. Actigraph monitors assessed 3 sleep behaviors: sleep latency, sleep hours, and sleep efficiency.

RESULTS

Hierarchical linear models indicated that texting and working on the computer were associated with shorter sleep, whereas time spent talking on the phone predicted longer sleep. Time spent with friends predicted shorter sleep latencies, while family time predicted longer sleep latencies. Age moderated the association between time spent with friends and sleep efficiency, as well as between family time and sleep efficiency. Specifically, longer time spent interacting with friends was associated with higher sleep efficiency but only among younger adolescents. Furthermore, longer family time was associated with higher sleep efficiency but only for older adolescents.

CONCLUSION

Findings are discussed in terms of the importance of regulating adolescents' technology use and improving opportunities for face-to-face interactions with friends, particularly for younger adolescents.

Awareness of wearing an accelerometer does not affect physical activity in youth

BACKGROUND

This study aimed to investigate whether awareness of being monitored by an accelerometer has an effect on physical activity in young people.

METHODS

Eighty healthy participants aged 10-18 years were randomized between blinded and nonblinded groups. The blinded participants were informed that we were testing the reliability of a new device for body posture assessment and these participants did not receive any information about physical activity. In contrast, the nonblinded participants were informed that the device was an accelerometer that assessed physical activity levels and patterns. The participants were instructed to wear the accelerometer for 4 consecutive days (2 school days and 2 school-free days).

RESULTS

Missing data led to the exclusion of 2 participants assigned to the blinded group. When data from the blinded group were compared with these from the nonblinded group, no differences were found in the duration of any of the following items: (i) wearing the accelerometer, (ii) total physical activity, (iii) sedentary activity, and (iv) moderate-to-vigorous activity.

CONCLUSIONS

Our study shows that the awareness of wearing an accelerometer has no influence on physical activity patterns in young people. This study improves the understanding of physical activity assessment and underlines the objectivity of this method.

TRIAL REGISTRATION

NCT02844101 (retrospectively registered at July 13th 2016).

Promoting Healthy Lifestyle and Well-Being in Adolescents through Outdoor Physical Activity

Health-enhancing physical activities (PA) performed outdoors could markedly contribute to the adoption of a healthy lifestyle in adolescence. The differences between PA preferences and actual opportunities for these PA are an issue that has received frequent attention. To date, the extent to which these differences are reflected in adolescents meeting PA recommendations and their well-being has not been explored. In total, 10,086 respondents took part in an on-line research project regarding PA preferences. Of them, 2446 also completed the International Physical Activity Questionnaire (Long Form) and the World Health Organization (WHO) W-5 questionnaire to assess well-being. Finally, 1278 of these respondents were involved in objective PA monitoring using pedometers. The study aimed to explore the prevalence and trends regarding outdoor PA. Moreover, we assessed whether the agreement between preferred PA and PA actually undertaken was associated with higher odds for meeting PA recommendations and achieving a higher level of well-being. Of a selection of outdoor activities, Czech and Polish boys preferred cycling, swimming, and downhill skiing, while girls preferred swimming activities, skating, and cycling. The agreement between preferred and PA actually undertaken was associated with higher odds for meeting the weekly PA recommendations and higher levels of well-being both in boys and girls. Evaluation of outdoor PA preferences and taking these preferred activities into account when forming conditions for them was important in the efficient promotion of the physical and mental health of adolescents.

Permanent play facility provision is associated with children's time spent sedentary and in light physical activity during school hours: A cross-sectional study

Objective: To study the associations between: 1) number of permanent outdoor play facilities per pupil and 2) the size of the outdoor play area per pupil with sedentary time and physical activity (PA) during school hours in six-, nine-, and 15-year olds. We conducted a cross-sectional study of nationally representative samples of Norwegian six- (n = 1071), nine- (n = 1421) and 15-year-olds (n = 1106) in 2011 (the Physical Activity Among Norwegian Children Study). The participation rates were 56.4%, 73.1% and 57.8% for six-, nine- and 15-year olds, respectively. We assessed PA objectively for seven consecutive days using accelerometers, the size of a school's outdoor play area (SOPA) using an online map service and the permanent play facility (PPF) provision using a standardized form during school site visits. We successfully measured SOPA and PPF in 99 schools, from which 3040 participants provided valid accelerometer data. We used generalized least-squares random-effects models with robust variance estimation to assess associations. Our results indicate that better provision of permanent play facilities may reduce sedentary time and increase time spent in light PA among six-year-olds. Permanent play facility provision was not associated with sedentary time or PA among nine- and 15-year-olds. Associations found between outdoor play area size, physical activity and sedentary time were negligible. Future research should investigate what types of permanent play facilities may be associated with physical activity in both children and adolescents.

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Permanent play facility provision was associated with sedentary time.

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Permanent play facility provision was associated with light PA.

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Permanent play facility provision was not associated with MVPA.

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Outdoor play area size was not associated with sedentary time or PA.

The effect of a school-centered multicomponent intervention on daily physical activity and sedentary behavior in primary school children: The Active Living study

The aim of the current study was to examine the effectiveness of a school-centered multicomponent PA intervention, called 'Active Living', on children's daily PA levels. A quasi-experimental design was used including 9 intervention schools and 9 matched control schools located in the Netherlands. The baseline measurement took place between March-June 2013, and follow-up measurements were conducted 12months afterwards. Accelerometer (ActiGraph, GT3X+) data of 520 children aged 8-11years were collected and supplemented with demographics and weather conditions data. Implementation magnitude of the interventions was measured by keeping logbooks on the number of implemented physical environmental interventions (PEIs) and social environmental interventions (SEIs). Multilevel multivariate linear regression analyses were used to study changes in sedentary behavior (SB), light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA) between baseline and follow-up. Finally, effect sizes (ESs) were calculated using Cohen's d. No pooled effects on PA and SB were found between children exposed and not exposed to Active Living after 12months. However, children attending Active Living schools that implemented larger numbers of both PEIs and SEIs engaged in 15 more minutes of LPA per weekday at follow-up than children in the control condition (ES=0.41; p<.05). Moreover, children attending these schools spent less time in SB at follow-up (ES=0.33), although this effect was non-significant. No significant effects were found on MVPA. A school-centered multicomponent PA intervention holds the potential to activate children, but a comprehensive set of intervention elements with a sufficient magnitude is necessary to achieve at least moderate effect sizes.

Differences in Spatial Physical Activity Patterns between Weekdays and Weekends in Primary School Children: A Cross-Sectional Study Using Accelerometry and Global Positioning System

Targeting the weekend to promote physical activity (PA) in children seems to be promising given that they tend to be less physically active and, particularly, as the age-related decline in PA is more marked during weekends. Considering the ambiguity of why children are not able to maintain their PA level on weekends, the aim of the present study was to objectively investigate differences in children's spatial PA patterns between week and weekend days using the combination of Global Positioning System (GPS) and accelerometry. Seventy-four second graders (aged 7⁻9 years) and 98 sixth graders (aged 11⁻14 years) wore an accelerometer and GPS sensor for seven consecutive days to determine where children spend time and engage in PA. Time-matched accelerometer and GPS data was mapped with a geographic information system and multilevel analyses accounting for the hierarchical structure of the data were conducted. Differences between weekdays and weekends regarding the total time spent and the absolute and relative level of PA in various settings were found in both age groups. The findings support previous research pointing to the importance of targeting weekend PA, especially when children grow older. Future interventions should encourage children to use outdoor spaces more frequently on weekends, rather than stay at home, and to commute actively to destinations other than school.

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.

Physical activity is not associated with spirometric indices in lung-healthy German youth

In lung disease, physical activity improves lung function and reduces morbidity. However, healthy populations are not well studied. We estimate the relationship between spirometric indices and accelerometric physical activity in lung-healthy adolescents.895 nonsmoking German adolescents without chronic lung disease (45% male, mean±sd age 15.2±0.26 years) from the GINIplus and LISAplus cohorts completed questionnaires, spirometry, 7-day accelerometry and an activity diary. Physical activity was measured as minutes, quintiles and regularity of daily moderate, vigorous and moderate-to-vigorous physical activity (MVPA), participation in sport and active commuting to school. Primary outcomes were forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC and forced expiratory flow at 25-75% of FVC; they were separately correlated with physical activity and adjusted for confounders of respiratory function, including early-life exposures.Adolescents averaged 40 min MVPA per day, typical for European youth. 79% participated in sports and 51% commuted actively. An association was suggested between 3% higher FVC (∼100 mL) and either extreme MVPA quintile or percentage of days with >30 min MVPA (p<0.05). However, after Bonferroni correction all associations between spirometry, active lifestyle and physical activity were nonsignificant.Spirometric indices were not significantly associated with active lifestyle or measures of activity in lung-healthy adolescents after adjustment for confounding and multiple-comparison artefacts.

Spatial physical activity patterns among primary school children living in neighbourhoods of varying socioeconomic status: a cross-sectional study using accelerometry and Global Positioning System

Background

Neighbourhood socioeconomic status (SES) has been shown to be related to health status and overweight independent of individual SES. However, results about the association between neighbourhood SES and physical activity among children are ambiguous. Particularly, it is unknown how socioeconomic factors influence the spatial context of children’s moderate-vigorous physical activity (MVPA) and sedentary behaviour (SB). This study aimed to investigate by means of Global Positioning System (GPS) and accelerometry whether locations where children engage in MVPA and SB differ by neighbourhood SES.

Methods

Participants included 83 children aged 7–9 from nine public schools located in a low- and high-SES area in Zurich, Switzerland. Children wore an accelerometer and GPS sensor for seven consecutive days. Time-matched accelerometer and GPS data was mapped with a geographic information system and each data point assigned to one of eight activity settings. The amount and proportion of MVPA and SB were calculated for every setting. To investigate differences between the two SES groups, multilevel analyses accounting for the hierarchical structure of the data were conducted.

Results

Both SES groups achieved most minutes in MVPA at own school, on streets and at home and recorded the highest proportions of MVPA in recreational facilities, streets and other schools. The highest amounts and proportions of SB were found at home and own school. High-SES children accumulated significantly more minutes in MVPA and SB in parks, sport facilities, other schools and streets, while the low-SES group spent more time in both activities in other places. When taking the total time spent in a setting into account and using the proportion of MVPA or SB, the only differences between the two groups were found at other schools and outside, where the high-SES children showed a significantly higher activity level (p-values <0.001).

Conclusions

Several differences in the spatial activity pattern between children from low- and high-SES neighbourhoods were found, independent of their individual SES. The findings seem to highlight the importance of providing safe streets and access to appropriate types of recreational facilities to reach recommended PA levels. Further policies to reduce SB within home and school environment are needed.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-2954-8) contains supplementary material, which is available to authorized users.

Evaluation of the ability of three physical activity monitors to predict weight change and estimate energy expenditure

Activity monitors such as the Actical accelerometer, the Sensewear armband, and the Intelligent Device for Energy Expenditure and Activity (IDEEA) are commonly validated against gold standards (e.g., doubly labeled water, or DLW) to determine whether they accurately measure total daily energy expenditure (TEE) or activity energy expenditure (AEE). However, little research has assessed whether these parameters or others (e.g., posture allocation) predict body weight change over time. The aims of this study were to (i) test whether estimated energy expenditure or posture allocation from the devices was associated with weight change during and following a low-calorie diet (LCD) and (ii) compare free-living TEE and AEE predictions from the devices against DLW before weight change. Eighty-seven participants from 2 clinical trials wore 2 of the 3 devices simultaneously for 1 week of a 2-week DLW period. Participants then completed an 8-week LCD and were weighed at the start and end of the LCD and 6 and 12 months after the LCD. More time spent walking at baseline, measured by the IDEEA, significantly predicted greater weight loss during the 8-week LCD. Measures of posture allocation demonstrated medium effect sizes in their relationships with weight change. Bland-Altman analyses indicated that the Sensewear and the IDEEA accurately estimated TEE, and the IDEEA accurately measured AEE. The results suggest that the ability of energy expenditure and posture allocation to predict weight change is limited, and the accuracy of TEE and AEE measurements varies across activity monitoring devices, with multi-sensor monitors demonstrating stronger validity.

School grounds and physical activity: Associations at secondary schools, and over the transition from primary to secondary schools

This paper aims to further understanding of the physical environments of secondary schools and their associations with young peoples' physical activity. Accelerometer-derived physical activity measurements from 299 participants in the SPEEDY study (Norfolk, UK) were obtained from baseline measurements (age 9-10y) and +4y follow-up. These were linked to objective measures of primary and secondary school environments as measured by the SPEEDY grounds audit tool. We saw considerable differences in the nature of school grounds between primary and secondary schools. Cross-sectional associations were seen between active travel provision scores and commuting time moderate-to-vigorous physical activity (MVPA) for 13-14 year old boys and adolescents living further from school. However, few associations were seen between changes in school grounds scores and changes in school-based MVPA.

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.

Built Environment Influences of Children's Physical Activity: Examining Differences by Neighbourhood Size and Sex

Neighbourhoods can facilitate or constrain moderate-to-vigorous physical activity (MVPA) among children by providing or restricting opportunities for MVPA. However, there is no consensus on how to define a child’s neighbourhood. This study examines the influence of the neighbourhood built environment on objectively measured MVPA among 435 children (aged 9–14 years) in London (ON, Canada). As there is no consensus on how to delineate a child’s neighbourhood, a geographic information system was used to generate measures of the neighbourhood built environment at two buffer sizes (500 m and 800 m) around each child’s home. Linear regression models with robust standard errors (cluster) were used to analyze the relationship between built environment characteristics and average daily MVPA during non-school hours on weekdays. Sex-stratified models assessed sex-specific relationships. When accounting for individual and neighbourhood socio-demographic variables, park space and multi-use path space were found to influence children’s MVPA. Sex-stratified models found significant associations between MVPA and park space, with the 800 m buffer best explaining boys’ MVPA and the 500 m buffer best explaining girls’ MVPA. Findings emphasize that, when designing built environments, programs, and policies to facilitate physical activity, it is important to consider that the size of the neighbourhood influencing a child’s physical activity may differ according to sex.

Localization of Physical Activity in Primary School Children Using Accelerometry and Global Positioning System

Background

Ecological approaches have highlighted the importance of the built environment as a factor affecting physical activity. However, knowledge on children’s activity patterns is still incomplete. Particularly, data on the spatial context of physical activity is limited, which limits the potential to design location-based interventions effectively. Using global positioning system (GPS) and accelerometry, this study aimed to identify locations where children engage in moderate-vigorous physical activity (MVPA).

Methods

Participants included 119 children (11–14 years, 57% girls) from public schools in Winterthur, Switzerland. During a regular school week between February and April 2013, children wore an accelerometer and GPS sensor for seven consecutive days. Time-matched accelerometer and GPS data was mapped with a geographic information system and each data point was assigned to one of seven defined activity settings. Both the absolute amount of MVPA and proportion of time in MVPA were calculated for every setting. Multilevel analyses accounting for the hierarchical structure of the data were conducted to investigate any gender differences.

Results

Children achieved most MVPA on streets (34.5%) and on school grounds (33.4%). The proportion children spent in MVPA was highest in recreational facilities (19.4%), at other schools (19.2%) and on streets (18.6%). Boys accumulated significantly more MVPA overall and on other school grounds (p < 0.05) and showed a significantly higher proportion of time in MVPA at own school and outside of Winterthur (p < 0.05).

Conclusions

The results indicate the importance of streets and school grounds as activity-promoting environments. The high use of streets may be an indicator for active transportation, which appears to contribute to an active lifestyle in both genders. In contrast, the school setting is more likely to encourage physical activity in boys. Recreational facilities seem to be conducive for MVPA among both genders, although infrequently visited during the week of measurement.

The relationship between adolescents' physical activity, fundamental movement skills and weight status

The aim of this study was to determine if a potential relationship among physical activity (PA), fundamental movement skills and weight status exists amongst early adolescent youth. Participants were a sample of 85 students; 54 boys (mean age = 12.94 ± 0.33 years) and 31 girls (mean age = 12.75 ± 0.43 years). Data gathered during physical education class included PA (accelerometry), fundamental movement skills and anthropometric measurements. Standard multiple regression revealed that PA and total fundamental movement skill proficiency scores explained 16.5% (P < 0.001) of the variance in the prediction of body mass index. Chi-square tests for independence further indicated that compared with overweight or obese adolescents, a significantly higher proportion of adolescents classified as normal weight achieved mastery/near-mastery in fundamental movement skills. Results from the current investigation indicate that weight status is an important correlate of fundamental movement skill proficiency during adolescence. Aligned with most recent research, school- and community-based programmes that include developmentally structured learning experiences delivered by specialists can significantly improve fundamental movement skill proficiency in youth.

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

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

Neighborhood Crime-Related Safety and Its Relation to Children's Physical Activity

Crime is both a societal safety and public health issue. Examining different measures and aspects of crime-related safety and their correlations may provide insight into the unclear relationship between crime and children's physical activity. We evaluated five neighborhood crime-related safety measures to determine how they were interrelated. We then explored which crime-related safety measures were associated with children's total moderate-to-vigorous physical activity (MVPA) and MVPA in their neighborhoods. Significant positive correlations between observed neighborhood incivilities and parents' perceptions of general crime and disorder were found (r = 0.30, p = 0.0002), as were associations between parents' perceptions of general crime and disorder and perceptions of stranger danger (r = 0.30, p = 0.0002). Parent report of prior crime victimization in their neighborhood was associated with observed neighborhood incivilities (r = 0.22, p = 0.007) and their perceptions of both stranger danger (r = 0.24, p = 0.003) and general crime and disorder (r = 0.37, p < 0.0001). After accounting for covariates, police-reported crime within the census block group in which children lived was associated with less physical activity, both total and in their neighborhood (beta = -0.09, p = 0.005, beta = -0.01, p = 0.02, respectively). Neighborhood-active children living in the lowest crime-quartile neighborhoods based on police reports had 40 min more of total MVPA on average compared to neighborhood-active children living in the highest crime-quartile neighborhoods. Findings suggest that police reports of neighborhood crime may be contributing to lower children's physical activity.

Independent associations between child and parent perceived neighborhood safety, child screen time, physical activity and BMI: a structural equation modeling approach

OBJECTIVE

The main objective of this study was to investigate whether children's perceptions of neighborhood safety are associated with their weight status and weight-related behaviors, independently of their parents' perceptions.

METHODS

Data were from the baseline wave (collected in 2005-2008) of the Quebec Adipose and Lifestyle Investigation in Youth (QUALITY), an ongoing prospective study of 630 children aged 8-10 years (from Quebec, Canada) at risk of obesity. Weight and height were measured, and World Health Organization age- and sex-specific body mass index (BMI) z-scores were computed. Physical activity was measured by accelerometry, and time spent watching television, playing computer and video games during week and weekend days was self-reported. Structural equation modeling was used to simultaneously estimate the associations between parent and child perceived safety, with children's BMI z-score, physical activity and screen time.

RESULTS

The results suggest that, when parent perceived safety was at the mean, children who perceived their neighborhood as being safest had nearly an additional 70 daily activity counts per minute (representing an ~10% increase in overall physical activity level) compared with children who perceived it as being least safe. Among children who perceived a mean level of safety, those whose parents perceived their neighborhood as being safest spent approximately an hour less per day in front of screens compared with those whose parents perceived their neighborhood as being least safe. Parent and child perceptions of safety both indirectly contribute to children's weight status by differentially impacting weight-related behaviors.

CONCLUSION

Findings indicate that targeting both parent and child perceived neighborhood safety could bolster efforts to promote healthy weight and weight-related behaviors among children.

Design and methods for "Commit to Get Fit" - a pilot study of a school-based mindfulness intervention to promote healthy diet and physical activity among adolescents

INTRODUCTION

Cardiovascular prevention is more effective if started early in life, but available interventions to promote healthy lifestyle habits among youth have been ineffective. Impulsivity in particular has proven to be an important barrier to the adoption of healthy behaviors in youth. Observational evidence suggests that mindfulness interventions may reduce impulsivity and improve diet and physical activity. We hypothesize that mindfulness training in adjunct to traditional health education will improve dietary habits and physical activity among teenagers by reducing impulsive behavior and improving planning skills.

METHODS/DESIGN

The Commit to Get Fit study is a pilot cluster randomized controlled trial examining the feasibility, acceptability and preliminary efficacy of school-based mindfulness training in adjunct to traditional health education for promotion of a healthy diet and physical activity among adolescents. Two schools in central Massachusetts (30 students per school) will be randomized to receive mindfulness training plus standard health education (HE-M) or an attention-control intervention plus standard health education (HE-AC). Assessments will be conducted at baseline, intervention completion (2 months), and 8 months. Primary outcomes are feasibility and acceptability. Secondary outcomes include physical activity, diet, impulsivity, mood, body mass index, and quality of life.

CONCLUSIONS

This study will provide important information about feasibility and preliminary estimates of efficacy of a school-delivered mindfulness and health education intervention to promote healthy dietary and physical activity behaviors among adolescents. Our findings will provide important insights about the possible mechanisms by which mindfulness training may contribute to behavioral change and inform future research in this important area.

Accelerometer-based measures in physical activity surveillance: current practices and issues

OBJECTIVE

Self-reports of physical activity (PA) have been the mainstay of measurement in most non-communicable disease (NCD) surveillance systems. To these, other measures are added to summate to a comprehensive PA surveillance system. Recently, some national NCD surveillance systems have started using accelerometers as a measure of PA. The purpose of this paper was specifically to appraise the suitability and role of accelerometers for population-level PA surveillance.

METHODS

A thorough literature search was conducted to examine aspects of the generalisability, reliability, validity, comprehensiveness and between-study comparability of accelerometer estimates, and to gauge the simplicity, cost-effectiveness, adaptability and sustainability of their use in NCD surveillance.

CONCLUSIONS

Accelerometer data collected in PA surveillance systems may not provide estimates that are generalisable to the target population. Accelerometer-based estimates have adequate reliability for PA surveillance, but there are still several issues associated with their validity. Accelerometer-based prevalence estimates are largely dependent on the investigators' choice of intensity cut-off points. Maintaining standardised accelerometer data collections in long-term PA surveillance systems is difficult, which may cause discontinuity in time-trend data. The use of accelerometers does not necessarily produce useful between-study and international comparisons due to lack of standardisation of data collection and processing methods. To conclude, it appears that accelerometers still have limitations regarding generalisability, validity, comprehensiveness, simplicity, affordability, adaptability, between-study comparability and sustainability. Therefore, given the current evidence, it seems that the widespread adoption of accelerometers specifically for large-scale PA surveillance systems may be premature.

Relationship between the objectively-assessed neighborhood area and activity behavior in Swiss youth

Background

Neighborhood attributes are modifiable determinants of physical activity (PA) and sedentary behavior (SB). We tested whether the objectively-assessed built and social environment was associated with PA and SB in Swiss youth and whether sex, age and the socioeconomic position (Swiss-SEP) modified such associations.

Methods

We combined data of 1742 youth (ages 4 to 17) from seven studies conducted within Switzerland between 2005–2010. All youth provided accelerometer data and a home address, which was linked to objective environmental data and the Swiss-SEP-index. Associations between neighborhood attributes and PA were analyzed by multivariable multilevel regression analyses.

Results

The extent of green areas and building density was positively associated with PA in the total sample (p < 0.05). Factors representing centrally located areas, and more schoolchildren living nearby tended to increase PA in secondary schoolchildren, boys and those from lower-ranked socioeconomic areas. In primary schoolchildren, the extent of green areas was positively associated with PA (p = 0.05). Associations between neighborhood attributes and PA were more pronounced in youth from low socioeconomic areas.

Conclusions

The results indicate that some associations between neighborhood attributes and PA differ by age, sex and socioeconomic area. This should be taken into account when planning interventions to increase childhood PA.

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Comprehensive assessment of objectively measured neighborhood attributes in Europe

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Effects of neighborhood attributes on PA differed by age-group, sex and socioeconomic neighborhood.

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Associations between neighborhood attributes and PA were more pronounced in youth from low socioeconomic areas.

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Strongest associations with green spaces and centrally located areas