The changing relationship between rainfall and children's physical activity in spring and summer: a longitudinal study

Digital endpoints in clinical trials: emerging themes from a multi-stakeholder Knowledge Exchange event

BACKGROUND

Digital technologies, such as wearable devices and smartphone applications (apps), can enable the decentralisation of clinical trials by measuring endpoints in people's chosen locations rather than in traditional clinical settings. Digital endpoints can allow high-frequency and sensitive measurements of health outcomes compared to visit-based endpoints which provide an episodic snapshot of a person's health. However, there are underexplored challenges in this emerging space that require interdisciplinary and cross-sector collaboration. A multi-stakeholder Knowledge Exchange event was organised to facilitate conversations across silos within this research ecosystem.

METHODS

A survey was sent to an initial list of stakeholders to identify potential discussion topics. Additional stakeholders were identified through iterative discussions on perspectives that needed representation. Co-design meetings with attendees were held to discuss the scope, format and ethos of the event. The event itself featured a cross-disciplinary selection of talks, a panel discussion, small-group discussions facilitated via a rolling seating plan and audience participation via Slido. A transcript was generated from the day, which, together with the output from Slido, provided a record of the day's discussions. Finally, meetings were held following the event to identify the key challenges for digital endpoints which emerged and reflections and recommendations for dissemination.

RESULTS

Several challenges for digital endpoints were identified in the following areas: patient adherence and acceptability; algorithms and software for devices; design, analysis and conduct of clinical trials with digital endpoints; the environmental impact of digital endpoints; and the need for ongoing ethical support. Learnings taken for next generation events include the need to include additional stakeholder perspectives, such as those of funders and regulators, and the need for additional resources and facilitation to allow patient and public contributors to engage meaningfully during the event.

CONCLUSIONS

The event emphasised the importance of consortium building and highlighted the critical role that collaborative, multi-disciplinary, and cross-sector efforts play in driving innovation in research design and strategic partnership building moving forward. This necessitates enhanced recognition by funders to support multi-stakeholder projects with patient involvement, standardised terminology, and the utilisation of open-source software.

Multilevel and general linear modeling of weather and time effects on the emotional and behavioral states of children with profound intellectual and multiple disabilities

Introduction

Eliciting the emotional and behavioral states of children with severe or profound intellectual disabilities (IDs) and profound intellectual and multiple disabilities (PIMD) due to their complex and atypical developmental trajectories has become increasingly elusive. It is evident that the environment, influenced by weather conditions and time of the day, plays a pivotal role in molding children's behaviors, emotions, and interactions. This underscores the significance of the environment as a critical factor in exploring the communication dynamics of children with PIMD/IDs.

Methods

Over five months during fall and winter seasons, we conducted 105 video-recorded sessions with 20 children aged 8 to 16 with PIMD/IDs. These sessions aimed to capture the emotional and behavioral states interpreted by caregivers while simultaneously collecting indoor and outdoor weather indices, location, and time data. Using cross-classified multilevel and general linear models adjusted for individual characteristics and location variability with subsequent simple slope analyses, we examined the main and seasonal interaction effects of indoor and outdoor weather indices and time of the day on the emotional and behavioral states of children with PIMD/IDs.

Results

The models revealed that higher atmospheric pressure (atm), indicative of pleasant and favorable weather conditions, was associated with increased engagement (indoor: p < 0.01; outdoor: p < 0.01) and interest (outdoor: p < 0.01) behaviors. In contrast, engagement levels decreased before lunchtime (p < 0.01; p < 0.001), and inclement or unstable weather conditions characterized by low-pressure systems (p < 0.05) and stronger wind speed (p < 0.05) led to more refusal or disagreement. During winter, children displayed significantly more agreement with their caregivers (p < 0.001). Interestingly, they also engaged more on cloudy days (p < 0.05). Furthermore, simple slope analyses revealed that high atm conditions in fall were linked to more engagement (p < 0.05) while humid conditions predicted more assent behaviors (p < 0.001). However, cloudy weather predicted less attentional focusing (p < 0.05) and interest (p < 0.01) behaviors in winter.

Conclusion

This study confirms that fluctuations in weather indices, including seasonal changes and time of the day, can provide potential pathway indicators and supplement behavioral observations to elicit the behavioral states of children with PIMD/IDs. These findings highlight the importance of considering these factors when designing meaningful interactions and communication interventions for this population.

The impact of weather on time allocation to physical activity and sleep of child-parent dyads

PURPOSE

Previous studies showed that unfavourable weather conditions discourage physical activity. However, it remains unclear whether unfavourable weather conditions have a differential impact on physical activity in children compared with adults. We aim to explore the differential impact of weather on time allocation to physical activity and sleep by children and their parents.

METHOD

We use nationally representative data with time use indicators objectively measured on multiple occasions for >1100 Australian pairs of 12-13-year-old children and their middle-aged parents, coupled with daily meteorological data. We employ an individual fixed effects regression model to estimate the causal impact of weather.

RESULTS

We find that unfavourable weather conditions, as measured by cold or hot temperatures or rain, cause children to reduce moderate- and vigorous-intensity physical activity time and increase sedentary time. However, such weather conditions have little impact on children's sleep time or the time allocation of their parents. We also find substantial differential weather impact, especially on children's time allocation, by weekdays/weekends and parental employment status, suggesting that these factors may contribute to explaining the differential weather impact that we observed. Our results additionally provide evidence of adaptation, as temperature appears to have a more pronounced impact on time allocation in colder months and colder regions.

CONCLUSION

Our finding of a negative impact of unfavourable weather conditions on the time allocated to physical activity by children indicates a need to design policies to encourage them to be more physically active on days with unfavourable weather conditions and hence improve child health and wellbeing. Evidence of a more pronounced and negative impact on the time allocated to physical activity by children than their parents suggests that extreme weather conditions, including those associated with climate change, could make children vulnerable to reduced physical activity.

The Impact of Temperature on 24-Hour Movement Behaviors among Chinese Freshmen Students

BACKGROUND

Human populations worldwide have experienced substantial climate change issues. Gaps in scientific literature remain regarding the relationship between temperature and 24-hour movement behavior among people. The purpose of this study is to examine the impact of temperature on 24-hour movement behavior including physical activity (PA), sedentary behavior (SB) and sleep duration among university students living in Beijing, China.

METHODS

We conducted follow-up health surveys on 44,693 freshmen students enrolled at Tsinghua University from 2012 to 2018. PA and SB were measured by using the short version of the International Physical Activity Questionnaire (IPAQ-s); sleep duration was estimated by using The Pittsburgh Sleep Quality Index (CPSQI). Corresponding temperature data measured by the Beijing Meteorological Service were collected to include average daily temperature from the nearest weather station to Tsinghua university. The data were analyzed using linear individual fixed-effect regressions.

RESULTS

An increase in temperature (temperature range 2.29-28.73 °C) by 1 °C was associated with an increase in 0.66 weekly minutes of vigorous physical activity (VPA) (95% confidence interval [CI] = 0.49, 0.82), an increase in 0.56 weekly minutes of moderate physical activity (MPA)(95% CI = 0.32, 0.79), an increase in 1.21 weekly minutes of moderate to vigorous physical activity (MVPA) (95% CI = 0.90, 1.53), an increase in 0.55 weekly minutes of walking (95% CI = 0.31, 0.78), an increase in 1.76 weekly minutes of total PA (95% CI = 1.35, 2.17), and a reduction in 1.60 weekly minutes of sleeping (95% CI = -2.09, -1.11). There was no significant correlation between temperature and sedentary behavior among participants.

CONCLUSIONS

Temperature was significantly positively correlated with physical activity levels in the Chinese freshmen students, and significantly negatively correlated with sleep duration. Replication of this study is warranted among various populations within China. The evidence of this novel study focused on understanding the relationship between climate change and 24-hour movement behaviors among people for developing effective adaptation strategies to climate change to improve people's health behavior. This study has important implications for future study, as knowledge of the impact of temperature on movement behavior may help in the interpretation of their results and translate into improving people's health behavior.

Descriptive epidemiology of the prevalence of adolescent active travel to school in Asia: a cross-sectional study from 31 countries

OBJECTIVE

This study aimed to examine the prevalence of adolescent active travel to school (ATS) across 31 countries and territories in Asia, overall and by age group, sex and body mass index (BMI) category.

DESIGN

Cross-sectional study.

SETTING

31 Asian countries.

PARTICIPANTS

152 368 adolescents aged 13-17 years with complete data for age, sex, measured weight and height and active travel to school from 31 Asian countries from the Global School-based student Health Survey (GSHS).

PRIMARY OUTCOME

Self-reported active travel to school categorised into passive (0 days) and active (1-7 days).

RESULTS

Overall prevalence of adolescent ATS in Asia based on random-effect meta-analysis was 55%, ranging from 18% (UAE) to 84% (Myanmar). There was limited subregional variation: 47% in the Eastern Mediterranean (EM), 56% in the South East Asia and 64% in the Western Pacific. Summarised by random-effect meta-analysis, being an older adolescent aged 16 years and older (vs younger age below 16 years: OR: 1.08; 95% CI: 1.00 to 1.16) was positively associated with ATS. This association was strongest in EM countries. Summarised by random-effect meta-analysis, females (vs males: OR: 0.79; 95% CI: 0.71 to 0.89) and adolescents with overweight/obesity (vs underweight and normal BMI: OR: 0.92; 95% CI: 0.86 to 0.99) were less likely to use ATS. Association with sex was strongest in EM countries. Heterogeneity was considerable in all meta-analyses.

CONCLUSION

The prevalence of adolescent ATS in Asia varies substantially. Overall, older and male adolescents, and adolescents with underweight and normal BMI category are more likely to actively travel to school. However, the main contributor to differences in ATS between and within regions remain unknown. Although there is substantial scope for improving ATS rates in Asia, any policy actions and interventions should be cognisant of local built, social and natural environmental contexts that may influence active travel behaviour.

Considerations to address missing data when deriving clinical trial endpoints from digital health technologies

Digital health technologies (DHTs) enable us to measure human physiology and behavior remotely, objectively and continuously. With the accelerated adoption of DHTs in clinical trials, there is an unmet need to identify statistical approaches to address missing data to ensure that the derived endpoints are valid, accurate, and reliable. It is not obvious how commonly used statistical methods to handle missing data in clinical trials can be directly applied to the complex data collected by DHTs. Meanwhile, current approaches used to address missing data from DHTs are of limited sophistication and focus on the exclusion of data where the quantity of missing data exceeds a given threshold. High-frequency time series data collected by DHTs are often summarized to derive epoch-level data, which are then processed to compute daily summary measures. In this article, we discuss characteristics of missing data collected by DHT, review emerging statistical approaches for addressing missingness in epoch-level data including within-patient imputations across common time periods, functional data analysis, and deep learning methods, as well as imputation approaches and robust modeling appropriate for handling missing data in daily summary measures. We discuss strategies for minimizing missing data by optimizing DHT deployment and by including the patients' perspective in the study design. We believe that these approaches provide more insight into preventing missing data when deriving digital endpoints. We hope this article can serve as a starting point for further discussion among clinical trial stakeholders.

A framework for handling missing accelerometer outcome data in trials

Accelerometers and other wearable devices are increasingly being used in clinical trials to provide an objective measure of the impact of an intervention on physical activity. Missing data are ubiquitous in this setting, typically for one of two reasons: patients may not wear the device as per protocol, and/or the device may fail to collect data (e.g. flat battery, water damage). However, it is not always possible to distinguish whether the participant stopped wearing the device, or if the participant is wearing the device but staying still. Further, a lack of consensus in the literature on how to aggregate the data before analysis (hourly, daily, weekly) leads to a lack of consensus in how to define a "missing" outcome. Different trials have adopted different definitions (ranging from having insufficient step counts in a day, through to missing a certain number of days in a week). We propose an analysis framework that uses wear time to define missingness on the epoch and day level, and propose a multiple imputation approach, at the day level, which treats partially observed daily step counts as right censored. This flexible approach allows the inclusion of auxiliary variables, and is consistent with almost all the primary analysis models described in the literature, and readily allows sensitivity analysis (to the missing at random assumption) to be performed. Having presented our framework, we illustrate its application to the analysis of the 2019 MOVE-IT trial of motivational interviewing to increase exercise.

Associations between weather conditions and physical activity and sedentary time in children and adolescents: A systematic review and meta-analysis

This systematic review and meta-analysis aimed to investigate the associations between weather conditions and physical activity (PA) and sedentary time (ST) in children and adolescents. A systematic search of six databases identified 11,816 articles, of which 26 studies were included in the review. Several weather conditions were included, such as rainfall, temperature, wind speed, day length, sunlight, humidity, snowfall, and clouds. Meta-analyses showed that higher temperatures were associated with more moderate-to-vigorous PA, while lower temperature and heavily rainfall was associated with longer ST. Children and adolescents showed more PA and less ST during favorable weather conditions. Future longitudinal and intervention studies on PA and ST should focus on how weather conditions promote or hinder these behaviors.

Seasons, weather, and device-measured movement behaviors: a scoping review from 2006 to 2020

BACKGROUND

This scoping review summarized research on (a) seasonal differences in physical activity and sedentary behavior, and (b) specific weather indices associated with those behaviors.

METHODS

PubMed, CINAHL, and SPORTDiscus were searched to identify relevant studies. After identifying and screening 1459 articles, data were extracted from 110 articles with 118,189 participants from 30 countries (almost exclusively high-income countries) on five continents.

RESULTS

Both physical activity volume and moderate-to-vigorous physical activity (MVPA) were greater in summer than winter. Sedentary behavior was greater in winter than either spring or summer, and insufficient evidence existed to draw conclusions about seasonal differences in light physical activity. Physical activity volume and MVPA duration were positively associated with both the photoperiod and temperature, and negatively associated with precipitation. Sedentary behavior was negatively associated with photoperiod and positively associated with precipitation. Insufficient evidence existed to draw conclusions about light physical activity and specific weather indices. Many weather indices have been neglected in this literature (e.g., air quality, barometric pressure, cloud coverage, humidity, snow, visibility, windchill).

CONCLUSIONS

The natural environment can influence health by facilitating or inhibiting physical activity. Behavioral interventions should be sensitive to potential weather impacts. Extreme weather conditions brought about by climate change may compromise health-enhancing physical activity in the short term and, over longer periods of time, stimulate human migration in search of more suitable environmental niches.

Tracking Children's Physical Activity Patterns across the School Year: A Mixed-Methods Longitudinal Case Study

Despite the breadth of health benefits associated with regular physical activity (PA), many children in the UK are not sufficiently active enough to meet health guidelines, and tend to become less active as they mature into and throughout adolescence. Research has indicated that children's school, home and neighbourhood environments can all significantly influence their opportunities to engage in moderate-to-vigorous physical activity (MVPA). However, less is known about how children's MVPA patterns within these key environments may change across the school year. The current mixed-methods case study aims to explore this issue by tracking key stage 2 (KS2) and key stage 3 (KS3) children's MVPA patterns across the school year. Fifty-eight children (29 boys, 29 girls, KS2 = 34, KS3 = 24) wore an integrated global positioning systems (GPS) and heart rate (HR) monitor over four consecutive days in the first term of school (autumn), before these measurements were repeated in the two remaining school terms (winter-summer). A subsample of children (n = 6-8 per group) were invited to take part in one of six focus groups each term to further explore their PA behaviours and identify the barriers and facilitators to PA. The children's MVPA was significantly lower (p = 0.046) in term 2 (winter/spring term) than during the warmer terms (autumn and summer). All the locations showed reductions in MVPA in term 2, except indoor MVPA, which increased, and MVPA on foot in the neighbourhood, which remained consistent. Focus groups revealed location, friends, and the variety of options to be associated with MVPA, and poor weather, parental permission, and time limitations to be barriers to MVPA. This mixed-methodological, repeated-measures design study highlights differences in the activity patterns and perceptions of children over the school year. Future studies should implement longitudinal, multi-method approaches to gain deeper insight into how children's PA behaviours differ over time. Consequently, this can inform future health policies promoting children's PA throughout the year.

The Weather Impact on Physical Activity of 6-12 Year Old Children: A Clustered Study of the Health Oriented Pedagogical Project (HOPP)

It is commonly known that children do not engage in a sufficient amount of physical activity. Weather conditions and day length may influence physical activity of children. Little is known about the relationship between physical activity and seasons. The purpose of this study was to investigate the relationships between weather conditions and physical activity in 6-12 year old children based on hip-worn Actigraph wGT3X-BT accelerometer data. The study sample consisted of 2015 subjects aged 6-12 years from the Health Oriented Pedagogical Project (HOPP) study carried out in Horten municipality and Akershus county, Norway. Six days of sedentary and moderate-to-vigorous physical activity data was gathered in January-June and September-October, 2015, presented as daily averages. The accelerometer-monitored physical activity of children grouped within nine schools was matched with regional weather conditions and assessed with the means of linear mixed models. Increased day length was associated with decreased sedentary behavior. Warmer temperature and dry weather were associated with increased moderate-to-vigorous physical activity after adjusting for age and sex. One-hour increase in daylight resulted in a decrease of sedentary time by, on average, 2 min (95% CI = (-2.577, -0.798)). For every 5 °C increase in temperature (range: -0.95 and 15.51 °C) and dry weather, average moderate-to vigorous physical activity increased by 72 and 67 min (males and females, respectively) (p < 0.001). Days with precipitation had, on average, 10 fewer minutes of moderate-to-vigorous physical activity compared with days without precipitation (95% CI = (-16.704, -3.259)). Higher temperatures and dry weather led to higher physical activity levels, seeing larger increases among boys than girls. A school-based physical activity intervention program should be adjusted regarding local weather conditions in line with the present findings.

Influence of meteorological conditions on physical activity in adolescents

Background

It has been shown that meteorological conditions and season affect physical activity (PA) during adolescence. Today, meteorological conditions have never been combined to study their influence on PA level in a single sample of a large adolescent multicountries population. The aim of this study was to explore the influence of meteorological conditions on PA in adolescents from several European countries.

Methods

The study included 2024 healthy adolescents aged 12.5–17.4 years who participated in the Healthy Lifestyle in Europe by Nutrition in Adolescence cross-sectional study. Participants wore a uniaxial accelerometer for 7 consecutive days to measure total PA and moderate to vigorous physical activity (MVPA) in a one-off measurement manner. Comparison of PA according to meteorological conditions was done using linear mixed models.

Results

The highest difference of MVPA was observed in boys on free days when comparing the best meteorological conditions versus the worse (ie, +39% with highest temperature, +29% without rainfall, +39% with highest sunlight duration and +21% with highest length of day) and in girls on free days (ie, +26% with highest sunlight duration). This increase in MVPA contributed to a simultaneous increase in total PA when considering the same meteorological condition parameters.

Conclusions

Meteorological conditions act as a determinant of PA differentially between boys and girls. PA and MVPA in boys are mainly modified by meteorological conditions on free days whereas PA and MVPA in girls are modified by sunlight duration.

A mixed-studies systematic review and meta-analysis of school-based interventions to promote physical activity and/or reduce sedentary time in children

PURPOSE

The aim of this mixed-studies systematic review was to ascertain the effectiveness of school-based interventions in increasing physical activity (PA) and/or reducing sedentary time (ST) in children aged 5-11 years, as well as to explore their effectiveness in relation to categories of the theory of expanded, extended, and enhanced opportunity (TEO).

METHODS

Adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, 5 databases were searched using predefined search terms. Following title and abstract screening of 1115 records, the removal of duplicates (n = 584) and articles that did not meet the inclusion criteria agreed to a priori (n = 419) resulted in 112 records that were full-text screened. Two independent reviewers subsequently used the mixed-methods appraisal tool to assess the methodological quality of 57 full-text studies that met the inclusion criteria after full-text screening. The interventions were summarised using the TIDierR checklist and TEO. The strength of evidence was determined using a 5-level rating system utilising a published decision tree.

RESULTS

Overall evidence ratings for interventions implemented within school settings were: no evidence of effects on moderate-to-vigorous physical activity (MVPA) and inconclusive evidence of effects on sedentary time. In relation to the TEO, expansion of PA appeared to be the most promising intervention type for MVPA, with moderate evidence of effect, whereas extension and enhancement of PA opportunity demonstrated no evidence of effect. A critical issue of possible compensatory behavior was identified by analysis of intervention effect in relation to PA measurement duration; when studies measured changes in PA during the actual intervention, there was moderate evidence of effect, whereas those that measured changes in PA during the school day presented inconclusive evidence of effect, and those that measured changes in PA over a whole day yielded no evidence of effect. Two meta-analyses of those studies using a whole-day accelerometer measure for MVPA or ST showed a significant but moderate effect for MVPA (effect size = 0.51; 95% confidence interval (CI): 0.02-0.99) and a large but nonsignificant effect for ST (effect size = 1.15; 95%CI: -1.03 to 3.33); both meta-analyses demonstrated low precision, considerable inconsistency, and high heterogeneity.

CONCLUSION

The findings have important implications for future intervention research in terms of intervention design, implementation, and evaluation.

Associations of weather conditions with adolescents' daily physical activity, sedentary time, and sleep duration

Weather has been recognized as an environmental factor that affects daily activities. However, the effects of a humid subtropical climate on daily activity behavior are unclear. This study investigated the associations of weather conditions with physical activity (PA), sedentary time (ST), and sleep duration in a sample of 740 Hong Kong adolescents (mean age: 14.7 ± 1.6 years). The activPAL was used to assess the time spent during moderate to vigorous PA (MVPA), ST, and sleep. Weather data (e.g., temperature, relative humidity, rainfall amount, and sunlight duration) were obtained from the Hong Kong Observatory. Linear mixed models were constructed to examine the associations of weather conditions with the durations of MVPA, ST, and sleep on weekdays and weekend days, respectively. The analysis included valid data from 561 students (51.9% male). Among Hong Kong adolescents, a higher relative humidity was associated with reduced MVPA on weekdays and weekends, more ST on weekdays, and a longer sleep duration on weekends. A longer duration of sunlight induced less MVPA on weekends, but a longer sleep duration on weekdays. On weekends, higher temperatures correlated with increases in MVPA and ST but a decrease in sleep duration. Rainfall correlated inversely with sleep duration and positively with ST on weekdays. The associations of rainfall with MVPA exhibited opposite trends on weekdays and weekends. In summary, the relationships between weather conditions and daily activities exhibited day-type patterns. The findings suggest that environment-controlled indoor PA should be recommended during weather conditions of high relative humidity and higher temperatures.

Efficacy of a free-play intervention to increase physical activity during childcare: a randomized controlled trial

The primary aim of this study was to assess the efficacy of a childcare-based intervention in increasing child physical activity by allowing children unrestricted access to outdoor areas for free-play when structured activity is not taking place. A randomized controlled trial was conducted in six childcare services. Intervention services provided children unrestricted access outdoors for active free-play, while control services provided their usual scheduled periods of outdoor play. Consent was obtained from 231 children. Child moderate to vigorous activity (MVPA), the primary trial outcome, was assessed via accelerometer at baseline and 3 months post baseline. Intervention effects were examined using Generalised Linear Mixed Models. Controlling for child age, gender and baseline outcome measure, at follow-up there were no significant differences between groups in minutes of MVPA in-care (mean difference: 4.85; 95% CI: -3.96, 13.66; P = 0.28), proportion of wear time in-care spent in MVPA (mean difference: 1.52%; 95% CI: -0.50, 3.53; P = 0.14) or total physical activity in-care (mean difference in counts per minute: 23.18; 95% CI: -4.26, 50.61; P = 0.10), nor on measures of child cognition (P = 0.45-0.91). It was concluded that interventions addressing multiple aspects of the childcare and home environment might provide the greatest potential to improve child physical activity.

Seasonal and weather variation of sleep and physical activity in 12-14-year-old children

Background: Understanding variation in physical activity (PA) and sleep is necessary to develop novel intervention strategies targeting adolescents' health behaviors. We examined the extent to which PA and sleep vary by aspects of the physical environment. Participants: We performed a cross-sectional analysis of 669 adolescents in the Project Viva cohort. Methods: We estimated total PA, sleep duration, sleep efficiency, and sleep midpoint timing from wrist accelerometers. We used multivariable linear regression models and generalized estimated equations to assess associations of PA and sleep with season and daily weather conditions obtained from the National Oceanic and Atmospheric Administration archive. Results: Mean age was 12.9 (SD 0.6) years; 51% were female and 68% were white. Mean sleep duration was 466 (SD 42) min per night and total PA was 1,652 (SD 431) counts per min per day. Sleep midpoint time was 41 (95% CI: 27 to 54) min later in summer, 28 (95% CI: -41 to -14) min earlier in spring, and 29 (95% CI: -43 to -15) min earlier in autumn compared to winter. Higher temperature and longer day length both were associated with small reductions of nightly sleep duration. Adolescents were less physically active during winter and on rainy and short sunlight days. There was an inverse U-shaped relationship between PA and mean temperature. Conclusions: Season was associated with large changes in sleep timing, and smaller changes in other sleep and PA measurements. Given the importance of sleep and circadian alignment, future health behavioral interventions may benefit by targeting "season-specific" interventions.

Longitudinal associations between weather, season, and mode of commuting to school among Spanish youths

AIM

To study the associations of weather conditions with the travel mode choice for commuting to and from school.

METHODS

A total of 6979 Spanish youths aged 7 to 18 years old (80% adolescents aged 12-18 years old, 51% male) completed a 5-day survey of mode of commuting to school in autumn, winter, and spring. Weather data from the nearest weather station to each school were registered. We used Google Maps™ to calculate the distance from home to school. Multilevel logistic regression models were used to estimate odds of active travel based on weather and season.

RESULTS

We analyzed a total of 163 846 discrete journeys. In winter, children (aged 7 to 11 years old) were less likely to choose an active mode of commuting to school (OR: 0.72, 95% CI: 0.59-0.89, P = 0.003). In spring, adolescents were more likely to choose an active mode of commuting to school (OR: 1.43, 95% CI: 1.19-1.73, P < 0.001). With higher mean temperatures, adolescents were more likely to choose an active mode of commuting from school (OR: 1.02, 95% CI: 1.00-1.04, P = 0.029).

CONCLUSION

Certain weather conditions seem to influence the travel mode choice for commuting to and from school in youth, including season and temperature.

Physical Activity, Inactivity, and Health During Youth-The Year That Was 2017

It is well known that physical activity is important for children's current and future mental and physical health. Despite this, there appears to be a secular decline in children's physical activity (Cameron et al. [ 2 ]; Dalene et al. [ 3 ]). Furthermore, (frustratingly) interventions aiming to increase children's physical activity have limited success (Metcalf et al. [ 10 ]), demonstrating a need for more information on the amenability of activity levels to change.

Daily Weather and Children's Physical Activity Patterns

INTRODUCTION

Understanding how the weather affects physical activity (PA) may help in the design, analysis, and interpretation of future studies, especially when investigating PA across diverse meteorological settings and with long follow-up periods. The present longitudinal study first aims to examine the influence of daily weather elements on intraindividual PA patterns among primary school children across four seasons, reflecting day-to-day variation within each season. Second, we investigate whether the influence of weather elements differs by day of the week (weekdays vs weekends), gender, age, and body mass index.

METHOD

PA data were collected by ActiGraph accelerometers for 1 wk in each of four school terms that reflect each season in southeast Australia. PA data from 307 children (age range 8.7-12.8 yr) were matched to daily meteorological variables obtained from the Australian Government's Bureau of Meteorology (maximum temperature, relative humidity, solar radiation, day length, and rainfall). Daily PA patterns and their association with weather elements were analyzed using multilevel linear mixed models.

RESULTS

Temperature was the strongest predictor of moderate and vigorous PA, followed by solar radiation and humidity. The relation with temperature was curvilinear, showing optimum PA levels at temperatures between 20°C and 22°C. Associations between weather elements on PA did not differ by gender, child's age, or body mass index.

CONCLUSIONS

This novel study focused on the influence of weather elements on intraindividual PA patterns in children. As weather influences cannot be controlled, knowledge of its effect on individual PA patterns may help in the design of future studies, interpretation of their results, and translation into PA promotion.

One Size Does Not Fit All: Contextualising Family Physical Activity Using a Write, Draw, Show and Tell Approach

Understanding family physical activity (PA) behaviour is essential for designing effective family-based PA interventions. However, effective approaches to capture the perceptions and "lived experiences" of families are not yet well established. The aims of the study were to: (1) demonstrate how a "write, draw, show and tell" (WDST) methodological approach can be appropriate to family-based PA research, and (2) present two distinct family case studies to provide insights into the habitual PA behaviour and experiences of a nuclear and single-parent family. Six participants (including two "target" children aged 9-11 years, two mothers and two siblings aged 6-8 years) from two families were purposefully selected to take part in the study, based on their family structure. Participants completed a paper-based PA diary and wore an ActiGraph GT9X accelerometer on their left wrist for up to 10 weekdays and 16 weekend days. A range of WDST tasks were then undertaken by each family to offer contextual insight into their family-based PA. The selected families participated in different levels and modes of PA, and reported contrasting leisure opportunities and experiences. These novel findings encourage researchers to tailor family-based PA intervention programmes to the characteristics of the family.

Risk Assessment of Mycotoxins in Stored Maize Grains Consumed by Infants and Young Children in Nigeria

Maize is a major complimentary food for infants (0-4years) and young children (5-12years) in Nigeria. In this study, we assessed the risk of exposure of infants and young children (IYC) to some major mycotoxins in stored maize grains from five agro-ecological zones of Nigeria. The probable daily intake approach was employed to determine exposure to five mycotoxins while the margin of exposure (MOE) and population at risk of primary hepatocellular carcinoma approaches were used to characterize the risk of consuming aflatoxin contaminated maize. Infants and young children in the Derived Savannah zone are more exposed to aflatoxins, ochratoxins, and zearalenone while those in the Northern Guinea Savanna zone are mainly exposed to deoxynivalenol and fumonisins. The mean national MOE for infants and children were 0.12 and 0.3 respectively while the risk of developing primary liver cancer was estimated at 152.7 and 61.1 cancer/year/100,000 population of infants and children, respectively. Infants and young children consuming mycotoxin contaminated maize in Nigeria are therefore vulnerable to the adverse health effects. Mycotoxin contamination of maize is still a challenge in Nigeria; mitigation efforts should target the value chain and stricter tolerable limits should be enforced.

Weather and children's physical activity; how and why do relationships vary between countries?

BACKGROUND

Globally most children do not engage in enough physical activity. Day length and weather conditions have been identified as determinants of physical activity, although how they may be overcome as barriers is not clear. We aim to examine if and how relationships between children's physical activity and weather and day length vary between countries and identify settings in which children were better able to maintain activity levels given the weather conditions they experienced.

METHODS

In this repeated measures study, we used data from 23,451 participants in the International Children's Accelerometry Database (ICAD). Daily accelerometer-measured physical activity (counts per minute; cpm) was matched to local weather conditions and the relationships assessed using multilevel regression models. Multilevel models accounted for clustering of days within occasions within children within study-cities, and allowed us to explore if and how the relationships between weather variables and physical activity differ by setting.

RESULTS

Increased precipitation and wind speed were associated with decreased cpm while better visibility and more hours of daylight were associated with increased cpm. Models indicated that increases in these variables resulted in average changes in mean cpm of 7.6/h of day length, -13.2/cm precipitation, 10.3/10 km visibility and -10.3/10kph wind speed (all p < 0.01). Temperature showed a cubic relationship with cpm, although between 0 and 20 degrees C the relationship was broadly linear. Age showed interactions with temperature and precipitation, with the associations larger among younger children. In terms of geographic trends, participants from Northern European countries and Melbourne, Australia were the most active, and also better maintained their activity levels given the weather conditions they experienced compared to those in the US and Western Europe.

CONCLUSIONS

We found variation in the relationship between weather conditions and physical activity between ICAD studies and settings. Children in Northern Europe and Melbourne, Australia were not only more active on average, but also more active given the weather conditions they experienced. Future work should consider strategies to mitigate the impacts of weather conditions, especially among young children, and interventions involving changes to the physical environment should consider how they will operate in different weather conditions.

Seasonal Variation in Children's Physical Activity and Sedentary Time

PURPOSE

Understanding seasonal variation in physical activity is important for informing public health surveillance and intervention design. The aim of the current study was to describe seasonal variation in children's objectively measured physical activity and sedentary time.

METHODS

Data are from the UK Millennium Cohort Study. Participants were invited to wear an accelerometer for 7 d on five occasions between November 2008 and January 2010. Outcome variables were sedentary time (<100 counts per minute, min·d(-1)) and moderate to vigorous physical activity (MVPA) (>2241 counts per minute, min·d(-1)). The season was characterized using a categorical variable (spring, summer, autumn, or winter) and a continuous function of day of the year. Cross-classified linear regression models were used to estimate the association of each of these constructs with the outcome variables. Modification of the seasonal variation by sex, weight status, urban/rural location, parental income, and day of the week (weekday/weekend) was examined using interaction terms in regression models.

RESULTS

At least one wave of valid accelerometer data was obtained from 704 participants (47% male; baseline age, 7.6 (0.3) yr). MVPA was lower in autumn and winter relative to spring, with the magnitude of this difference varying by weekday/weekend, sex, weight status, urban/rural location, and family income (P for interaction <0.05 in all cases). Total sedentary time was greater in autumn and winter compared with spring; the seasonal effect was stronger during the weekend than during the weekday (P for interaction <0.01).

CONCLUSIONS

Lower levels of MVPA and elevated sedentary time support the implementation of intervention programs during autumn and winter. Evidence of greater seasonal variation in weekend behavior and among certain sociodemographic subgroups highlights targets for tailored intervention programs.

The correlates of after-school sedentary behavior among children aged 5-18 years: a systematic review

BACKGROUND

Children and adolescents spend a large proportion of the after-school period in sedentary behaviors (SB). Identifying context-specific correlates is important for informing strategies to reduce these behaviors. This paper systematically reviews the correlates of children's and adolescents' after-school SB.

METHODS

A computerized literature search was performed in October 2015 for peer-reviewed original research journal articles published in English before October 2015. Eligibility criteria included: 1) sample aged 5-18 years; 2) quantified the amount of SB or component of this that the children/adolescents were performing after school; 3) a measure of SB as the dependent outcome; and 4) the association between potential correlates and after-school SB.

RESULTS

Data were synthesized in October 2015. Thirty-one studies met the eligibility criteria: 22 studies among children (≤ 12 years), six among adolescents (>12 years), two had a combined sample of children and adolescents and one cohort followed children from childhood to adolescence. Findings were separated by after-school location i.e. after-school programs (n = 4 studies) and unidentified locations (n = 27). There was insufficient evidence to draw conclusions on all but two of the 58 potential correlates: sex and age. Among children at unidentified locations there was a null association between sex (male) and overall after-school SB, a null association between sex (male) and after-school TV viewing, a positive association between age and overall after-school SB and an inconsistent association between age and after-school TV viewing. No correlates of after-school sedentary behaviour while at after-school programs were identified.

CONCLUSIONS

Only two correlates have been investigated frequently enough to determine an overall association; neither correlate is modifiable. Due to the lack of consistent investigation of potential correlates, further evidence is required to accurately identify potential intervention targets.

PROSPERO REGISTRATION NUMBER

CRD42014009180.