Fear of movement and competence frustration mediate the relationship between pain catastrophising and physical function in people living with axSpA: an online cross-sectional survey.

The objective of this study is to examine the contribution of pain catastrophising to Axial Spondyloarthritis (axSpA) patient's physical function and to test the mediating role of fear of movement, and uniquely, the contribution of competence frustration to the fear-avoidance model. Participants (N = 98, 70% female, M age = 45.62, SD 12.16) completed an online survey (December 2020-May 2021) distributed in the United Kingdom via the National Axial Spondyloarthritis Society (n ≈ 3500; NASS, 2019). The PROCESS SPSS macro was used to test three mediation models using percentile bootstrap 95% confidence intervals (PBCI). A significant indirect effect on the relationship between pain and physical function via fear of movement (ß = 0.10, 95% PBCI = 0.030-0.183) was observed (Model 1). Model 2 showed the relationship between pain catastrophising and physical function to be significantly mediated by fear of movement (ß = 0.16, 95% PBCI = 0.005-0.322). Finally, Model 3 showed a significant indirect effect on the relationship between pain catastrophising and physical function via competence frustration (ß = 0.15, 95% PBCI = 0.014-0.309) but not through fear of movement (ß = 0.062, 95% PBCI = - 0.134 to 0.248). To our knowledge, this is the first study to examine and demonstrate the unique contribution of competence need frustration to the Fear-avoidance model in people that live with axSpA. Identifying modifiable factors that contribute to disease outcomes such as physical function can improve the care and quality of life for people living with a disease currently without a cure.

Predicting Accelerometer-Assessed Estimates of Adolescents' Multidimensional Physical Activity: A Self-Determination Theory Approach.

Based on the tenets in self-determination theory, a dual-process model of motivational processes was tested to predict accelerometer-assessed estimates of adolescents' light physical activity (LPA), moderate to vigorous physical activity (MVPA), and sedentary time. Here, we hypothesized that (a) perceptions of psychological need support for exercise would be positively associated with LPA and MVPA and negatively associated with sedentary time via exercise-related psychological need satisfaction and autonomous exercise motivation and (b) perceptions of psychological need thwarting for exercise would be negatively associated with LPA and MVPA and positively associated with sedentary time via exercise-related psychological need frustration and controlled exercise motivation. Adolescents (N = 338; 234 female) age 11-15 years (M = 12.75, SD = .90) wore an ActiGraph accelerometer for 8 days and completed questionnaires pertaining to the self-determination-theory variables. Results showed psychological need support to indirectly and positively predict LPA and MVPA via psychological need satisfaction and autonomous exercise motivation. Although directly predictive of need frustration and indirectly predictive of controlled motivation and amotivation, the hypothesized effects from psychological need thwarting to the behavioral outcomes were nonsignificant. The current findings highlight the important role that need-supportive environments play in facilitating autonomous exercise motivation and behavior by being conducive to exercise-related psychological need satisfaction.

Correlates of physical activity in adults with spondyloarthritis and rheumatoid arthritis: a systematic review.

Physical activity (PA) is a primary non-pharmacological treatment option for those living with rheumatoid arthritis (RA) and spondyloarthritis (SpA). The aim of this systematic literature review was to summarize and present an updated synthesis of the factors associated with PA in the RA and SpA populations. A tailored search of PubMed (inc. Medline), Web of Science, Embase, APA PsycNET, and Scopus was conducted for research published between 2004 and June 2019. Methodological quality was assessed using The National Institutes of Health (NIH) Quality Assessment Tools for Observational Cohort and Cross-sectional Studies, Case-Control Studies, and Controlled Intervention Studies. Forty RA and eleven SpA articles met the inclusion criteria. Methodological quality was generally fair to good, with two RA studies rated as poor. Correlates are discussed in the sociodemographic, physical, psychological, social, and environmental categories. Environmental factors were not measured in any RA study. In individuals living with RA, consistent positive associations were found between PA and high-density lipoprotein, self-efficacy, and motivation. Consistent negative associations were found for functional disability and fatigue. In individuals with SpA, consistent positive associations were found between PA and quality of life, and consistent negative associations with functional disability. Physical and psychological factors are most consistently related with PA parameters in those living with RA and SpA. Many variables were inconsistently studied and showed indeterminant associations. Studies with prospective designs are needed to further understand the factors associated with PA in these populations, especially in those living with SpA.

Influence of obesity prevalence on social norms and weight control motivation: a cross-sectional comparison of the Netherlands and the UK.

This cross-sectional survey study explored associations between perceived bodyweight norms, psychological need satisfaction and motivation for weight control among 500 adult residents of two countries with different overweight/obesity prevalence: the UK (63% prevalence) and the Netherlands (50%). A hypothesised model of the effects of descriptive norms (i.e. perceptions of what is typical for most people) and injunctive norms (i.e. perceptions of what is typically approved by others) on autonomous motivation, mediated through basic psychological need satisfaction, was analysed using structural equation modelling. Descriptive norms did not differ between countries, yet UK adults reported a lower-weight injunctive norm. Perceiving higher bodyweights to be normal negatively predicted motivation to manage one's bodyweight mediated through an undermining effect on psychological need satisfaction. Perceiving higher bodyweights to be normal may have the potential to reduce individual motivation for weight control, but the sensitivity of people's perceptions to objective differences in overweight prevalence appears limited.

Predictors of in-school and out-of-school sport injury prevention: A test of the trans-contextual model.

The current study aimed to predict secondary school students' motivation toward sport injury prevention in "in-school" and "out-of-school" contexts, and their sport injury prevention behavior at 3-month follow-up using the trans-contextual model (TCM). Hong Kong secondary school students (N = 1566; mean age = 13.34 years, range = 11 to 19; female = 49.42%) were recruited. Participants were asked to complete a survey comprising previously validated scales measuring TCM constructs at baseline and a measure of sport injury prevention behavior at follow-up three months later. Structural equation modeling (SEM) was used to examine the hypothesized paths among TCM constructs. A SEM specifying hypothesized paths among TCM variables showed acceptable fit with the data (χ2 (29) = 418.55, CFI = .93, TLI = .90, and RMSEA = .09, 90% CI [.09, .10], and SRMR = .05). Findings supported tenets of the TCM: the effects of perceived autonomy support from PE teachers on in-school autonomous motivation toward injury prevention, the trans-contextual relationship between students' "in-school" and "out-of-school" autonomous motivation toward injury prevention, and the effects of autonomous motivation toward injury prevention on social cognitive variables and subsequent sport injury prevention behaviors. Results supported the tenets proposed within the TCM in predicting students' "in-school" and "out-of-school" autonomous motivation toward sport injury prevention. Findings underscore the potential importance of autonomy support from PE teachers in facilitating students' sport injury prevention behaviors. Further longitudinal and intervention research is warranted to establish temporal and causal effects of TCM variables in sport injury prevention.

Applying the trans-contextual model to promote sport injury prevention behaviors among secondary school students.

The current study tested the effects of an intervention based on the trans-contextual model (TCM) on secondary school PE students' sport injury prevention behavior and on theory-based motivational and social cognition mediators. Participants were PE students (N = 1168; Mage  = 13.322 ± 1.045, range = 12-16; female = 51.721%) who participated in a 3-month cluster-randomized controlled trial. Schools were randomly assigned to a treatment group, in which PE teachers received training to be more supportive of psychological needs in teaching sport injury prevention, or a control group, in which PE teachers received no training. Participants completed survey measures of TCM variables and self-reported sport injury prevention behavior at baseline and at 3-month post-intervention follow-up. The proposed TCM model exhibited adequate fit with the data, χ2  = 143.080 (df = 19), CFI = 0.956, TLI = 0.916, RMSEA = 0.078 (90% CI = 0.066-0.090), and SRMR = 0.058. We found positive, statistically significant direct intervention effects on changes in perceived psychological need support (ß = 0.064, p = 0.020). We also found positive, significant direct (ß = 0.086-0.599, p < 0.001) and indirect (ß = 0.002-0.027, p = 0.020-0.032) intervention effects on changes in TCM variables and behaviors to prevent sport injuries. Our findings support the TCM as a useful framework for building an intervention for promoting sport injury prevention behaviors among secondary school students.

Effect of novel technology-enabled multidimensional physical activity feedback in primary care patients at risk of chronic disease - the MIPACT study: a randomised controlled trial.

BACKGROUND: Technological progress has enabled the provision of personalised feedback across multiple dimensions of physical activity that are important for health. Whether this multidimensional approach supports physical activity behaviour change has not yet been examined. Our objective was to examine the effectiveness of a novel digital system and app that provided multidimensional physical activity feedback combined with health trainer support in primary care patients identified as at risk of chronic disease. METHODS: MIPACT was a parallel-group, randomised controlled trial that recruited patients at medium (≥10 and < 20%) or high (≥20%) risk of cardiovascular disease and/or type II diabetes from six primary care practices in the United Kingdom. Intervention group participants (n = 120) received personal multidimensional physical activity feedback using a customised digital system and web-app for 3 months plus five health trainer-led sessions. All participants received standardised information regarding physical activity. Control group participants (n = 84) received no further intervention. The primary outcome was device-based assessment of physical activity at 12 months. RESULTS: Mean intervention effects were: moderate-vigorous physical activity: -1.1 (95% CI, - 17.9 to 15.7) min/day; moderate-vigorous physical activity in ≥10-min bouts: 0.2 (- 14.2 to 14.6) min/day; Physical Activity Level (PAL): 0.00 (- 0.036 to 0.054); vigorous physical activity: 1.8 (- 0.8 to 4.2) min/day; and sedentary time: 10 (- 19.3 to 39.3) min/day. For all of these outcomes, the results showed that the groups were practically equivalent and statistically ruled out meaningful positive or negative effects (>minimum clinically important difference, MCID). However, there was profound physical activity multidimensionality, and only a small proportion (5%) of patients had consistently low physical activity across all dimensions. CONCLUSION: In patients at risk of cardiovascular disease and/or type II diabetes, MIPACT did not increase mean physical activity. Using a sophisticated multidimensional digital approach revealed enormous heterogeneity in baseline physical activity in primary care patients, and practitioners may need to screen for low physical activity across dimensions rather than rely on disease-risk algorithms that are heavily influenced by age. TRIAL REGISTRATION: This trial is registered with the ISRCTN registry ( ISRCTN18008011 ; registration date 31 July 2013).

How are we measuring physical activity and sedentary behaviour in the four home nations of the UK? A narrative review of current surveillance measures and future directions.

BACKGROUND/OBJECTIVES: To explore and describe the comparability between the surveys of the UK home nations (England, Northern Ireland, Scotland, Wales) that monitor compliance with the Chief Medical Officers' physical activity (PA) recommendations. We also suggest ways to improve the UK national PA and sedentary behaviour (SB) surveillance systems. METHODS: We identified national surveys that monitor PA and SB through searching UK-wide and devolved administration websites, the Global Observatory for Physical Activity Country Cards and the Active Healthy Kids Report Cards. Subsequently, we extracted information from survey documentation on the survey commissioners and contractors, method of administration, current questionnaire details relevant to the PA recommendations, questionnaire changes over the previous decade and the most recent prevalence figures. RESULTS: For adults and older adults, five surveys assess the moderate-to-vigorous PA (MVPA) recommendation, three assess muscle strengthening and three assess SB. For older adults only, three assess balance and co-ordination. For children, seven assess MVPA, none assess muscle strengthening and five assess SB. Only one survey reports on the under 5 PA recommendation. There is no part of the recommendations for which comparable estimates can be calculated across all four home nations. The greatest variation is among the SB questions and reporting. No survey has regularly used device-based measures. CONCLUSION: UK surveillance of the PA recommendations is complex, undertaken separately in the home nations, using multiple surveys that cover adults and children separately. We recommend that the costs and benefits of harmonising the existing questionnaires are considered, along with the potential introduction of device-based measures.

Breastfeeding and childhood obesity: A 12-country study.

This study aimed to examine the association between breastfeeding and childhood obesity. A multinational cross-sectional study of 4,740 children aged 9-11 years was conducted from 12 countries. Infant breastfeeding was recalled by parents or legal guardians. Height, weight, waist circumference, and body fat were obtained using standardized methods. The overall prevalence of obesity, central obesity, and high body fat were 12.3%, 9.9%, and 8.1%, respectively. After adjustment for maternal age at delivery, body mass index (BMI), highest maternal education, history of gestational diabetes, gestational age, and child's age, sex, birth weight, unhealthy diet pattern scores, moderate-to-vigorous physical activity, sleeping, and sedentary time, exclusive breastfeeding was associated with lower odds of obesity (odds ratio [OR] 0.76, 95% confidence interval, CI [0.57, 1.00]) and high body fat (OR 0.60, 95% CI [0.43, 0.84]) compared with exclusive formula feeding. The multivariable-adjusted ORs based on different breastfeeding durations (none, 1-6, 6-12, and > 12 months) were 1.00, 0.74, 0.70, and 0.60 for obesity (Ptrend = .020) and 1.00, 0.64, 047, and 0.64 for high body fat (Ptrend = .012), respectively. These associations were no longer significant after adjustment for maternal BMI. Breastfeeding may be a protective factor for obesity and high body fat in 9- to 11-year-old children from 12 countries.

Joint associations between weekday and weekend physical activity or sedentary time and childhood obesity.

OBJECTIVE: To evaluate the single and joint associations of objectively measured moderate-to-vigorous physical activity (MVPA) and sedentary time on week and weekend days with obesity in children from 12 countries across all inhabited continents. METHODS: A multinational, 12-country cross-sectional study of 5779 children aged 9-11 years was conducted. Time spent in MVPA and sedentary behaviors was assessed by waist-worn accelerometry. Logistic regression was used to examine the independent and joint associations of MVPA and sedentary time on weekdays and weekend with the odds of obesity. RESULTS: After adjustment for all confounding factors, the odds ratios (ORs) of childhood obesity were the highest among children with a low level of MVPA on both weekdays and weekend (OR 4.67), high among children with a high level of MVPA on weekdays and a low level of MVPA on weekend (OR 1.99) and high among children with a low level of MVPA on weekdays and a high levels of MVPA on weekend (OR 2.20), compared to those with a high level of MVPA on both weekdays and weekend. Similarly, the ORs of childhood obesity were significantly higher among children with a high level of sedentary time on both weekdays and weekend (OR 1.87) compared with those with low levels of sedentary time on both weekdays and weekend. CONCLUSIONS: Lower levels of MVPA or higher levels of sedentary time on either weekdays or weekend were associated with increased odds of obesity in 9-11 year old children in 12 countries.

Associations between meeting combinations of 24-hour movement recommendations and dietary patterns of children: A 12-country study.

The purpose of this study was to examine whether meeting movement behavior recommendations (i.e., ≥60 min of moderate-to-vigorous physical activity [MVPA] per day, ≤2 h of recreational screen time per day, and between 9 and 11 h of nightly sleep), and combinations of these recommendations, are associated with dietary patterns of children. This cross-sectional study was conducted between 2011 and 2013 and included 5873 children 9-11 years of age from 12 countries around the world. MVPA and nightly sleep duration were measured using 24-hour waist-worn accelerometry. Screen time habits were assessed via self-report. A food frequency questionnaire was used to assess dietary patterns, and the whole diet was described by two components derived from principal component analysis: "healthy" and "unhealthy" dietary pattern scores. Covariates included in the multilevel statistical models included age, sex, highest parental education, and body mass index z-score. A healthier dietary pattern score was observed when more movement behavior recommendations were met. Among the three movement behaviors, limiting screen time habits to the recommended amount was most strongly associated with healthier dietary patterns. Similarly, a less unhealthy dietary pattern was observed when more movement behavior recommendations were met. Surprisingly, the highest unhealthy dietary pattern was associated with children meeting the MVPA recommendation alone. Combinations including ≤2 h of screen time per day were those most strongly associated with a less unhealthy dietary pattern. Findings were similar across study sites and in boys and girls. In conclusion, meeting more movement behavior recommendations is generally associated with better dietary patterns in children from around the world, with limiting screen time habits showing the strongest relationships.

Association between breakfast frequency and physical activity and sedentary time: a cross-sectional study in children from 12 countries.

BACKGROUND: Existing research has documented inconsistent findings for the associations among breakfast frequency, physical activity (PA), and sedentary time in children. The primary aim of this study was to examine the associations among breakfast frequency and objectively-measured PA and sedentary time in a sample of children from 12 countries representing a wide range of human development, economic development and inequality. The secondary aim was to examine interactions of these associations between study sites. METHODS: This multinational, cross-sectional study included 6228 children aged 9-11 years from the 12 International Study of Childhood Obesity, Lifestyle and the Environment sites. Multilevel statistical models were used to examine associations between self-reported habitual breakfast frequency defined using three categories (breakfast consumed 0 to 2 days/week [rare], 3 to 5 days/week [occasional] or 6 to 7 days/week [frequent]) or two categories (breakfast consumed less than daily or daily) and accelerometry-derived PA and sedentary time during the morning (wake time to 1200 h) and afternoon (1200 h to bed time) with study site included as an interaction term. Model covariates included age, sex, highest parental education, body mass index z-score, and accelerometer waking wear time. RESULTS: Participants averaged 60 (s.d. 25) min/day in moderate-to-vigorous PA (MVPA), 315 (s.d. 53) min/day in light PA and 513 (s.d. 69) min/day sedentary. Controlling for covariates, breakfast frequency was not significantly associated with total daily or afternoon PA and sedentary time. For the morning, frequent breakfast consumption was associated with a higher proportion of time in MVPA (0.3%), higher proportion of time in light PA (1.0%) and lower min/day and proportion of time sedentary (3.4 min/day and 1.3%) than rare breakfast consumption (all p ≤ 0.05). No significant associations were found when comparing occasional with rare or frequent breakfast consumption, or daily with less than daily breakfast consumption. Very few significant interactions with study site were found. CONCLUSIONS: In this multinational sample of children, frequent breakfast consumption was associated with higher MVPA and light PA time and lower sedentary time in the morning when compared with rare breakfast consumption, although the small magnitude of the associations may lack clinical relevance. TRIAL REGISTRATION: The International Study of Childhood Obesity, Lifestyle and the Environment (ISCOLE) is registered at (Identifier NCT01722500 ).

Relationships Between Outdoor Time, Physical Activity, Sedentary Time, and Body Mass Index in Children: A 12-Country Study.

PURPOSE: This study investigated the relationship between outdoor time and physical activity (PA), sedentary time (SED), and body mass index z scores among children from 12 lower-middle-income, upper-middle-income, and high-income countries. METHODS: In total, 6478 children (54.4% girls) aged 9-11 years participated. Outdoor time was self-reported, PA and SED were assessed with ActiGraph GT3X+ accelerometers, and height and weight were measured. Data on parental education, neighborhood collective efficacy, and accessibility to neighborhood recreation facilities were collected from parent questionnaires. Country latitude and climate statistics were collected through national weather data sources. Gender-stratified multilevel models with parental education, climate, and neighborhood variables as covariates were used to examine the relationship between outdoor time, accelerometry measures, and body mass index z scores. RESULTS: Each additional hour per day spent outdoors was associated with higher moderate- to vigorous-intensity PA (boys: +2.8 min/d; girls: +1.4 min/d), higher light-intensity PA (boys: +2.0 min/d; girls: +2.3 min/d), and lower SED (boys: -6.3 min/d; girls: -5.1 min/d). Effect sizes were generally weaker in lower-middle-income countries. Outdoor time was not associated with body mass index z scores. CONCLUSIONS: Outdoor time was associated with higher PA and lower SED independent of climate, parental education, and neighborhood variables, but effect sizes were small. However, more research is needed in low- and middle-income countries.

Temporal and bi-directional associations between sleep duration and physical activity/sedentary time in children: An international comparison.

The purpose of this multinational and cross-sectional study was to investigate whether nighttime sleep duration was associated with physical activity (PA) and sedentary time (SED) the following day, whether daytime PA/SED were associated with sleep duration the subsequent night, and whether the associations were modified by sex and study sites. Data from 5779 children aged 9-11years were analyzed. A waist-worn Actigraph GT3X+ accelerometer was used to assess children's 24-h movement behaviours for 7days, i.e. sleep duration, total SED, light-intensity physical activity (LPA), and moderate- to vigorous-intensity physical activity (MVPA). Multilevel linear regression models were used to account for the repeated measures nested within participants (there were up to 7 sleep→PA/SED and PA/SED→sleep pairings per participant) and schools, and adjusted for covariates. To facilitate interpretation, all sleep and PA/SED variables were standardized. Results showed that the relationship between sleep and PA/SED is bi-directional in this international sample of children. Specifically, for each one standard deviation (SD) unit increase in sleep duration, SED the following day decreased by 0.04 SD units, while LPA and MVPA increased by 0.04 and 0.02 SD units, respectively. Sleep duration decreased by 0.02 SD units and increased by 0.04 SD units for each one SD unit increase in SED and MVPA, respectively. Sleep duration was not affected by changes in LPA. These associations differed across sex and study sites in both directions. However, since the observed effect sizes are subtle, public health initiatives should consider the clinical and practical relevance of these findings.

Human development index, children's health-related quality of life and movement behaviors: a compositional data analysis.

PURPOSE: Health-related quality of life has been related to physical activity, sedentary behavior, and sleep among children from developed nations. These relationships have rarely been assessed in developing nations, nor have behaviors been considered in their true context, as mutually exclusive and exhaustive parts of the movement behavior composition. This study aimed to explore whether children's health-related quality of life is related to their movement behavior composition and if the relationship differs according to human development index. METHODS: Children aged 9-11 years (n = 5855), from the 12-nation cross-sectional observational International Study of Childhood Obesity, Lifestyle and the Environment 2011-2013, self-reported their health-related quality of life (KIDSCREEN-10). Daily movement behaviors were from 24-h, 7-day accelerometry. Isometric log-ratio mixed-effect linear models were used to calculate estimates for difference in health-related quality of life for the reallocation of time between daily movement behaviors. RESULTS: Children from countries of higher human development index reported stronger positive relationships between health-related quality of life and moderate-to-vigorous physical activity, relative to the remaining behaviors (r = 0.75, p = 0.005) than those from lower human development index countries. In the very high human development index strata alone, health-related quality of life was significantly related to the movement behavior composition (p = 0.005), with moderate-to-vigorous physical activity (relative to remaining behaviors) being positively associated with health-related quality of life. CONCLUSIONS: The relationship between children's health-related quality of life and their movement behaviors is moderated by their country's human development index. This should be considered when 24-h movement behavior guidelines are developed for children around the world.

Sleep patterns and sugar-sweetened beverage consumption among children from around the world.

OBJECTIVE: To examine the relationships between objectively measured sleep patterns (sleep duration, sleep efficiency and bedtime) and sugar-sweetened beverage (SSB) consumption (regular soft drinks, energy drinks, sports drinks and fruit juice) among children from all inhabited continents of the world. DESIGN: Multinational, cross-sectional study. SETTING: The International Study of Childhood Obesity, Lifestyle and the Environment (ISCOLE). SUBJECTS: Children (n 5873) 9-11 years of age. RESULTS: Sleep duration was 12 min per night shorter in children who reported consuming regular soft drinks 'at least once a day' compared with those who reported consuming 'never' or 'less than once a week'. Children were more likely to sleep the recommended 9-11 h/night if they reported lower regular soft drink consumption or higher sports drinks consumption. Children who reported consuming energy drinks 'once a week or more' reported a 25-min earlier bedtime than those who reported never consuming energy drinks. Children who reported consuming sports drinks '2-4 d a week or more' also reported a 25-min earlier bedtime compared with those who reported never consuming sports drinks. The associations between sleep efficiency and SSB consumption were not significant. Similar associations between sleep patterns and SSB consumption were observed across all twelve study sites. CONCLUSIONS: Shorter sleep duration was associated with higher intake of regular soft drinks, while earlier bedtimes were associated with lower intake of regular soft drinks and higher intake of energy drinks and sports drinks in this international study of children. Future work is needed to establish causality and to investigate underlying mechanisms.

Outdoor time and dietary patterns in children around the world.

Background: Whether outdoor time is linked to dietary patterns of children has yet to be empirically tested. The objective of this study was to examine the association between outdoor time and dietary patterns of children from 12 countries around the world. Methods: This multinational, cross-sectional study included 6229 children 9-11 years of age. Children self-reported the time that they spent outside before school, after school and on weekends. A composite score was calculated to reflect overall daily outdoor time. Dietary patterns were assessed using a food frequency questionnaire, and two components were used for analysis: healthy and unhealthy dietary pattern scores. Results: On average, children spent 2.5 h outside per day. After adjusting for age, sex, parental education, moderate-to-vigorous physical activity, screen time and body mass index z-score, greater time spent outdoors was associated with healthier dietary pattern scores. No association was found between outdoor time and unhealthy dietary pattern scores. Similar associations between outdoor time and dietary patterns were observed for boys and girls and across study sites. Conclusions: Greater time spent outside was associated with a healthier dietary pattern in this international sample of children. Future research should aim to elucidate the mechanisms behind this association.

The home electronic media environment and parental safety concerns: relationships with outdoor time after school and over the weekend among 9-11 year old children.

BACKGROUND: Time spent outdoors is associated with higher physical activity levels among children, yet it may be threatened by parental safety concerns and the attraction of indoor sedentary pursuits. The purpose of this study was to explore the relationships between these factors and outdoor time during children's discretionary periods (i.e., after school and over the weekend). METHODS: Data from 462 children aged 9-11 years old were analysed using generalised linear mixed models. The odds of spending > 1 h outdoors after school, and > 2 h outdoors on a weekend were computed, according to demographic variables, screen-based behaviours, media access, and parental safety concerns. Interactions with sex and socioeconomic status (SES) were explored. RESULTS: Boys, low SES participants, and children who played on their computer for < 2 h on a school day had higher odds of spending > 1 h outside after school than girls, high SES children and those playing on a computer for ≥2 h, respectively. Counterintuitive results were found for access to media devices and crime-related safety concerns as both of these were positively associated with time spent outdoors after school. A significant interaction for traffic-related concerns*sex was found; higher road safety concerns were associated with lower odds of outdoor time after school in boys only. Age was associated with weekend outdoor time, which interacted with sex and SES; older children were more likely to spend > 2 h outside on weekends but this was only significant among girls and high SES participants. CONCLUSIONS: Our results suggest that specific groups of children are less likely to spend their free time outside, and it would seem that only prolonged recreational computer use has a negative association with children's outdoor time after school. Further research is needed to explore potential underlying mechanisms, and parental safety concerns in more detail.

Adiposity and the isotemporal substitution of physical activity, sedentary time and sleep among school-aged children: a compositional data analysis approach.

BACKGROUND: Daily activity data are by nature compositional data. Accordingly, they occupy a specific geometry with unique properties that is different to standard Euclidean geometry. This study aimed to estimate the difference in adiposity associated with isotemporal reallocation between daily activity behaviours, and to compare the findings from compositional isotemporal subsitution to those obtained from traditional isotemporal substitution. METHODS: We estimated the differences in adiposity (body fat%) associated with reallocating fixed durations of time (isotemporal substitution) between accelerometer-measured daily activity behaviours (sleep, sedentary time and light and moderate-to-vigorous physical activity (MVPA)) among 1728 children aged 9-11 years from Australia, Canada, Finland and the UK (International Study of Childhood Obesity, Lifestyle and the Environment, 2011-2013). We generated estimates from compositional isotemporal substitution models and traditional non-compositional isotemporal substitution models. RESULTS: Both compositional and traditional models estimated a positive (unfavourable) difference in body fat% when time was reallocated from MVPA to any other behaviour. Unlike traditional models, compositional models found the differences in estimated adiposity (1) were not necessarily symmetrical when an activity was being displaced, or displacing another (2) were not linearly related to the durations of time reallocated, and (3) varied depending on the starting composition. CONCLUSION: The compositional isotemporal model caters for the constrained and therefore relative nature of activity behaviour data and enables all daily behaviours to be included in a single statistical model. The traditional model treats data as real variables, thus the constrained nature of time is not accounted for, nor reflected in the findings. Findings from compositional isotemporal substitution support the importance of MVPA to children's health, and suggest that while interventions to increase MVPA may be of benefit, attention should be directed towards strategies to avoid decline in MVPA levels, particularly among already inactive children. Future applications of the compositional model can extend from pair-wise reallocations to other configurations of time-reallocation, for example, increasing MVPA at the expense of multiple other behaviours.

Health-Related Quality of Life and Lifestyle Behavior Clusters in School-Aged Children from 12 Countries.

OBJECTIVE: To evaluate the relationship between children's lifestyles and health-related quality of life and to explore whether this relationship varies among children from different world regions. STUDY DESIGN: This study used cross-sectional data from the International Study of Childhood Obesity, Lifestyle and the Environment. Children (9-11 years) were recruited from sites in 12 nations (n = 5759). Clustering input variables were 24-hour accelerometry and self-reported diet and screen time. Health-related quality of life was self-reported with KIDSCREEN-10. Cluster analyses (using compositional analysis techniques) were performed on a site-wise basis. Lifestyle behavior cluster characteristics were compared between sites. The relationship between cluster membership and health-related quality of life was assessed with the use of linear models. RESULTS: Lifestyle behavior clusters were similar across the 12 sites, with clusters commonly characterized by (1) high physical activity (actives); (2) high sedentary behavior (sitters); (3) high screen time/unhealthy eating pattern (junk-food screenies); and (4) low screen time/healthy eating pattern and moderate physical activity/sedentary behavior (all-rounders). Health-related quality of life was greatest in the all-rounders cluster. CONCLUSIONS: Children from different world regions clustered into groups of similar lifestyle behaviors. Cluster membership was related to differing health-related quality of life, with children from the all-rounders cluster consistently reporting greatest health-related quality of life at sites around the world. Findings support the importance of a healthy combination of lifestyle behaviors in childhood: low screen time, healthy eating pattern, and balanced daily activity behaviors (physical activity and sedentary behavior). TRIAL REGISTRATION: ClinicalTrials.gov: NCT01722500.