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This commentary provides a critical discussion of current research investigating the correlates and determinants of physical activity in young people, with specific focus on conceptual, theoretical and methodological issues. We draw on current child and adolescent literature and our own collective expertise to illustrate our discussion. We conclude with recommendations that will strengthen future research and help to advance the field.

Few studies have investigated physical activity changes over the transition from primary to secondary school. This study assessed change in physical activity and the psychosocial correlates across 12 months in two cohorts of adolescent girls, who were either in primary school in year 1, moving to secondary school in year 2 (Transition cohort) or an older cohort (Secondary cohort) who remained in early secondary school. Female adolescents (n = 191, 38% response rate) in South Australia self-reported physical activity and psychosocial correlates of physical activity. Changes between baseline and 12-month follow-up were assessed using paired t-tests. Multiple regression modelling identified psychosocial predictors of physical activity change. Physical activity declined in the transition but not the secondary cohort. The decline was most pronounced during school break times. Independent predictors of physical activity change were: change in enjoyment in the transition cohort, and changes in enjoyment, perceived outcomes, and friend encouragement in the secondary cohort. Transitioning from primary to secondary school is a critical period during which physical activity typically declines, particularly among females. Effective physical activity promotion in this vulnerable group will depend on a deeper understanding of the sociocultural, curricular and environmental influences on physical activity that are unique to each school context.

Physical activity is pivotal for childrentionnalth and well-being, yet participation declines across teenage years. Efforts to increase physical activity need to be strengthened to combat this,however, evidence for the design and planning of physical activity promotion in children is lacking. The aim was to identify predictors of physical activity that were relatively consistent across three different measures of physical activity, in pre- and early adolescent South Australians. This is the first study to compare correlates of physical activity across three measures of physical activity in a single sample, in this age group. Children (n = 324) aged 9-13 years and their parents were surveyed on personal, interpersonal and environmental correlates of physical activity. Child physical activity was objectively measured using pedometers (7 days). Self-reported physical activi ty was determined from organised sport participation and the Physical Activity Questionnaire for Adolescents. Regression models were used to identify consistent predictors of three physical activity measures. Consistent predictors across multiple physical activity measures were: Parent support for physical activity, having appropriate clothing for sport, enjoyment of physical activity and perceived availability of sporting clubs. These predictors identify potential avenues for directing intervention efforts to increase physical activity in early adolescents. Refereed/Peer-reviewed

ObjectiveDuring the early years, parents have a major influence on children's diets and developing food choices. We investigated parenting styles as predictors of 2–5-year-old children's diets and whether general nutrition knowledge (GNK) mediated these influences.DesignCross-sectional research. Questionnaires measured demographic and lifestyle variables, family environment, parenting styles and feeding practices, child diet and GNK. Regression models tested GNK as a mediator of relationships between parenting variables and child diet (fruit/vegetable and non-core food consumption), controlling for confounders and family environment.SettingQuestionnaires were completed by main caregivers at home.SubjectsParents of children aged 2–5 years (n269).ResultsHigher child fruit/vegetable consumption was associated with lower over-reactive parenting and restriction, higher authoritative parenting and dining together as a family; with lax parenting approaching statistical significance (P= 0·083) and 19 % of variance explained by the model. GNK was not a significant predictor. Conversely, non-core food consumption was associated with higher over-reactive and lax parenting as well as child age, increased takeaway food consumption and higher television viewing; GNK had a small effect (P= 0·043) and 28 % of variance was explained by the model. GNK was a significant mediator only for authoritative parenting on non-core food (effect = −0·005).ConclusionsThese findings highlight that young children's diets may be improved by interventions targeting a range of positive and supportive parenting practices in conjunction with nutrition knowledge education for parents of young children. Further insights will come from closer attention to the nature and role of restrictive feeding practicesv. laxness and longitudinal research.

Two studies were conducted to examine the interactions between gender, play area, motor skills and free play activity in 8-11 year old school children. In both studies, boys were more active than girls. In boys, but not in girls, energy expenditure was greater for high-skill than for low-skill children (p = 0.0002), and increased as play area increased (p = 0.01). These results suggest that motor skills and play space are important variables in determining the free play activity of boys, but not of girls. This may be related to widely different play styles among boys and girls.

Rising youth obesity is a serious public health concern. There is a widespread view that declining physical activity is contributing to this trend. A total of 929 young South Australians (age=9-15 years) were surveyed in 1985 and 2004 on usual physical activity in several contexts, including attitudes to physical activity. Eight of 10 South Australian schools participating in the 1985 Schools Health and Fitness Survey were revisited in 2004. Comparisons were made on: organised sport, active transport, physical education (PE), playground activity, vigorous physical activity (VPA), total leisure-time physical activity (LTPA), and attitudes to PE and school sport. The questionnaire and method of administration were identical in both surveys. There were no differences between surveys in club and school sport participation, walking to school, and reported enjoyment of PE and school sport. In 2004 fewer children rode to school, but PE classes were more frequent. The percentage of children who 'sit and talk' during school breaks had increased, with a decreased percentage of older girls who 'run around' during school breaks. There was a significantly higher LTPA in MET.min in 2004 for boys, which was particularly evident at higher percentiles. There were no changes in mean or distribution of LTPA for the whole sample or girls. The percentage of respondents reporting >/=3 bouts of VPA in the previous week rose from 51% (1985) to 76% (2004). There is no consistent evidence of declining physical activity among South Australian youth. It is apparent that physical activity in some contexts has declined, while in other contexts levels are the same or higher than in 1985. This underscores the complex nature of physical activity and the influences on this behaviour.

Aim This study aimed to investigate fatigue, and its correlates, in children and adolescents with physical disabilities. Method Sixty-five young people aged 8 to 17 years (35 males, 30 females; mean age 13y 2mo, SD 2y 8mo) with mild to moderate physical disabilities (Gillette Functional Assessment Questionnaire levels 7–10) were recruited. Self-reported fatigue was measured using the PedsQL Multidimensional Fatigue Scale. Physical activity was measured using 7-day hip-worn accelerometer. Associations between fatigue, physical activity, and socio-demographic characteristics were examined using analysis of covariance, with significance (α) set at 0.05. Results were compared with normative data from other paediatric populations. Results Among children with physical disabilities, fatigue was associated with being physically inactive (F-statistic=4.42, p=0.040), female (F=4.37, p=0.042), and of low socio-economic status (F=3.94, p=0.050). Fatigue was not associated with age, weight status, or functional impairment. Young people with physical disabilities experienced high levels of fatigue compared with other paediatric health populations, and comparable to the paediatric cancer population. Interpretation Fatigue is an important issue for young people with physical disabilities. Clinicians and researchers working with this group should be mindful that fatigue is likely to impact on an individual's ability to undertake new treatment regimens or interventions. Interventions aimed at reducing fatigue are warranted. Increasing physical activity might play a role in reducing fatigue.

Background: The purpose of this study was to identify the independent association of frequency of walking trips between home and school with daily physical activity in a sample of school-aged children. Methods: Participants were 109 children (mean age = 12.05 years [±0.71]) attending nine primary schools in Adelaide, South Australia. Physical activity was derived from accelerometers with total counts as the outcome variable. Transport patterns were self-reported for each of the previous five school days. Walking trips were summed for each day and across the school week. The relationship between the number of active transport journeys andindividual school day and school week physical activity was modelled separately in boys and girls using multiple linear regression. Results: Frequency of walking was positively associated with school day and school week accelerometer counts in boys, accounting for 6% and 12% of the explained variance in total counts, respectively. There were no significant associations among girls. Conclusion: Despite sex-specific differences in associations between active transport to school and total physical activity, active transport is likely to have important ancillary benefits for development of independence and physical activity habits, and should continue to be promoted. Refereed/Peer-reviewed

There is emerging evidence of socioeconomic gradients in adiposity among Australian youth. Behavioral mechanisms for these trends are unexplained.In total, 194 South Australian children (97 boys, 11.48+/-0.43 years; 97 girls, 11.60+/-0.38 years) were assessed for pubertal status, stature, weight, skinfolds and waist girth. Socioeconomic status (SES) was represented by postcode of residence (Socioeconomic Index for Areas) and parent education. Children reported moderate-to-vigorous physical activity (MVPA), TV viewing (TV) and dietary intake (daily energy intake as a ratio of predicted basal metabolic rate (DEI/BMR); and fat intake), using three x 24 h recall. Path analysis (partial least-squared method) was used to analyze the independence and interdependence of pathways linking SES, anthropometric variables and measured behaviors.SES was negatively associated with waist girth and skinfolds in girls, and waist girth in boys. In models including behavioral variables, these SES gradients in girls were largely unattenuated; accordingly, physical activity and dietary intake were not confirmed as mediators of the association of SES and girls' adiposity. In boys there was evidence that the negative relationship between SES and waist girth was mediated by fat intake.The inverse relationships between SES and girls' adiposity were unexplained by the behavioral attributes measured in this study. Mediators of SES gradients in youth adiposity remain elusive, and may require intensive methodologies to explicate.

The present study investigated the interactions between parents' and children's physical activity levels by examining whether or not parents who exercise have children who participate in sport. Of primary interest was an investigation of trends in these interactions over time. Information was collected from 10-13 y old children in 1985 (n = 2463) and then again in 1997-99 (n = 1469), about their sports participation and their perceptions of parents' exercise habits. Boys' participation in at least one sport declined from 87% in 1985 to 76% in 1997/1999 while, among girls, participation fell from 80% to 71%. According to their children's perceptions, mothers exercising regularly fell from 36% to 31% between surveys, while fathers exercising regularly fell from 39% to 32%. Interactions between parents' and children's exercise and sports behaviours were examined employing chi-square analysis techniques. Results showed gender-specific relationships for the 1985 sample, such that active fathers were associated with increased participation in sports by boys, and inactive mothers were associated with less participation in sports by girls. These interactions seemed to diminish over time. It is possible that changes in social structures during this time may be affecting familial behaviour relationships, such as the role modelling of active behaviours.

Children of low socio-economic position (SEP) consume poorer diets than those of high SEP; however, there is limited understanding of why socio-economic gradients in diet occur. Some evidence suggests that determinants of dietary intake may differ between SEP groups. The aim of the present study was to determine whether the associations between personal and environmental variables and children's fruit and vegetable intake, and healthy dietary behaviours are moderated by SEP. A total of 395 children aged 9 to 13 years and their parents were recruited in Adelaide, South Australia. Personal and environmental dietary predictors were measured using child-completed online questionnaires and telephone interviews with parents. Dietary intake was measured using an online FFQ. First, dietary predictors were identified using correlated component regression, and subsequently tested for moderation by four SEP indicators using partial least-squares structural equation modelling. Fruit and vegetable intake and healthy behaviours were predicted by self-efficacy, attitudes and a supportive home environment. For girls, only the associations of self-efficacy with healthy behaviours were moderated by occupation. For boys, income moderated the associations of fruit and vegetable intake with attitudes, and healthy behaviours with supportive home environments. Occupation and employment moderated the associations of boys' family environments and fruit intake, and attitudes with healthy behaviours. Reducing socio-economic disparities in children's healthy dietary intake may be more successfully achieved by tailoring health promotion policies and interventions according to variables that moderate the relationships between dietary intake and SEP. Refereed/Peer-reviewed

Socioeconomically disadvantaged children are at higher risk of consuming poor diets, in particular less fruits and vegetables and more non-core foods and sweetened beverages. Currently the drivers of socioeconomically related differences in children's dietary intake are not well understood. This systematic review explored whether dietary predictors vary for children of different socioeconomic circumstances. Seven databases and reference lists of included material were searched for studies investigating predictors of 9-13-year-old children's diet in relation to socioeconomic position. Individual- and population-based cross-sectional, cohort and epidemiological studies published in English and conducted in developed countries were included. Twenty-eight studies were included in this review; most were conducted in Europe (n = 12) or North America (n = 10). The most frequently used indicators of socioeconomic position were parent education and occupation. Predictors of children's dietary intake varied among children of different socioeconomic circumstances. Socioeconomic position was consistently associated with children's nutrition knowledge, parent modelling, home food availability and accessibility. Indeterminate associations with socioeconomic position were observed for parent feeding practices and food environment near school. Differences in the determinants of eating between socioeconomic groups provide a better understanding of the drivers of socioeconomic disparities in dietary intake, and how to develop targeted intervention strategies. Refereed/Peer-reviewed

Objective: This study aimed to explore sleep duration in young Australians on different types of days across weight classes. Methods: Use of time and anthropometric data were collected on 8,866 nights from 3,884 9–18 year old Australians. The association between sleep duration and weight status was examined using factorial ANOVA for four day types: S-S (to bed and waking on school days); S-NS (to bed on school day and waking on non-school day); NS-NS (to bed and waking on non-school days); NS-S (to bed on non-school day and waking on school day). Results: Sleep duration varied with weight status when all day types were considered together (p=0.0012). Obese adolescents slept less than normal and underweight adolescents. However, the relationship varied for different day types; with the strongest relationship for NS-S days (on which obese children slept 65 min less than very underweight children, p

Background: The after-school period is potentially a "critical window" for promoting physical activity in children. The purpose of this study was to qualitatively explore children's perceptions of the factors influencing their engagement in physical activity during the after-school period as the first phase in the development of a questionnaire. Conclusions: In this study, hearing children's voices allowed the emergence of factors which may not be exposed using existing surveys. These findings are grounded in children's perceptions and therefore serve as a valuable contribution to the existing literature, potentially leading to improved intervention and questionnaire design. Methods: Fifty-four South Australian children age 10-13 years participated in same gender focus groups. Transcripts, field notes, and activity documents were analyzed using content analysis. Through an inductive thematic approach, data were coded and categorized into perceived barriers and facilitators according to a social ecological model. Results: Children identified a number of factors, including safety in the neighborhood and home settings, distance to and from places, weather, availability of time, perceived competence, enjoyment of physical activity, peer influence, and parent influence. New insights into bullying and teasing by peers and fear of dangerous animals and objects were revealed by the children. Refereed/Peer-reviewed

Objectives: The eat well be active Community Programs (ewba) aimed to prevent obesity among children aged 0–18 years in two Australian communities from 2006 to 2010. Methods: ewba was a multi-strategy intervention in children's settings. The evaluation was quasi-experimental, including a before and after survey with intervention (INT) and non-randomised comparison (COMP) communities. Outcome measures included BMI-z score (zBMI) and overweight/obesity prevalence in children aged 4-5 years; and zBMI, waist circumference (WC) z-score and overweight/ obesity prevalence in children aged 10-12 years. Results: After 3 years, among the 4–5 years old, mean zBMI was significantly lower in both INT (−0.20, p < 0.05) and COMP (−0.15, p < 0.05), however, changes were not significantly different between INT and COMP. There was a larger reduction in overweight/obesity prevalence in INT (−6.3 %) compared to COMP (−3.7 %) (p < 0.05, χ 2 test). In the 10–12 years old, mean zBMI did not change significantly in INT or COMP. There was a significant reduction in WC z-score in INT (−0.17, p < 0.05) but not in COMP (−0.10, p = NS), although not significantly different between INT and COMP (p = 0.092). Conclusions: These findings suggest that the ewba community intervention had a moderate impact, showing modest improvements in weight status at 3-year follow-up. Refereed/Peer-reviewed

Objectives: To explore children's perceptions of the factors influencing their engagement in physical activity during the "critical" lunchtime period, using a social-ecological framework. Design: This study was an in-depth descriptive qualitative design. Methods: Fifty-four South Australian children aged 10-13 years participated in same-gender focus groups. Transcripts, field notes and activity documents were analysed using content analysis. Using an inductive thematic approach, data were coded and categorised into perceived barriers and facilitators according to a social-ecological model. Results: Children identified a range of environmental, social and intrapersonal barriers and facilitators. Bullying/teasing, the school uniform and school rules were exposed as explicit barriers to lunchtime play. Other important barriers included lack of access to, and poor suitability of, space, lack of access to programs/facilities and equipment, and lack of peer and teacher support. Perceived facilitators of lunchtime physical activity centred on access to equipment, enjoyment, motivation to improve skills, and peer support and acceptance. The freedom to make up or modify rules for games was also perceived to be a facilitator of lunchtime play. Conclusions: Communicating with children has been an effective approach in uncovering perceived barriers and facilitators to lunchtime play that may not have been previously considered in the quantitative correlate literature. Lunchtime interventions targeting children's physical activity should focus on addressing the barriers perceived to be important to lunchtime play. Language: en

1.Discipline of Paediatrics, University of Adelaide, Adelaide, 5000, Australia2.Child and Adolescent Respiratory and Sleep Health Centre (CARSHC), Women’s and Children’s Hospital, North Adelaide, 5006, Australia3.Nutritional Physiology Research Centre, University of South Australia, Adelaide, 5000, Australia

Objective: To describe trends in health attitudes and self-perceptions among school-age South Australians between 1985 and 2004. Methods: The questionnaire from the 1985 Australian Schools Health and Fitness Survey was administered during 2004 in those South Australian schools that participated in the 1985 survey. Using chi square, responses were compared for 10–15 year-olds (1985, n=398; 2004, n=467) on attitudes to: visiting the doctor and dentist, smoking, sleep, diet, exercise, stress, having friends, and knowledge about fitness and health. Additionally, self-perceptions of health and fitness were compared. Results: Among boys and girls between 1985 and 2004, there were significant declines in the perceived importance of regularly visiting the dentist and doctor, but improved attitudes to being a non-smoker. Among boys, the perceived importance of sleep and diet declined between surveys. A smaller percentage of boys and girls in the latter survey perceived their current health status as ‘good’. In the lower SES sample, the percentage of girls rating healthy diet as ‘very important’ was lower in 2004. Conclusions: There have been general declines in perceived importance of many health-related behaviours among South Australian youth between 1985–2004. In contrast, the perceived importance of not smoking was higher in 2004 than 1985. Implications: The relative success of anti-smoking campaigns targeting youth suggests that health education must be accompanied by broader environmental support in order to effect positive behavioural change.

This study examined whether active commuting to and from school was associated with more frequent walking and cycling to other neighborhood destinations. Parents reported on free-time physical activity and frequency of active commuting among 1,643 South Australians (9–15 years), as well as their perceptions of risk associated with active commuting in the neighborhood. Groups were formed on the basis of active and motorized transport to and from school and compared on the frequency of walking and cycling to other neighborhood destinations. Those who actively commuted between home and school were approximately 30% more likely to actively commute to other neighborhood destinations, independent of age, free-time physical activity, and neighborhood risk. Active commuting to and from school is part of a broader habit of walking and cycling in the neighborhood among school age South Australians. The advantages of promoting active transport between home and school might extend beyond the energy expenditure of that journey alone.

It is not clear whether the global increase in weight problems in children is the result of excessive energy intake or decreasing energy expenditure. Methodological limitations have made it difficult to analyse. There is evidence that at least part of the problem may lie with increasing energy consumption, but it is important to examine the other side of the energy equation also. However, it is not possible to conclusively describe physical activity trends because of the absence of suitable baseline data. One solution is to summate all available evidence in as many areas of daily activities as possible and then draw tentative conclusions. This review summarises available trend data on direct representations of physical activity in a range of contexts, together with indirect measures such as sedentariness, fitness, and attitudes. The conclusions drawn are: physical activity in clearly defined contexts such as active transport, school physical education, and organised sports is declining in many countries; young people would like to be active but are often constrained by external factors such as school policy or curricula, parental rules in relation to safety and convenience, and physical environmental factors.

Assessment of correlates of physical activity occurring at different times of the day, locations and contexts, is imperative to understanding children’s physical activity behaviour. The purpose of this review was to identify the correlates of children’s physical activity (aged 8–14 years) occurring during the school break time and after-school periods. A review was conducted of the peer-reviewed literature, published between 1990 and January 2011. A total of 22 studies (12 school break time studies, 10 after-school studies) were included in the review. Across the 22 studies, 17 studies were cross-sectional and five studies were interventions. In the school break time studies, 39 potential correlates were identified, of which gender and age were consistently associated with school break time physical activity in two or more studies, and family affluence, access to a gym, access to four or more physical activity programs and the condition of a playing field were all associated with school break time physical activity in only one study. Access to loose and fixed equipment, playground markings, size of and access to play space and the length of school break time were all positively associated with changes in school break time physical activity in intervention studies. Thirty-six potential correlates of after-school physical activity were identified. Gender (with boys more active), younger age, lower body mass index (for females), lower TV viewing/playing video games, and greater access to facilities were associated with higher levels of after-school physical activity in two or more studies. Parent supervision was negatively associated with females’ after-school physical activity in one study. This review has revealed a relatively small number of studies investigating the school break time and after-school periods in the specified age range and only a few correlates have demonstrated a consistent association with physical activity. This highlights the infancy of this area and a need for further investigation into time-specific physical activity behaviour so that interventions designed for these specific periods can target the important correlates. Refereed/Peer-reviewed

Excessive 'screen time' has been associated with a range of psychosocial disturbances and increasing pediatric obesity. This study describes the magnitude, distribution, composition and time-distribution of children's screen use; examines correlates of screen use; and characterises 'extreme' screen users (top quartile).1,039 South Australian children aged 10-13 years old completed a multimedia 24-hour activity recall diary on 2-4 occasions in 2002, including at least one school day and one non-school day.The median screen time was 229 minutes.d(-1). This was higher in boys (264 vs. 196 minutes; p0.001) and on non-school days (260 vs. 190 minutes; p0.001), increased with age (p=0.003), and decreased with socio-economic status (SES; p=0.003). Television consumed 73% of all screen time, video games 19%, non-game computer use 6%, and cinema 2%. The top quartile of screen users were more likely to be boys (OR=3.8), have low physical activity (OR=4.3), spend25% of screen time playing video games (OR=1.8), sleep less, and be of lower SES.Interventions to reduce screen time should target inactive, low-SES boys, encourage earlier bedtimes, and limit video game use.

Background: To frame interventions, it is useful to understand context- and time-specific correlates of children's physical activity. To do this, we need accurate assessment of these correlates. There are currently no measures that assess correlates at all levels of the social ecological model, contain items that are specifically worded for the lunchtime and/or after-school time periods, and assess correlates that have been conceptualised and defined by children. The aim of this study was to develop and evaluate the psychometric properties of the lunchtime and after-school Youth Physical Activity Survey for Specific Settings (Y-PASS) questionnaires. Methods: The Y-PASS questionnaire was administered to 264 South Australian children (146 boys, 118 girls; mean age = 11.7 +/- 0.93 years). Factorial structure and internal consistency of the intrapersonal, sociocultural and physical environmental/policy lunchtime and after-school subscales were examined through an exploratory factor analysis. The test-retest reliability of the Y-PASS subscales was assessed over a one-week period on a subsample of children (lunchtime Y-PASS: n = 12 boys, 12 girls, mean age of 11.6 +/- 0.8 years; after-school Y-PASS: n = 9 boys, 13 girls; mean age = 11.4 +/- 0.9 years). Results: For the lunchtime Y-PASS, three factors were identified under each of the intrapersonal, sociocultural and physical environmental/policy subscales. For the after-school Y-PASS, six factors were identified in the intrapersonal subscale, four factors in the sociocultural subscale and seven factors in the physical environmental/policy subscale. Following item reduction, all subscales demonstrated acceptable internal consistency (Cronbach alpha = 0.78 - 0.85), except for the lunchtime sociocultural subscale (Cronbach alpha = 0.55). The factors and items demonstrated fair to very high test-retest reliability (ICC = 0.26 - 0.93). Conclusion: The preliminary reliability and factorial structure evidence suggests the Y-PASS correlate questionnaires are robust tools for measuring correlates of context-specific physical activity in children. The multi-dimensional factor structure provides justification for exploring physical activity correlates from a social ecological perspective and demonstrates the importance of developing items that are context specific. Further development and refinement of the Y-PASS questionnaires is recommended, including a confirmatory factor analysis and exploring the inclusion of additional items. Refereed/Peer-reviewed

This study examined the convergent validity of a computerized use of time diary (MARCA) relative to pedometry. Participants aged 9–16 years wore a pedometer and completed the MARCA. Comparing pedometer data and self-report data collected for the same day (n = 297 participants), the correlation (Spearman’s rho) with PAL was 0.54 and with MVPA was 0.50. Comparing mean daily step counts over 6–7 days with averaged self-report data collected on different days (n = 1713 participants) Spearman’s rho for PAL was 0.45 and for MVPA was 0.44. Thus, the MARCA showed validity similar or superior to most self-report instruments for young people.