A systematic review of the prevalence of sedentary behavior during the after-school period among children aged 5-18 years

BACKGROUND: Independent of physical activity levels, youth sedentary behaviors (SB) have negative health outcomes. SB prevalence estimates during discretionary periods of the day (e.g., after-school), inform the need for targeted period-specific interventions. This systematic review aimed to determine children's and adolescents' SB prevalence during the after-school period.

METHODS: A computerized search was conducted in October 2015 (analysed November 2015). Inclusion criteria were: published in a peer-reviewed English journal; participants aged 5-18 years; measured overall after-school sedentary time (ST) objectively, and/or specific after-school SBs (e.g., TV viewing) objectively or subjectively; and provided the percentage of the after-school period spent in ST/SB or duration of behavior and period to calculate this. Where possible, findings were analyzed by location (e.g., after-school care/'other' locations). The PRISMA guidelines were followed.

RESULTS: Twenty-nine studies were included: 24 included children (≤12 years), four assessed adolescents (>12 years) and one included both; 20 assessed ST and nine assessed SB. On average, children spent 41% and 51% of the after-school period in ST when at after-school care and other locations respectively. Adolescents spent 57% of the after-school period in ST. SBs that children and adolescents perform include: TV viewing (20% of the period), non-screen based SB (including homework; 20%), screen-based SB (including TV viewing; 18%), homework/academics (13%), motorised transport (12%), social SB (9%), and screen-based SB (excluding TV viewing; 6%).

CONCLUSION: Children spent up to half of the after-school period in ST and this is higher among adolescents. A variety of screen- and non-screen based SBs are performed after school, providing key targets for interventions.

Validation of thigh-based accelerometer estimates of postural allocation in 5-12 year-olds

OBJECTIVES: To validate activPAL3™ (AP3) for classifying postural allocation, estimating time spent in postures and examining the number of breaks in sedentary behaviour (SB) in 5-12 year-olds. DESIGN: Laboratory-based validation study. METHODS: Fifty-seven children completed 15 sedentary, light- and moderate-to-vigorous intensity activities. Direct observation (DO) was used as the criterion measure. The accuracy of AP3 was examined using a confusion matrix, equivalence testing, Bland-Altman procedures and a paired t-test for 5-8y and 9-12y. RESULTS: Sensitivity of AP3 was 86.8%, 82.5% and 85.3% for sitting/lying, standing, and stepping, respectively, in 5-8y and 95.3%, 81.5% and 85.1%, respectively, in 9-12y. Time estimates of AP3 were equivalent to DO for sitting/lying in 9-12y and stepping in all ages, but not for sitting/lying in 5-12y and standing in all ages. Underestimation of sitting/lying time was smaller in 9-12y (1.4%, limits of agreement [LoA]: -13.8 to 11.1%) compared to 5-8y (12.6%, LoA: -39.8 to 14.7%). Underestimation for stepping time was small (5-8y: 6.5%, LoA: -18.3 to 5.3%; 9-12y: 7.6%, LoA: -16.8 to 1.6%). Considerable overestimation was found for standing (5-8y: 36.8%, LoA: -16.3 to 89.8%; 9-12y: 19.3%, LoA: -1.6 to 36.9%). SB breaks were significantly overestimated (5-8y: 53.2%, 9-12y: 28.3%, p<0.001). CONCLUSIONS: AP3 showed acceptable accuracy for classifying postures, however estimates of time spent standing were consistently overestimated and individual error was considerable. Estimates of sitting/lying were more accurate for 9-12y. Stepping time was accurately estimated for all ages. SB breaks were significantly overestimated, although the absolute difference was larger in 5-8y. Surveillance applications of AP3 would be acceptable, however, individual level applications might be less accurate.

The dietary, physical activity and sedentary behaviours of Victorian regional secondary school students

The aim of this study was to investigate the dietary, physical activity and sedentary behaviours of adolescents from four secondary schools in Warrnambool, regional Victoria. In 2004, a random sample of students (n=712), stratified by school year level, was generated from school enrolment databases and 443 students completed a lifestyle questionnaire. Twenty per cent of students were physically active for 60 minutes or more per day; 28 per cent used electronic media in free time for a maximum of two hours per day. Only seven per cent of students met these two Australian physical activity recommendations. Fruit, vegetables and dairy products were consumed every day by 39 per cent, 40 per cent and 71 per cent of students respectively; three serves per day of each of these foods are recommended for Australian adolescents. Compared with boys, girls were less physically active (p<0.001), consumed more fruit (p=0.011) and vegetables (p<0.001), but fewer dairy products (p<0.024). Seventeen per cent of students were overweight or obese; these students were less physically active than normal weight peers (p<0.018). The dietary, physical and sedentary behaviours of regional Victorian secondary school students in this study were inadequate when compared with Australian recommendations. Dietary and physical activity habits are still evolving in adolescence and unhealthy habits can still be changed.

Associations of TV viewing and physical activity with the metabolic syndrome in Australian adults

Aims/hypothesis We analysed a sample of Australian adults to determine the strength of associations of TV viewing and participation in physical activity with the metabolic syndrome.

Methods This population-based cross-sectional study included 6,241 adults aged ge35 years who were free from diagnosed diabetes mellitus and self-reported ischaemic disease and were not taking lipid-lowering or antihypertensive drugs. The metabolic syndrome was defined according to the 1999 World Health Organization criteria. Participants self-reported TV viewing time and physical activity time for the previous week.

Results The adjusted odds ratio of having the metabolic syndrome was 2.07 (95% CI 1.49–2.88) in women and 1.48 (95% CI 0.95–2.31) in men who watched TV for >14 h per week compared with those who watched le7.0 h per week. Compared with those who were less active (<2.5 h per week), the odds ratio for the metabolic syndrome was 0.72 (95% CI 0.58–0.90) in men and 0.53 (95% CI 0.38–0.74) in women who were active (ge2.5 h per week). Longer TV viewing (>14 h per week) was associated with an increased risk of insulin resistance, obesity and dyslipidaemia in both men and women. A total physical activity time of ge2.5 h per week was associated with a reduced prevalence of both insulin resistance and dyslipidaemia in both sexes and reduced prevalence of both obesity and hypertension in women.

Conclusions/interpretation Increased TV viewing time was associated with an increased prevalence of the metabolic syndrome, while physical activity was associated with a reduced prevalence. Population strategies addressing the metabolic syndrome should focus on reducing sedentary behaviours such as TV viewing, as well as increasing physical activity.

Can Australain general practitioners tackle chidhood overweight/obesity? Methods and processes from the LEAP (live, eat, and play) randomized controlled trial

Background: General practitioners (GPs) could make an important contribution to management of childhood overweight. However, there are no efficacy data to support this, and the feasibility of this approach is unknown.

Objectives: To determine if GPs and families can be recruited to a randomized controlled trial (RCT), and if GPs can successfully deliver an intervention to families with overweight/obese 5- to 9-year-old children.

Methods: A convenience sample of 34 GPs from 29 family medical practices attended training sessions on management of childhood overweight. Practice staff trained in child anthropometry conducted a cross-sectional body mass index (BMI) survey of 5- to 9-year-old children attending these practices. The intervention focused on achievable goals in nutrition, physical activity and sedentary behaviour, and was delivered in four solution-focused behaviour change consultations over 12 weeks.

Results: General practitioners were recruited from across the sociodemographic spectrum. All attended at least two of the three education sessions and were retained throughout the trial. Practice staff weighed and measured 2112 children in the BMI survey, of whom 28% were overweight/obese (17.5% overweight, 10.5% obese), with children drawn from all sociodemographic quintiles. Of the eligible overweight/obese children, 163 (40%) were recruited and retained in the LEAP RCT; 96% of intervention families attended at least their first consultation.

Conclusions: Many families are willing to tackle childhood overweight with their GP. In addition, GPs and families can participate successfully in the careful trials that are needed to determine whether an individualized, family-based primary care approach is beneficial, harmful or ineffective.

Acute effects of advertisements on children's choices, preferences, and ratings of liking for physical activities and sedentary behaviours : a randomised controlled pilot study

The acute decision prompting effects of social marketing via television (TV) advertisements promoting physical activity to children are unknown. This pilot study aimed to determine the acute effects of an Australian government-sponsored TV advertisement (called ‘Get Moving’), promoting more physical activity and less sedentary behaviour, on children's choices, preferences, and ratings of liking for physical activities and sedentary behaviours. Thirty-one children aged 10–12 years were recruited from a single public school, and randomised to one of two treatment groups or two control groups (Solomon four-group design). Treatment participants watched an episode of The Simpsons® embedded every 10 min with three 30 s Get Moving advertisements plus standard advertisements. Control participants watched the same episode plus standard advertisements, but without the Get Moving advertisements. The following dependent variables were assessed immediately before and/or after exposure: activity preference (participants selected either verbally or by pointing to one of eight picture cards depicting four physical activities and four sedentary behaviours); ratings of liking (participants rated how much they liked or disliked each of these activities/behaviours either verbally or by pointing to one of nine values with an adjacent smile or frown on a Likert-type scale); and time spent in physical activities was assessed by direct observation during a 10 min free-time session. No significant effects or trends were seen for any of the dependent variables. Further research is needed to determine whether different content and/or higher doses of exposure to physical activity promoting advertisements are needed to influence children's activity choices.

Joint associations of multiple leisure-time sedentary behaviours and physical activity with obesity in Australian adults

Background
Television viewing and physical inactivity are independently associated with risk of obesity. However, how the combination of multiple leisure-time sedentary behaviours (LTSB) and physical activity (LTPA) may contribute to the risk of obesity is not well understood. We examined the joint associations of multiple sedentary behaviours and physical activity with the odds of being overweight or obese.

Methods
A mail survey collected the following data from adults living in Adelaide, Australia (n = 2210): self-reported height, weight, six LTSB, LTPA and sociodemographic variables. Participants were categorised into four groups according to their level of LTSB (dichotomised into low and high levels around the median) and LTPA (sufficient: ≥ 2.5 hr/wk; insufficient: < 2.5 hr/wk). Logistic regression analysis examined the odds of being overweight or obese (body mass index ≥ 25 kg/m2) by the combined categories.

Results
The odds of being overweight or obese relative to the reference category (low sedentary behaviour time and sufficient physical activity) were: 1.54 (95% confidence interval [CI]: 1.20–1.98) for the combination of low sedentary behaviour time and insufficient physical activity; 1.55 (95% CI: 1.20–2.02) for the combination of high sedentary behaviour time and sufficient physical activity; and 2.26 (95% CI: 1.75–2.92) for the combination of high sedentary behaviour time and insufficient physical activity.

Conclusion
Those who spent more time in sedentary behaviours (but were sufficiently physically active) and those who were insufficiently active (but spent less time in sedentary behaviour) had a similar risk of being overweight or obese. Reducing leisure-time sedentary behaviours may be as important as increasing leisure-time physical activity as a strategy to fight against obesity in adults.

Family physical activity and sedentary environments and weight change in children

Objective. To examine associations between family physical activity and sedentary environment and changes in body mass index (BMI) z-scores among 10-12-year-old children over three years.
Method. Design. Longitudinal (three-year follow-up). Subjects. In total, 152 boys and 192 girls aged 10-12 years at baseline.
Measurements. Measured height and weight at baseline and follow-up (weight status, BMI z-scores); aspects of the family physical activity and sedentary environment (parental and sibling modelling, reinforcement, social support, family-related barriers, rules/restrictions, home physical environment) measured with a questionnaire completed by parents at baseline.
Results. At baseline, 29.6% of boys and 21.9% of girls were overweight or obese, and mean (standard deviation, SD) BMI z-scores were 0.44 (0.99) and 0.28 (0.89), respectively. There was a significant change in BMI z-score among girls (mean change=0.19, SD=0.55, p<0.001), but not boys. Among boys, the number of items at home able to be used for sedentary behaviour (B=0.11, p=0.037) was associated with relatively greater increases in BMI z-score. Among girls, sibling engagement in physical activity at least three times/wk (B=-0.17, p=0.010) and the number of physical activity equipment items at home (B=-0.05, p=0.018) were associated with relatively greater decreases in BMI z-score.
Conclusion. Sibling physical activity and environmental stimuli for sedentary behaviours and physical activity within the home may be important targets for prevention of weight gain during the transition from childhood to adolescence.

Sedentary lifestyle as a risk factor for low back pain : a systematic review

Objectives To review systematically studies examining the association between sedentary lifestyle and low back pain (LBP) using a comprehensive definition of sedentary behaviour including prolonged sitting both at work and during leisure time.

Methods Journal articles published between 1998 and 2006 were obtained by searching computerized bibliographical databases. Quality assessment of studies employing a cohort or case–control design was performed to assess the strength of the evidence.

Results Using pre-determined keywords, we identified 1,778 titles of which 1,391 were considered irrelevant. Then, 20 of the remaining 387 publications were scrutinized for full review after an examination of all the 387 abstracts. Finally, 15 studies (10 prospective cohorts and 5 case–controls) were included in the methodological quality assessment, of which 8 (6 cohorts and 2 case–controls; 53%) were classified as high-quality studies. One high-quality cohort study reported a positive association, between LBP and sitting at work only; all other studies reported no significant associations. Hence, there was limited evidence to demonstrate that sedentary behaviour is a risk factor for developing LBP.

Conclusions The present review confirms that sedentary lifestyle by itself is not associated with LBP.

Residential density and adolescent overweight in a rapidly urbanising region of mainland China

Objective This study investigated the association of residential density with overweight among adolescents in an urban area of China.

Methods Using multistage proportional sampling methods, a population-based cross-sectional study was conducted in Nanjing between September and November 2004 (n=2375; mean age=13.9+/-1.0 years old; 46.2% boys; survey response rate=89.3%). Body mass index was calculated from self-reported body weight and height. Overweight, the main outcome variable, was defined as a BMI >/=85 percentile value for age- and gender-specific reference data according to the recommendation for Chinese adolescents. The primary explanatory variable was the residential density of the urban districts. Mixed-effects logistic regression models were used for the analysis.

Results Students in the higher and middle tertiles of residential density had a 2.17-fold (95% CI 1.41 to 3.33) and 1.89-fold (95% CI 1.22 to 2.92) higher likelihood of being overweight, respectively, compared with those in the lower tertile. The associations were slightly attenuated but still significant after adjusting for time spent in recreational physical activity and sedentary behaviour (viewing TV and sitting for academic study).

Conclusions Residential density was positively associated with overweight among urban Chinese adolescents. Our findings warrant further research examining attributes of urban environments associated with adolescents' obesity in China and potential mechanisms between them.

Correlates of sedentary behaviours in preschool children : a review

Background: Sedentary behaviour has been linked with a number of health outcomes. Preschool-aged children spend significant proportions of their day engaged in sedentary behaviours. Research into the correlates of sedentary behaviours in the preschool population is an emerging field, with most research being published since 2002. Reviews on correlates of sedentary behaviours which include preschool children have previously been published; however, none have reported results specific to the preschool population. This paper reviews articles reporting on correlates of sedentary behaviour in preschool children published between 1993 and 2009.
Methods: A literature search was undertaken to identify articles which examined correlates of sedentary behaviours in preschool children. Articles were retrieved and evaluated in 2008 and 2009.
Results: Twenty-nine studies were identified which met the inclusion criteria. From those studies, 63 potential correlates were identified. Television viewing was the most commonly examined sedentary behaviour. Findings from the review suggest that child’s sex was not associated with television viewing and had an indeterminate association with sedentary behaviour as measured by accelerometry. Age, body mass index, parental education and race had an indeterminate association with television viewing, and outdoor playtime had no association with television viewing. The remaining 57 potential correlates had been investigated too infrequently to be able to draw robust conclusions about associations.
Conclusions: The correlates of preschool children’s sedentary behaviours are multi-dimensional and not well established. Further research is required to provide a more comprehensive understanding of the influences on preschool children’s sedentary behaviours to better inform the development of interventions.

Obesity prevention in the family day care setting : impact of the romp & chomp intervention on opportunities for children's physical activity and healthy eating

Background The Romp & Chomp intervention reduced the prevalence of overweight/obesity in pre-school children in Geelong, Victoria, Australia through an intervention promoting healthy eating and active play in early childhood settings. This study aims to determine if the intervention successfully created more health promoting family day care (FDC) environments.
Methods The evaluation had a cross-sectional, quasi-experimental design with the intervention FDC service in Geelong and a comparison sample from 17 FDC services across Victoria. A 45-item questionnaire capturing nutrition- and physical activity-related aspects of the policy, socio-cultural and physical environments of the FDC service was completed by FDC care providers (in 2008) in the intervention (n = 28) and comparison (n = 223) samples.
Results Select results showed intervention children spent less time in screen-based activities (P = 0.03), organized active play (P < 0.001) and free inside play (P = 0.03) than comparison children. There were more rules related to healthy eating (P < 0.001), more care provider practices that supported children’s positive meal experiences (P < 0.001), fewer unhealthy food items allowed (P = 0.05), higher odds of staff being trained in nutrition (P = 0.04) and physical activity (P < 0.001), lower odds of having set minimum times for outside (P < 0.001) and organized (P = 0.01) active play, and of rewarding children with food (P < 0.001).
Conclusions Romp & Chomp improved the FDC service to one that discourages sedentary behaviours and promotes opportunities for children to eat nutritious foods. Ongoing investment to increase children’s physical activity within the setting and improving the capacity and health literacy of care providers is required to extend and sustain the improvements.