Is television viewing a suitable marker of sedentary behavior in young people?

Are context-specific measures of parental-reported physical activity and sedentary behaviour associated with accelerometer data in 2-9-year-old European children?

OBJECTIVE

The aim of the present study was to investigate if context-specific measures of parental-reported physical activity and sedentary behaviour are associated with objectively measured physical activity and sedentary time in children.

DESIGN

Cross-sectional study.

SETTING

Seven European countries taking part in the IDEFICS (Identification and Prevention of Dietary- and Lifestyle-induced Health Effects in Children and Infants) study.

SUBJECTS

Data were analysed from 2-9-year-old children (n 5982) who provided both parental-reported and accelerometer-derived physical activity/sedentary behaviour measures. Parents reported their children's daily screen-time, weekly sports participation and daily outdoor playtime by means of the Outdoor Playtime Checklist (OPC) and Outdoor Playtime Recall Questions (OPRQ).

RESULTS

Sports participation, OPC- and OPRQ-derived outdoor play were positively associated with accelerometer-derived physical activity. Television viewing and computer use were positively associated with accelerometer-derived sedentary time. All parental-reported measures that were significantly associated with accelerometer outcomes explained only a minor part of the variance in accelerometer-derived physical activity or sedentary time.

CONCLUSIONS

Parental-reported measures of physical activity and sedentary behaviour are not useful as a proxy for 2-9-year-old children's physical activity and sedentary time. Findings do not preclude the use of context-specific measures but imply that conclusions should be limited to the context-specific behaviours that are actually measured. Depending on the aim of the study, future research should carefully consider the choice of measurements, including the use of subjective or objective measures of the behaviour of interest or a combination of both.

Trends in television time, non-gaming PC use and moderate-to-vigorous physical activity among German adolescents 2002-2010

Background

Studies in youth highlight that moderate-to-vigorous physical activity (MVPA) and screen-time behaviours such as television viewing and PC use are associated with a range of health outcomes. However, little is known about recent trends in these behaviours in adolescents. This paper presents time trends in German adolescents’ television time, non-gaming PC use as well as MVPA from 2002 to 2010.

Methods

Data were derived from the cross-sectional German Health Behaviour in School-aged Children (HBSC) study in 2002, 2006 and 2010. Analyses were based on 16,918 11-to 15-year olds boys (49.1%) and girls. Outcome variables were time spent in TV viewing and using a PC (weekday and weekend day) as well as the number of days achieving 60 minutes of MVPA. Changes in both screen-time behaviours and MVPA over time were analysed using sex-specific linear regression, controlling for age and family affluence.

Results

TV viewing on weekdays, but not at weekends, declined steadily over time with a difference between 2002 and 2010 of 12.4 min/day in girls and 18.3 min/day in boys (p for trend < .01). We found a strong increase in PC use for non-gaming purposes over time for girls only, with a difference between 2002 and 2010 of 54.1 min/weekday and 68.8 min/weekend day (p < .001). For MVPA we found a slight statistically significant increase in terms of meeting PA guidelines as well as days/week in MVPA for boys and girls (p < .001). In 2010 14.0% of girls and 19.9% of boys met PA guideline.

Conclusion

Although MVPA increased from 2002 to 2010 in German adolescents, the time spent in MVPA was still low. Despite the observed decrease in TV viewing, there was no overall decline in the observed screen-based behaviours, especially for girls. This is mainly due to a marked increase in use of a PC for chatting on-line, internet, emailing, homework etc. among girls during the last ten years which outweighs the corresponding decrease in TV viewing. The findings highlight a need for strategies and interventions aimed at reducing screen-time behaviours and promoting MVPA.

Children's sedentary behaviour: descriptive epidemiology and associations with objectively-measured sedentary time

BACKGROUND

Little is known regarding the patterning and socio-demographic distribution of multiple sedentary behaviours in children. The aims of this study were to: 1) describe the leisure-time sedentary behaviour of 9-10 year old British children, and 2) establish associations with objectively-measured sedentary time.

METHODS

Cross-sectional analysis in the SPEEDY study (Sport, Physical activity and Eating behaviour: Environmental Determinants in Young people) (N=1513, 44.3% boys). Twelve leisure-time sedentary behaviours were assessed by questionnaire. Objectively-measured leisure-time sedentary time (Actigraph GT1M, <100 counts/minute) was assessed over 7 days. Differences by sex and socioeconomic status (SES) in self-reported sedentary behaviours were tested using Kruskal-Wallis tests. The association between objectively-measured sedentary time and the separate sedentary behaviours (continuous (minutes) and categorised into 'none' 'low' or 'high' participation) was assessed using multi-level linear regression.

RESULTS

Sex differences were observed for time spent in most sedentary behaviours (all p ≤ 0.02), except computer use. Girls spent more time in combined non-screen sedentary behaviour (median, interquartile range: girls: 770.0 minutes, 390.0-1230.0; boys: 725.0, 365.0 - 1182.5; p = 0.003), whereas boys spent more time in screen-based behaviours (girls: 540.0, 273.0 - 1050.0; boys: 885.0, 502.5 - 1665.0; p < 0.001). Time spent in five non-screen behaviours differed by SES, with higher values in those of higher SES (all p ≤ 0.001). Regression analyses with continuous exposures indicated that reading (β = 0.1, p < 0.001) and watching television (β = 0.04, p < 0.01) were positively associated with objectively-measured sedentary time, whilst playing board games (β = -0.12, p < 0.05) was negatively associated. Analysed in categorical form, sitting and talking (vs. none: 'low' β = 26.1,ns; 'high' 30.9, p < 0.05), playing video games (vs. none: 'low' β = 49.1, p < 0.01; 'high' 60.2, p < 0.01) and watching television (vs. lowest tertile: middle β = 22.2,ns; highest β = 31.9, p < 0.05) were positively associated with objectively-measured sedentary time whereas talking on the phone (vs. none: 'low' β = -38.5, p < 0.01; 'high' -60.2, p < 0.01) and using a computer/internet (vs. none: 'low' β = -30.7, p < 0.05; 'high' -4.2,ns) were negatively associated.

CONCLUSIONS

Boys and girls and children of different socioeconomic backgrounds engage in different leisure-time sedentary behaviours. Whilst a number of behaviours may be predictive of total sedentary time, collectively they explain little overall variance. Future studies should consider a wide range of sedentary behaviours and incorporate objective measures to quantify sedentary time where possible.

Determinants of change in children's sedentary time

BACKGROUND

Understanding the determinants of sedentary time during childhood contributes to the development of effective intervention programmes.

PURPOSE

To examine family and home-environmental determinants of 1-year change in objectively measured sedentary time after-school and at the weekend.

METHODS

Participants wore accelerometers at baseline and 1 year later. Longitudinal data for after-school and weekend analyses were available for 854 (41.5%male, mean ± SD age 10.2 ± 0.3 years) and 718 (41.8%male, age 10.2 ± 0.3 years) participants. Information on 26 candidate determinants, including socioeconomic status (SES), availability of electronic media and parental rules for sedentary behaviours was self-reported by children or their parents at baseline. Change in the proportion of registered time spent sedentary was used as the outcome variable in multi-level linear regression models, adjusted for age, sex, body mass index and baseline sedentary time. Simple and multiple models were run and interactions with sex explored.

RESULTS

Children from higher socioeconomic status families exhibited greater increases in after-school (beta; 95% CI for change in % time spent sedentary 1.02; 0.37, 1.66) and weekend (1.42; 0.65, 2.18) sedentary time. Smaller increases in after-school sedentary time were observed in children with more siblings (-1.00; -1.69, -0.30), greater availability of electronic media (-0.81; -1.29, -0.33) and, for boys, more frequent family visits to the park (-1.89; -3.28, -0.51) and family participation in sport (-1.28; -2.54, -0.02). Greater maternal weekend screen-time (0.45; 0.08, 0.83) and, in girls, greater parental restriction on playing outside (0.91; 0.08, 1.74) were associated with larger increases in weekend sedentary time. The analytical sample was younger, more likely to be female, had lower BMI and was of higher SES than the original baseline sample.

CONCLUSIONS

Intervention strategies aimed at reducing parents' weekend screen-time, increasing family participation in sports or recreation (boys) and promoting freedom to play outside (girls) may contribute towards preventing the age-related increase in sedentary time.

Examination of mid-intervention mediating effects on objectively assessed sedentary time among children in the Transform-Us! cluster-randomized controlled trial

Background

The optimal targets and strategies for effectively reducing sedentary behavior among young people are unknown. Intervention research that explores changes in mediated effects as well as in outcome behaviors is needed to help inform more effective interventions. Therefore, the purpose of this study was to examine the mid-intervention mediating effects on children’s objectively assessed classroom and total weekday sedentary time in the Transform-Us! intervention.

Methods

The results are based on 293 children, aged 7- to 9-years-old at baseline, from 20 schools in Melbourne, Australia. Each school was randomly allocated to one of four groups, which targeted reducing sedentary time in the school and family settings (SB; n = 74), increasing or maintaining moderate- to vigorous-intensity physical activity in the school and family settings (PA; n = 75), combined SB and PA (SB + PA; n = 80), or the current practice control (C; n = 64). Baseline and mid-intervention data (5–9 months) were collected in 2010 and analyzed in 2012. Classroom and total weekday sedentary time was objectively assessed using ActiGraph accelerometers. The hypothesized mediators including, child enjoyment, parent and teacher outcome expectancies, and child perceived access to standing opportunities in the classroom environment, were assessed by questionnaire.

Results

The SB + PA group spent 13.3 min/day less in weekday sedentary time at mid-intervention compared to the control group. At mid-intervention, children in the SB group had higher enjoyment of standing in class (0.9 units; 5-unit scale) and all intervention groups had more positive perceptions of access to standing opportunities in the classroom environment (0.3-0.4 units; 3-unit scale), compared to the control group. However, none of the hypothesized mediator variables had an effect on sedentary time; thus, no mediating effects were observed.

Conclusions

While beneficial intervention effects were observed on some hypothesized mediating variables and total weekday sedentary time at mid-intervention, no significant mediating effects were found. Given the dearth of existing information, future intervention research is needed that explores mediated effects. More work is also needed on the development of reliable mediator measures that are sensitive to change overtime.

Trial registration

ACTRN12609000715279

ISRCTN83725066

Independence of physical activity and screen time as predictors of cardiorespiratory fitness in youth

BACKGROUND

Screen time (ST) is associated with physical activity (PA) levels. We aimed to investigate the relationship between ST and fitness.

METHODS

We assessed fitness and daily ST in 7,466 10-16-y-old schoolchildren from the east of England. The differences in fitness between ST groups, and the association between ST and fitness were assessed.

RESULTS

ST was negatively associated with fitness in boys of all ages (P < 0.001) and girls in grades 6-9 (P < 0.005). Boys were less likely to be fit if they reported >2 h/d ST (odds ratio (OR): 0.70, 95% confidence interval (CI): 0.58-0.85) or >4 h/d (OR: 0.45, 95% CI: 0.35-0.57) ST, as were girls reporting >4 h/d ST (OR: 0.58, 95% CI: 0.43-0.78). Controlling for PA levels attenuated these odds in boys reporting >2 h/d ST (OR: 0.81, 95% CI: 0.66-0.91) or >4 h/d ST (OR: 0.65, 95% CI: 0.50-0.84) and in girls reporting >4 h/d ST (OR: 0.68, 95% CI: 0.50-0.93).

CONCLUSION

These first data from English children show a negative association between ST and fitness in youth. Of note, very high levels of daily ST (>4 h) are associated with poor fitness. Some of the associations were mediated by PA levels. Our data support international recommendations to limit ST to <2 h/d; we believe such guidance should be issued in the United Kingdom.

Physical Activity, Sedentary Behavior, and Dietary Patterns among Children

Energy balance-related behavioral patterns find their origin in early childhood. The current paper provides an overview of studies that have examined such behavioral patterns, i.e., the clustering of dietary behaviors, physical activity, and/or sedentary behavior. The paper discusses the importance of examining energy balance-related behavioral patterns in children, outlines methods to examine these patterns, and provides examples of patterns that have been found (e.g., the universal sedentary-snacking and healthy intake patterns, as well as more unique or local patterns), child and parental characteristics predicting such patterns (e.g., child gender and maternal educational level), and the relationship of these patterns with overweight and related measures.

Understanding the physical and social contexts of children's nonschool sedentary behavior: an ecological momentary assessment study

BACKGROUND

Research on children's sedentary behavior has relied on recall-based self-report or accelerometer methods, which do not assess the context of such behavior.

PURPOSE

This study used ecological momentary assessment (EMA) to determine where and with whom children's sedentary behavior occurs during their nonschool time.

METHODS

Children (N = 120) ages 9-13 years (51% male, 33% Hispanic) wore mobile phones that prompted surveys (20 total) for 4 days. Surveys measured current activity (eg, exercise, watching TV), physical location (eg, home, outdoors), and social company (eg, family, friends).

RESULTS

Children engaged in a greater percentage of leisure-oriented (eg, watching TV) than productive (eg, reading, doing homework) sedentary behavior (70% vs 30%, respectively). Most of children's sedentary activity occurred at home (85%). Children's sedentary activity took place most often with family members (58%). Differences in physical context of sedentary behavior were found for older vs. younger children (P < .05). Type of sedentary behavior differed by gender, racial/ethnic group, and social context (P < .05).

CONCLUSION

Children may prefer or have greater opportunities to be sedentary in some contexts than others. Research demonstrates the potential for using EMA to capture real-time information about children's sedentary behavior during their nonschool time.

Using the SenseCam to improve classifications of sedentary behavior in free-living settings

BACKGROUND

Studies have shown relationships between important health outcomes and sedentary behavior, independent of physical activity. There are known errors in tools employed to assess sedentary behavior. Studies of accelerometers have been limited to laboratory environments.

PURPOSE

To assess a broad range of sedentary behaviors in free-living adults using accelerometers and a Microsoft SenseCam that can provide an objective observation of sedentary behaviors through first person-view images.

METHODS

Participants were 40 university employees who wore a SenseCam and Actigraph accelerometer for 3-5 days. Images were coded for sitting and standing posture and 12 activity types. Data were merged and aggregated to a 60-second epoch. Accelerometer counts per minute (cpm) of <100 were compared with coded behaviors. Sensitivity and specificity analyses were performed. Data were collected in June and July 2011 and analyzed in April 2012.

RESULTS

TV viewing, other screen use, and administrative activities were correctly classified by the 100-cpm cutpoint. However, standing behaviors also fell under this threshold, and driving behaviors exceeded it. Multiple behaviors occurred simultaneously. A nearly 30-minute per day difference was found in sedentary behavior estimates based on the accelerometer versus the SenseCam.

CONCLUSIONS

Researchers should be aware of the strengths and weaknesses of the 100-cpm accelerometer cutpoint for identifying sedentary behavior. The SenseCam may be a useful tool in free-living conditions to better understand health behaviors such as sitting.

Convergent validity of preschool children's television viewing measures among low-income Latino families: a cross-sectional study

BACKGROUND

Television viewing is an important modifiable risk factor for childhood obesity. However, valid methods for measuring children's TV viewing are sparse and few studies have included Latinos, a population disproportionately affected by obesity. The goal of this study was to test the reliability and convergent validity of four TV viewing measures among low-income Latino preschool children in the United States.

METHODS

Latino children (n=96) ages 3-5 years old were recruited from four Head Start centers in Houston, Texas (January, 2009, to June, 2010). TV viewing was measured concurrently over 7 days by four methods: (1) TV diaries (parent reported), (2) sedentary time (accelerometry), (3) TV Allowance (an electronic TV power meter), and (4) Ecological Momentary Assessment (EMA) on personal digital assistants (parent reported). This 7-day procedure was repeated 3-4 weeks later. Test-retest reliability was determined by intraclass correlations (ICC). Spearman correlations (due to nonnormal distributions) were used to determine convergent validity compared to the TV diary.

RESULTS

The TV diary had the highest test-retest reliability (ICC=0.82, p<0.001), followed by the TV Allowance (ICC=0.69, p<0.001), EMA (ICC=0.46, p<0.001), and accelerometry (ICC=0.36-0.38, p<0.01). The TV Allowance (r=0.45-0.55, p<0.001) and EMA (r=0.47-0.51, p<0.001) methods were significantly correlated with TV diaries. Accelerometer-determined sedentary minutes were not correlated with TV diaries. The TV Allowance and EMA methods were significantly correlated with each other (r=0.48-0.53, p<0.001).

CONCLUSIONS

The TV diary is feasible and is the most reliable method for measuring US Latino preschool children's TV viewing.

Patterns of sedentary behaviours in Irish female adolescents

Engagement in excessive sedentary behaviour represents a health risk for adolescents. The current study aimed to investigate patterns of sedentary behaviour amongst Irish female adolescents aged between 15 and 19 years old. 314 adolescents completed a questionnaire on their sedentary behaviour habits, health behaviours (physical activity, smoking, and alcohol use), enjoyment of sedentary behaviour, value on health, and sedentary facilitators in their home. Parents provided information on parental education, the child's weight and height, and parental sedentary behaviour habits. Cluster analysis found that five distinct sedentary clusters existed in this sample: Unproductive/Social Sedentary, Reading/Productive Behaviours, Mixed Sedentary Interests, Restricted Interests/High Television, and Academic Sedentary. The clusters differed on smoking and alcohol use, enjoyment of sedentary behaviour, and parental engagement in sedentary behaviour. The findings from this study support the use of a socio-ecological framework for investigating the development of sedentary behaviour patterns.

Objectively measured sedentary time and physical activity time across the lifespan: a cross-sectional study in four age groups

Background

From a health perspective it is suggested to promote a positive balance between time spent in light intensity physical activity (LIPA) and sedentary behaviour (SB) (i.e. spending more time in LIPA than time spent in SB). However, no studies have reported prevalence rates of the LIPA-SB balance yet. The aim of this study was to objectively investigate the time spent in SB, in LIPA and moderate-to-vigorous intensity physical activity (MVPA) in four Belgian age groups and to explore which proportion of the population had a favorable balance between LIPA and SB and combined this with recommended amount of MVPA.

Methods

Accelerometer data from 7 cross-sectional studies (N=2083) in four age groups (preschoolers, primary schoolchildren, secondary schoolchildren and adults) were aggregated. Differences in SB and PA between age groups and between men and women were determined by two-way MANCOVA. LIPA-SB balance was calculated and participants were categorized into one of four groups: (1) positive LIPA-SB balance (LIPA> SB) & sufficient MVPA (2) negative LIPA-SB balance & sufficient MVPA (3) positive LIPA-SB balance & insufficient MVPA (4) negative LIPA-SB balance & insufficient MVPA.

Results

For the total sample, 55% of the waking time was spent in SB, 39% in LIPA and 6% in MVPA. Differences in SB between age groups was dependent from gender (p<0.001). Further, a positive LIPA-SB balance was assessed in 18% of the total sample and only 10% combined this positive balance with recommended amount of MVPA. Secondary schoolgirls were most at risk, with only 1% of the sample combining a positive LIPA-SB balance with sufficient MVPA. Another risk group was the large proportion (43%) of adult men who combined sufficient MVPA with a negative LIPA-SB balance.

Conclusion

A high proportion of the Belgian population is at risk if taking into account both SB and PA levels. Secondary schoolgirls have the unhealthiest SB and PA profile and are therefore an important target group for interventions both increasing MVPA and decreasing SB. In men more attention should be given in promoting a positive LIPA-SB balance independently from their compliance with the MVPA guidelines.

Associations of children's independent mobility and active travel with physical activity, sedentary behaviour and weight status: a systematic review

Health benefits from children's independent mobility and active travel beyond school travel are largely unexplored.

OBJECTIVES

This review synthesized the evidence for associations of independent mobility and active travel to various destinations with physical activity, sedentary behaviour and weight status.

DESIGN

Systematic review.

METHODS

A systematic search in six databases (PubMed, Scopus, CINAHL, SportDiscus, PsychInfo, TRIS) for papers published between January 1990 and March 2012 was undertaken, focussing on children aged 3-18 years. Study inclusion and methodological quality were independently assessed by two reviewers.

RESULTS

52 studies were included. Most studies focussed solely on active travel to and/or from school, and showed significant positive associations with physical activity. The same relationship was detected for active travel to leisure-related places and independent mobility with physical activity. An inverse relationship between active travel to school and weight status was evident but findings were inconsistent. Few studies examined correlations between active travel to school and self-reported screen-time or objectively measured sedentary behaviour, and findings were unclear.

CONCLUSIONS

Studies on independent mobility suggested that children who have the freedom to play outdoors and travel actively without adult supervision accumulate more physical activity than those who do not. Further investigation of children's active travel to leisure-related destinations, measurement of diverse sedentary behaviour beyond simply screen-based activities, and consistent thresholds for objectively measured sedentary behaviour in children will clarify the inconsistent evidence base on associations of active travel with sedentary behaviour and weight status.

Methods of Measurement in epidemiology: sedentary Behaviour

BACKGROUND

Research examining sedentary behaviour as a potentially independent risk factor for chronic disease morbidity and mortality has expanded rapidly in recent years.

METHODS

We present a narrative overview of the sedentary behaviour measurement literature. Subjective and objective methods of measuring sedentary behaviour suitable for use in population-based research with children and adults are examined. The validity and reliability of each method is considered, gaps in the literature specific to each method identified and potential future directions discussed.

RESULTS

To date, subjective approaches to sedentary behaviour measurement, e.g. questionnaires, have focused predominantly on TV viewing or other screen-based behaviours. Typically, such measures demonstrate moderate reliability but slight to moderate validity. Accelerometry is increasingly being used for sedentary behaviour assessments; this approach overcomes some of the limitations of subjective methods, but detection of specific postures and postural changes by this method is somewhat limited. Instruments developed specifically for the assessment of body posture have demonstrated good reliability and validity in the limited research conducted to date. Miniaturization of monitoring devices, interoperability between measurement and communication technologies and advanced analytical approaches are potential avenues for future developments in this field.

CONCLUSIONS

High-quality measurement is essential in all elements of sedentary behaviour epidemiology, from determining associations with health outcomes to the development and evaluation of behaviour change interventions. Sedentary behaviour measurement remains relatively under-developed, although new instruments, both objective and subjective, show considerable promise and warrant further testing.

The effect of the UP4FUN pilot intervention on objectively measured sedentary time and physical activity in 10-12 year old children in Belgium: the ENERGY-project

Bakckground

The first aim was to examine the effect of the UP4FUN pilot intervention on children’s total sedentary time. The second aim was to investigate if the intervention had an effect on children’s physical activity (PA) level. Finally, we aimed to investigate demographic differences (i.e. age, gender, ethnicity, living status and having siblings) between children in the intervention group who improved in sedentary time and PA at post-test and children in the intervention group who worsened in sedentary time and PA at post-test.

Methods

The six weeks UP4FUN intervention was tested in a randomized controlled trial with pre-test post-test design with five intervention and five control schools in Belgium and included children of the 5^th and 6^th grade. The children wore accelerometers for seven days at pre- and post-test. Analyses included children with valid accelerometer data for at least two weekdays with minimum 10h-wearing time and one weekend day with 8h-wearing time.

Result

Final analyses included 372 children (60% girls, mean age = 10.9 ± 0.7 years). There were no significant differences in the change in sedentary time or light PA between intervention and control schools for the total sample or for the subgroup analyses by gender. However, children (specifically girls) in the intervention group had a higher decrease in moderate-to-vigorous PA than children in the control group. In the intervention group, children who lived with both parents and children with one or more siblings were less likely to reduce sedentary time after exposure to the intervention. Older children, girls and children who lived with both parents were less likely to increase light PA after the intervention.

Conclusion

The UP4FUN intervention did not result in an effect on children’s sedentary time. Based on the high amounts of accelerometer-derived sedentary time in this age group, more efforts are needed to develop strategies to reduce children’s sedentary time.

The effect of a healthy lifestyle programme on 8-9 year olds from social disadvantage

AIMS

This study assessed the efficacy of a school-based healthy lifestyle intervention (Sport for LIFE) for increasing physical activity, decreasing sedentary behaviour, reducing screen time behaviour, encouraging healthy attitudes and behaviour to nutrition, and reducing body mass index (BMI) in 8-9-year-old primary school children from lower socioeconomic backgrounds in Northern Ireland.

METHODS

A non-randomised controlled trial of 416 children from 24 schools took part. Schools were randomly assigned to one of two groups, an intervention or control group with 12 schools in each group. The intervention group received a 12-week school-based programme based on social cognitive theory. At baseline and follow-up, groups completed questionnaires assessing physical activity, screen time behaviour and dietary patterns. On each occasion anthropometric assessments of height and weight were taken. Physical activity and sedentary behaviour were measured by accelerometry.

RESULTS

Significant effects were observed for vigorous, moderate and light activity for the intervention group at follow-up. Sedentary behaviour was significantly reduced for the intervention group but not for the control group. No significant effects of the intervention on BMI, screen time behaviour or attitudes to nutrition, with the exception of non-core foods, were shown.

CONCLUSIONS

The programme was effective in increasing physical activity and reducing sedentary behaviour, however no significant changes in screen time behaviour and attitude to nutrition, with the exception of non-core foods, were observed. Future research ideas are offered for tackling low levels of physical activity in children.

Clustering of energy balance-related behaviors in 5-year-old children: lifestyle patterns and their longitudinal association with weight status development in early childhood

Background

This study identified lifestyle patterns by examining the clustering of eating routines (e.g. eating together as a family, having the television on during meals, duration of meals) and various activity-related behaviors (i.e. physical activity (PA) and sedentary screen-based behavior) in 5-year-old children, as well as the longitudinal association of these patterns with weight status (BMI and overweight) development up to age 8.

Methods

Data originated from the KOALA Birth Cohort Study (N = 2074 at age 5). Principal component analysis (PCA) was used to identify lifestyle patterns. Backward regression analyses were used to examine the association of lifestyle patterns with parent and child background characteristics, as well as the longitudinal associations between the patterns and weight status development.

Results

Four lifestyle patterns emerged from the PCA: a ‘Television–Snacking’ pattern, a ‘Sports–Computer’ pattern, a ‘Traditional Family’ pattern, and a “Fast’ Food’ pattern. Child gender and parental educational level, working hours and body mass index were significantly associated with the scores for the patterns. The Television–Snacking pattern was positively associated with BMI (standardized regression coefficient β = 0.05; p < 0.05), and children with this pattern showed a positive tendency toward being overweight at age 8 (Odds ratio (OR) = 1.27, p = 0.06). In addition, the Sports–Computer pattern was significantly positively associated with an increased risk of becoming overweight at age 7 (OR = 1.28, p < 0.05).

Conclusions

The current study showed the added value of including eating routines in cross-behavioral clustering analyses. The findings indicate that future interventions to prevent childhood overweight should address eating routines and activity/inactivity simultaneously, using the synergy between clustered behaviors (e.g. between television viewing and snacking).

Screen time and passive school travel as independent predictors of cardiorespiratory fitness in youth

OBJECTIVE

The most prevalent sedentary behaviours in children and adolescents are engagement with small screen media (screen-time) and passive travel (by motorised vehicle). The objective of this research was to assess the independence of these behaviours from one another and from physical activity as predictors of cardiorespiratory fitness in youth.

METHODS

We measured cardiorespiratory fitness in n=6819 10-16 year olds (53% male) who self-reported their physical activity (7-day recall) school travel and screen time habits. Travel was classified as active (walking, cycling) or passive; screen time as <2 h, 2-4 h or >4 h.

RESULTS

The multivariate odds of being fit were higher in active travel (Boys: OR 1.32, 95% CI: 1.09-1.59; Girls: OR 1.46, 1.15-1.84) than in passive travel groups. Boys reporting low screen time were more likely to be fit than those reporting >4 h (OR 2.11, 95% CI: 1.68-2.63) as were girls (OR 1.66, 95% CI: 1.24-2.20). These odds remained significant after additionally controlling for physical activity.

CONCLUSION

Passive travel and high screen time are independently associated with poor cardiorespiratory fitness in youth, and this relationship is independent of physical activity levels. A lifestyle involving high screen time and habitual passive school travel appears incompatible with healthful levels of cardiorespiratory fitness in youth.

Self-reported TV and computer time do not represent accelerometer-derived total sedentary time in 10 to 12-year-olds

Screen-time activities are often used as proxies for sedentary time. We studied associations of self-reported television (TV), computer and total screen-time with accelerometer-derived total sedentary time in European children (10-12 years). Analyses showed significant positive associations between TV, computer and total screen-time with total sedentary time for the total sample, however, the explained variance was low and stratified analyses only revealed a significant positive association between total screen-time and total sedentary time in boys and between computer time and total sedentary time in Dutch children. This suggests that self-reported TV and computer time do not adequately reflect total sedentary time in schoolchildren.

Beyond Screen Time: Assessing Recreational Sedentary Behavior among Adolescent Girls

Most studies of sedentary behavior have focused on television use or screen time. This study aims to examine adolescent girls' participation in a variety of recreational sedentary behaviors (e.g., talking on the phone and hanging around), and their association with physical activity (PA), dietary behaviors, and body mass index. Data were from a sample of 283 adolescent girls. Recreational sedentary behavior, PA, and dietary behaviors were self-reported, and girls' height and weight were measured. Over 95% of girls engaged in at least one recreational sedentary behavior during the recall period. Watching television and hanging around were the most common behaviors. Watching television, using the Internet, and hanging around were associated with less PA; watching television, hanging around, and talking on the phone were associated with less healthful dietary behaviors. No associations were found with body mass index. Interventions may benefit from capitalizing on and intervening upon girls' common recreational sedentary behaviors.

The fault, dear viewer, lies not in the screens, but in ourselves: relationships between screen media and childhood overweight/obesity

This article summarizes recent findings about associations between electronic screen media and childhood overweight/obesity, hypothesized mechanisms, and mediators. Recommendations are made for parents and clinicians.

Correlates of objectively measured sedentary behavior in US preschool children

OBJECTIVE

To identify correlates of objectively measured sedentary behavior in a diverse sample of preschool children.

METHODS

A total of 331 children (51% male, 51% black) from a wide range of ethnic and socioeconomic backgrounds in greater Columbia, South Carolina, were recruited for this study. Sedentary behavior (minutes/hour) was measured by using ActiGraph accelerometers (<37.5 counts per 15 seconds) over a 2-week period. All potential correlates except for anthropometric data of children were measured by a parent survey. Correlation and regression analyses were conducted to examine associations between 29 potential correlates across multiple domains (demographic, biological, psychosocial, behavioral, and physical environmental) and sedentary behavior measured by accelerometry in preschool children.

RESULTS

Girls spent more time in sedentary behavior than boys (33.2 vs 32.4 minutes/hour; P = .05). Six and 8 potential correlates were found to be significant in univariate analyses for boys and girls, respectively. In the gender-specific final model, for boys, a child's weekday TV/video games and physical activity equipment in the home were significant correlates of sedentary behavior (R(2) = 0.091). For girls, BMI z score and child's athletic coordination were significantly associated with sedentary behavior (R(2) = 0.069).

CONCLUSION

Several factors were identified as correlates of objectively measured sedentary behavior in American preschool children. However, there were no common correlates that influenced sedentary behavior for both boys and girls. Future interventions for reducing sedentary behavior could target correlates identified in this study.

Temporal trends and recent correlates in sedentary behaviours in Chinese children

BACKGROUND

Sedentary behaviours (television, video and computer) are related to health outcomes independent of physical activity. Few studies have examined trends and correlates of sedentary behaviours among youth in developing nations. The current study is to examine temporal trends in sedentary behaviours and recent correlates of screen use in Chinese children during a period of economic transition.

METHODS

Secondary analysis of China Health and Nutrition Surveys. Cross-sectional data on sedentary behaviours including screen use among children aged 6-18 years from four surveys in 1997 (n = 2,469), 2000 (n = 1,838), 2004 (n = 1,382) and 2006 (n = 1,128). Temporal trends in screen use by socio-demographic characteristics were examined. The correlates of spending more than 2 hours per day on screen time in the most recent survey data (2006, n = 986) were analysed using survey logistic regression analysis.

RESULTS

Daily screen time significantly increased in each subgroup by age, sex and urban/rural residence, with the largest increase for urban boys aged 13-18 years from 0.5 hours to 1.7 hours, and for rural boys aged 6-12 years from 0.7 hours to 1.7 hours (p < 0.0001). Daily time in both homework and extracurricular cultural activity increased significantly from 2000 to 2004 but was stable from 2004 to 2006. Boys (OR: 1.41, 95%CI: 1.09 -1.82), having a TV in the bedroom (OR: 1.86, 95%CI: 1.15 - 3.01), having access to internet at home (OR: 1.93, 95%CI: 1.12 - 3.31) or at internet cafés (OR: 2.01, 95%CI: 1.21 - 3.34), or often watching TV with parents (OR: 2.27, 95%CI: 1.37 - 3.74) were all associated with being more likely to be high screen users (≥ 2 hours/day). While children aged 13-18 years (OR: 0.67, 95%CI: 0.46-0.97) were less likely to be high screen users. Children whose parents often have rules on their TV viewing (OR: 0.64, 95%CI: 0.37 - 1.10) were slightly but not significantly less likely to be high screen users.

CONCLUSION

This study confirms sedentary behaviour has increased over the last decade in Chinese children. Efforts to ensure Chinese youth meet screen time guidelines include limiting access to screen technologies and encouraging parents to monitor their own screen time and to set limits on their child's screen time.

Relationship between young peoples' sedentary behaviour and biomedical health indicators: a systematic review of prospective studies

The aim of this systematic review was to describe the prospective relationship between childhood sedentary behaviour and health indicators. We identified prospective studies from searches in PubMed, EMBASE, PsycInfo and Cochrane, from January 1989 through April 2010. Two reviewers independently screened the titles and abstracts for eligibility, rated the methodological quality of the studies, and extracted data. We identified 31 papers, examining 27 different cohorts. The quality score of the studies ranged from 38 to 88%. Nine studies were scored as high quality. According to the best evidence synthesis we found insufficient evidence for a longitudinal positive relationship between 'sedentary time'- mainly TV viewing - and body mass index (BMI) and more specific indicators of fat mass. One high quality and two low quality studies found a significant inverse relationship between sedentary time - mainly TV viewing - and aerobic fitness, leading to moderate evidence for this inverse relationship. There was insufficient evidence for a longitudinal relationship between sedentary time and blood pressure, blood lipids or bone mass. Our systematic review suggests that there is moderate evidence for a longitudinal inverse relationship between screen time and aerobic fitness during childhood. Thus there is evidence to limit screen time in young people in order to prevent low levels of fitness. The possible detrimental health effects of prolonged or excessive sitting on other health indicators needs further study.

Correlates of physical activity and inactivity in urban Mexican youth

OBJECTIVES

To evaluate correlates of physical activity in Mexico City school youth.

METHODS

A cross-sectional survey was conducted with 1,004 school youth (490 males and 514 females), 9-18 years of age resident in Mexico City. Age, height, body mass index (BMI), socioeconomic status (SES), time viewing television and playing video games (physical inactivity), and perceived sport/physical activity status of mother and father were evaluated as potential correlates of physical activity [Physical Activity Questionnaire (PAQ)]. Multiple linear regression analyses (backward elimination) by age group and sex were used.

RESULTS

Physical activity declined in older adolescents, while differences between the two younger age groups were minimal. Television time showed a similar tendency. Overall, fathers were perceived as being active in sport/physical activity more frequently than mothers. Significant predictors of activity differed by age group and sex. For the total sample, age (negative) and perceived sport/activity status of the mother (positive) were significant predictors of the PAQ in boys, and age and the BMI (negative) and height and perceived sport/activity status of both parents (positive) were significant predictors for girls. Age (negative) was the main predictor for inactivity in both males and females.

CONCLUSIONS

Potential correlates of physical activity and inactivity considered in this analysis were limited and accounted for relatively little of the variance in physical activity. The role of perceived sport/activity of the parents, especially among younger boys and girls, is particularly of interest and merits more detailed study. Nevertheless, many other variables also need to be considered.

Associations between activity-related behaviours and standardized BMI among Australian adolescents

OBJECTIVES

To examine the relationships between physical activity, sedentary behaviour and body mass index (BMI) among a sample of Australian adolescents.

METHODS

Anthropometric, demographic and behavioural data were collected from students (n=3040 mean age 14.6, 44% female) from 12 secondary schools in South West Victoria, Australia (response rate=48.6%). The appropriate descriptive, univariate and regression analysis were used to examine the strength of the associations between physical activity, sedentary behaviour and odds of overweight or obese and the effect of interaction between physical activity and sedentary behaviour on odds of overweight and obese.

RESULTS

Males were more likely to be active during the school day than females and had higher median hours of screen time per school day. Physical activity during the school day was associated with higher standardized BMI (BMI-z) among males. Higher levels of activity after school were associated with lower BMI-z for males and females. For both males and females the odds of overweight or obese were higher among the least active. An interaction was observed for females whereby the prevalence of overweight and obesity among the most physically active was lowest for the least sedentary and highest for the most sedentary.

CONCLUSIONS

The relationships between physical activity, sedentary behaviour and BMI-z were complex. Interventions to reduce BMI through increasing physical activity or decreasing sedentary behaviour need to consider the complex inter-relationships between these variables and moderating factors such as age, sex and socio economic status in their design and interpretation.

Reducing Sedentary Behavior

There is growing interest in the role of sedentary behavior as a risk factor for poor health, independent of physical activity (PA). To guide the spectrum of descriptive, analytic, and intervention studies on sedentary behavior, the authors advocate a behavioral epidemiology framework. This 5-phase framework is useful because it outlines a series of sequential stages important for developing, evaluating, and diffusing interventions to reduce sedentary behavior and improve population health. Studies of sedentary behavior and health outcomes (phase I) have found consistent evidence that excessive use of screen-based media is linked to overweight and obesity in children, and there is some evidence among adults that overall sedentary time is associated with risk factors for cardiometabolic disease, some cancers, and mortality. Biological mechanisms to explain possible relationships have started to emerge but are mostly based on animal models. Obtaining valid and reliable measurements of sedentary behavior (phase II) remains a research priority because self-reports are prone to recall bias, and it appears that sedentary habits do not appear to be well represented by measures of individual behaviors such as TV viewing. Studies have identified few modifiable correlates of sedentary behavior (phase III), although research appears to be limited to studies of TV viewing or to scenarios in which sedentary behavior is defined as an absence of PA. Rigorous intervention research (phase IV) has focused almost exclusively on reducing self-reported TV viewing among children and adolescents, and there is consistent evidence that these interventions are efficacious. There appear to be no interventions focused exclusively on reducing sedentary behavior of adults. Translation studies (phase V) are absent because the underlying evidence is still emerging. Future research should focus on examining causal associations between sedentary behavior and health, developing objective measures of domain-specific sitting time, and identifying modifiable correlates of sedentary behavior that can be used as leverage points for behavioral interventions.

Descriptive epidemiology of screen and non-screen sedentary time in adolescents: a cross sectional study

Background

Much attention has been paid to adolescents' screen time, however very few studies have examined non-screen sedentary time (NSST). This study aimed to (1) describe the magnitude and composition of screen sedentary time (SST) and NSST in Australian adolescents, (2) describe the socio-demographic correlates of SST and NSST, and (3) determine whether screen time is an adequate surrogate for total sedentary behaviour in this population.

Methods

2200 9-16 year old Australians provided detailed use of time data for four days. Non-screen sedentary time (NSST) included time spent participating in activities expected to elicit <3 METs whilst seated or lying down (other than sleeping), excluding screen-based activities (television, playing videogames or using computers). Total sedentary time was the sum of screen time and NSST.

Results

Adolescents spent a mean (SD) of 345 (105) minutes/day in NSST, which constituted 60% of total sedentary time. School activities contributed 42% of NSST, socialising 19%, self-care (mainly eating) 16%, and passive transport 15%. Screen time and NSST showed opposite patterns in relation to key socio-demographic characteristics, including sex, age, weight status, household income, parental education and day type. Because screen time was negatively correlated with NSST (r = -0.58), and exhibited a moderate correlation (r = 0.53) with total sedentary time, screen time was only a moderately effective surrogate for total sedentary time.

Conclusions

To capture a complete picture of young people's sedentary time, studies should endeavour to measure both screen time and NSST.

Brief report: Association between socio-demographic factors, screen media usage and physical activity by type of day in Spanish adolescents

This study examined the relationship between socio-demographic factors, screen media time usage, and light, moderate and vigorous activities on weekdays and weekends. Cross-sectional data was collected from 323 Spanish adolescents (mean age 13.59 years) who completed an interview administered recall questionnaire. Structural equation models indicated that male and younger adolescents spent more time on vigorous activities at the weekend, while females and older adolescents showed a greater involvement in light activities both on weekdays and weekends. State school students reported engaging in light and vigorous activities for longer periods than private school students on weekends. TV viewing was negatively linked to vigorous activities during weekdays and to light and moderate activities on weekends. The amount of mobile phone usage, however, was positively linked to light activities during weekdays, but negatively on weekends. The negative relationship between adolescents' use of screen media (TV and mobile phone) and physical activity and its possible displacement, depending on the type of day, added useful comparable knowledge for policies promoting an active lifestyle. Further research is required to provide evidence of the causality in the observed relationships.

Children's screen viewing is related to psychological difficulties irrespective of physical activity

OBJECTIVE

We hypothesized that greater screen use would be associated with greater psychological difficulties and that children with high levels of screen entertainment use and low levels of physical activity would have the most-negative psychological profiles.

METHODS

Participants were 1013 children (age, mean ± SD: 10.95 ± 0.41 years), who self-reported average daily television hours and computer use and completed the Strengths and Difficulties Questionnaire. Sedentary time (minutes per day with <100 cpm) and moderate/vigorous physical activity (MVPA) (minutes with ≥ 2000 cpm) were measured by using accelerometers. Multivariate regression models examined the association between television viewing, computer use, sedentary time, and Strengths and Difficulties Questionnaire scores, with adjustment for MVPA, age, gender, level of deprivation, and pubertal status.

RESULTS

Greater television and computer use were related to higher psychological difficulty scores after adjustment for MVPA, sedentary time, and confounders. However, sedentary time was inversely related to psychological difficulties after adjustment. Children who spent >2 hours per day watching television or using a computer were at increased risk of high levels of psychological difficulties (television, odds ratio [OR]: 1.61 [95% confidence interval [CI]: 1.20-2.15]; computer, OR: 1.59 [95% CI: 1.32-1.91]), and this risk increased if the children also failed to meet physical activity guidelines (television, OR: 1.70 [95% CI: 1.09-2.61]; computer, OR: 1.81 [95% CI: 1.02-3.20]).

CONCLUSION

Both television viewing and computer use are important independent targets for intervention for optimal well-being for children, irrespective of levels of MVPA or overall sedentary time.

Tracking of sedentary behaviours of young people: a systematic review

OBJECTIVE

To review the empirical evidence concerning the strength of tracking of sedentary behaviours from childhood and adolescence.

METHODS

Published English language studies were located from computerised and manual searches in 2009. Included studies were prospective, longitudinal studies with at least one sedentary behaviour for at least two time-points, with tracking coefficients reported, and included children (aged 3-11 years) and adolescents (12-18 years) at baseline.

RESULTS

Based on data from 21 independent samples, tracking coefficients (r) ranged from 0.08 (over 16 years) to 0.73 (over 2 years) for TV viewing, from 0.18 (boys over 3 years) to 0.52 (over 2 years) for electronic game/computer use, from 0.16 (girls over 4 years) to 0.65 (boys over 2 years) for total screen time, and from -0.15 (boys over 2 years) to 0.48 (over 1 year) for total sedentary time. Study follow-up periods ranged from 1 to up to 27 years, and tracking coefficients tended to be higher with shorter follow-ups.

CONCLUSIONS

Sedentary behaviours track at moderate levels from childhood or adolescence. Data suggest that sedentary behaviours may form the foundation for such behaviours in the future and some may track slightly better than physical activity.