Physical activity and sedentary behavior: a review of longitudinal studies of weight and adiposity in youth

Research priorities for child and adolescent physical activity and sedentary behaviours: an international perspective using a twin-panel Delphi procedure

Background

The quantity and quality of studies in child and adolescent physical activity and sedentary behaviour have rapidly increased, but research directions are often pursued in a reactive and uncoordinated manner.

Aim

To arrive at an international consensus on research priorities in the area of child and adolescent physical activity and sedentary behaviour.

Methods

Two independent panels, each consisting of 12 experts, undertook three rounds of a Delphi methodology. The Delphi methodology required experts to anonymously answer questions put forward by the researchers with feedback provided between each round.

Results

The primary outcome of the study was a ranked set of 29 research priorities that aimed to be applicable for the next 10 years. The top three ranked priorities were: developing effective and sustainable interventions to increase children’s physical activity long-term; policy and/or environmental change and their influence on children’s physical activity and sedentary behaviour; and prospective, longitudinal studies of the independent effects of physical activity and sedentary behaviour on health.

Conclusions

These research priorities can help to guide decisions on future research directions.

Multicomponent intervention to reduce daily sedentary time: a randomised controlled trial

OBJECTIVES

To test the efficacy of a multicomponent technology intervention for reducing daily sedentary time and improving cardiometabolic disease risk among sedentary, overweight university employees.

DESIGN

Blinded, randomised controlled trial.

SETTING

A large south-eastern university in the USA.

PARTICIPANTS

49 middle-aged, primarily female, sedentary and overweight adults working in sedentary jobs enrolled in the study. A total of 40 participants completed the study.

INTERVENTIONS

Participants were randomised to either: (1) an intervention group (N=23; 47.6+9.9 years; 94.1% female; 33.2+4.5 kg/m(2)); (2) or wait-list control group (N=17; 42.6+8.9 years; 86.9% female; 31.7+4.9 kg/m(2)). The intervention group received a theory-based, internet-delivered programme, a portable pedal machine at work and a pedometer for 12 weeks. The wait-list control group maintained their behaviours for 12 weeks.

OUTCOME MEASURES

Primary (sedentary and physical activity behaviour measured objectively through StepWatch) and secondary (heart rate, blood pressure, height, weight, waist circumference, per cent body fat, cardiorespiratory fitness, fasting lipids) outcomes were measured at baseline and postintervention (12 weeks). Exploratory outcomes including intervention compliance and process evaluation measures were also assessed postintervention.

RESULTS

Compared to controls, the intervention group reduced daily sedentary time (mean change (95%CI): -58.7 min/day (-118.4 to 0.99; p<0.01)) after adjusting for baseline values and monitor wear time. Intervention participants logged on to the website 71.3% of all intervention days, used the pedal machine 37.7% of all working intervention days and pedalled an average of 31.1 min/day.

CONCLUSIONS

These findings suggest that the intervention was engaging and resulted in reductions in daily sedentary time among full-time sedentary employees. These findings hold public health significance due to the growing number of sedentary jobs and the potential of these technologies in large-scale worksite programmes.

TRIAL REGISTRATION

ClinicalTrials.gov #NCT01371084.

Sizing the association between lifestyle behaviours and fatness in a large, heterogeneous sample of youth of multiple ethnicities from 4 countries

Background

The magnitude of the relationship between lifestyle risk factors for obesity and adiposity is not clear. The aim of this study was to clarify this in order to determine the level of importance of lifestyle factors in obesity aetiology.

Methods

A cross-sectional analysis was carried out on data on youth who were not trying to change weight (n = 5714), aged 12 to 22 years and from 8 ethnic groups living in New Zealand, Australia, Fiji and Tonga. Demographic and lifestyle data were measured by questionnaires. Fatness was measured by body mass index (BMI), BMI z-score and bioimpedance analysis, which was used to estimate percent body fat and total fat mass (TFM). Associations between lifestyle and body composition variables were examined using linear regression and forest plots.

Results

TV watching was positively related to fatness in a dose-dependent manner. Strong, dose-dependent associations were observed between fatness and soft drink consumption (positive relationship), breakfast consumption (inverse relationship) and after-school physical activity (inverse relationship). Breakfast consumption-fatness associations varied in size across ethnic groups. Lifestyle risk factors for obesity were associated with percentage differences in body composition variables that were greatest for TFM and smallest for BMI.

Conclusions

Lifestyle factors were most strongly related to TFM, which suggests that studies that use BMI alone to quantify fatness underestimate the full effect of lifestyle on adiposity. This study clarifies the size of lifestyle-fatness relationships observed in previous studies.

Comparison of sedentary behaviors between children with autism spectrum disorders and typically developing children

Time spent in sedentary behavior is largely due to time spent engaged with electronic screen media. Little is known about the extent to which sedentary behaviors for children with autism spectrum disorder differ from typically developing children. We used parental report to assess and compare time spent in sedentary behaviors for 53 children with autism spectrum disorder and 58 typically developing children aged 3-11 years. We also determined how sedentary behavior was related to child weight status (body mass index z-score). Overall, children with autism spectrum disorder spent an hour more in sedentary behaviors on weekdays compared to typically developing children (5.2 vs 4.2 h, p = 0.03), and most of this difference was due to screen time. The age- and sex-adjusted estimate of weekday total daily screen time was 1.6 h (typically developing) compared to 2.5 h (autism spectrum disorder, p = 0.004 for difference). A significant relationship between BMI z-score and total sedentary behavior time on weekend days was observed among young children with ASD, but not among TD children. The modest association between weekend sedentary behaviour time and BMI z-score among children with ASD suggests that sedentary behaiour is linked to relative weight status in these children. Further research is needed to confirm these findings and identify causal pathways.

Current mHealth technologies for physical activity assessment and promotion

CONTEXT

Novel mobile assessment and intervention capabilities are changing the face of physical activity (PA) research. A comprehensive systematic review of how mobile technology has been used for measuring PA and promoting PA behavior change is needed.

EVIDENCE ACQUISITION

Article collection was conducted using six databases from February to June 2012 with search terms related to mobile technology and PA. Articles that described the use of mobile technologies for PA assessment, sedentary behavior assessment, and/or interventions for PA behavior change were included. Articles were screened for inclusion and study information was extracted.

EVIDENCE SYNTHESIS

Analyses were conducted from June to September 2012. Mobile phone-based journals and questionnaires, short message service (SMS) prompts, and on-body PA sensing systems were the mobile technologies most utilized. Results indicate that mobile journals and questionnaires are effective PA self-report measurement tools. Intervention studies that reported successful promotion of PA behavior change employed SMS communication, mobile journaling, or both SMS and mobile journaling.

CONCLUSIONS

mHealth technologies are increasingly being employed to assess and intervene on PA in clinical, epidemiologic, and intervention research. The wide variations in technologies used and outcomes measured limit comparability across studies, and hamper identification of the most promising technologies. Further, the pace of technologic advancement currently outstrips that of scientific inquiry. New adaptive, sequential research designs that take advantage of ongoing technology development are needed. At the same time, scientific norms must shift to accept "smart," adaptive, iterative, evidence-based assessment and intervention technologies that will, by nature, improve during implementation.

Association of objectively measured physical activity with body components in European adolescents

Background

Physical activity (PA) is suggested to contribute to fat loss not only through increasing energy expenditure “per se” but also increasing muscle mass; therefore, it would be interesting to better understand the specific associations of PA with the different body’s components such as fat mass and muscle mass. The aim of the present study was to examine the association between objectively measured PA and indices of fat mass and muscle components independently of each other giving, at the same time, gender-specific information in a wide cohort of European adolescents.

Methods

A cross-sectional study in a school setting was conducted in 2200 (1016 males) adolescents (14.7 ±1.2 years). Weight, height, skinfold thickness, bioimpedance and PA (accelerometry) were measured. Indices of fat mass (body mass index, % fat mass, sum of skinfolds) and muscular component (assessed as fat-free mass) were calculated. Multiple regression analyses were performed adjusting for several confounders including fat-free mass and fat mass when possible.

Results

Vigorous PA was positively associated with height (p < 0.05) in males, whilst, vigorous PA, moderate-vigorous PA and average PA were negatively associated with all the indices of fat mass (all p < 0.01) in both genders, except for average PA in relation with body mass index in females. Regarding muscular components, vigorous PA showed positive associations with fat-free mass and muscle mass (all p < 0.05) in both genders. Average PA was positively associated with fat-free mass (both p < 0.05) in males and females.

Conclusion

The present study suggests that PA, especially vigorous PA, is negatively associated with indices of fat mass and positively associated with markers of muscle mass, after adjusting for several confounders (including indices of fat mass and muscle mass when possible). Future studies should focus not only on the classical relationship between PA and fat mass, but also on PA and muscular components, analyzing the independent role of both with the different PA intensities.

Associations between familial affluence and obesity risk behaviours among children

BACKGROUND

Results of studies examining associations between socioeconomic status and obesity among children are mixed.

OBJECTIVE

To examine whether physical activity, television viewing, computer use, and fruit, vegetable, soft drink and sweet consumption differed according to familial affluence of children attending schools in disadvantaged communities.

METHOD

A total of 218 children (seven to 11 years of age) recruited from three Calgary (Alberta) schools located in two adjacent socioeconomically disadvantaged neighbourhoods completed online surveys during the spring of 2005/2006. The number of days per week participating in vigorous physical activity for more than 20 min, and weekly frequency of fruit, vegetable, sweet and soft drink consumption were collected. Time spent watching television and using a computer during a normal school day was also captured. A family affluence scale was used to assess socioeconomic status (number of family holidays in the past year, ownership of motor vehicles and computers, and bedroom sharing). Associations between familial affluence and obesity risk behaviours were estimated using Pearson's correlation and demographic-adjusted logistic regression ORs.

RESULTS

Higher family affluence scale scores were significantly associated with weekly fruit consumption (r=0.14). Children with lower affluence were less likely to participate in vigorous physical activity five days/week or more (OR=0.39), and to use a computer for more than 2 h/day (OR=0.41) than children with higher affluence. Linear trends between familial affluence and the likelihood of participating in physical activity and using a computer were also found. However, no other behaviours were related to affluence.

CONCLUSIONS

Increasing opportunities for physical activity and accessibility to healthy food may be important for reducing obesity risk among less affluent children.

Actividad física, conductas sedentarias y calidad de vida en adolescentes universitarios de Ciudad Guzmán, Jalisco, México

Con el objeto de evaluar la asociación de la actividad física y conductas sedentarias con la calidad de vida en universitarios en Ciudad Guzmán, Jalisco, México, se estudiaron 881 adolescentes de 17-19 años de edad. Se utilizaron los cuestionarios en línea: Youth Quality of Life Instrument Research versión y el Youth Risk Behavior Survey. Se obtuvo razón de momios [RM] mediante regresión logística simple y múltiple. El número de días de actividad física se relacionó con el índice total superior, dominios general superior, personal superior y ambiental superior. Jugar en > 2 equipos deportivos se relacionó con el índice total superior, dominio general superior, dominio personal superior y dominio ambiental superior. Tener 4-5 clases de educación física a la semana se relacionó con el dominio general superior. Pasar dos o menos horas al día frente a la pantalla se relacionó con el dominio relacional superior. En conclusión, en los universitarios adolescentes mexicanos se asoció a indicadores de mejor calidad de vida, el realizar actividad física 4 o más días a la semana, asistir a clases de educación física 4 o 5 semanales, participar en 2 o más equipos deportivos y pasar menos de 2 horas diarias horas frente a pantallas en actividades recreativas.

The relationship between cell phone use, physical and sedentary activity, and cardiorespiratory fitness in a sample of U.S. college students

BACKGROUND

Today's cell phones increase opportunities for activities traditionally defined as sedentary behaviors (e.g., surfing the internet, playing video games). People who participate in large amounts of sedentary behaviors, relative to those who do not, tend to be less physically active, less physically fit, and at greater risk for health problems. However, cell phone use does not have to be a sedentary behavior as these devices are portable. It can occur while standing or during mild-to-moderate intensity physical activity. Thus, the relationship between cell phone use, physical and sedentary activity, and physical fitness is unclear. The purpose of this study was to investigate these relationships among a sample of healthy college students.

METHODS

Participants were first interviewed about their physical activity behavior and cell phone use. Then body composition was assessed and the validated self-efficacy survey for exercise behaviors completed. This was followed by a progressive exercise test on a treadmill to exhaustion. Peak oxygen consumption (VO2 peak) during exercise was used to measure cardiorespiratory fitness. Hierarchical regression was used to assess the relationship between cell phone use and cardiorespiratory fitness after controlling for sex, self-efficacy, and percent body fat. Interview data was transcribed, coded, and Chi-square analysis was used to compare the responses of low and high frequency cell phone users.

RESULTS

Cell phone use was significantly (p = 0.047) and negatively (β = -0.25) related to cardio respiratory fitness independent of sex, self-efficacy, and percent fat which were also significant predictors (p < 0.05). Interview data offered several possible explanations for this relationship. First, high frequency users were more likely than low frequency users to report forgoing opportunities for physical activity in order to use their cell phones for sedentary behaviors. Second, low frequency users were more likely to report being connected to active peer groups through their cell phones and to cite this as a motivation for physical activity. Third, high levels of cell phone use indicated a broader pattern of sedentary behaviors apart from cell phone use, such as watching television.

CONCLUSION

Cell phone use, like traditional sedentary behaviors, may disrupt physical activity and reduce cardiorespiratory fitness.

First report on path analysis for cardiometabolic components in a nationally representative sample of pediatric population in the Middle East and North Africa (MENA): the CASPIAN-III Study

BACKGROUND/AIMS

This study aimed to test a potential model of the relationship between various cardiometabolic risk factors including obesity, unhealthy diet, low physical activity, dyslipidemia, and high blood pressure in a large population-based sample of children and adolescents.

METHODS

In this nationwide study, a representative sample of 5,528 students aged 10-18 years was selected by multistage random cluster sampling from 27 provinces of Iran. Demographic, anthropometric, biological, and biochemical factors were determined. Structural equation modeling (path analysis) was applied to evaluate the causal relationship between these variables.

RESULTS

The mean age of study participants was 14.7 ± 2.41 years and the mean body mass index (BMI) was 19.4 ± 4.1. Higher socioeconomic status was directly associated with unhealthy diet, low physical activity and BMI in both sexes. Age had a positive direct effect on low physical activity in both sexes. BMI showed the greatest direct effect on total cholesterol, triglyceride, low-density lipoprotein cholesterol, and mean arterial pressure in comparison with the direct effects of unhealthy diet and low physical activity. BMI was associated negatively with high-density lipoprotein cholesterol in both groups.

CONCLUSIONS

No previous study has used path analysis for determining the interactions examined in this study among a nationally representative sample of children in the Middle East and North Africa (MENA). The results of this study underline the imperative need for the weight loss and lifestyle change from childhood as the first-line preventive strategy for metabolic syndrome and noncommunicable diseases.

Factors associated with screen time among school-age children in Korea

The purpose of this study was to investigate the association of sociodemographic, psychosocial, and behavioral characteristics with screen time among school-age children in Korea. This study employed a nonexperimental, cross-sectional study design. A total of 370 children attending four elementary schools participated in the study. Self-report method was used, and instruments included screen time (time spent on TV/video/computer/video games), sleep duration, eating behavior, pros and cons of exercise, and exercise self-efficacy. According to the results, 45.7% of the children had screen time of 1-2.9 hr/day and 8.9% had 3 or more hr/day. Increased screen time showed an association with gender (boy), higher body mass index, fast food consumption, higher cons of exercise, having a working mother, and attendance at a school in an inner city area (p < .05). Understanding the factors associated with screen time may provide useful information in the development of health promotion programs aimed at decreasing sedentary behaviors.

Origins of balance disorders during a daily living movement in obese: can biomechanical factors explain everything?

Obese people suffer from postural deficits and are more subject to falls than their lean counterpart. To improve prevention and post-fall rehabilitation programs, it seems important to better understand the posturo-kinetic disorders in daily life situations by determining the contribution of some key factors, mainly morphological characteristics and physical activity level, in the apparition of these disorders. Twelve severe android obese and eight healthy non obese adults performed a reaching task mobilizing the whole body. To further determine the origin of the postural and motor behavior differences, non obese individuals also performed an experimental session with additional constraints which simulated some of the obese morphological characteristics. Impact of the sedentary lifestyle was also studied by dissociation of the obese in two subgroups: physically « active » and physically « inactive ». Movement kinetics and kinematics were characterized with an optoelectronic system synchronized to a force platform. The mechanical equilibrium pattern was evaluated through the displacements of the Centre of Mass (CoM) and the centre of foot pressure within the Base of Support (BoS). Results showed that obesity decreased movement speed (≈-23%, p<0.01), strongly increased CoM displacement (≈+30%, p<0.05) and induced an important spatio-temporal desynchronization (≈+40%, p<0.05) of the focal and postural components of the movement during the transition between the descending and ascending movements. The role of some morphological characteristics and of physical activity on obese patients' postural control disorder is discussed and set back in the more general context of overall factors contributing to postural deficits with obesity.

The health indicators associated with screen-based sedentary behavior among adolescent girls: a systematic review

PURPOSE

Evidence suggests sitting time is independently associated with a range of health issues in adults, yet the relationship between sedentary behavior and health indicators in young people is less clear. Age-related increases in sedentary behavior are well-documented; the behavioral patterns of adolescent girls are of particular concern. More than one third of adolescent girls' sedentary behavior time is accumulated through use of recreational screen-based behaviors. The objective of this review was to investigate the association between recreational screen-based sedentary behavior and the physical, behavioral, and psychosocial health indicators for adolescent girls. A secondary objective was to identify studies that have adjusted sedentary behavior indicators for physical activity.

METHODS

A structured electronic search of all publication years (through December 2011) was conducted to identify studies in: CINAHL, Communications and Mass Media Complete, ERIC, MEDLINE with Full Text, PsycINFO, and SPORTDiscus with Full Text. Included publications were observational and interventional studies involving adolescent girls (12-18 years) that examined associations between screen-based, sedentary behavior and health indicators (physical, psychosocial, and/or behavioral). The search identified 33 studies that evaluated health indicators of screen-based sedentary behaviors among adolescent girls.

RESULTS

Strong evidence for a positive association between screen-based sedentary behavior and weight status was found. A positive association was observed between screen-time and sleep problems, musculoskeletal pain and depression. Negative associations were identified between screen time and physical activity/fitness, screen time and psychological well-being, and screen time and social support. The relationship between screen-based sedentary behavior and diet quality was inconclusive. Less than half of the studies adjusted sedentary behavior indicators for physical activity.

CONCLUSIONS

Screen-based sedentary behavior is associated with a range of adverse health consequences, but additional longitudinal studies are needed to better understand the health impacts. In addition, screen-time guidelines for youth should be regularly revised and updated to reflect rapid technological changes.

Adolescent time use clusters: a systematic review

PURPOSE

Recent research suggests that patterns or clusters of time use may affect health in ways that cannot be explained by the effect of individual behaviors alone. The aim of this research was to systematically review the literature examining adolescent time use clusters and associated correlates.

METHODS

Systematic searches of six online databases for relevant observational studies were conducted. At least two authors reviewed abstract and full text selection meeting eligibility criteria. Included studies were quality scored, had data extracted, and cluster types and cluster associations interpreted.

RESULTS

Nineteen studies were identified for inclusion, and 18 of them investigated cluster-correlate associations. Twenty-nine cluster types were identified, characterized by both individual (e.g., church) and co-occurring behaviors (e.g., physical activity and screen [technoactive]). Nineteen correlate categories were identified (e.g., socioeconomic and weight status). Consistent patterns of cluster-correlate association were found. For example, the technoactive cluster type is more likely to be male and to have low school orientation.

CONCLUSIONS

Despite the between-study differences, consistent cluster and cluster-correlate patterns were still evident. Cluster analysis of adolescent time use behaviors appears to be an emerging and useful classification technique, one which may have implications for targeted health-related interventions.

Childhood physical activity, sports and exercise and noncommunicable disease: a special focus on India

Establishing the relationship between childhood physical inactivity and noncommunicable disease (NCD) is difficult, since chronic disease and mortality are not direct health outcomes of physical inactivity in children. Published literature explores the relationship of physical inactivity with appearance of early childhood disease risk markers, the adverse impact of which may take some time to appear. Promoting childhood physical activity has multiple benefits including delay in evolution of risk factors contributing to adult degenerative disease. It is clear from available literature that physical inactivity or its surrogates constitute an important independent risk factor for NCD. This is likely to be underestimated not only because of measurement issues, but also because physical inactivity may act through other risk factors for NCD. To recognize and intervene on the issue of physical inactivity in children is important not only for the benefit of the child but in the context of NCD in later life. Studies on physical inactivity and its functional correlates are limited in India and this would be an important area for future research.

The relationship between physical activity, physical fitness and overweight in adolescents: a systematic review of studies published in or after 2000

Background

Not only in adults but also in children and adolescents, obesity increases the risk for several health disorders. In turn, many factors including genetic variations and environmental influences (e.g. physical activity) increase the risk of obesity. For instance, 25 to 40 percent of people inherit a predisposition for a high body mass index (BMI). The purpose of this systematic review was to summarize current cross-sectional and longitudinal studies on physical activity, fitness and overweight in adolescents and to identify mediator and moderator effects by evaluating the interaction between these three parameters.

Methods

The electronic academic databases PubMed, SportDiscus, WEB OF KNOWLEDGE and Ovid were searched for studies on physical activity, fitness and overweight in adolescents aged 11 to 19 years (cross-sectional studies) and in adolescents up to 23 years old (longitudinal studies) published in English in or after 2000.

Results

Twelve cross-sectional and two longitudinal studies were included. Only four studies analyzed the interaction among physical activity, fitness and overweight in adolescents and reported inconsistent results. All other studies analyzed the relationship between either physical activity and overweight, or between fitness and overweight. Overweight—here including obesity—was inversely related to physical activity. Similarly, all studies reported inverse relations between physical fitness and overweight. Mediator and moderator effects were detected in the interrelationship of BMI, fitness and physical activity. Overall, a distinction of excessive body weight as cause or effect of low levels of physical activity and fitness is lacking.

Conclusions

The small number of studies on the interrelationship of BMI, fitness and physical activity emphasizes the need for longitudinal studies that would reveal 1) the causality between physical activity and overweight / fitness and overweight and 2) the causal interrelationships among overweight, physical activity and fitness. These results must be carefully interpreted given the lack of distinction between self-reported and objective physical activity and that studies analyzing the metabolic syndrome or cardiovascular disease were not considered. The importance of physical activity or fitness in predicting overweight remains unknown.

Physical activity and 3-year BMI change in overweight and obese children

OBJECTIVES

Targeting physical activity (PA) is a mainstay in obesity treatment, but its BMI benefits are poorly quantified. We studied long-term predictive PA-BMI relationships in overweight/obese children presenting to primary care.

METHODS

Three-year follow-up of 182 overweight/obese 5- to 10-year-olds recruited from 45 Melbourne general practices.

PREDICTOR

7-day accelerometry (counts per minute, cpm).

OUTCOMES

change in BMI z score, BMI category, and clinically significant BMI improvement (z score change ≥0.5).

ANALYSIS

Linear and logistic regression.

RESULTS

Mean (SD) baseline and 3-year BMI z scores were 1.8 (0.6) and 1.8 (0.7), and mean (SD) activity scores 334 (111) and 284 (104) cpm, respectively. Baseline activity did not predict BMI change. However, for every 100 cpm increase in change in activity over 3 years, BMI z score fell by 0.11 (95% confidence interval [CI] 0.03-0.20; P = .006). There were also trends toward greater odds of staying in the same, versus moving to a higher, BMI category (odds ratio 1.85, 95% CI 0.99-3.46) and clinically significant BMI improvement (odds ratio 1.96, 95% CI 0.90-4.27; P = .09). Change in percentage time spent in moderate-vigorous (P = .01), but not sedentary (P = .39) or light (P = .59), activity predicted reduced BMI z score.

CONCLUSIONS

Sustained increase in moderate-vigorous PA predicts reducing BMI z score over 3 years in overweight/obese children presenting to primary care. However, the small BMI change associated with even the largest activity changes may explain disappointing BMI outcomes of brief primary care interventions targeting PA.

Cognitive-behavioural physical activity treatment in African-American pre-schoolers: effects of age, sex, and BMI

AIM

Prevalence of overweight and obesity in children of 5 years and younger has greatly increased in countries including Australia, Canada, the UK and the USA, with African-Americans most affected in the USA. Low amounts of physical activity may be a primary cause. Interventions intended to increase physical activity during pre-school have had minimal effects.

METHODS

A physical activity intervention derived from self-efficacy and social cognitive theory administered by pre-school teachers in the USA (Start For Life) was contrasted with typical care over 8 weeks. The 30-min-per-day treatment incorporated structured gross motor skill physical activities and training in self-management and self-regulation skills. The African-American children in the treatment (n = 154, 21 classrooms) and control (n = 121, 11 classrooms) groups ranged in age from 3.5 to 5.6 years.

RESULTS

Mixed-model repeated measures analysis of variances indicated significantly (P ≤ 0.05) greater increases in moderate-to-vigorous physical activity (MVPA) and vigorous physical activity (VPA) in the treatment group when both the children and classrooms were the unit of analysis. Time in sedentary activities was not affected. Together, age, sex and body mass index (BMI) percentile significantly predicted treatment-related changes in MVPA (R(2) = 0.11) and VPA (R(2) = 0.11), with age (β = -0.22 and β = -0.23, respectively) and BMI percentile (β = -0.24 and β = -0.23, respectively) contributing uniquely to the explained variances indicating greater treatment effects for participants who were younger and had a lower BMI percentile.

CONCLUSIONS

The Start For Life treatment was associated with increased MVPA by approximately 1 h per week, with most of that change being in VPA. After sufficient replication, adjustments may be made to maximise treatment effects.

School and individual-level characteristics are associated with children's moderate to vigorous-intensity physical activity during school recess

OBJECTIVE

The objective of this study was to identify school environmental characteristics associated with moderate to vigorous physical activity during school recess, including morning and lunch breaks.

METHODS

Accelerometry data, child-level characteristics and school physical activity, policy and socio-cultural data were collected from 408 sixth grade children (mean age 11 years) attending 27 metropolitan primary schools in Perth, Western Australia. Hierarchical modelling identified key characteristics associated with children's recess moderate to vigorous physical activity (RMVPA).

RESULTS

Nearly 40% of variability in children's RMVPA was explained by school environment and individual characteristics identified in this study. Children's higher daily RMVPA was associated with newer schools, schools with a higher number of grassed surfaces per child and fewer shaded grassed surfaces, and the physical education coordinator meeting Australian physical activity guidelines.

CONCLUSIONS

Characteristics of the school physical and social environments are strongly correlated with children's MPVA during recess.

IMPLICATIONS

The school environment is an ideal target for maximising children's physical activity during recess. Future research could examine the impact of modifying these environmental characteristics on children's school physical activity.

Physical activity, fitness and the energy cost of activities: implications for obesity in children and adolescents in the tropics

The tropics cover a large section of the world in which both developed and developing countries are situated. Rapid socioeconomic development, modernization, urbanization, and globalization have affected both the food market and physical activity (PA), which in turn have propelled the obesity epidemic in the tropics. There is growing concern that overweight and obesity are emerging as major health problems among children and adolescents in the tropics, despite the fact that undernutrition still exists in many of these countries. Physical inactivity, a low metabolic rate, and lack of physical fitness (PF) have been linked to overweight and obesity. Moreover, PF in several tropical countries is declining, and these changes may be a threat to future health, as low PA and PF levels are important risk factors for noncommunicable chronic diseases. Previous studies have reported that the relationships among PA, PF, overweight, and obesity are inconsistent and inconclusive. There is no indication that variances in the energy cost of physical activities lead to obesity. Despite a lack of definite evidence to prove a causal relationship, there is enough certainty that physical inactivity and low fitness levels are linked to overweight and obesity. Hence, people living in tropical countries need to be encouraged to lead a healthier lifestyle by increasing their PA levels and reducing sedentary behaviors to prevent overweight or obesity.

Television, adiposity, and cardiometabolic risk in children and adolescents

BACKGROUND

It is largely unknown how TV use relates to depot-specific adiposity or cardiometabolic risk in children.

PURPOSE

To examine relationships between having a TV in the bedroom and TV viewing time with total fat mass, abdominal subcutaneous and visceral adiposity, and cardiometabolic risk in children and adolescents.

METHODS

A cross-sectional study of 369 children and adolescents aged 5-18 years was conducted (2010-2011; analysis 2011-2012). Waist circumference; resting blood pressure; fasting triglycerides, high-density lipoprotein cholesterol [HDL-C] and glucose; fat mass by dual-energy x-ray absorptiometry; and abdominal subcutaneous and visceral adiposity by MRI were assessed. Cardiometabolic risk was defined as three or more risk factors including adverse levels of waist circumference, blood pressure, triglycerides, HDL-C, and glucose. Logistic regression analysis was used to compute ORs of high fat mass; subcutaneous and visceral adipose tissue mass (top age-adjusted quartile); and cardiometabolic risk, based on self-reported TV present in the bedroom and TV viewing time, controlling for age, gender, ethnicity, moderate-to-vigorous physical activity level, and unhealthy diet.

RESULTS

In multivariable models, presence of a TV in the bedroom and TV viewing time were associated with (p<0.05) higher odds of high waist circumference (OR=1.9-2.1); fat mass (OR=2.0-2.5); and subcutaneous adiposity (OR=2.1-2.9), whereas viewing TV ≥5 hours/day was associated with high visceral adiposity (OR=2.0). Having a TV in the bedroom was associated with elevated cardiometabolic risk (OR=2.9) and high triglycerides (OR=2.0).

CONCLUSIONS

Having a bedroom TV and TV viewing time were related to high waist circumference, fat mass, and abdominal subcutaneous adiposity. TV viewing time was related to visceral adiposity, and bedroom TV was related to cardiometabolic risk in children, controlling for moderate-to-vigorous physical activity and an unhealthy diet.

REGISTRATION

This study is registered at Clinicaltrials.govNCT01595100.

What helps children to be more active and less sedentary? Perceptions of mothers living in disadvantaged neighbourhoods

BACKGROUND

  Increasing children's participation in physical activity and decreasing time spent in sedentary behaviours is of great importance to public health. Despite living in disadvantaged neighbourhoods, some children manage to engage in health-promoting physical activity and avoid high levels of screen-based activities (i.e. watching TV, computer use and playing electronic games). Understanding how these children manage to do well and whether there are unique features of their home or neighbourhood that explain their success is important for informing strategies targeting less active and more sedentary children. The aim of this qualitative study was to gain in-depth insights from mothers regarding their child's resilience to low physical activity and high screen-time.

METHODS

  Semi-structured face-to-face interviews were conducted with 38 mothers of children who lived in disadvantaged neighbourhoods in urban and rural areas of Victoria, Australia. The interviews were designed to gain in-depth insights about perceived individual, social and physical environmental factors influencing resilience to low physical activity and high screen-time.

RESULTS

  Themes relating to physical activity that emerged from the interviews included: parental encouragement, support and modelling; sports culture in a rural town; the physical home and neighbourhood environment; child's individual personality; and dog ownership. Themes relating to screen-time behaviours encompassed: parental control; and child's individual preferences.

CONCLUSIONS

  The results offer important insights into potential avenues for developing 'resilience' and increasing physical activity and reducing screen-time among children living in disadvantaged neighbourhoods. In light of the negative effects of low physical activity and high levels of screen-time on children's health, this evidence is urgently needed.

Television viewing associated with adverse dietary outcomes in children ages 2-6

The aim of this paper was to systematically review the evidence for the association between television viewing and diet in children ages 2-6. Data sources included PubMed, PsycINFO, EMBASE, ERIC, SportDISCUS, Sociological Abstracts, Web of Science and hand searches of reference lists of relevant articles. Twelve studies were reviewed in which the relationship between television viewing and diet was assessed in children between the ages of 2 and 6. All but one study reported significant relationship between television viewing time and adverse dietary outcomes. Parent-reported television viewing time was used to assay child television viewing in all included studies. Food frequency survey was the most frequent method of dietary assessment, and parent served as proxies for children in all studies. Lower fruit and/or vegetable intake was the most frequently reported dietary outcome, followed by increased energy intake with increased television viewing. The majority of studies reported adverse dietary outcomes with as little as 1 h of daily television exposure. While these results are consistent with recommendations from child health advocates to limit television viewing in young children, they also suggest that further efforts to limit television viewing in young children may be needed to aid in obesity prevention.

Comparing participation in activities among children with disabilities

INTRODUCTION

Compared to typically developing peers, children with disabilities due to neurodevelopmental disorders and disabilities (NDD/D) and to chronic medical conditions (CMC) have reduced participation in activities. The extent to which these two groups of children have different levels of participation is unknown and was examined in this study.

METHODS

The 2006 Participation and Activity Limitation Survey children dataset collected by Statistics Canada was analyzed. Children with disabilities due to NDD/D and CMC were identified following review and classification of all ICD-10 codes in the dataset by two pediatricians. Dependent variables were parent-reported child participation in supervised and unsupervised physical activities within and outside of school, educational activities, and social/recreational activities. Logistic regression analyses, with relevant covariates (child and familial characteristics), were used to analyze the data.

RESULTS

Children with NDD/D were significantly more likely to take part in supervised and unsupervised physical activity at school than children with CMC (p<0.001). A similar trend was observed for participation in school outings, although the effect was not significant at p<0.01. Finally, a trend in the opposite direction was observed for educational activities, as children with NDD/D were less likely to take part in these activities than children with CMC.

DISCUSSION

Finding decreased participation among children with CMC compared with NDD/D was not predicted a priori but has potential implications for their mental and physical health.

CONCLUSIONS

Gaining a better understanding of the barriers to participation in physical activity may contribute to improving the overall health status of children with CMC.

Diet, physical activity, weight status, and culture in a sample of children from the developing world

Objective. Barbados, a small developing state at the end of the nutrition transition, faces an obesity epidemic. Although there is hope of stemming the epidemic in childhood, no descriptions of children's dietary and physical activity (PA) patterns are available for planning purposes. We describe the food and activity preferences and adult encouragement of active and sedentary behaviors for children 9–11 years in relation to weight status and the cultural context. Design. We used data from a pilot study preceding a large-scale ongoing study on the local drivers of the obesity epidemic among preadolescent children. PA, sedentary activity, and dietary intakes were assessed from recalls. Weight and height were measured. Setting. Barbados. Subjects. Sixty-two (62), 9–11-year-old school children. Results. Sugar-sweetened beverages provided 21% of energy consumed. Energy intake significantly explained BMI. Parents selected significantly more of children's sedentary activities and encouraged mostly homework and chores (59%). Children's self-selected school-based activity was significantly related to BMI. Conclusions. Childhood obesity prevention recommendations and research should focus on culture-specific practices that promote acquired taste for excess sugar and parent-child interactions regarding PA. Child influenced by school-based activity intervention may an important area for preventive intervention research.

The mediating effects of dietary habits on the relationship between television viewing and body mass index among youth

OBJECTIVE

There is evidence to suggest that excessive television viewing is an independent determinant of obesity in young people. However, the pathways between television viewing and obesity are not fully understood. Therefore, the purpose of this study was to examine whether the relationship between television and body mass index (BMI) is mediated by television snacking and junk food consumption.

METHODS

Results are based on 15,973 youth in grades 6-10 who participated in the Canadian 2009/2010 health behaviour in school-aged children survey (HBSC). Participants self-reported their weight and height and BMI z-scores were calculated based on World Health Organization growth standards. Participants reported the frequency of snacking while watching television and the frequency of eating junk food (sweets, soft drinks, baked goods, French fries, potato chips). Total hours per week of television were calculated. A contemporary multiple mediation analysis was used to examine associations.

RESULTS

A modest positive relationship was observed between television viewing and BMI. The mean BMI z-score was 0.15 units higher in youth in the highest television viewing quartile by comparison with the youth in the lowest quartile. However, contrary to our hypothesis, television snacking and junk food consumption were not significant positive mediators of the television and BMI relationship.

CONCLUSION

The pathways between television viewing and obesity are complicated and remain poorly understood. Future research using longitudinal or experimental designs, more precise measurement tools and formal mediation analyses is needed. This research should consider mediators related to both energy intake and expenditure.

Associations between factors within the home setting and screen time among children aged 0-5 years: a cross-sectional study

BACKGROUND

Excessive engagement in screen time has several immediate and long-term health implications among pre-school children. However, little is known about the factors that influence screen time in this age group. Therefore, the purpose of this study was to use the Ecologic Model of Sedentary Behavior as a guide to examine associations between intrapersonal, interpersonal, and physical environment factors within the home setting and screen time among pre-school children.

METHODS

Participants were 746 pre-school children (≤ 5 years old) from the Kingston, Ontario, Canada area. From May to September, 2011, parents completed a questionnaire regarding several intrapersonal (child demographics), interpersonal (family demographics, parental cognitions, parental behavior), and physical environment (television, computer, or video games in the bedroom) factors within the home setting. Parents also reported the average amount of time per day their child spent watching television and playing video/computer games. Associations were examined using linear and logistic regression models.

RESULTS

Most participants (93.7%) watched television and 37.9% played video/computer games. Several intrapersonal, interpersonal, and physical environment factors within the home setting were associated with screen time. More specifically, age, parental attitudes, parental barriers, parental descriptive norms, parental screen time, and having a television in the bedroom were positive predictors of screen time; whereas, parental education, parental income, and parental self-efficacy were negative predictors of screen time in the linear regression analysis. Collectively these variables explained 64.2% of the variance in screen time. Parental cognitive factors (self-efficacy, attitudes, barriers, descriptive norms) at the interpersonal level explained a large portion (37.9%) of this variance.

CONCLUSIONS

A large proportion of screen time in pre-school children was explained by factors within the home setting. Parental cognitive factors at the interpersonal level were of particular relevance. These findings suggest that interventions aiming to foster appropriate screen time habits in pre-school children may be most effective if they target parents for behavioral change.

Comparison of physical activity between children with autism spectrum disorders and typically developing children

Regular physical activity is important for promoting health and well-being; however, physical activity behaviors in children with autism spectrum disorders (ASD) have received little attention. We compared physical activity levels among 53 children with ASD and 58 typically developing children aged 3-11 years who participated in the Children's Activity and Meal Patterns Study (CHAMPS). After adjustment for age and sex the amount of time spent daily in moderate and vigorous activity was similar in children with ASD (50.0 minutes/day and typically developing children 57.1 minutes/day). However, parents reported that children with ASD participated in significantly fewer types of physical activities than did typically developing children (6.9 vs. 9.6, p <.0001) and spent less time annually participating in these activities than typically developing children (158 vs. 225 hours per year, p < 0.0001) after adjusting for age and sex. Although both groups of children engaged in similar levels of moderate and vigorous activity as measured by accelerometry, children with ASD engaged in fewer physical activities and for less time according to parental report, suggesting that some of the activity in children with ASD is not captured by standard questionnaire-based measures.

Systematic review of effective strategies for reducing screen time among young children

Screen-media use among young children is highly prevalent, disproportionately high among children from lower-income families and racial/ethnic minorities, and may have adverse effects on obesity risk. Few systematic reviews have examined early intervention strategies to limit TV or total screen time; none have examined strategies to discourage parents from putting TVs in their children's bedrooms or remove TVs if they are already there. In order to identify strategies to reduce TV viewing or total screen time among children <12 years of age, we conducted a systematic review of seven electronic databases to June 2011, using the terms "intervention" and "television," "media," or "screen time." Peer-reviewed intervention studies that reported frequencies of TV viewing or screen-media use in children under age 12 were eligible for inclusion. We identified 144 studies; 47 met our inclusion criteria. Twenty-nine achieved significant reductions in TV viewing or screen-media use. Studies utilizing electronic TV monitoring devices, contingent feedback systems, and clinic-based counseling were most effective. While studies have reduced screen-media use in children, there are several research gaps, including a relative paucity of studies targeting young children (n = 13) or minorities (n = 14), limited long-term (>6 month) follow-up data (n = 5), and few (n = 4) targeting removing TVs from children's bedrooms. Attention to these issues may help increase the effectiveness of existing strategies for screen time reduction and extend them to different populations.

A hitchhiker's guide to assessing sedentary behaviour among young people: deciding what method to use

OBJECTIVE

To provide a user's guide for selecting an appropriate method to assess sedentary behaviours among children and adolescents.

DESIGN

While recommendations regarding specific instruments are not provided, the guide offers information about key attributes and considerations for objective (accelerometry; inclinometers; direct observation; screen monitoring devices) and subjective (self-report; parent report; and time use diaries/logs) approaches to assess sedentary behaviour Attributes of instruments and other factors to be considered in the selection of assessment instruments include: population (age); sample size; respondent burden; method/delivery mode; assessment time frame; physical activity information required (data output); data management; measurement error; cost (instrument and administration) and other limitations.

METHODS

Expert consensus among members of the Australasian Child and Adolescent Obesity Research Network's (ACAORN) Physical Activity and Sedentary Behaviour Special Interest Group.

RESULTS

We developed decision flow charts to assist researchers and practitioners select an appropriate method of assessing sedentary behaviour, identified attributes of each method and described five real-life scenarios to illustrate considerations associated with the selection of each method of measurement.

CONCLUSIONS

It is important that researchers, practitioners and policy makers understand the strengths and limitations of different methods of assessing sedentary behaviour among youth, and are guided on selection of the most appropriate instrument/s to suit their needs.

Objectively assessed physical activity and weight status in Maltese 11-12 year-olds

The objectives of the study were to identify levels of physical activity and sedentary time and assess how they differ by weight status in Maltese boys and girls. Participants were 234 Maltese children aged 11-12 years, of which 187 (80%) provided complete data. Physical activity was assessed using accelerometry and weight status determined through gender-specific age-adjusted Body mass index (BMI). Self-reported mode of transport to school, TV and computer time, gaming and mobile phone use were assessed by questionnaire. Total physical activity was generally very low and significantly lower for girls than boys at all times on weekdays and on weekends till 7 pm. Overweight and obesity prevalence was 27% and 18.6%, respectively. Differences in overall physical activity were observed between non-overweight, and overweight and obese boys (p=0.003). Differences in moderate to vigorous intensity physical activity (MVPA) in boys were significant across all weight categories (p=0.001) and in girls (p=0.020) between the overweight (27.6 min), the non-overweight (26.4 min) and the obese (18.9 min). For weekdays, mean physical activity differences (p=0.013) were observed between non-overweight (515.5 cpm) and obese boys (416.4 cpm). Differences in MVPA were found (p=0.038) between non-overweight (4.4 min) and obese boys in the 6 am-3 pm period. Differences were also found between overweight (13.2 min) and obese girls (8.1 min) (p=0.024) in that period. On weekends, mean physical activity differences were found between non-overweight and overweight boys from 8 am-7 pm but not for girls. Physical activity levels in this sample were very low when compared to recommended levels, while the prevalence of overweight and obesity and sedentary time were high. Girls are significantly less active than boys throughout the week. Activity level differences and patterning across the day and week were related to weight status with obese children showing markedly less activity. These results suggest that we need to provide more opportunities for overweight and obese children to be active throughout the week, with a particular emphasis on physical activity during school hours.

Behavioral risk factors for overweight in early childhood; the 'Be active, eat right' study

Background

The lifestyle-related behaviors having breakfast, drinking sweet beverages, playing outside and watching TV have been indicated to have an association with childhood overweight, but research among young children (below 6 years old) is limited. The aim of the present study was to assess the associations between these four behaviors and overweight among young children.

Methods

This cross-sectional study used baseline data on 5-year-old children (n = 7505) collected for the study ‘Be active, eat right’. Age and sex-specific cut-off points for body mass index of the International Obesity Task Force were used to assess overweight/obesity. Multivariable logistic regression analyses were applied.

Results

For children whom had breakfast <7 days/week and watched TV >2 hours/day, the odds ratio (OR) for having overweight (obesity included) was, respectively, 1.49 (95% confidence interval (CI): 1.13-1.95), and 1.25 (95% CI: 1.03-1.51). There was a positive association between the number of risk behaviors present and the risk for having overweight. For children with 3 or all of the risk behaviors having breakfast <7 days/week, drinking sweet beverages >2 glasses/day, playing outside <1 h/day, watching TV >2 hs/day, the OR for overweight was 1.73 (95% CI: 1.11-2.71) (all models adjusted for children’s sex and sociodemographic characteristics).

Conclusion

Given the positive association between the number of behavioral risk factors and overweight, further studies are needed to evaluate the effectiveness of behavioral counseling of parents of toddlers in preventing childhood overweight. In the meantime we recommend physicians to target all four behaviors for counseling during well-child visits.

Dietary factors associated with overweight and body adiposity in Finnish children aged 6-8 years: the PANIC Study

OBJECTIVES

To investigate the associations of dietary factors with overweight, body fat percentage (BF%), waist circumference (WC) and hip circumference (HC) among children.

DESIGN

Cross-sectional analysis of the Physical Activity and Nutrition in Children (PANIC) Study among 510 children (263 boys, 247 girls) aged 6-8 years from Kuopio, Finland.

METHODS

The children's weight, height, WC and HC were measured. Overweight was defined by International Obesity Task Force body mass index cutoffs. The BF% was measured by dual-energy X-ray absorptiometry, nutrient intakes and meal frequency by 4-day food records and eating behaviour by Children's Eating Behaviour Questionnaire.

RESULTS

Daily consumption of all the three main meals was inversely associated with overweight (odds ratio (OR) 0.37, 95% confidence interval (CI) 0.18-0.75), BF% (β -0.12, P = 0.012), WC (β -0.16, P = 0.002) and HC (β -0.15, P = 0.002). Enjoyment of food, food responsiveness and emotional overeating were directly associated with overweight (OR 1.57, 95% CI 1.04-2.35; OR 4.68, 95% CI 2.90-7.54; OR 2.60, 95% CI 1.52-4.45, respectively), BF% (β 0.13, P = 0.004; β 0.30, P<0.001; β 0.09, P = 0.035, respectively), WC (β 0.14, P = 0.003; β 0.40, P<0.001; β 0.19, P<0.001, respectively) and HC (β 0.15, P = 0.001; β 0.38, P<0.001; β 0.15, P = 0.001, respectively). Satiety responsiveness was inversely associated with overweight (OR 0.42, 95% CI 0.26-0.67), BF% (β -0.20, P<0.001), WC (β -0.26, P<0.001) and HC (β -0.26, P<0.001). Slowness in eating was inversely associated with overweight (OR 0.61, 95% CI 0.41-0.92), WC (β -0.16, P = 0.001) and HC (β -0.17, P<0.001). Protein intake was directly associated with BF% (β 0.11, P = 0.017), WC (β 0.11, P = 0.020) and HC (β 0.13, P = 0.008).

CONCLUSIONS

Promoting regular consumption of main meals and healthy eating behaviours should be emphasized in the prevention of overweight among children. More research is needed on the association of protein-rich foods with body adiposity in children.

Validation and extension of a simple questionnaire to assess physical activity in pre-school children

OBJECTIVE

To (i) validate a recently proposed questionnaire tool for the simple assessment of physical activity (PA) in pre-school children by comparison with accelerometry and heart-rate recordings; and (ii) extend the tool by adding more questions to improve validity and to refine the classification from two to three categories (PA low, medium, high).

SETTING

Baseline data of an intervention evaluation study.

SUBJECTS

Pre-school children.

DESIGN

Children were categorized as either physically active or non-active, based on their parents' answers to the five-item questionnaire. Activity and heart rate were recorded for 6 d (Actiheart device; CamNtech, Cambridge, UK). Nightly sleeping periods were removed and mean accelerometry counts (MACT), time spent in moderate-to-vigorous intensity physical activity (MVPA) and time spent in sedentary behaviour (SB) were computed. In a second step, additional questions that improved validity were added, resulting in an extended seven-item questionnaire.

RESULTS

For 748 (90·4 %) of the participating children aged 2·3-6·7 years, the questionnaires were filled out sufficiently for classification. Children classified as physically active showed 9·6 % higher MACT (P < 0·0003), spent more time in MVPA and insignificantly less time in SB. Using the extended questionnaire, children with PA classified as medium (reference: low) showed 11·0 % more MACT, spent 11·8 % more time in MVPA and 4·8 % less time in SB. Children with PA classified as high showed 16·9 % more MACT, spent 20·2 % more time in MVPA and 7·2 % less time in SB.

CONCLUSIONS

With validated PA questionnaires for pre-school children lacking, the proposed questionnaire might be a reasonable option to include for PA assessment in epidemiological studies where more elaborate measurements are unavailable.

Neighborhood disorder and screen time among 10-16 year old Canadian youth: a cross-sectional study

Background

Screen time activities (e.g., television, computers, video games) have been linked to several negative health outcomes among young people. In order to develop evidence-based interventions to reduce screen time, the factors that influence the behavior need to be better understood. High neighborhood disorder, which may encourage young people to stay indoors where screen time activities are readily available, is one potential factor to consider.

Methods

Results are based on 15,917 youth in grades 6-10 (aged 10-16 years old) who participated in the Canadian 2009/10 Health Behaviour in School-aged Children Survey (HBSC). Total hours per week of television, video games, and computer use were reported by the participating students in the HBSC student questionnaire. Ten items of neighborhood disorder including safety, neighbors taking advantage, drugs/drinking in public, ethnic tensions, gangs, crime, conditions of buildings/grounds, abandoned buildings, litter, and graffiti were measured using the HBSC student questionnaire, the HBSC administrator questionnaire, and Geographic Information Systems. Based upon these 10 items, social and physical neighborhood disorder variables were derived using principal component analysis. Multivariate multilevel logistic regression analyses were used to examine the relationship between social and physical neighborhood disorder and individual screen time variables.

Results

High (top quartile) social neighborhood disorder was associated with approximately 35-45% increased risk of high (top quartile) television, computer, and video game use. Physical neighborhood disorder was not associated with screen time activities after adjusting for social neighborhood disorder. However, high social and physical neighborhood disorder combined was associated with approximately 40-60% increased likelihood of high television, computer, and video game use.

Conclusion

High neighborhood disorder is one environmental factor that may be important to consider for future public health interventions and strategies aiming to reduce screen time among youth.

Reaching the healthy people goals for reducing childhood obesity: closing the energy gap

BACKGROUND

The federal government has set measurable goals for reducing childhood obesity to 5% by 2010 (Healthy People 2010), and 10% lower than 2005-2008 levels by 2020 (Healthy People 2020). However, population-level estimates of the changes in daily energy balance needed to reach these goals are lacking.

PURPOSE

To estimate needed per capita reductions in youths' daily "energy gap" (calories consumed over calories expended) to achieve Healthy People goals by 2020.

METHODS

Analyses were conducted in 2010 to fit multivariate models using National Health and Nutrition Examination Surveys 1971-2008 (N=46,164) to extrapolate past trends in obesity prevalence, weight, and BMI among youth aged 2-19 years. Differences in average daily energy requirements between the extrapolated 2020 levels and Healthy People scenarios were estimated.

RESULTS

During 1971-2008, mean BMI and weight among U.S. youth increased by 0.55 kg/m(2) and by 1.54 kg per decade, respectively. Extrapolating from these trends to 2020, the average weight among youth in 2020 would increase by ∼1.8 kg from 2007-2008 levels. Averting this increase will require an average reduction of 41 kcal/day in youth's daily energy gap. An additional reduction of 120 kcal/day and 23 kcal/day would be needed to reach Healthy People 2010 and Healthy People 2020 goals, respectively. Larger reductions are needed among adolescents and racial/ethnic minority youth.

CONCLUSIONS

Aggressive efforts are needed to reverse the positive energy imbalance underlying the childhood obesity epidemic. The energy-gap metric provides a useful tool for goal setting, intervention planning, and charting progress.

Eating habits and total and abdominal fat in Spanish adolescents: influence of physical activity. The AVENA study

OBJECTIVE

To evaluate the association between specific dietary habits and body fatness in Spanish adolescents, and to analyze the role of leisure-time physical activity (LTPA) in this association.

METHODS

In this cross-sectional study, 1,978 adolescents (1,017 girls) aged 13.0-18.5 years from the AVENA (Alimentación y Valoración del Estado Nutricional en Adolescentes) study were included. Particular dietary habits (breakfast, mid-morning snack, lunch, afternoon snack, dinner, and nighttime snack, as well as time spent eating, number of meals, consumption of soft drinks, and ready-to-eat foods) and LTPA were self-reported and analyzed as dichotomic variables (yes/no). The sum of six skinfold thicknesses and waist circumference (WC) values were the main body fatness variables.

RESULT

Skinfolds and WC values were lower in adolescents who reported consumption of mid-morning snack, afternoon snack, more than four meals per day, and an adequate speed of eating, independently of participation in LTPA. Moreover, a beneficial influence of breakfast consumption on skinfolds and WC values was observed in those adolescent boys who did not participate in LTPA (p for interactions = .044 and .040, respectively).

CONCLUSIONS

In Spanish adolescents, certain healthy dietary habits (i.e., mid-morning snack, afternoon snack, > 4 meals per day, adequate eating speed) are associated with lower body fatness, independently of engaging in LTPA. In addition, among boys with non-LTPA, those who skipped breakfast showed the highest body fatness values, indicating a beneficial influence of daily breakfast on body fat in this particular group.

Weight status of European preschool children and associations with family demographics and energy balance-related behaviours: a pooled analysis of six European studies

This study aimed to (i) gain insight in the prevalence of overweight indices in European preschoolers (4-7 years); (ii) identify energy balance-related behaviours associated with overweight/obesity; and (iii) identify children at risk for overweight/obesity. Secondary analyses of six European data sets were conducted according to standardized protocols. Based on objectively measured height and weight, prevalence of overweight and obesity across the countries ranged from 8% to 30% and 1% to 13%, respectively, with highest rates in Southern European countries (i.e. Spain and Greece). Positive associations between sedentary behaviours and overweight indices were found. Physical activity and dietary behaviours were not associated, possibly because of methodological limitations. Children of parents with high body mass index or low socioeconomic status were at increased risk of overweight/obesity. In conclusion, large differences in prevalence of overweight and obesity among preschoolers across Europe were observed. Future obesity prevention interventions in preschoolers should target screen time giving specific attention to children from overweight and/or low socioeconomic status parents. There is a need for high methodological quality studies, preferably with a long-term prospective design using sensitive, valid and reliable measures of behaviours, assessing whether and which physical activity and dietary behaviours are associated with overweight in preschoolers.

Physical activity fluctuations and body fat during adolescence

OBJECTIVE

The objective of the study was to test the hypothesis that greater fluctuations in physical activity lead to greater increases in body fat during adolescence.

METHODS

Seven hundred fifty-six adolescents in Montreal, Canada, aged 12-13 years at baseline, completed a 7-d physical activity recall questionnaire every 3 months over 5 years. Body mass index (BMI), waist circumference, and triceps and subscapular skinfold thickness were measured at baseline and at the end of follow-up. Subject-specific linear regressions, expressing physical activity as a function of time, were fitted and physical activity fluctuation scores were obtained by averaging the absolute values of regression residuals. The association between body fat after 5 years and the physical activity fluctuation score was assessed in linear regressions adjusting for baseline body fat, average number of physical activity sessions per week, diet and sociodemographic variables.

RESULTS

Among boys, there were statistically significant positive associations between physical activity fluctuation and BMI (β, 95% confidence interval: 0.12, 0.02-0.21) and triceps skinfold (0.40, 0.17-0.63). The associations with waist circumference or subscapular skinfold were not statistically significant (0.22, -0.04-0.49; 0.13, -0.05-0.32, respectively). In girls, there were statistically significant negative associations between physical activity fluctuation and BMI (-0.12, -0.20 to -0.03), waist circumference (-0.54, -0.91 to -0.17), subscapular skinfold (-0.41, -0.56 to -0.26) and triceps skinfold (-0.22, -0.38 to -0.05).

CONCLUSION

Physical activity fluctuations appear to affect body fat during adolescence. Sex-specific interventions may be needed given that greater physical activity fluctuations seem unfavourable for boys and beneficial for girls.

Improving psychological treatment for obesity. Which eating behaviours should we target?

People who are obese and want to lose weight without surgery deserve the best treatment that we can offer. In the absence of robust and enduring treatment effects for psychological interventions for obesity, it is useful to return to first principles. From a behavioural perspective, the first task is to identify the full range of target eating behaviours involved in obesity. Surprisingly, a consensus on the key target eating behaviours typically involved in obesity does not seem to currently exist. In this opinion piece, we discuss which eating behaviours might be important to consider when treating obesity, and provide a self-report questionnaire that aims to identify these behaviours (see Supplementary material). We believe that it is important to be aware of the full range of eating behaviours that are potentially relevant to obesity, as different eating behaviours may be problematic for different people. Target eating behaviours associated with obesity may also be different from those of key relevance to eating disorders. Factors that should be taken into account when assessing target eating behaviours and developing effective treatments for obesity are also discussed. Particular attention is paid to 'grazing,' a relatively neglected high risk eating behaviour for weight gain.

How to make overweight children exercise and follow the recommendations

As regular physical activity of high enough intensity is essential in the management of overweight, efforts should be made to increase physical activity adherence in overweight children. To make overweight children exercise and follow the recommendations, it is essential to have insight into determinants of exercise initiation and adherence. According to the Self-determination Theory, creating opportunities to satisfy the need for autonomy (i.e., having choices), competence (i.e., feeling effective) and relatedness (i.e., being socially connected) might increase autonomous motivation for physical activity in overweight children and promote a long-lasting active lifestyle. To increase feelings of autonomy in overweight children, exercise programs could be delivered in an autonomy-supportive manner by providing choices, supporting the child's initiatives, avoiding use of external rewards, offering relevant information and rationale for changing behaviour, making a decisional balance and using autonomy supportive language, while minimizing pressure and control. Perceived competence in physical activities could be increased by offering activities tailored to the capabilities of the overweight child, helping the children set realistic goals, learning the children self-management skills, providing the children with appropriate feedback and organizing separate exercise sessions for overweight children. Feelings of relatedness in overweight children might increase by adopting an empathic approach, showing interest in the child's well-being and problems, showing enjoyment and enthusiasm, knowing the names of the children, talking to the children as equals, offering group sessions and talks, encouraging club participation and having a sports partner and encouraging parental support.

Sedentary behavior and adiposity-associated inflammation: the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Sedentary behavior is associated with adiposity and cardiometabolic risk.

PURPOSE

To determine the associations between sedentary behavior and measures of adiposity-associated inflammation.

METHODS

Between 2002 and 2005, a total of 1543 Multi-Ethnic Study of Atherosclerosis participants completed detailed health history questionnaires, underwent physical measurements, and had blood assayed for adiponectin, leptin, tumor necrosis factor-alpha (TNF-α) and resistin. Analyses included linear regression completed in 2010. The mean age was 64.3 years and nearly 50% were female. Forty-one percent were non-Hispanic white, 24% Hispanic-American, 20% African-American, and 14% Chinese-American.

RESULTS

In linear regression analyses and with adjustment for age, gender, ethnicity, education, BMI, smoking, alcohol consumption, hypertension, diabetes mellitus, dyslipidemia, hormone therapy and waist circumference, sedentary behavior was associated with higher natural log ("ln") of leptin and ln TNF-α but a lower ln adiponectin-to-leptin ratio (β=0.07, β=0.03 and -0.07, p<0.05 for all). Compared to the first tertile, and after the same adjustment, the second and third tertiles of sedentary behavior were associated with higher levels of ln leptin (β=0.11 and β=0.12, respectively; p<0.05 for both) but lower levels of the adiponectin-to-leptin ratio (β=-0.09 and -0.11, respectively; p<0.05 for both).

CONCLUSIONS

Sedentary behavior is associated with unfavorable levels of adiposity-associated inflammation.

Being Normal Weight but Feeling Overweight in Adolescence May Affect Weight Development into Young Adulthood-An 11-Year Followup: The HUNT Study, Norway

Objectives. To explore if self-perceived overweight in normal weight adolescents influence their weight development into young adulthood and if so, whether physical activity moderates this association. Methods. A longitudinal study of 1196 normal weight adolescents (13-19 yrs) who were followed up as young adults (24-30 yrs) in the HUNT study. Lifestyle and health issues were assessed employing questionnaires, and standardized anthropometric measurements were taken. Chi square calculations and regression analyses were performed to investigate the associations between self-perceived overweight and change in BMI or waist circumference (WC) adjusted for age, age squared, sex, and other relevant cofactors. Results. Adolescents, defined as being normal weight, but who perceived themselves as overweight had a larger weight gain into young adulthood than adolescents who perceived themselves as normal weight (difference in BMI: 0.66 units [CI95%: 0.1, 1.2] and in WC: 3.46 cm [CI95%: 1.8, 5.1]). Level of physical activity was not found to moderate this association. Conclusions. This study reveals that self-perceived overweight during adolescence may affect development of weight from adolescence into young adulthood. This highlights the importance of also focusing on body image in public health interventions against obesity, favouring a "healthy" body weight taking into account natural differences in body shapes.

Association between TV viewing, computer use and overweight, determinants and competing activities of screen time in 4- to 13-year-old children

OBJECTIVE

TV viewing and computer use is associated with childhood overweight, but it remains unclear as to how these behaviours could best be targeted. The aim of this study was to determine to what extent the association between TV viewing, computer use and overweight is explained by other determinants of overweight, to find determinants of TV viewing and computer use in the home environment and to investigate competing activities.

METHOD

A cross-sectional study was carried out among 4072 children aged 4-13 years in the city of Zwolle, the Netherlands. Data collection consisted of measured height, weight and waist circumference, and a parental questionnaire on socio-demographic characteristics, child's nutrition, physical activity (PA) and sedentary behaviour. Associations were studied with logistic regression analyses, for older and younger children, boys and girls separately.

RESULTS

The odds ratio (OR) of being overweight was 1.70 (95% confidence interval (CI): 1.07-2.72) for viewing TV >1.5 h among 4- to 8-year-old children adjusted for all potential confounders. Computer use was not significantly associated with overweight. Determinants of TV viewing were as follows: having >2 TVs in the household (OR: 2.38; 95% CI: 1.66-3.41), a TV in the child's bedroom and not having rules on TV viewing. TV viewing and computer use were both associated with shorter sleep duration and not with less PA.

CONCLUSION

Association between TV viewing and overweight is not explained by socio-demographic variables, drinking sugared drinks and eating snacks. Factors in the home environment influence children's TV viewing. Parents have a central role as they determine the number of TVs, rules and also their children's bedtime. Therefore, interventions to reduce screen time should support parents in making home environmental changes, especially when the children are young.

Social stratification and adolescent overweight in the United States: how income and educational resources matter across families and schools

The current study examines how poverty and education in both the family and school contexts influence adolescent weight. Prior research has produced an incomplete and often counterintuitive picture. We develop a framework to better understand how income and education operate alone and in conjunction with each other across families and schools. We test it by analyzing data from Wave 1 of the U.S.-based National Longitudinal Study of Adolescent Health (N = 16,133 in 132 schools) collected in 1994-1995. Using hierarchical logistic regression models and parallel indicators of family- and school-level poverty and educational resources, we find that at the family-level, parent's education, but not poverty status, is associated with adolescent overweight. At the school-level, the concentration of poverty within a school, but not the average level of parent's education, is associated with adolescent overweight. Further, increases in school poverty diminish the effectiveness of adolescents' own parents' education for protecting against the risks of overweight. The findings make a significant contribution by moving beyond the investigation of a single socioeconomic resource or social context. The findings push us to more fully consider when, where, and why money and education matter independently and jointly across health-related contexts.