Gary S. Goldfield

Systematic review of sedentary behaviour and health indicators in school-aged children and youth

Accumulating evidence suggests that, independent of physical activity levels, sedentary behaviours are associated with increased risk of cardio-metabolic disease, all-cause mortality, and a variety of physiological and psychological problems. Therefore, the purpose of this systematic review is to determine the relationship between sedentary behaviour and health indicators in school-aged children and youth aged 5-17 years. Online databases (MEDLINE, EMBASE and PsycINFO), personal libraries and government documents were searched for relevant studies examining time spent engaging in sedentary behaviours and six specific health indicators (body composition, fitness, metabolic syndrome and cardiovascular disease, self-esteem, pro-social behaviour and academic achievement). 232 studies including 983,840 participants met inclusion criteria and were included in the review. Television (TV) watching was the most common measure of sedentary behaviour and body composition was the most common outcome measure. Qualitative analysis of all studies revealed a dose-response relation between increased sedentary behaviour and unfavourable health outcomes. Watching TV for more than 2 hours per day was associated with unfavourable body composition, decreased fitness, lowered scores for self-esteem and pro-social behaviour and decreased academic achievement. Meta-analysis was completed for randomized controlled studies that aimed to reduce sedentary time and reported change in body mass index (BMI) as their primary outcome. In this regard, a meta-analysis revealed an overall significant effect of -0.81 (95% CI of -1.44 to -0.17, p = 0.01) indicating an overall decrease in mean BMI associated with the interventions. There is a large body of evidence from all study designs which suggests that decreasing any type of sedentary time is associated with lower health risk in youth aged 5-17 years. In particular, the evidence suggests that daily TV viewing in excess of 2 hours is associated with reduced physical and psychosocial health, and that lowering sedentary time leads to reductions in BMI.

Physical activity in the treatment of childhood overweight and obesity: current evidence and research issues.

PURPOSE This paper reviews the utility of exercise as a treatment for overweight and obese children and adolescents. METHODS Computer database searches identified 13 studies that met the following criteria for inclusion: 1) obese children or adolescents were provided either different types of exercise programs or an exercise program compared with a no-exercise control, 2) subjects were randomly assigned to groups or assigned by matching on demographic and anthropometric variables, and 3) the exercise program was at least 2 months in duration. RESULTS The only area in which there were a sufficient number of studies to make a quantitative analysis was the comparison of diet versus diet plus exercise programs, which suggested that exercise adds to the effect of diet in the short-term treatment of pediatric obesity. There was not enough research to evaluate the effects of exercise alone. The majority of findings indicate fitness changes are greater for subjects provided exercise alone or exercise combined with diet in comparison with subjects provided no exercise (control) or diet alone. CONCLUSIONS Research on effects of exercise or physical activity in pediatric obesity treatments are encouraging and may be important for improving treatment outcome for obesity and comorbid conditions. Recommendations for future research are presented.

Body Dissatisfaction, Dietary Restraint, Depression, and Weight Status in Adolescents.

BACKGROUND Adolescence may be a crucial period for developing obesity and associated mental health problems. This study examined the relationship of weight status on body image, eating behavior, and depressive symptoms in youth. METHODS A survey was conducted on 1490 youth attending grades 7-12. Participants completed questionnaires on body image, eating behavior, and mood and were measured for height and weight to calculate body mass index (BMI). Weight classification was based on the International Obesity Task Force guidelines, whereby youth at or above the 95th BMI percentile for age and sex were classified as obese, those between 85th and 94th BMI percentile as overweight, and those between 5th and 84th BMI percentile as normal weight. Several multivariate analyses of variance (MANOVAs) were conducted to examine these relationships. RESULTS Clear relationships emerged between body image and weight classification. Obese youth reported higher body dissatisfaction than overweight youth, who reported more body dissatisfaction than normal weight youth. These effects were independent of age and gender. A relationship was also found for dietary restraint and weight status whereby higher restraint scores were associated with greater adiposity. Similarly, obese youth reported greater depressive symptoms, including anhedonia, negative self-esteem, and higher overall depression scores compared with overweight and normal-weight youth. CONCLUSIONS Psychopathology in obese youth is well known in clinical samples but this study suggests that obese youth in the community may be at increased risk of developing body dissatisfaction, dietary restraint, and depressive symptoms compared with overweight or normal weight youth.

Cost-effectiveness of group and mixed family-based treatment for childhood obesity

OBJECTIVE: Family-based, behavioral treatment has been shown to be an effective intervention for the management of pediatric obesity. The goal of this study was to compare the cost-effectiveness of two protocols for the delivery of family-based behavioral treatment.REASEARCH METHODS AND PROCEDURES: Thirty-one families with obese children were randomized to groups in which families were provided mixed treatment incorporating both group and individualized treatment vs group treatment only. Cost-effectiveness of treatment was defined as the magnitude of reduction in standardized BMI and percentage overweight per dollar spent for recruitment and treatment. Anthropometric data were assessed at baseline, 6 months and 12 months post-randomization.RESULTS: Results for the 24 families with complete data showed the group intervention was significantly more cost-effective than the mixed treatment. This was due to the similarity between the two groups in Z-BMI or percentage overweight change for children and their parents, while the mixed treatment was significantly more expensive to deliver than the group treatment.DISCUSSION: These findings suggest that a family-based, behavioral intervention employing group treatment alone is a more cost-effective approach to treating pediatric obesity than a mixed group plus individual format.

Overweight and obese teenagers: why is adolescence a critical period?

This paper discusses the critical period of adolescence and its potential role in the development and persistence of obesity. The adolescent years are characteristic of changes in body composition (location and quantity of body fat), physical fitness and decreased insulin sensitivity during puberty. This period of growth and maturation is also marked with behavioural changes in diet, physical activity, sedentary behaviour and psychological health. Physical activity and sport participation decline during adolescence especially in teenage girls, while sedentary behaviour, risk for depression and body esteem issues increase during the teenage years. These physiological and behavioural changes during adolescence warrant the attention of health practitioners to prevent the onset and continuation of obesity throughout the lifespan.

Effects of Open-Loop Feedback on Physical Activity and Television Viewing in Overweight and Obese Children: A Randomized, Controlled Trial

OBJECTIVES. Television viewing and physical inactivity increase the risk of obesity in youth. Thus, identifying new interventions that increase physical activity and reduce television viewing would be helpful in the prevention and treatment of pediatric obesity. This study evaluated the effects of open-loop feedback plus reinforcement versus open-loop feedback alone on physical activity, targeted sedentary behavior, body composition, and energy intake in youth. METHODS. Thirty overweight or obese 8- to 12-year-old children were randomly assigned to an intervention (n = 14) or control group (n = 16). Participants wore accelerometers every day for 8 weeks and attended biweekly meetings to download the activity monitors. For children in the open-loop feedback plus reinforcement (intervention) group, accumulating 400 counts of physical activity on pedometers earned 1 hour of television/VCR/DVD time, which was controlled by a Token TV electronic device. Open-loop feedback control subjects wore activity monitors but had free access to targeted sedentary behavior. RESULTS. Compared with controls, the open-loop feedback plus reinforcement group demonstrated significantly greater increases in daily physical activity counts (+65% vs +16%) and minutes per day of moderate-to-vigorous physical activity (+9.4 vs +0.3) and greater reductions in minutes per day spent in television viewing (−116.1 vs +14.3). The intervention group also showed more favorable changes in body composition, dietary fat intake, and energy intake from snacks compared with controls. Reductions in sedentary behavior were directly related to reductions in BMI, fat intake, snack intake, and snack intake while watching television. CONCLUSIONS. Providing feedback of physical activity in combination with reinforcing physical activity with sedentary behavior is a simple method of modifying the home environment that may play an important role in treating and preventing child obesity.

Physical Activity Promotion in the Preschool Years: A Critical Period to Intervene

The primary aim of this paper is to provide a rationale for the necessity of intervening with a physical activity intervention in the preschool years and why the daycare environment is amenable to such intervention. We also review the prevalence of physical activity, sedentary behaviour and obesity in the preschool population and the impact that these lifestyle behaviours and conditions have on the health of preschool aged children, as secondary objectives. Moreover we discuss implications for intervention and research using a “lessons learned” model based on our research team’s experience of conducting a randomized controlled trial aimed at increasing physical activity, reducing sedentary behaviour and improving motor skill development and body composition in preschoolers. Lastly, we make conclusions based on the literature and highlight issues and directions that need to be addressed in future research in order to maximize health promotion and chronic disease prevention in the pediatric population.

Parental activity as a determinant of activity level and patterns of activity in obese children.

Abstract The purposes of this study were to measure the level and pattern of moderate-to-vigorous physical activity (MVPA = > 4.5 METs) and examine predictors of activity in obese children. Fifty-one 8–12-year-old children seeking obesity treatment wore accelerometers for 3 or 4 days. Children averaged 12.2 bouts of MVPA per day that lasted an average of 4.2 min, while parents engaged in 3.9 bouts of MVPA that lasted 4.2 min. Hierarchical regression models showed parent activity improved the prediction of obese childrens activity levels and the number of bouts of MVPA but not the duration of MVPA. These results suggest that programs to increase physical activity in obese children should structure the activity in short bouts and attempt to increase parental physical activity.

Open-loop feedback to increase physical activity in obese children.

OBJECTIVE: The present study investigated whether making access to sedentary activities contingent on physical activity would increase physical activity.DESIGN: Experimental.PARTICIPANTS: Thirty-four obese children aged 8–12 y were randomized to one of three groups in which children had to accumulate 750 or 1500 pedometer counts to earn 10 min of access to video games or movies, or to a control group in which access to sedentary behaviors was provided noncontingently.MEASUREMENTS: Physical activity in the 20 min experimental session was measured by electronic pedometer and triaxial accelerometer (ie TriTrac®). Activity liking was measured by visual analog scales. Anthropometric and demographic characteristics were also assessed.RESULTS: Children in the 750 and 1500 count contingency groups engaged in significantly more physical activity and spent more time in moderate intensity activity or higher compared with controls. Children in the Contingent 1500 group engaged in more activity and spent more time in moderate or greater intensity activity compared to children in the Contingent 750 group.CONCLUSION: Findings suggest that contingent access to sedentary activities can reinforce physical activity in obese children, and changes in physical activity level depend in part on the targeted physical activity goal.

Effects of Aerobic Training, Resistance Training, or Both on Percentage Body Fat and Cardiometabolic Risk Markers in Obese Adolescents: The Healthy Eating Aerobic and Resistance Training in Youth Randomized Clinical Trial

IMPORTANCE Little evidence exists on which exercise modality is optimal for obese adolescents. OBJECTIVE To determine the effects of aerobic training, resistance training, and combined training on percentage body fat in overweight and obese adolescents. DESIGN, SETTING, AND PARTICIPANTS Randomized, parallel-group clinical trial at community-based exercise facilities in Ottawa (Ontario) and Gatineau (Quebec), Canada, among previously inactive postpubertal adolescents aged 14 to 18 years (Tanner stage IV or V) with body mass index at or above the 95th percentile for age and sex or at or above the 85th percentile plus an additional diabetes mellitus or cardiovascular risk factor. INTERVENTIONS After a 4-week run-in period, 304 participants were randomized to the following 4 groups for 22 weeks: aerobic training (n = 75), resistance training (n = 78), combined aerobic and resistance training (n = 75), or nonexercising control (n = 76). All participants received dietary counseling, with a daily energy deficit of 250 kcal. MAIN OUTCOMES AND MEASURES The primary outcome was percentage body fat measured by magnetic resonance imaging at baseline and 6 months. We hypothesized that aerobic training and resistance training would each yield greater decreases than the control and that combined training would cause greater decreases than aerobic or resistance training alone. RESULTS Decreases in percentage body fat were -0.3 (95% CI, -0.9 to 0.3) in the control group, -1.1 (95% CI, -1.7 to -0.5) in the aerobic training group (P = .06 vs controls), and -1.6 (95% CI, -2.2 to -1.0) in the resistance training group (P = .002 vs controls). The -1.4 (95% CI, -2.0 to -0.8) decrease in the combined training group did not differ significantly from that in the aerobic or resistance training group. Waist circumference changes were -0.2 (95% CI, -1.7 to 1.2) cm in the control group, -3.0 (95% CI, -4.4 to -1.6) cm in the aerobic group (P = .006 vs controls), -2.2 (95% CI -3.7 to -0.8) cm in the resistance training group (P = .048 vs controls), and -4.1 (95% CI, -5.5 to -2.7) cm in the combined training group. In per-protocol analyses (≥ 70% adherence), the combined training group had greater changes in percentage body fat (-2.4, 95% CI, -3.2 to -1.6) vs the aerobic group (-1.2; 95% CI, -2.0 to -0.5; P = .04 vs the combined group) but not the resistance group (-1.6; 95% CI, -2.5 to -0.8). CONCLUSIONS AND RELEVANCE Aerobic, resistance, and combined training reduced total body fat and waist circumference in obese adolescents. In more adherent participants, combined training may cause greater decreases than aerobic or resistance training alone. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00195858.