Effects of reinforcing increases in active behavior versus decreases in sedentary behavior for obese children

A dual process model to predict adolescents' screen time and physical activity

OBJECTIVE

Many adolescents report a lack of physical activity (PA) and excess screen time (ST). Psychological theories aiming to understand these behaviours typically focus on predictors of only one behaviour. Yet, behaviour enactment is often a choice between options. This study sought to examine predictors of PA and ST in a single model. Variables were drawn from dual process models, which portray behaviour as the outcome of deliberative and automatic processes.

DESIGN

411 Finnish vocational school students (age 17-19) completed a survey, comprising variables from the Reasoned Action Approach (RAA) and automaticity pertaining to PA and ST, and self-reported PA and ST four weeks later.

MAIN OUTCOME MEASURES

Self-reported time spent on PA and ST and their predictors.

RESULTS

PA and ST correlated negatively (r = -.17, p = .03). Structural equation modelling revealed that intentions and habit for PA predicted PA while ST was predicted by intentions and habit for ST and negatively by PA intentions. RAA-cognitions predicted intentions.

CONCLUSION

PA and ST and their psychological predictors seem to be weakly interlinked. Future studies should assess more behaviours and related psychological influences to get a better picture of connections between different behaviours.

HighlightsPhysical activity and screen time are largely mutually exclusive classes of behaviours and might therefore be related in terms of their psychological predictors.411 adolescent vocational school students self-reported variables from the Reasoned Action Approach and behavioural automaticity related to physical activity and leisure time screen time behaviours as well as those behaviours.Structural equation modelling revealed expected within-behaviour predictions but, against expectations, no strong connections between the two behaviour classes in terms of their predictors. Only intentions to engage in physical activity negatively predicted screen time.Future research should aim to measure a wider range of mutually exclusive classes of behaviours that cover a large share of the day to uncover relations between behaviours and their respective predictors.

Learning about Activity and Understanding Nutrition for Child Health (LAUNCH): Rationale, design, and implementation of a randomized clinical trial of a family-based pediatric weight management program for preschoolers

Obesity affects nearly 2 million preschool age children in the United States and is not abating. However, research on interventions for already obese preschoolers is limited. To address this significant gap in the literature, we developed an intervention targeting obesity reduction in 2 to 5year olds, Learning about Activity and Understanding Nutrition for Child Health (LAUNCH). This paper describes the rationale, design, participant enrollment, and implementation of a 3-arm randomized, parallel-group clinical trial comparing LAUNCH to a motivational-interviewing intervention (MI) and standard care (STC), respectively. Whereas LAUNCH was designed as a skills based intervention, MI focused on addressing the guardian's motivation to make changes in diet and activity and providing tools to do so at the guardian's level of readiness to implement changes. Child body mass index z-score was the primary outcome, assessed at pretreatment, posttreatment (Month 6), and 6 and 12month follow-ups (Months 12 and 18). Mechanisms of weight change (e.g., dietary intake, physical activity) and environmental factors associated with weight (e.g., foods available in the home, caregiver diet) were also assessed. This study is unique because it is one of the few randomized controlled trials to examine a developmentally informed, clinic and home skills based behavioral family intervention for preschoolers who are already obese. Being obese during the preschool years increases the likelihood of remaining obese as an adult and is associated with serious health conditions; if this intervention is successful, it has the potential to change the health trajectories for young children with obesity.

Behavioral Economic Factors Related to Pediatric Obesity

Behavioral economics (BE) suggests that food and activity choices are governed by costs, available alternatives, and reinforcement. This article reviews basic, translational, and intervention research using a BE framework with overweight or obese children up to age 18. We address BE concepts and methods, and discuss developmental issues, the continuum of BE intervention approaches, findings of studies focused on increasing the cost of unwanted behaviors (ie, energy-dense food intake and sedentary behavior) and decreasing the cost of desired behaviors (ie, healthy food intake and PA), and our team's recent basic behavioral studies using BE approaches with minority adolescents.

Current influences and approaches to promote future physical activity in 11-13 year olds: a focus group study

BACKGROUND

Many children and adolescents are failing to meet current physical activity (PA) guidelines and consequently not achieving the benefits associated with regular participation in PA, with girls consistently less active than boys. In order to design interventions to increase physical activity in adolescents it is important to understand their perceptions of and preferences for physical activity.

METHODS

One hundred eighty participants, mean (SD) age 12.1 (0.5) years, completed the Physical Activity Questionnaire for Children (PAQ-C) and had height and weight measured. This information was used to select a subsample of participants (n64; mean (SD) age 12.3 (0.4) years; 39 females; 25 males; 25 % overweight/obese) to take part in focus group discussions. Participants were grouped based on PAQ-C responses into 'low-active' and 'highly-active' groups, so that those with similar existing levels of PA were in the same focus group. A semi-structured discussion guide was employed to explore the key influences on current PA participation and to actively seek ideas on how best to promote future PA in this population. In total, nine focus groups (mixed-gender) were conducted within the school setting. All focus groups were audio recorded, transcribed verbatim and analysed thematically.

RESULTS

A number of themes emerged in relation to influences on current PA including friendship and peers, family and other people, the consequences of not taking part in PA, changing priorities, and cost and access to resources. With regards to the future provision of PA, participants favoured opportunities to try new activities, increased provision of school-based activities which can be undertaken with friends and activities which incorporated the use of technology and encouragement through rewards and incentives. Gender differences were apparent in relation to the types of activities participants preferred taking part in. Differences were also observed between 'low-active' and 'highly-active' groups in relation to barriers to current participation in PA.

CONCLUSIONS

This study has highlighted a number of influences on current and future participation in PA, which differed based on gender and existing PA levels, for example, maximising the potential of the school day and including technology and incentives. These components can inform targeted interventions to increase PA in low active adolescents.

Screen-Time Weight-loss Intervention Targeting Children at Home (SWITCH): a randomized controlled trial

BACKGROUND

Screen-based activities, such as watching television (TV), playing video games, and using computers, are common sedentary behaviors among young people and have been linked with increased energy intake and overweight. Previous home-based sedentary behaviour interventions have been limited by focusing primarily on the child, small sample sizes, and short follow-up periods. The SWITCH (Screen-Time Weight-loss Intervention Targeting Children at Home) study aimed to determine the effect of a home-based, family-delivered intervention to reduce screen-based sedentary behaviour on body composition, sedentary behaviour, physical activity, and diet over 24 weeks in overweight and obese children.

METHODS

A two-arm, parallel, randomized controlled trial was conducted. Children and their primary caregiver living in Auckland, New Zealand were recruited via schools, community centres, and word of mouth. The intervention, delivered over 20 weeks, consisted of a face-to-face meeting with the parent/caregiver and the child to deliver intervention content, which focused on training and educating them to use a wide range of strategies designed to reduce their child's screen time. Families were given Time Machine TV monitoring devices to assist with allocating screen time, activity packages to promote alternative activities, online support via a website, and monthly newsletters. Control participants were given the intervention material on completion of follow-up. The primary outcome was change in children's BMI z-score from baseline to 24 weeks.

RESULTS

Children (n = 251) aged 9-12 years and their primary caregiver were randomized to receive the SWITCH intervention (n = 127) or no intervention (controls; n = 124). There was no significant difference in change of zBMI between the intervention and control groups, although a favorable trend was observed (-0.016; 95% CI: -0.084, 0.051; p = 0.64). There were also no significant differences on secondary outcomes, except for a trend towards increased children's moderate intensity physical activity in the intervention group (24.3 min/d; 95% CI: -0.94, 49.51; p = 0.06).

CONCLUSIONS

A home-based, family-delivered intervention to reduce all leisure-time screen use had no significant effect on screen-time or on BMI at 24 weeks in overweight and obese children aged 9-12 years.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials RegistryWebsite: http://www.anzctr.org.au

TRIAL REGISTRATION NUMBER

ACTRN12611000164998.

Sedentary behavior as a daily process regulated by habits and intentions

OBJECTIVE

Sedentary behavior is a health risk but little is known about the motivational processes that regulate daily sedentary behavior. This study was designed to test a dual-process model of daily sedentary behavior, with an emphasis on the role of intentions and habits in regulating daily sedentary behavior.

METHOD

College students (N = 128) self-reported on their habit strength for sitting and completed a 14-day ecological momentary assessment study that combined daily diaries for reporting motivation and behavior with ambulatory monitoring of sedentary behavior using accelerometers.

RESULTS

Less than half of the variance in daily sedentary behavior was attributable to between-person differences. People with stronger sedentary habits reported more sedentary behavior on average. People whose intentions for limiting sedentary behavior were stronger, on average, exhibited less self-reported sedentary behavior (and marginally less monitored sedentary behavior). Daily deviations in those intentions were negatively associated with changes in daily sedentary behavior (i.e., stronger than usual intentions to limit sedentary behavior were associated with reduced sedentary behavior). Sedentary behavior also varied within people as a function of concurrent physical activity, the day of week, and the day in the sequence of the monitoring period.

CONCLUSIONS

Sedentary behavior was regulated by both automatic and controlled motivational processes. Interventions should target both of these motivational processes to facilitate and maintain behavior change. Links between sedentary behavior and daily deviations in intentions also indicate the need for ongoing efforts to support controlled motivational processes on a daily basis.

A cluster randomized controlled trial of an incentive-based outdoor physical activity program

OBJECTIVE

To evaluate an incentive-based physical activity intervention to increase physical activity and fitness among children in a 9-month cluster randomized controlled trial.

STUDY DESIGN

Children aged 6-12 years were randomized to control (n = 138 from 106 families) or intervention arm (n = 147 from 106 families). The intervention included incentives for meeting step targets as measured by pedometers and structured weekend outdoor activities. Outcomes included trends in activity for the intervention group and between-group differences in pedometer steps, 6-minute walk test, body mass index, and parent-reported Pediatric Quality of Life Inventory.

RESULTS

At follow-up, children in the intervention group recorded significantly more pedometer steps than controls over the entire week (8660 vs 7767; P = .010), on weekdays (8646 vs 7826; P = .041), and on weekends (8779 vs 7684; P = .018). Three different trajectory classes were identified. The first group increased activity but was not sustained, the second group met the target step levels, and the third group significantly surpassed the step goals. The intervention group showed trends toward longer 6-minute walk test times and higher Pediatric Quality of Life Inventory scores, but the differences were not statistically significant.

CONCLUSION

Incentives for increased step activity were effective in producing greater steps and showed a (nonsignificant) trend toward improvements in other health outcomes. Thus, future incentive trials should be incorporate greater step targets and longer follow-up periods to provide evidence of the long-term effect of these incentives on children's health.

Examining the validity of the ActivPAL monitor in measuring posture and ambulatory movement in children

Background

Decreasing sedentary activities that involve prolonged sitting may be an important strategy to reduce obesity and other physical and psychosocial health problems in children. The first step to understanding the effect of sedentary activities on children’s health is to objectively assess these activities with a valid measurement tool.

Purpose

To examine the validity of the ActivPAL monitor in measuring sitting/lying, standing, and walking time, transition counts and step counts in children in a laboratory setting.

Methods

Twenty five healthy elementary school children (age 9.9 ± 0.3 years; BMI 18.2 ± 1.9; mean ± SD) were randomly recruited across the Auckland region, New Zealand. Children were fitted with ActivPAL monitors and observed during simulated free-living activities involving sitting/lying, standing and walking, followed by treadmill and over-ground activities at various speeds (slow, normal, fast) against video observation (criterion measure). The ActivPAL sit-to-stand and stand-to-sit transition counts and steps were also compared with video data. The accuracy of step counts measured by the ActivPAL was also compared against the New Lifestyles NL-2000 and the Yamax Digi-Walker SW-200 pedometers.

Results

We observed a perfect correlation between the ActivPAL monitor in time spent sitting/lying, standing, and walking in simulated free-living activities with direct observation. Correlations between the ActivPAL and video observation in total numbers of sit-to-stand and stand-to-sit transitions were high (r = 0.99 ± 0.01). Unlike pedometers, the ActivPAL did not misclassify fidgeting as steps taken. Strong correlations (r = 0.88-1.00) between ActivPAL step counts and video observation in both treadmill and over-ground slow and normal walking were also observed. During treadmill and over-ground fast walking and running, the correlations were low (r = 0.21-0.46).

Conclusion

The ActivPAL monitor is a valid measurement tool for assessing time spent sitting/lying, standing, and walking, sit-to-stand and stand-to-sit transition counts and step counts in slow and normal walking. The device did not measure accurately steps taken during treadmill and over-ground fast walking and running in children.

Physical activity in the prevention of childhood obesity

The current high prevalence of childhood obesity and its co-morbidities is concomitant with a low level of physical activity and an abundance of sedentary pastimes for Westernised children. To increase the participation of a majority of children in a sustained physical activity, interventions require a fair understanding and consideration of the influences of this behaviour, especially as children are overweight or obese. Basically, the physical activity behaviour of children depends on biological, sociocultural and psychosocial factors and their interplay. The recent literature lends support to the fact that some psychosocial factors such as self-efficacy and physical competence may be solid anchor points upon which to improve the participation of overweight and obese children in free-living physical activity. Thus, interventionists should first concentrate on improving these personal dimensions around which physiological and environmental factors might revolve. The development of motor skills may be a good means for enhancing the self-image of obese children.

Evaluating Parents and Adult Caregivers as “Agents of Change” for Treating Obese Children: Evidence for Parent Behavior Change Strategies and Research Gaps

This scientific statement addresses parents and adult caregivers (PACs) as “agents of change” for obese children, evaluating the strength of evidence that particular parenting strategies can leverage behavior change and reduce positive energy balance in obese youth. The statement has 3 specific aims. The first is to review core behavior change strategies for PACs as used in family-based treatment programs and to provide a resource list. The second is to evaluate the strength of evidence that greater parental “involvement” in treatment is associated with better reductions in child overweight. The third is to identify research gaps and new opportunities for the field. This review yielded limited and inconsistent evidence from randomized controlled clinical trials that greater PAC involvement necessarily is associated with better child outcomes. For example, only 17% of the intervention studies reported differential improvements in child overweight as a function of parental involvement in treatment. On the other hand, greater parental adherence with core behavior change strategies predicted better child weight outcomes after 2 and 5 years in some studies. Thus, the literature lacks conclusive evidence that one particular parenting strategy or approach causally is superior to others in which children have a greater focus in treatment. A number of research gaps were identified, including the assessment of refined parenting phenotypes, cultural tailoring of interventions, examination of family relationships, and incorporation of new technologies. A conceptual model is proposed to stimulate research identifying the determinants of PAC feeding and physical activity parenting practices, the results of which may inform new treatments. The statement addresses the need for innovative research to advance the scope and potency of PAC treatments for childhood obesity.

Etiologies of obesity in children: nature and nurture

Childhood obesity is a profoundly complex problem and serves as an example of a biospsychosocial issue. Scientific inquiry has provided incredible insight into the complex etiology of weight gain but must be viewed as an interaction between a human's propensity to conserve calories for survival in a world with an abundance of it. This article provides a brief overview divided between biological (nature) and psychosocial and behavioral (nurture) factors.

"If there wasn't the technology then I would probably be out everyday": a qualitative study of children's strategies to reduce their screen viewing

OBJECTIVE

To explore the views of British 10-11 year old children towards reducing their screen-viewing and their screen-viewing reduction strategies.

METHOD

10 focus groups were conducted with 55 10-11 year old children (30 girls, 25 boys) in Bristol (UK) in 2010. Data were transcribed and transcripts were analysed using thematic analysis.

RESULTS

Three main themes were developed: Reaction to Reduction; Reduction: What, when and what else instead?; and Strategies to reduce screen-viewing. Participants reacted largely positively to reducing their screen-viewing although enjoyment, established routines and favourite TV programmes presented barriers. A range of screen-viewing modes were put forward as candidates for reduction and participants believed they would replace screen-viewing with both physically active and non-screen sedentary behaviours. Reduction strategies identified comprised the provision of alternative activities, facilities and after school clubs, peer-led educational interventions, behavioural strategies such as the use of rewards, charts and time limits which involved children's parents and parent-child collaboration. Unexpectedly, participants identified the focus group itself as a means of encouraging self-reflection and initiating change.

CONCLUSION

Children appeared open to screen-viewing reduction and identified the strategies that they may respond to best. This can inform the development of interventions designed to reduce screen-viewing.

Prevention of overweight and obesity in children under the age of 6 years

Although obesity was rarely observed among children 30 years ago, it is now evident among Canadian children of all ages. Currently, 15.2% of 2- to 5-year-old children are overweight, whereas 6.3% are obese. Limited data suggest that poor dietary and physical activity patterns are increasing obesity risk among these young children. Body weight and lifestyle behaviours are known to track from childhood to adulthood, thereby increasing the risk for obesity and other chronic diseases later in life. Intrauterine life, infancy, and the preschool years may all include critical periods that program the long-term regulation of energy balance, and therefore obesity-prevention strategies should be initiated in utero and continue throughout childhood and adolescence. Although single-strategy obesity-prevention initiatives have had limited success, programs that target multiple behaviours may help reduce body weight and body fat among young children. Parental involvement is key to the success of obesity-prevention programs at a young age, as parents have primary control over their children's food and activity environments. Accordingly, parental obesity is the best predictor of childhood obesity. Parents should be encouraged to teach and role model healthy lifestyle behaviours for their young children. Health professionals can also be involved in obesity prevention, as they are ideally placed to identify young children at risk for obesity. By calculating and plotting the body mass index for all children, and initiating obesity-prevention strategies in utero, health professionals can help curb the rise in overweight and obesity among young children.

A randomized trial of the effects of reducing television viewing and computer use on body mass index in young children

OBJECTIVE

To assess the effects of reducing television viewing and computer use on children's body mass index (BMI) as a risk factor for the development of overweight in young children.

DESIGN

Randomized controlled clinical trial.

SETTING

University children's hospital.

PARTICIPANTS

Seventy children aged 4 to 7 years whose BMI was at or above the 75th BMI percentile for age and sex.

INTERVENTIONS

Children were randomized to an intervention to reduce their television viewing and computer use by 50% vs a monitoring control group that did not reduce television viewing or computer use.

MAIN OUTCOME MEASURES

Age- and sex-standardized BMI (zBMI), television viewing, energy intake, and physical activity were monitored every 6 months during 2 years.

RESULTS

Children randomized to the intervention group showed greater reductions in targeted sedentary behavior (P < .001), zBMI (P < .05), and energy intake (P < .05) compared with the monitoring control group. Socioeconomic status moderated zBMI change (P = .01), with the experimental intervention working better among families of low socioeconomic status. Changes in targeted sedentary behavior mediated changes in zBMI (P < .05). The change in television viewing was related to the change in energy intake (P < .001) but not to the change in physical activity (P =.37).

CONCLUSIONS

Reducing television viewing and computer use may have an important role in preventing obesity and in lowering BMI in young children, and these changes may be related more to changes in energy intake than to changes in physical activity.

Partnering with libraries to promote walking among community-dwelling adults: a Kingston gets active pilot pedometer-lending project

Most adults do not walk enough to obtain health benefits. Pedometers have been successfully utilized to motivate and increase walking. Given that libraries are a place where community members seek health resources, they are a logical setting for increasing community accessibility to pedometers. The purpose was to examine the feasibility of lending pedometers to library patrons to increase walking. In five Canadian public libraries, 90 pedometers were made available for 6 months. A total of 41 library patrons (33 women, 8 men, age range 18 to 65 or older) completed a survey about their walking patterns and pedometer use. More than 330 loans were made. Chisquare analysis found significant associations between walking and motivation to walk more (p < .05), walking and goal setting (p < .05), and motivation to walk more and setting a walking goal (p < .001). Results provide preliminary evidence that lending pedometers through local libraries is an effective, low-cost approach to enhance walking in community members.

Food reinforcement and eating: a multilevel analysis

Eating represents a choice among many alternative behaviors. The purpose of this review is to provide an overview of how food reinforcement and behavioral choice theory are related to eating and to show how this theoretical approach may help organize research on eating from molecular genetics through treatment and prevention of obesity. Special emphasis is placed on how food reinforcement and behavioral choice theory are relevant to understanding excess energy intake and obesity and how they provide a framework for examining factors that may influence eating and are outside of those that may regulate energy homeostasis. Methods to measure food reinforcement are reviewed, along with factors that influence the reinforcing value of eating. Contributions of neuroscience and genetics to the study of food reinforcement are illustrated by using the example of dopamine. Implications of food reinforcement for obesity and positive energy balance are explored, with suggestions for novel approaches to obesity treatment based on the synthesis of behavioral and pharmacological approaches to food reinforcement.

Physical activity and sedentary lifestyle in children as time-limited functions: usefulness of the principal component analysis method

This study was designed to examine the hourly variation in and the interplay between physical activity and sedentary behavior (SB) in order to highlight key time periods for physical activity interventions for children. Data for physical activity and SB obtained with ActiGraph in 56 boys and 47 girls aged from 8 to 11 years. These data were divided into sixty minute-time samples for moderate-to-vigorous physical activity (MVPA) and SB, and analyzed using a principal component analysis (PCA) and correlation statistics. The PCA provides 10 factors which account for 80.4% of the inertia. Only two of these factors did not display competition between MVPA and SB. Contrary to some reports, a coefficient of correlation of -.68 (p < 10(-4)) was found between daily time spent at MVPA and SB. Some salient traits of children's behaviors were shown through PCA. The results suggested that efficacy of interventions targeting the morning hours (07:00 AM-11:59 AM) and the afternoon period (02:00 PM-05:59 PM) warrants attention.

Increasing children's physical activity: a peer modelling, rewards and pedometer-based intervention

BACKGROUND/OBJECTIVES

To evaluate a peer modelling, rewards and pedometer-feedback intervention designed to increase children's physical activity and which uses the same behaviour-change principles underlying the Food Dude Healthy Eating Programme.

SUBJECTS/METHODS

The study was conducted in two primary schools in Wales. Participants were 47 children (21 boys, 26 girls) from the experimental school and 53 children (29 boys, 24 girls) from a matched control school, aged 9-11 years. Children in the experimental school took part in the intervention; over 8 days they were introduced to fictional role models (the Fit n' Fun Dudes) via visual and audio intervention materials and received small rewards when their daily pedometer step counts increased by 1500 steps per day relative to their baselines. Pedometer measures were taken from children in both schools at baseline, intervention (baseline 2 for the control school) and 12-week follow-up.

RESULTS

Among experimental girls, steps per day were significantly higher during the intervention (14 686+/-2540) and at follow-up (13 737+/-3288) compared to baseline (10 864+/-2481, P<0.001) and control girls (P<0.005). Experimental boys showed significantly higher daily steps during the intervention compared to baseline (16 237+/-4204 cf. 13 452+/-3258, P<0.001) and control boys (P<0.005). There were no significant differences between activity levels of experimental and control boys at follow-up.

CONCLUSIONS

The intervention resulted in substantial increases in children's physical activity, which was well maintained over a 12-week period in girls.

The health benefits of interactive video game exercise

The purpose of this study was to evaluate the effectiveness of interactive video games (combined with stationary cycling) on health-related physical fitness and exercise adherence in comparison with traditional aerobic training (stationary cycling alone). College-aged males were stratified (aerobic fitness and body mass) and then assigned randomly to experimental (n = 7) or control (n = 7) conditions. Program attendance, health-related physical fitness (including maximal aerobic power (VO2 max), body composition, muscular strength, muscular power, and flexibility), and resting blood pressure were measured before and after training (60%–75% heart rate reserve, 3 d/week for 30 min/d for 6 weeks). There was a significant difference in the attendance of the interactive video game and traditional training groups (78% ± 18% vs. 48% ± 29%, respectively). VO2 max was significantly increased after interactive video game (11% ± 5%) but not traditional (3% ± 6%) training. There was a significantly greater reduction in resting systolic blood pressure after interactive video game (132 ± 6 vs. 123 ± 6 mmHg) than traditional (131 ± 7 vs. 128 ± 8 mmHg) training. There were no significant changes in body composition after either training program. Attendance mediated the relationships between condition and changes in health outcomes (including VO2 max, vertical jump, and systolic blood pressure). The present investigation indicates that a training program that links interactive video games to cycle exercise results in greater improvements in health-related physical fitness than that seen after traditional cycle exercise training. It appears that greater attendance, and thus a higher volume of physical activity, is the mechanism for the differences in health-related physical fitness.

Reducing sedentary behavior: the relationship between park area and the physical activity of youth

This study was designed to determine whether the characteristics of the neighborhood environment are related to the substitution of physical activity for sedentary behavior among youth. Fifty-eight 8- to 15-year-old youth were studied in a within-subjects crossover design with three phases: baseline, increased sedentary behavior, and decreased sedentary behavior. The relations between changes in physical activity and design, diversity, and density attributes of the neighborhood environment were determined using random coefficient models. Compared with girls, boys showed greater increases in physical activity when sedentary behaviors were reduced and greater decreases in physical activity when sedentary behaviors were increased. Greater access to parks was associated with greater physical activity when sedentary behaviors were reduced.

Association of family environment with children's television viewing and with low level of physical activity

OBJECTIVE

This study examined associations between the family environment and children's television (TV) viewing and likelihood of being low-active.

RESEARCH METHODS AND PROCEDURES

In 2001, children were recruited from 19 primary schools in Melbourne, Australia. Parents completed a questionnaire about their child's TV viewing and the family environment. Children also completed a questionnaire and wore an accelerometer for 8 days. Movement counts were used to identify low-active children (lowest quartile). Data were analyzed in May 2004.

RESULTS

The sample consisted of 878 children (mean age = 11.5 +/- 0.6 yrs). Multiple logistic regression revealed that socioeconomic status [adjusted odds ratios (AOR) = 0.4 boys], frequency families watched TV together (AOR = 2.0 boys), mothers' (AOR = 1.8 boys; AOR = 2.5 girls) and fathers' (AOR = 2.6 boys; AOR = 2.8 girls) TV viewing, and rules prohibiting TV during mealtimes (AOR = 0.6 boys; AOR = 0.6 girls) related to children watching TV >or=2 h/d. Variables associated with low-level physical activity included self-reported enjoyment of Internet use (AOR = 1.7 boys) and preference for watching TV (AOR = 2.3 girls), perception that mother uses computer a lot (AOR = 1.9 boys) and likes using the computer (AOR = 0.6 girls), fathers' reported computer/electronic games use (AOR = 1.7 girls), frequency families used computer together (AOR = 0.4 girls), rules that TV viewing must be supervised (AOR = 1.9 boys; AOR = 0.6 girls), and having pay TV (AOR = 0.6 boys) and electronic games at home (AOR = 2.6 boys).

DISCUSSION

These findings suggest that the relationships between the family environment and TV viewing and low-level activity are complex and that these behaviors are distinct.

Relationships between media use, body fatness and physical activity in children and youth: a meta-analysis

OBJECTIVE

To review the empirical evidence of associations between television (TV) viewing, video/computer game use and (a) body fatness, and (b) physical activity.

DESIGN

Meta-analysis.

METHOD

Published English-language studies were located from computerized literature searches, bibliographies of primary studies and narrative reviews, and manual searches of personal archives. Included studies presented at least one empirical association between TV viewing, video/computer game use and body fatness or physical activity among samples of children and youth aged 3-18 y.

MAIN OUTCOME MEASURE

The mean sample-weighted corrected effect size (Pearson r).

RESULTS

Based on data from 52 independent samples, the mean sample-weighted effect size between TV viewing and body fatness was 0.066 (95% CI=0.056-0.078; total N=44,707). The sample-weighted fully corrected effect size was 0.084. Based on data from six independent samples, the mean sample-weighted effect size between video/computer game use and body fatness was 0.070 (95% CI=-0.048 to 0.188; total N=1,722). The sample-weighted fully corrected effect size was 0.128. Based on data from 39 independent samples, the mean sample-weighted effect size between TV viewing and physical activity was -0.096 (95% CI=-0.080 to -0.112; total N=141,505). The sample-weighted fully corrected effect size was -0.129. Based on data from 10 independent samples, the mean sample-weighted effect size between video/computer game use and physical activity was -0.104 (95% CI=-0.080 to -0.128; total N=119,942). The sample-weighted fully corrected effect size was -0.141.

CONCLUSION

A statistically significant relationship exists between TV viewing and body fatness among children and youth although it is likely to be too small to be of substantial clinical relevance. The relationship between TV viewing and physical activity is small but negative. The strength of these relationships remains virtually unchanged even after correcting for common sources of bias known to impact study outcomes. While the total amount of time per day engaged in sedentary behavior is inevitably prohibitive of physical activity, media-based inactivity may be unfairly implicated in recent epidemiologic trends of overweight and obesity among children and youth. Relationships between sedentary behavior and health are unlikely to be explained using single markers of inactivity, such as TV viewing or video/computer game use.

Psychometric properties of optimism and pessimism: results from the Girls' Health Enrichment Multisite Studies

Background. This study investigated the relationships among optimism, pessimism, physical activity, and dietary behaviors among 8- to 10-year-old African-American girls in the Girls' Health Enrichment Multisite Studies (GEMS). Methods. Ninety-two girls were randomly assigned to a 12-week physical activity and diet intervention or comparison group and completed psychosocial assessments including the Youth Life Orientation Test (YLOT) of optimism and pessimism, physical performance self-concept, physical activity self-efficacy, physical activity outcome expectancies, and physical activity and sedentary preferences. Also, preferences for bottled water and sweetened beverages were assessed. Physical activity and dietary intake were assessed by self-report and parent-report at baseline and follow-up. Also, physical activity was objectively assessed by wearing an accelerometer for 3 days. The psychometric properties of the optimism-pessimism subscales were analyzed. Results. The measures of optimism and pessimism in children were reliable (r = 0.75-0.82). In the multiple regression analyses without the intervention interaction terms, pessimism was positively and significantly related to increases in MET-adjusted usual activity (P = 0.008) and sedentary behaviors (P = 0.0004). Additionally, a negative (P = 0.026) pessimism by intervention interaction term for MET-adjusted usual activity was found such that the intervention group had a lower change in physical activity per unit increase in pessimism compared to the control group.

CONCLUSIONS

Among 8- to 10-year-old African-American girls, pessimism was related to increased sedentary behaviors and usual activity. Previous studies have reported relationships between optimism and health-compromising behaviors. This study found that pessimism may positively or negatively influence efforts to increase health-promoting behaviors. Future research should confirm and clarify the meaning of these findings.

Physical activity and sedentary behavior: a population-based study of barriers, enjoyment, and preference

The associations of physical activity and sedentary behavior with barriers, enjoyment, and preferences were examined in a population-based mail survey of 1,332 adults. Respondents reporting high enjoyment and preference for physical activity were more likely to report high levels of activity. Those reporting cost, the weather, and personal barriers to physical activity were less likely to be physically active. Preference for sedentary behavior was associated with the decreased likelihood of being physically active, and the weather a barrier to physical activity was associated with the increased likelihood of sedentary behavior. These constructs can be used to examine individual and environmental influences on physical activity and sedentary behavior in specific populations and could inform the development of targeted interventions.

Obesity: responding to the global epidemic

Obesity has reached epidemic proportions in the United States and other developed nations. In the United States, 27% of adults are obese and an additional 34% are overweight. Research in the past decade has shown that genetic influences clearly predispose some individuals to obesity. The marked increase in prevalence, however, appears to be attributable to a toxic environment that implicitly discourages physical activity while explicitly encouraging the consumption of supersized portions of high-fat, high-sugar foods. Management of the obesity epidemic will require a two-pronged approach. First, better treatments, including behavioral, pharmacologic, and surgical interventions, are needed for individuals who are already obese. The second and potentially more promising approach is to prevent the development of obesity by tackling the toxic environment. This will require bold public policy initiatives such as regulating food advertising directed at children. The authors call not for the adoption of a specific policy initiative, but instead propose that policy research, based on viewing obesity as a public health problem, become a central focus of research.

Ethnic differences in physical activity and inactivity patterns and overweight status

OBJECTIVE

To examine the relationship between physical activity and inactivity patterns and overweight in U.S. adolescents using baseline and 1-year change in activity and inactivity data.

RESEARCH METHODS AND PROCEDURES

Nationally representative data from 12,759 participants (6997 non-Hispanic whites, 2676 non-Hispanic blacks, 2185 Hispanics, and 901 Asians) in the National Longitudinal Study of Adolescent Health (1995 and 1996). Data on moderate to vigorous and low-intensity physical activity, TV/video viewing, and video game/computer use were obtained from questionnaires. Multivariate models assessed the association of overweight (body mass index > or = 95th percentile Centers for Disease Control and Prevention/National Center for Health Statistics 2000 curves) with initial (and 1-year change) activity and inactivity levels, controlling for age, ethnicity, socioeconomic status, urban residence, cigarette smoking, and region of residence.

RESULTS

Overweight prevalence was positively associated with high level TV/video viewing among white boys (odds ratio [OR] = 1.52; 95% confidence interval [1.08 to 2.14]) and girls (OR = 2.45 [1.51 to 3.97]). The odds of overweight decreased with high levels of moderate to vigorous physical activity among white boys (OR = 0.81 [0.76 to 0.87]), non-Hispanic black boys (OR = 0.86 [0.76 to 0.98]) and girls (OR = 0.88 [0.78 to 0.99]), and Hispanic boys (OR = 0.90 [0.83 to 0.97]) and girls (OR = 0.91 [0.84 to 0.99]).

DISCUSSION

Predicted probabilities generated from the logistic regression models, which examined the experimental effects of altering hours of TV/video viewing and bouts of moderate to vigorous physical activity, show lower overweight among adolescents who watched less TV per week combined with frequent moderate to vigorous physical activity than those who watched more TV per week combined with fewer bouts of weekly moderate to vigorous physical activity. Predicted probabilities suggest important sex and ethnic differences in these associations.

Reducing sedentary behavior: role in modifying physical activity

Decreased physical activity is associated with the increased incidence of obesity. Behavioral economic research demonstrates that reducing sedentary behaviors in children increases physical activity. Understanding how people choose physical or sedentary activities can aid in developing public health initiatives that increase access to physical activity, while reducing access to sedentary behaviors.

Effects of contingent television on physical activity and television viewing in obese children

OBJECTIVE

Elevated television (TV) viewing and physical inactivity promote obesity in children. Thus, changes in physical activity and sedentary behavior seem critical to treating childhood obesity. PRESENT STUDY: Using a randomized, 2-arm design, this pilot study tested the effects of contingent TV on physical activity and TV viewing in 10 obese children. TV viewing was contingent on pedaling a stationary cycle ergometer for experimental participants but was not contingent on pedaling for control participants. The study was conducted over 12 weeks, including a 2-week baseline period.

RESULTS

Multivariate analyses indicated that the intervention significantly increased pedaling and reduced TV-viewing time. During the treatment phase, the experimental group pedaled 64.4 minutes per week on average, compared with 8.3 minutes by controls. The experimental group watched 1.6 hours of TV per week on average, compared with 21.0 hours per week on average by controls during this phase. Secondary analyses indicated that the experimental group showed significantly greater reductions in total body fat and percent leg fat. Total pedaling time during intervention correlated with greater reductions in percent body fat (r = -0.68).

CONCLUSIONS

Contingencies in the home environment can be arranged to modify physical activity and TV viewing and may have a role in treating childhood obesity. Contingent TV may be one method to help achieve this goal.

An objective measure of reinforcement and its implications for exercise promotion in sedentary Hispanic and Anglo women

An objective measure for the assessment of exercise and sedentary activity choices was evaluated for reliability in 38 sedentary women, aged 18-45, in El Paso, TX. Twenty-two Hispanic women and 16 Anglo women participated. An equal number of obese and nonobese women comprised each group of participants. Using five computer-generated slot machine games, participants were allowed to earn points for access to a bicycle/stair stepper or videos/magazines. Exercise alternatives remained easily accessible while the sedentary choices became progressively difficult to access. Two sessions were completed at least 2 weeks apart for reliability. Reliability for choosing to be physically active from session to session was rI = .83 for all participants, rI = .90 for Hispanics, and rI = .74 for Anglos. Hispanic women earned twice the number of points for access to exercise (m = 20 +/- 2; 40% of the available points) as Anglo women (m = 10 +/- 3; 20% of the available points), independent of body mass index (BMI) or socioeconomic status (SES). Hispanic women's choices to exercise were independent of acculturation level; however, Hispanic women of higher SES and lower BMI chose to exercise more than Hispanic women of lower SES and higher BMI. Hispanic women may find exercise more reinforcing than Anglo women, which has important implications for exercise interventions. In addition, results indicated that self-reported liking and enjoyment of exercise were not related to the choice to actually engage in exercise. The behavioral economic methods presented in this study provide preliminary results to support the use of an objective, reliable method to assess the determinants of exercise and sedentary activity choices in sedentary, Hispanic and Anglo women.

Comparison of health promotion and deterrent prompts in increasing use of stairs over escalators

This study compared the effectiveness of two point-of-decision prompts within the same environmental setting. The effects of a health promotion sign were compared with activity change resulting from a deterrent sign. Individuals were observed using the upward stairs or upward escalator at a midwest regional air port during a 5-week period in which intervention signs were compared with no sign conditions on activity choice. During Weeks 1, 3, and 5 behaviors were assessed without any prompts. During Week 2, a health promotion sign was posted at the behavioral choice point which read "Keep your heart healthy, use the stairs." During Week 4, a deterrent sign which read "Please limit escalator use to staff and those unable to use the stairs" was posted at the same behavioral choice point. Younger (<40) women (14.8%) and men (10.8%) used the stairs more frequently, followed by older women (9.3%) and older men (6.9%). A hierarchical log linear analysis showed that stair use increased during both interventions, which was significantly moderated by age. Point-of-decision prompts appear to be effective environmental interventions for promoting increases in 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(R)). 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.

Determinants of adolescent physical activity and inactivity patterns

OBJECTIVES

Despite recognition of the important influence of environmental determinants on physical activity patterns, minimal empirical research has been done to assess the impact of environmental/contextual determinants of physical activity. This article aims to investigate environmental and sociodemographic determinants of physical activity and inactivity patterns among subpopulations of US adolescents. We define environmental determinants as modifiable factors in the physical environment that impose a direct influence on the opportunity to engage in physical activity. The present research examines environmental and sociodemographic determinants of physical activity and inactivity with the implication that these findings can point toward societal-level intervention strategies for increasing physical activity and decreasing inactivity among adolescents.

STUDY DESIGN AND METHODOLOGY

The study population consists of nationally representative data from the 1996 National Longitudinal Study of Adolescent Health on 17 766 US adolescents enrolled in US middle and high schools (including 3933 non-Hispanic blacks, 3148 Hispanics, and 1337 Asians). Hours/week of inactivity (TV/video viewing and video/computer games) and times/week of moderate to vigorous physical activity were collected by questionnaire. Outcome variables were moderate to vigorous physical activity and inactivity, which were broken into categories (physical activity: 0-2 times/week, 3-4 times/week, and >/=5 times/week; inactivity: 0-10 hours/week, 11-24 hours/week, and >/=25 hours/week). Sociodemographic and environmental correlates of physical activity and inactivity were used as exposure and control variables and included sex, age, urban residence, participation in school physical education program, use of community recreation center, total reported incidents of serious crime in neighborhood, socioeconomic status, ethnicity, generation of residence in the United States, presence of mother/father in household, pregnancy status, work status, in-school status, region, and month of interview. Logistic regression models of high versus low and medium physical activity and inactivity were used to investigate sex and ethnic interactions in relation to environmental and sociodemographic factors to examine evidence for the potential impact of physical education and recreation programs and sociodemographic factors on physical activity and inactivity patterns.

RESULTS

Moderate to vigorous physical activity was lower and inactivity higher for non-Hispanic black and Hispanic adolescents. Participation in school physical education programs was considerably low for these adolescents and decreased with age. Participation in daily school physical education (PE) program classes (adjusted odds ratio [AOR]: 2.21; confidence interval [CI]: 1.82-2.68) and use of a community recreation center (AOR: 1.75; CI: 1.56-1.96) were associated with an increased likelihood of engaging in high level moderate to vigorous physical activity. Maternal education was inversely associated with high inactivity patterns; for example, having a mother with a graduate or professional degree was associated with an AOR of.61 (CI:.48-.76) for high inactivity. High family income was associated with increased moderate to vigorous physical activity (AOR: 1.43; CI: 1.22-1.67) and decreased inactivity (AOR:.70; CI:.59-.82). High neighborhood serious crime level was associated with a decreased likelihood of falling in the highest category of moderate to vigorous physical activity (AOR:.77; CI:.66-.91).

CONCLUSIONS

These results show important associations between modifiable environmental factors, such as participation in school PE and community recreation programs, with activity patterns of adolescents. Despite the marked and significant impact of participation in school PE programs on physical activity patterns of US adolescents, few adolescents participated in such school PE programs; only 21.3% of all adolescents

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.

Adolescent physical activity and inactivity vary by ethnicity: The National Longitudinal Study of Adolescent Health

OBJECTIVES

To determine the extent to which physical activity and inactivity patterns vary by ethnicity among subpopulations of US adolescents.

STUDY DESIGN

Nationally representative data from the 1996 National Longitudinal Study of Adolescent Health of >14,000 US adolescents (including 3135 non-Hispanic blacks, 2446 Hispanics, and 976 Asians).

METHODS

Hours per week of inactivity (TV viewing, playing video or computer games) and times per week of moderate to vigorous physical activity were collected by using questionnaire data. Multinomial logistic regression models of physical activity and inactivity were used to adjust for sociodemographic factors.

RESULTS

Large ethnic differences are seen for inactivity, particularly for hours of television or video viewing per week (non-Hispanic blacks, mean = 20.4; non-Hispanic whites, mean = 13.1). Physical activity (>/=5 bouts of moderate to vigorous physical activity per week, 5-8 metabolic equivalents) is lowest for female and minority adolescents. Ethnic differences are far greater for inactivity than for moderate to vigorous physical activity.

CONCLUSION

Minority adolescents, with the exception of Asian females, have consistently higher levels of inactivity. Results vary by sex; males have higher inactivity and physical activity, whereas lowest physical activity is found for non-Hispanic black and Asian females, although Asian females also have low inactivity and low levels of overweight. Overall, efforts to reduce the problem of adolescent overweight should focus on increasing activity levels of adolescents, particularly female, older, and major minority subpopulations.

Integrating theoretical approaches to promote physical activity

CONTEXT

Research on the promotion of physical activity has been based on a variety of conceptual models. These models generally target one level of analysis, such as the individual, community, or the environment, and differ in their relative contact with basic or applied science. There have been limited attempts to develop approaches that target multiple levels of analysis and can stimulate basic and applied research.

OBJECTIVE

Theoretical integration in a multidiscliplinary field such as promotion of physical activity should take into account that social, behavioral, and biomedical colleagues may use different explanatory models, and use different approaches to the development of scientific knowledge. This essay argues for the development of integration of theory across multiple domains that can incorporate methods and findings of basic and applied scientists, and that uses language and methods common to social, behavioral, and biomedical scientists.

METHOD

Behavioral choice theory is presented as an example of one theoretical approach that bridges different approaches to physical activity intervention, and that can stimulate both basic and applied research on physical activity. Behavioral research on choice was discussed in relationship to basic research, human laboratory research, and community and clinical research.

CONCLUSIONS

Implications of behavioral choice theory for community and environmental change was discussed. The essay ends with ideas for future directions in integration of theory for physical activity research.

Environmental and policy interventions to promote physical activity

BACKGROUND

Because most adults in industrialized countries do not meet physical activity guidelines, population-wide interventions are needed. Environmental and policy interventions are based on ecological models of behavior and have the potential to influence entire populations. Ecological models are particularly applicable to physical activity because the behavior must be done in specific physical settings. Cross-sectional data indicate that environmental and policy variables are associated with physical activity behaviors of young people and adults.

METHOD

Seven published evaluations of environmental and policy interventions to increase physical activity were reviewed.

RESULTS

Two studies showed that placing signs encouraging stair use can be effective. Quasi-experimental evaluations provided limited evidence that broad environmental changes can be effective. Large-scale policy interventions are currently being conducted in several countries. PROPOSED MODEL: A model describing the development of policy and environmental interventions is proposed, in the hope of stimulating more research in this area. Advocacy or planning groups identify and work with agencies that control policies and environments that can be altered to increase physical activity. Educational and policy/environmental interventions are seen as complementary.

CONCLUSION

Lack of conceptual models and the inherent difficulties of evaluation have hampered research on environmental and policy interventions. Further research is needed, and practitioners and researchers should work together to evaluate programs.

Theories and techniques for promoting physical activity behaviours

The primary goal of this article is to review theoretical models utilised in designing physical activity interventions for healthy adults. Physical activity offers numerous benefits for improved physical and psychological health. However, the majority of the population is sedentary and therefore at increased risk for morbidity and mortality. Many techniques have been developed for intervening with physical activity behaviours, some of which are based on theoretical models. While some of these models show more promise than others, no model is sufficient to thoroughly explain exercise behaviours or how to best intervene. In the final section, recommendations for future research are presented, and promising areas of development in physical activity interventions are discussed. This is not an exhaustive review of theoretical models but rather focuses on models most commonly applied to physical activity.