Promotion of physical activity among high-school girls: a randomized controlled trial

Practical physical activity measurement in youth: a review of contemporary approaches

BACKGROUND

The accurate evaluation of physical activity levels amongst youth is critical for quantifying physical activity behaviors and evaluating the effect of physical activity interventions. The purpose of this review is to evaluate contemporary approaches to physical activity evaluation amongst youth.

DATA SOURCES

The literature from a range of sources was reviewed and synthesized to provide an overview of contemporary approaches for measuring youth physical activity.

RESULTS

Five broad categories are described: self-report, instrumental movement detection, biological approaches, direct observation, and combined methods. Emerging technologies and priorities for future research are also identified.

CONCLUSIONS

There will always be a trade-off between accuracy and available resources when choosing the best approach for measuring physical activity amongst youth. Unfortunately, cost and logistical challenges may prohibit the use of "gold standard" physical activity measurement approaches such as doubly labelled water. Other objective methods such as heart rate monitoring, accelerometry, pedometry, indirect calorimetry, or a combination of measures have the potential to better capture the duration and intensity of physical activity, while self-reported measures are useful for capturing the type and context of activity.

Influence of sports, physical education, and active commuting to school on adolescent weight status

OBJECTIVE

To compare the associations between weight status and different forms of physical activity among adolescents.

METHODS

We conducted telephone surveys with 1718 New Hampshire and Vermont high school students and their parents as part of a longitudinal study of adolescent health. We surveyed adolescents about their team sports participation, other extracurricular physical activity, active commuting, physical education, recreational activity for fun, screen time, diet quality, and demographics. Overweight/obesity (BMI for age ≥ 85th percentile) and obesity (BMI for age ≥ 95 percentile) were based on self-reported height and weight.

RESULTS

Overall, 29.0% (n = 498) of the sample was overweight/obese and 13.0% (n = 223) were obese. After adjustments, sports team participation was inversely related to overweight/obesity (relative risk [RR] = 0.73 [95% confidence interval (CI): 0.61, 0.87] for >2 sports teams versus 0) and obesity (RR = 0.61 [95% CI: 0.45, 0.81] for >2 sports teams versus 0). Additionally, active commuting to school was inversely related to obesity (RR = 0.67 [95% CI: 0.45, 0.99] for >3.5 days per week versus 0). Attributable risk estimates suggest obesity prevalence would decrease by 26.1% (95% CI: 9.4%, 42.8%) if all adolescents played on 2 sports teams per year and by 22.1% (95% CI: 0.1%, 43.3%) if all adolescents walked/biked to school at least 4 days per week.

CONCLUSIONS

Team sport participation had the strongest and most consistent inverse association with weight status. Active commuting to school may reduce the risk of obesity, but not necessarily overweight, and should be studied further. Obesity prevention programs should consider strategies to increase team sport participation among all students.

Community-engaged interventions on diet, activity, and weight outcomes in U.S. schools: a systematic review

CONTEXT

Community engagement literature suggests that capacity-building approaches and community partnership in health intervention design, delivery, and analysis improve outcomes. School communities influence childhood diet and activity patterns affecting lifelong obesity risk. This systematic review's purpose is to assess whether incorporating community engagement principles in school-based interventions influences weight-related outcomes.

EVIDENCE ACQUISITION

Obesity-prevention interventions (published January 2000-2011) in diverse U.S. schools, meeting a minimum threshold of community engagement and targeting weight-, diet- or activity-related outcomes were identified in MEDLINE, PsycINFO, and CINAHL (December 2010-March 2011). Two reviewers scored community engagement performance on 24 metrics of capacity building and partner involvement along four research stages. Outcome performance was calculated as percentage of targeted primary and/or secondary outcomes achieved.

EVIDENCE SYNTHESIS

Sixteen studies were included, targeting anthropometric (n = 12); dietary (n = 13); and activity (n = 10) outcomes in schoolchildren (mean age=10.7 years). Studies averaged 46% of targeted outcomes (95% CI = 0.33, 0.60) and met 60% of community engagement metrics. Positive correlations existed between community engagement performance and all-outcome performance (r = 0.66, 95% CI = 0.25, 0.87) and secondary-outcome performance (r = 0.67, 95% CI = 0.22, 0.89), but not primary-outcome performance (r = 0.26, 95% CI = -0.27, 0.67). Number of outcomes met was not correlated with number of outcomes targeted, number of partners, or study size. Specific qualitative and quantitative trends suggested that capacity-building efforts, engagement in needs assessments and results dissemination, and durable partnerships positively influence outcomes.

CONCLUSIONS

Results suggest that meaningful partnership of diverse school communities within obesity prevention interventions can improve health outcomes.

The healthy options for nutrition environments in schools (Healthy ONES) group randomized trial: using implementation models to change nutrition policy and environments in low income schools

Background

The Healthy Options for Nutrition Environments in Schools (Healthy ONES) study was an evidence-based public health (EBPH) randomized group trial that adapted the Institute for Healthcare Improvement’s (IHI) rapid improvement process model to implement school nutrition policy and environmental change.

Methods

A low-income school district volunteered for participation in the study. All schools in the district agreed to participate (elementary = 6, middle school = 2) and were randomly assigned within school type to intervention (n = 4) and control (n =4) conditions following a baseline environmental audit year. Intervention goals were to 1) eliminate unhealthy foods and beverages on campus, 2) develop nutrition services as the main source on campus for healthful eating (HE), and 3) promote school staff modeling of HE. Schools were followed across a baseline year and two intervention years. Longitudinal assessment of height and weight was conducted with second, third, and sixth grade children. Behavioral observation of the nutrition environment was used to index the amount of outside foods and beverages on campuses. Observations were made monthly in each targeted school environment and findings were presented as items per child per week.

Results

From an eligible 827 second, third, and sixth grade students, baseline height and weight were collected for 444 second and third grade and 135 sixth grade students (51% reach). Data were available for 73% of these enrolled students at the end of three years. Intervention school outside food and beverage items per child per week decreased over time and control school outside food and beverage items increased over time. The effects were especially pronounced for unhealthy foods and beverage items. Changes in rates of obesity for intervention school (28% baseline, 27% year 1, 30% year 2) were similar to those seen for control school (22% baseline, 22% year 1, 25% year 2) children.

Conclusions

Healthy ONES adaptation of IHI’s rapid improvement process provided a promising model for implementing nutrition policy and environmental changes that can be used in a variety of school settings. This approach may be especially effective in assisting schools to implement the current federally-mandated wellness policies.

Twice-weekly, in-school jumping improves lean mass, particularly in adolescent boys

OBJECTIVE

To determine the effect of a twice-weekly, school-based, 10-min jumping regime on muscle and fat tissue in healthy adolescent boys and girls.

METHODS

We replaced regular warm-up activities with jumping in physical education (PE) classes of early high school students for 8 months to observe the effect on muscle and fat tissue. A total of 99 adolescents (46 boys, 53 girls; 13.8 ± 0.4 years) volunteered to participate. Intervention group subjects performed 10 min of varied jumping activity, while control subjects performed a regular PE warm-up. Biometrics, Tanner staging, age of peak height velocity (PHV), vertical jump, whole body lean tissue and fat mass (dual-energy X-ray absorptiometry-derived) were measured at baseline and follow-up. Physical activity was determined by questionnaire.

RESULTS

There were no differences in any measured variable between control and intervention groups at baseline. Boys had a significantly older age of PHV than girls (p = 0.02). No group differences were detected for 8-month change in height, weight or maturity measures for the combined sample; however, at 8 months, jumpers had accrued greater lean tissue mass than controls (p = 0.002). Sex-specific analysis revealed that intervention group boys had gained more lean tissue mass than controls (p = 0.016) and experienced significant fat loss (p = 0.010) than controls, an effect that was not observed in the girls.

CONCLUSION

Regular, short-duration, jumping activity during adolescence increased lean tissue mass and boys additionally lost fat mass. Sex-specific and/or maturation-specific factors may explain the disparity in effect.

Cardiorespiratory fitness and proximity to commercial physical activity facilities among 12th grade girls

PURPOSE

To investigate the relationship between proximity to commercial physical activity (PA) facilities and cardiorespiratory fitness of 12th grade girls.

METHODS

Adolescent girls (n = 786, 60% African American, mean age = 17.6 ± .6 years) performed a submaximal fitness test (Physical Work Capacity 170 test). Commercial PA facilities were mapped and counted within a .75-mile street-network buffer around girls' homes using Geographic Information Systems. Sedentary activities and vigorous physical activity (≥6 metabolic equivalents) were determined by the average number of 30-minute blocks reported per day on the 3-Day Physical Activity Recall. Mixed model regressions were calculated using school as a random variable.

RESULTS

Girls had higher weight-relative Physical Work Capacity 170 test scores if there was a commercial PA facility (n = 186, 12.4 ± 4.2 kg m/min/kg) within a .75-mile street-network buffer of home as compared with girls without a nearby facility (n = 600, 11.2 ± 3.6 kg m/min/kg). After adjusting for demographic variables, sports participation, sedentary behaviors, and vigorous physical activity, having one or more commercial PA facilities within a .75-mile street-network buffer of homes was significantly related to cardiorespiratory fitness.

CONCLUSIONS

Both with and without adjustment for covariates, the presence of a commercial PA facility within a .75-mile street-network buffer of a girl's home was associated with higher cardiorespiratory fitness.

Assessing sustainability of Lifestyle Education for Activity Program (LEAP)

Sustained intervention effects are needed for positive health impacts in populations; however, few published examples illustrate methods for assessing sustainability in health promotion programs. This paper describes the methods for assessing sustainability of the Lifestyle Education for Activity Program (LEAP). LEAP was a comprehensive school-based intervention that targeted change in instructional practices and the school environment to promote physical activity (PA) in high school girls. Previous reports indicated that significantly more girls in the intervention compared with control schools reported engaging in vigorous PA, and positive long-term effects on vigorous PA also were observed for girls in schools that most fully implemented and maintained the intervention 3 years following the active intervention. In this paper, the seven steps used to assess sustainability in LEAP are presented; these steps provide a model for assessing sustainability in health promotion programs in other settings. Unique features of the LEAP sustainability model include assessing sustainability of changes in instructional practices and the environment, basing assessment on an essential element framework that defined complete and acceptable delivery at the beginning of the project, using multiple data sources to assess sustainability, and assessing implementation longitudinally.

Benefits and environmental determinants of physical activity in children and adolescents

In this review, we identify the health benefits associated with physical activity (PA); address the physical activity and sedentary guidelines issued by public health scientists as well as children's compliance to these guidelines; discuss the importance of motor skill acquisition during early childhood; and identify different settings that contribute to physical activity participation and strategies for improving PA in these settings. Results show that regular participation in PA during childhood has numerous immediate benefits, including positive changes in adiposity, skeletal health, psychological health, and cardiorespiratory fitness. Additionally, motor skill development during early childhood may have immediate health benefits as well as long-lasting effects in adulthood. Furthermore, the benefits of PA during childhood also appear to positively influence adult health outcomes, such as increased bone mineral density. Key environmental settings that have been shown to influence children's PA behavior include child care, active commuting to and from school, school recess, school physical education, after-school programs, churches, medical settings, and the home environment. Recommendations for practitioners and researchers are discussed.

Interventions for preventing obesity in children

BACKGROUND

Prevention of childhood obesity is an international public health priority given the significant impact of obesity on acute and chronic diseases, general health, development and well-being. The international evidence base for strategies that governments, communities and families can implement to prevent obesity, and promote health, has been accumulating but remains unclear.

OBJECTIVES

This review primarily aims to update the previous Cochrane review of childhood obesity prevention research and determine the effectiveness of evaluated interventions intended to prevent obesity in children, assessed by change in Body Mass Index (BMI). Secondary aims were to examine the characteristics of the programs and strategies to answer the questions "What works for whom, why and for what cost?"

SEARCH METHODS

The searches were re-run in CENTRAL, MEDLINE, EMBASE, PsychINFO and CINAHL in March 2010 and searched relevant websites. Non-English language papers were included and experts were contacted.

SELECTION CRITERIA

The review includes data from childhood obesity prevention studies that used a controlled study design (with or without randomisation). Studies were included if they evaluated interventions, policies or programs in place for twelve weeks or more. If studies were randomised at a cluster level, 6 clusters were required.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias of included studies.  Data was extracted on intervention implementation, cost, equity and outcomes. Outcome measures were grouped according to whether they measured adiposity, physical activity (PA)-related behaviours or diet-related behaviours.  Adverse outcomes were recorded. A meta-analysis was conducted using available BMI or standardised BMI (zBMI) score data with subgroup analysis by age group (0-5, 6-12, 13-18 years, corresponding to stages of developmental and childhood settings).

MAIN RESULTS

This review includes 55 studies (an additional 36 studies found for this update). The majority of studies targeted children aged 6-12 years.  The meta-analysis included 37 studies of 27,946 children and demonstrated that programmes were effective at reducing adiposity, although not all individual interventions were effective, and there was a high level of observed heterogeneity (I(2)=82%).  Overall, children in the intervention group had a standardised mean difference in adiposity (measured as BMI or zBMI) of -0.15kg/m(2) (95% confidence interval (CI): -0.21 to -0.09).  Intervention effects by age subgroups were -0.26kg/m(2) (95% CI:-0.53 to 0.00) (0-5 years), -0.15kg/m(2) (95% CI -0.23 to -0.08) (6-12 years), and -0.09kg/m(2) (95% CI -0.20 to 0.03) (13-18 years). Heterogeneity was apparent in all three age groups and could not explained by randomisation status or the type, duration or setting of the intervention.  Only eight studies reported on adverse effects and no evidence of adverse outcomes such as unhealthy dieting practices, increased prevalence of underweight or body image sensitivities was found.  Interventions did not appear to increase health inequalities although this was examined in fewer studies.

AUTHORS' CONCLUSIONS

We found strong evidence to support beneficial effects of child obesity prevention programmes on BMI, particularly for programmes targeted to children aged six to 12 years. However, given the unexplained heterogeneity and the likelihood of small study bias, these findings must be interpreted cautiously. A broad range of programme components were used in these studies and whilst it is not possible to distinguish which of these components contributed most to the beneficial effects observed, our synthesis indicates the following to be promising policies and strategies:·         school curriculum that includes healthy eating, physical activity and body image·         increased sessions for physical activity and the development of fundamental movement skills throughout the school week·         improvements in nutritional quality of the food supply in schools·         environments and cultural practices that support children eating healthier foods and being active throughout each day·         support for teachers and other staff to implement health promotion strategies and activities (e.g. professional development, capacity building activities)·         parent support and home activities that encourage children to be more active, eat more nutritious foods and spend less time in screen based activitiesHowever, study and evaluation designs need to be strengthened, and reporting extended to capture process and implementation factors, outcomes in relation to measures of equity, longer term outcomes, potential harms and costs.Childhood obesity prevention research must now move towards identifying how effective intervention components can be embedded within health, education and care systems and achieve long term sustainable impacts.  

Interventions to promote physical activity among young and adolescent girls: a systematic review

A narrative systematic review was conducted to describe the available evidence from physical activity (PA) interventions that targeted girls aged 5-18 years and to determine their effectiveness and key characteristics of success. Systematic literature searches were conducted using four databases: PubMed, Web of Science, PsychInfo and SPORTDiscus and by examining the reference lists of included articles and published relevant reviews, to identify studies published in English from 2000 to July 2010. Randomized controlled trials or quasi-experimental designs with pre-test and post-test behavioral outcome data (objective or self-report measure) were included. Methodological quality was assessed using a checklist and conclusions were made concerning effectiveness. A total of 29 articles were reviewed, describing the evaluation of 21 interventions. Ten studies reported a favorable intervention effect upon PA outcomes, seven of which were rated as having a high methodological quality. Multi-component school-based interventions that also offer a physical education that address the unique needs of girls seemed to be the most effective. Although family support is revealed as ineffective, peer strategies showed promising evidence. The review finishes highlighting possible intervention strategies and reporting areas where further investigation is required.

The use of web-based interventions to prevent excessive weight gain

We reviewed web-based interventions for overweight and obesity prevention. A literature search was conducted using seven electronic databases. Manually searched articles were also included. Thirty studies fulfilled the inclusion criteria. Of these, 13 studied physical activity, eight studied dietary practices and nine studied a combination of physical activity and dietary practice. Twenty-eight of the studies (93%) reported positive changes in moderate to vigorous physical activity level, fruit and vegetable intake and psychological factors. A meta-analysis showed there were improvements, though not significant, in fruit and vegetable consumption (standardised mean difference, SMD = 0.61; 95% CI =-0.13 to 1.35) and physical activity (SMD = 0.15; 95% CI =-0.06 to 0.35). The review suggests that web-based interventions are a useful educational tool for increasing awareness and making healthy behaviour changes in relation to an excessive weight gain problem.

Reduction in overweight and obesity from a 3-year community-based intervention in Australia: the 'It's Your Move!' project

'It's Your Move!' was a 3-year intervention study implemented in secondary schools in Australia as part of the Pacific Obesity Prevention In Communities Project. This paper reports the outcome results of anthropometric indices and relevant obesity-related behaviours. The interventions focused on building the capacity of families, schools and communities to promote healthy eating and physical activity. Baseline response rates and follow-up rates were 53% and 69% respectively for the intervention group (n=5 schools) and 47% and 66% respectively for the comparison group (n=7 schools). Statistically significant relative reductions in the intervention versus comparison group were observed: weight (-0.74 kg, P < 0.04), and standardized body mass index (-0.07, P<0.03), and non-significant reductions in prevalence of overweight and obesity (0.75 odds ratio, P=0.12) and body mass index (-0.22, P=0.06). Obesity-related behavioural variables showed mixed results with no pattern of positive intervention outcomes. In conclusion, this is the first study to show that long-term, community-based interventions using a capacity-building approach can prevent unhealthy weight gain in adolescents. Obesity prevention efforts in this important transitional stage of life can be successful and these findings need to be translated to scale for a national effort to reverse the epidemic in children and adolescents.

Physical activity and the achievement gap among urban minority youth

OBJECTIVES

To outline the prevalence and disparities of physical activity among school-aged urban minority youth, causal pathways through which low levels of physical activity and fitness adversely affects academic achievement, and proven or promising approaches for schools to increase physical activity and physical fitness among youth.

METHODS

Literature review.

RESULTS

A large proportion of youth is insufficiently physically active. Estimates of population-wide levels of physical activity indicate that Black and Hispanic youth are less physically active than White youth, with disparities particularly evident for females. The population segments of youth with lowest levels of physical activity and fitness also have least access to school-based physical activity opportunities and resources. Physical activity affects metabolism and all major body systems, exerting powerful positive influences on the brain and spinal cord and, consequently, on emotional stability, physical health, and motivation and ability to learn. The cornerstone of school-based physical activity programs should be a high-quality physical education program based on national standards. Such programs are strongly recommended by the Task Force on Community Preventive Services as a way to increase physical activity and physical fitness among youth.

CONCLUSIONS

Physical inactivity is highly and disproportionately prevalent among school-aged urban minority youth, has a negative impact on academic achievement through its effects on cognition, and effective practices are available for schools to address this problem. Increasing students' physical activity and physical fitness can best be achieved through a comprehensive approach that includes physical education, wise use of recess and after-school times, co-curricular physical activity opportunities, and bicycling or walking to and from school.

What motivates girls to take up exercise during adolescence? Learning from those who succeed

OBJECTIVES

 The present study explored factors that underpin increased internalization (i.e., perceived autonomy) in motivation towards exercise over a 1-year period in adolescent girls.

DESIGN

 A mixed methods prospective study.

METHODS

 A total of 107 girls (mean age = 13.28 years) reported their exercise behaviour, exercise goals, and a multidimensional measure of motivation towards exercise on two occasions, 1 year apart. Ten girls reporting increased autonomous motivation were then interviewed.

RESULTS

 Two themes were extracted; growing up and seeking challenge. Most participants reported being more interested in exercising for their health as a result of growing up, through having greater understanding of the health-behaviour link and willingness to act now for future health gain. However, their motivation appeared to be only partially internalized, as health was still viewed primarily as a value promoted by respected others (parents, teachers, media). Furthermore, as many girls conflated being healthy with being thin, health for appearance-related weight control was experienced as an extrinsic (controlling) goal. The second theme was more suggestive of autonomous motivation; girls reported valuing exercise for the opportunity it provides to set and achieve personally meaningful challenges, facilitating a sense of competence and achievement.

CONCLUSIONS

 The findings may have a useful application in suggesting how exercise settings could be manipulated to increase enjoyment and participation during adolescence. In particular, the findings suggest that means of increasing the salience of the rewarding nature of setting and reaching personal challenges in an exercise setting are investigated.

A school-based intervention to promote physical activity among adolescent girls: rationale, design, and baseline data from the Girls in Sport group randomised controlled trial

Background

Physical activity levels decline markedly among girls during adolescence. School-based interventions that are multi-component in nature, simultaneously targeting curricular, school environment and policy, and community links, are a promising approach for promoting physical activity. This report describes the rationale, design and baseline data from the Girls in Sport group randomised trial, which aims to prevent the decline in moderate-to-vigorous intensity physical activity (MVPA) among adolescent girls.

Methods/Design

A community-based participatory research approach and action learning framework are used with measurements at baseline and 18-month follow-up. Within each intervention school, a committee develops an action plan aimed at meeting the primary objective (preventing the decline in accelerometer-derived MVPA). Academic partners and the State Department of Education and Training act as critical friends. Control schools continue with their usual school programming. 24 schools were matched then randomized into intervention (n = 12) and control (n = 12) groups. A total of 1518 girls (771 intervention and 747 control) completed baseline assessments (86% response rate). Useable accelerometer data (≥10 hrs/day on at least 3 days) were obtained from 79% of this sample (n = 1199). Randomisation resulted in no differences between intervention and control groups on any of the outcomes. The mean age (SE) of the sample was 13.6 (± 0.02) years and they spent less than 5% of their waking hours in MVPA (4.85 ± 0.06).

Discussion

Girls in Sport will test the effectiveness of schools working towards the same goal, but developing individual, targeted interventions that bring about changes in curriculum, school environment and policy, and community links. By using community-based participatory research and an action learning framework in a secondary school setting, it aims to add to the body of literature on effective school-based interventions through promoting and sustaining increased physical activity participation among adolescent girls.

Trial Registration Number

Australia and New Zealand Clinical Trials Register (ANZCTR): ACTRN12610001077055

A school-based intervention to promote physical activity among adolescent girls: rationale, design, and baseline data from the Girls in Sport group randomised controlled trial

BACKGROUND

Physical activity levels decline markedly among girls during adolescence. School-based interventions that are multi-component in nature, simultaneously targeting curricular, school environment and policy, and community links, are a promising approach for promoting physical activity. This report describes the rationale, design and baseline data from the Girls in Sport group randomised trial, which aims to prevent the decline in moderate-to-vigorous intensity physical activity (MVPA) among adolescent girls.

METHODS/DESIGN

A community-based participatory research approach and action learning framework are used with measurements at baseline and 18-month follow-up. Within each intervention school, a committee develops an action plan aimed at meeting the primary objective (preventing the decline in accelerometer-derived MVPA). Academic partners and the State Department of Education and Training act as critical friends. Control schools continue with their usual school programming. 24 schools were matched then randomized into intervention (n = 12) and control (n = 12) groups. A total of 1518 girls (771 intervention and 747 control) completed baseline assessments (86% response rate). Useable accelerometer data (≥ 10 hrs/day on at least 3 days) were obtained from 79% of this sample (n = 1199). Randomisation resulted in no differences between intervention and control groups on any of the outcomes. The mean age (SE) of the sample was 13.6 (± 0.02) years and they spent less than 5% of their waking hours in MVPA (4.85 ± 0.06).

DISCUSSION

Girls in Sport will test the effectiveness of schools working towards the same goal, but developing individual, targeted interventions that bring about changes in curriculum, school environment and policy, and community links. By using community-based participatory research and an action learning framework in a secondary school setting, it aims to add to the body of literature on effective school-based interventions through promoting and sustaining increased physical activity participation among adolescent girls.

TRIAL REGISTRATION NUMBER

Australia and New Zealand Clinical Trials Register (ANZCTR): ACTRN12610001077055.

School sports opportunities influence physical activity in secondary school and beyond

BACKGROUND

The purpose of the present study was to examine whether the availability of intramural or extramural sports in secondary schools is associated with physical activity levels in youth throughout secondary school and at age 20.

METHODS

Eight hundred and eight adolescents from 10 secondary schools in Montreal, Canada, provided physical activity data every 3 months during the school year from ages 13 to 17, and again at age 20. School administrators completed questionnaires on the availability of intramural and extramural sports. Three-level general linear models were used to examine associations among the number of intramural and extramural sports, moderate and vigorous physical activity controlling for age, sex, body mass index, mother's education, and school-level socioeconomic status.

RESULTS

Regardless of whether or not they reported participating in intramural sports, adolescents in schools with more intramural sports engaged in 3.6 (p = .03) more total, and 1.3 (p = 0.03) more vigorous activities per week than those attending schools with fewer intramural sports. Number of extramural sports was not statistically significantly associated with physical activity, regardless of whether or not individual students participated.

CONCLUSION

Providing more opportunities for intramural sports in secondary schools may be an effective strategy to help adolescents attain physical activity recommendations.

The influence of body mass index on long-term fitness from physical education in adolescent girls

BACKGROUND

Physical education (PE) can improve physical fitness; however, little research has evaluated PE's long-term influence. The purpose is to determine PE's longitudinal effects on fitness in a group of adolescent girls and to determine whether body mass index (BMI) status influenced any potential effects.

METHODS

Participants were enrolled in daily PE throughout their ninth grade. Data were collected at baseline and at the end of 9th, 10th, and 11th grades. BMI (kg/m(2) ) was classified into Centers for Disease Control and Prevention percentiles. Fitness was estimated from a 3-stage step test (change in exercise heart rate (HR) indicated improved fitness) and analyzed using repeated measures general linear modeling with adjustments for baseline BMI, baseline age, ethnicity, intervention status, and moderate-to-vigorous physical activity outside PE.

RESULTS

Complete data were available for 131 girls (61% of sample) who were predominantly African American, 13.8 ± 0.4 years, mean BMI 24.7 ± 6.1 kg/m(2) at the ninth-grade baseline. Overall, stage 1 HR (bpm) decreased from baseline to 9th grade (-5.5 ± 1.3, p < 0.0001), baseline to 10th grade (-7.2 ± 1.4, p < 0.0001), and baseline to 11th grade (-7.0 ± 1.5, p < 0.0001). Change differed by BMI status; fitness improvement was significant for normal and overweight, but not obese girls. After 2 years, change in stage 1 HR (bpm) was significantly different between BMI categories: normal-weight girls versus obese girls (-10.0 ± 3.2, p = 0.002) and overweight girls versus obese girls (-9.3 ± 3.9, p = 0.02).

CONCLUSION

Fitness differences by BMI exist after a PE program in adolescent girls: fitness improved and was maintained in normal-weight and overweight girls, whereby obese girls had no improvement in fitness.

Enjoyment of exercise moderates the impact of a school-based physical activity intervention

Background

A school-based physical activity intervention designed to encourage adolescent girls to be more active was more effective for some participants than for others. We examined whether baseline enjoyment of exercise moderated response to the intervention.

Methods

Adolescent girls with a low level of baseline activity who participated in a controlled trial of an intervention to promote increased physical activity participation (n = 122) self-reported their enjoyment of exercise and physical activity participation at baseline, mid-way through the intervention, and at the end of the 9-month intervention period. At all three time points, participants also underwent assessments of cardiovascular fitness (VO₂peak) and body composition (percent body fat). Repeated measures analysis of variance examined the relationship of baseline enjoyment to change in physical activity, cardiovascular fitness, body composition and enjoyment of exercise.

Results

A significant three-way interaction between time, baseline enjoyment, and group assignment (p < .01) showed that baseline enjoyment moderated the effect of the intervention on vigorous activity. Within the intervention group, girls with low enjoyment of exercise at baseline increased vigorous activity from pre-to post-intervention, and girls with high baseline enjoyment of exercise showed no pre-post change in vigorous activity. No differences emerged in the comparison group between low-and high-enjoyment girls.

Conclusion

Adolescent girls responded differently to a physical activity promotion intervention depending on their baseline levels of exercise enjoyment. Girls with low enjoyment of exercise may benefit most from a physical-education based intervention to increase physical activity that targets identified barriers to physical activity among low-active adolescent girls.

A school-based, peer leadership physical activity intervention for 6th graders: feasibility and results of a pilot study

BACKGROUND

The aim of this study was to promote physical activity in 6th graders by developing and testing the feasibility of an enhanced Presidential Active Lifestyle Award (PALA) program comprised of a peer leadership component and innovative exercise resource toolkit including DVDs.

METHODS

A racially/ethnically diverse sample of students received the standard PALA program (2 control schools, n = 61) or enhanced PALA+Peers program (2 intervention schools, n = 87) during 2006-2007 academic year.

RESULTS

Compared with the control condition, the intervention was successful in increasing moderate physical activity in all students (P = .02) and moderate and hard physical activity among girls (P = .03 and P = .04, respectively). Teachers and students reported a high level of satisfaction and receptivity with the intervention. All teachers thought the DVDs were well-received, and 87% of students reported that they would recommend the enhanced program to peers.

CONCLUSION

Coupling peer leadership and DVDs that promote physical activity may be an effective way to increase youth physical activity.

Do physical activity facilities near schools affect physical activity in high school girls?

OBJECTIVE

To investigate associations between the number of physical activity facilities within walking distance of school and physical activity behavior in 12th grade girls during after-school hours.

METHODS

Girls (N=1394) from 22 schools completed a self-report to determine physical activity after 3:00 p.m. The number of physical activity facilities within a 0.75-mile buffer of the school was counted with a Geographic Information System. Associations between the number of facilities and girls' physical activity were examined using linear mixed-model analysis of variance.

RESULTS

Overall, girls who attended schools with ≥5 facilities within the buffer reported more physical activity per day than girls in schools with <5 facilities. In addition, girls who attended rural schools with ≥5 facilities reported ∼12% more physical activity per day than girls who attended rural schools with <5 facilities. No difference existed for girls in urban/suburban schools with ≥5 vs. <5 facilities.

CONCLUSION

When school siting decisions are made, the number of physical activity facilities surrounding the school should be considered to encourage physical activity in 12th grade girls.

Quantifying the impact of fixed effects modeling of clusters in multiple imputation for cluster randomized trials

In cluster randomized trials (CRTs), identifiable clusters rather than individuals are randomized to study groups. Resulting data often consist of a small number of clusters with correlated observations within a treatment group. Missing data often present a problem in the analysis of such trials, and multiple imputation (MI) has been used to create complete data sets, enabling subsequent analysis with well-established analysis methods for CRTs. We discuss strategies for accounting for clustering when multiply imputing a missing continuous outcome, focusing on estimation of the variance of group means as used in an adjusted t-test or ANOVA. These analysis procedures are congenial to (can be derived from) a mixed effects imputation model; however, this imputation procedure is not yet available in commercial statistical software. An alternative approach that is readily available and has been used in recent studies is to include fixed effects for cluster, but the impact of using this convenient method has not been studied. We show that under this imputation model the MI variance estimator is positively biased and that smaller intraclass correlations (ICCs) lead to larger overestimation of the MI variance. Analytical expressions for the bias of the variance estimator are derived in the case of data missing completely at random, and cases in which data are missing at random are illustrated through simulation. Finally, various imputation methods are applied to data from the Detroit Middle School Asthma Project, a recent school-based CRT, and differences in inference are compared.

The Nutrition and Enjoyable Activity for Teen Girls (NEAT girls) randomized controlled trial for adolescent girls from disadvantaged secondary schools: rationale, study protocol, and baseline results

BACKGROUND

Child and adolescent obesity predisposes individuals to an increased risk of morbidity and mortality from a range of lifestyle diseases. Although there is some evidence to suggest that rates of pediatric obesity have leveled off in recent years, this has not been the case among youth from low socioeconomic backgrounds. The purpose of this paper is to report the rationale, study design and baseline findings of a school-based obesity prevention program for low-active adolescent girls from disadvantaged secondary schools.

METHODS/DESIGN

The Nutrition and Enjoyable Activity for Teen Girls (NEAT Girls) intervention will be evaluated using a group randomized controlled trial. NEAT Girls is a 12-month multi-component school-based intervention developed in reference to Social Cognitive Theory and includes enhanced school sport sessions, interactive seminars, nutrition workshops, lunch-time physical activity (PA) sessions, PA and nutrition handbooks, parent newsletters, pedometers for self-monitoring and text messaging for social support. The following variables were assessed at baseline and will be completed again at 12- and 24-months: adiposity, objectively measured PA, muscular fitness, time spent in sedentary behaviors, dietary intake, PA and nutrition social-cognitive mediators, physical self-perception and global self-esteem. Statistical analyses will follow intention-to-treat principles and hypothesized mediators of PA and nutrition behavior change will be explored.

DISCUSSION

NEAT Girls is an innovative intervention targeting low-active girls using evidence-based behavior change strategies and nutrition and PA messages and has the potential to prevent unhealthy weight gain and reduce the decline in physical activity and poor dietary habits associated with low socio-economic status. Few studies have reported the long-term effects of school-based obesity prevention programs and the current study has the potential to make an important contribution to the field.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry No: ACTRN12610000330044.

The Nutrition and Enjoyable Activity for Teen Girls (NEAT girls) randomized controlled trial for adolescent girls from disadvantaged secondary schools: rationale, study protocol, and baseline results

BACKGROUND

Child and adolescent obesity predisposes individuals to an increased risk of morbidity and mortality from a range of lifestyle diseases. Although there is some evidence to suggest that rates of pediatric obesity have leveled off in recent years, this has not been the case among youth from low socioeconomic backgrounds. The purpose of this paper is to report the rationale, study design and baseline findings of a school-based obesity prevention program for low-active adolescent girls from disadvantaged secondary schools.

METHODS/DESIGN

The Nutrition and Enjoyable Activity for Teen Girls (NEAT Girls) intervention will be evaluated using a group randomized controlled trial. NEAT Girls is a 12-month multi-component school-based intervention developed in reference to Social Cognitive Theory and includes enhanced school sport sessions, interactive seminars, nutrition workshops, lunch-time physical activity (PA) sessions, PA and nutrition handbooks, parent newsletters, pedometers for self-monitoring and text messaging for social support. The following variables were assessed at baseline and will be completed again at 12- and 24-months: adiposity, objectively measured PA, muscular fitness, time spent in sedentary behaviors, dietary intake, PA and nutrition social-cognitive mediators, physical self-perception and global self-esteem. Statistical analyses will follow intention-to-treat principles and hypothesized mediators of PA and nutrition behavior change will be explored.

DISCUSSION

NEAT Girls is an innovative intervention targeting low-active girls using evidence-based behavior change strategies and nutrition and PA messages and has the potential to prevent unhealthy weight gain and reduce the decline in physical activity and poor dietary habits associated with low socio-economic status. Few studies have reported the long-term effects of school-based obesity prevention programs and the current study has the potential to make an important contribution to the field.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry No: ACTRN12610000330044.

A cluster randomised trial to evaluate a physical activity intervention among 3-5 year old children attending long day care services: study protocol

BACKGROUND

Young children are not participating in recommended levels of physical activity and exhibit high levels of sedentary behaviour. Childcare services provide access to large numbers of young children for prolonged periods, yet there is limited experimental evidence regarding the effectiveness of physical activity interventions implemented in this setting. The aim of this study is to assess the effectiveness and acceptability of a multi-component physical activity intervention, delivered by childcare service staff, in increasing the physical activity levels of children attending long day care services.

METHODS/DESIGN

The study will employ a cluster randomised controlled trial design. Three hundred children aged between 3-5 years from twenty randomly selected long day care services in the Hunter Region of New South Wales, Australia will be invited to participate in the trial. Ten of the 20 long day care services will be randomly allocated to deliver the intervention with the remaining ten services allocated to a wait list control group. The physical activity intervention will consist of a number of strategies including: delivering structured fundamental movement skill activities, increasing physical activity opportunities, increasing staff role modelling, providing children with a physical activity promoting indoor and outdoor environment and limiting children's small screen recreation and sedentary behaviours. Intervention effectiveness will be measured via child physical activity levels during attendance at long day care. The study also seeks to determine the acceptability and extent of implementation of the intervention by services and their staff participating in the study.

DISCUSSION

The trial will address current gaps in the research evidence base and contribute to the design and delivery of future interventions promoting physical activity for young children in long day care settings.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12610000087055.

A web-based intervention to support increased physical activity among at-risk adults

Physical inactivity is an important contributor to the development of numerous chronic conditions and alone is an independent risk factor for diabetes, cardiovascular disease, and depression and yet, most Americans consistently fail to achieve the recommended amount of physical activity. As part of Project HealthDesign, we designed and prototyped a personal health record application (PHA) that delivers and supports a highly individualized, behaviorally based lifestyle physical activity intervention for sedentary adults. Through a user centered design approach, we engaged consumers, health care providers, and personal trainers for multiple facilitated group discussions and structured interviews to determine their needs and wants related to an activity PHA. The PHA was developed to include elements of evidence-based approaches which help participants adopt cognitive and behavioral skills such as goal-setting, self-monitoring, accepting social support, cognitive restructuring, contingency management, decisional balance, and relapse prevention. This PHA demonstrated the potential for research-based behavioral interventions to be delivered via a web portal. This finding is important for both consumers and their providers who have the desire to implement physical activity recommendations, but lack the tools to facilitate or undertake such interventions.

Hop, skip... no! Explaining adolescent girls' disinclination for physical activity

PURPOSE

This study aimed to develop and validate the Girls' Disinclination for Physical Activity Scale (G-DAS)and implement the scale along with an objective measure of physical activity (PA) in a longitudinal sample of adolescent girls.

METHODS

Participants were non-Hispanic White girls who were assessed at ages 13 years (n=151) and 15 years (n=98). Girls completed the G-DAS and the Physical Activity Enjoyment Scale and wore an accelerometer for 7 days.

RESULTS

Results supported a five-factor solution for the GDAS;factors represented reasons for disliking PA including low perceived competence, lack of opportunities, high perceived exertion, concern about physical appearance,and threats to girls' gender identity. Data supported the reliability and validity of the G-DAS. Low perceived competence was the most common reason girls reported disliking PA and predicted a decreased likelihood of maintaining sufficient PA across ages 13 to 15 years.

CONCLUSION

Developing PA-related skills prior to adolescence may reduce declines in adolescent girls' PA.

A meta-analysis of obesity interventions among U.S. minority children

PURPOSE

To quantitatively evaluate the efficacy of interventions designed to prevent or treat obesity among U.S. minority children using meta-analytic techniques.

METHODS

A total of 40 intervention trials involving 10,725 children aged 6-19 years were examined.

RESULTS

Interventions with more components showed a higher mean effect size than those with fewer components: among 32 controlled trials, d = .07 for one-component (n = 6); d = .08 for two-component (n = 15); d = .33 for three-component (n = 10); and d = .71 for four-component (n = 1) interventions. Interventions with parental involvement (n = 22, d = .21) and lifestyle interventions (n = 14, d = .34) showed a greater mean effect size than those without parental involvement (n = 10, d = .05) or lifestyle interventions (n = 18, d = .04), despite the fact that their 90% confidence intervals overlapped. Among uncontrolled trials (n = 8), two-component interventions (n = 5) yielded d = .86 and three-component interventions (n = 3) yielded d = .96.

CONCLUSIONS

Evidence indicates that, among U.S. minority children, obesity interventions with three or more components might be more efficacious than those using fewer components. Parental involvement, lifestyle change, culturally-based adaptation, and interactive computer programs seem to show promise in the reduction of obese minority children.

Mediators affecting girls' levels of physical activity outside of school: findings from the trial of activity in adolescent girls

BACKGROUND

Providing after school activities is a community level approach for reducing the decline in physical activity of girls as they reach early adolescence.

PURPOSE

The purpose of this study was to examine psychosocial, environmental, and behavioral factors as potential mediators of after school physical activity in adolescent girls.

METHODS

We assessed objectively measured levels of physical activity occurring outside of school and potential predictors and mediators of activity in girls participating in the Trial of Activity in Adolescent Girls (TAAG).

RESULTS

We found that the TAAG intervention had a statistically significant and positive effect on out of school activity in the 2006 cohort. Self-efficacy, friends' social support, total social support, and difficulty getting to and from community activities mediated the level of moderate to vigorous physical activity in girls.

CONCLUSIONS

Parents, communities, and schools should provide and enhance opportunities outside of the school day for adolescents to be active. Reducing transportation barriers and enlisting social support appear to be key.

When adolescents drop the ball: sustainability of physical activity in youth

BACKGROUND

A majority of youth do not attain the recommended levels of physical activity. To develop interventions that will be more efficient at enabling healthy levels of physical activity during adolescence, a better understanding is needed about which specific types of physical activity adolescents are more likely to sustain and when they tend to stop participating in each specific type of activity.

METHODS

From 1999 to 2005, 1276 adolescents, initially aged 12-13 years, completed a 7-day physical activity recall every 3 months during each of 5 years of secondary school. The prevalence of participation in each of 29 specific physical activities in each of Grades 7-11 was computed. Survival analyses were used to estimate when adolescents who reported each activity at baseline tended to discontinue the activity. All analyses were conducted in 2008.

RESULTS

The prevalence of participation in most activities declined over the 5 years; it did not increase for any activity. Within 2 years of baseline, the majority of adolescents discontinued participation in most activities in which they had reported participation at baseline. Sustained participation in a specific activity related both to its intensity (90%, 73%, and 40% of girls and 77%, 86%, and 60% of boys sustained participation in light-, moderate-, and vigorous-intensity activities, respectively) and its format (41% and 89% of girls and 69% and 90% of boys sustained participation in team and individual physical activities, respectively).

CONCLUSIONS

Participation in almost all physical activities declined during adolescence. The time of discontinuation varied across activity types. Promoting activities that attract and sustain secondary school students may improve physical activity levels throughout adolescence.

The impact of school-based prevention of overweight on psychosocial well-being of children

This review aimed to gain insight in the extent to which psychosocial effects of obesity prevention programmes have been studied, to give an overview of the methods used to measure the particular psychosocial aspects and - if possible - to quantify the effects found. Intervention studies (n = 267) covering the period 1990-October 2005 were derived from seven reviews about childhood obesity interventions. An additional search identified 2754 studies covering the period January 2005-February 2008. In total, 2901 papers (excluding 120 duplicates) were screened for inclusion. Sixty-nine papers covering 53 interventions were included and screened on measuring psychosocial variables. All original authors were contacted. Seven of the selected interventions measured psychosocial variables, five of which evaluated a net intervention effect as compared with a control condition. Only two interventions reported a statistically significant net intervention effect (a decrease in use of purging or diet pills and a decrease in peer ratings of aggression and observed verbal aggression). We conclude that a minority of childhood obesity interventions investigate the effects of their programmes on psychosocial well-being of children and adolescents. It is recommended that in the future, these programmes will be evaluated in a uniform way on a broad range of psychosocial aspects.

Relation of school environment and policy to adolescent physical activity

BACKGROUND

Physical activity (PA) declines as children and adolescents age. The purpose of this study was to examine how specific school factors relate to youth PA, TV viewing, and body mass index (BMI).

METHODS

A sample of 12- to 18-year-old adolescents in 3 cities (N = 165, 53% females, mean age 14.6 +/- 1.7 years, 44% nonwhite) completed surveys assessing days of physical education (PE) class per week, school equipment accessibility, after-school supervised PA, and after-school field access. Regression analyses were conducted to examine relationships between these school factors and PA at school facilities open to the public (never active vs active), overall PA level (days per week physically active for 60 minutes), BMI z score, and TV watching (hours per week).

RESULTS

Adjusting for demographics, days of PE per week and access to school fields after school were correlated with overall PA (beta= 0.286, p = .002, semipartial correlation .236 and beta= 0.801, p = .016, semipartial correlation .186, respectively). The association between after-school field access and overall PA was mediated by use of publicly accessible school facilities for PA. After-school supervised PA and school PA equipment were not associated with overall PA. In adjusted regression analyses including all school factors, days of PE remained correlated to overall PA independent of other school factors (beta= 0.264, p = .007, semipartial correlation = .136). There were no associations between school factors and BMI or TV watching.

CONCLUSIONS

Based on these study findings, PE is a promising intervention to address improving overall adolescent PA within the school setting.

Effect of school-based physical activity interventions on body mass index in children: a meta-analysis

BACKGROUND

The prevalence of childhood obesity is increasing at an alarming rate. Many local governments have enacted policies to increase physical activity in schools as a way to combat childhood obesity. We conducted a systematic review and meta-analysis to determine the effect of school-based physical activity interventions on body mass index (BMI) in children.

METHODS

We searched MEDLINE, EMBASE, CINAHL and the Cochrane Central Register of Controlled Trials up to September 2008. We also hand-searched relevant journals and article reference lists. We included randomized controlled trials and controlled clinical trials that had objective data for BMI from before and after the intervention, that involved school-based physical activity interventions and that lasted for a minimum of 6 months.

RESULTS

Of 398 potentially relevant articles that we identified, 18 studies involving 18 141 children met the inclusion criteria. The participants were primarily elementary school children. The study duration ranged from 6 months to 3 years. In 15 of these 18 studies, there was some type of co-intervention. Meta-analysis showed that BMI did not improve with physical activity interventions (weighted mean difference -0.05 kg/m(2), 95% confidence interval -0.19 to 0.10). We found no consistent changes in other measures of body composition.

INTERPRETATION

School-based physical activity interventions did not improve BMI, although they had other beneficial health effects. Current population-based policies that mandate increased physical activity in schools are unlikely to have a significant effect on the increasing prevalence of childhood obesity.

Systematic review of school-based interventions that focus on changing dietary intake and physical activity levels to prevent childhood obesity: an update to the obesity guidance produced by the National Institute for Health and Clinical Excellence

To determine the effectiveness of school-based interventions that focus on changing dietary intake and physical activity levels to prevent childhood obesity. MEDLINE and EMBASE were searched (January 2006 to September 2007) for controlled trials of school-based lifestyle interventions, minimum duration of 12 weeks, reporting weight outcome. Thirty-eight studies were included; 15 new studies and 23 studies included within the National Institute for Health and Clinical Excellence obesity guidance. One of three diet studies, five of 15 physical activity studies and nine of 20 combined diet and physical activity studies demonstrated significant and positive differences between intervention and control for body mass index. There is insufficient evidence to assess the effectiveness of dietary interventions or diet vs. physical activity interventions. School-based physical activity interventions may help children maintain a healthy weight but the results are inconsistent and short-term. Physical activity interventions may be more successful in younger children and in girls. Studies were heterogeneous, making it difficult to generalize about what interventions are effective. The findings are inconsistent, but overall suggest that combined diet and physical activity school-based interventions may help prevent children becoming overweight in the long term. Physical activity interventions, particularly in girls in primary schools, may help to prevent these children from becoming overweight in the short term.

Promoting physical activity in teen girls: insight from focus groups

PURPOSE

To describe adolescent girls' views about physical activity and explore strategies that nurses can use to promote physical activity.

STUDY DESIGN AND METHODS

A qualitative study using focus groups and interviews with 28 girls (12-18 years of age) recruited from schools and neighborhood health centers in a Midwest metropolitan area. An interview guide with 15 open-ended questions was used, and data were analyzed using content analysis.

RESULTS

Most girls preferred the phrase "physical activity" over "exercise." The benefits most frequently mentioned included positive physical attributes, mental health benefits, and staying healthy. Three major themes were identified: autonomy (ask them what they like to do, and then provide choices), fun (being with friends, variation, and enjoyment), and body image (gaining weight, appearance, and self-confidence).

CLINICAL IMPLICATIONS

Nursing interventions to promote physical activity and other healthy lifestyle changes that may prevent obesity should include active listening and a focus on the goals of the teen. Nurses need to evaluate their teaching and counseling approach, because the teens emphasized two points: "Don't tell me what to do" and "Don't put me down."

Process evaluation results from a school- and community-linked intervention: the Trial of Activity for Adolescent Girls (TAAG)

Process evaluation is a component of intervention research that evaluates whether interventions are delivered and received as intended. Here, we describe the process evaluation results for the Trial of Activity for Adolescent Girls (TAAG) intervention. The intervention consisted of four synergistic components designed to provide supportive school- and community-linked environments to prevent the decline in physical activity in adolescent girls. Process evaluation results indicate that the intervention components were delivered from intervention staff to teachers with high fidelity (84-97%) to the protocol and with lower fidelity (range: 18-93%) from teachers to students. Physical activity programs for girls, a unique feature of the TAAG intervention, increased from a mean of 10 programs per school to a mean of 16 and 15 in years 1 and 2, respectively, in intervention schools, with no change in control schools. These findings suggest that a multicomponent school- and community-based physical activity intervention can be delivered with fidelity and result in a middle school environment that supports physical activity for girls.

Clinical review: behavioral interventions to prevent childhood obesity: a systematic review and metaanalyses of randomized trials

CONTEXT

The efficacy of lifestyle interventions to encourage healthy lifestyle behaviors to prevent pediatric obesity remains unclear.

OBJECTIVE

Our objective was to summarize evidence on the efficacy of interventions aimed at changing lifestyle behaviors (increased physical activity, decreased sedentary activity, increased healthy dietary habits, and decreased unhealthy dietary habits) to prevent obesity.

DATA SOURCES

Data sources included librarian-designed searches of nine electronic databases, references from included studies and reviews (from inception until February 2006), and content expert recommendations.

STUDY SELECTION

Eligible studies were randomized trials enrolling children and adolescents assessing the impact of interventions on both lifestyle behaviors and body mass index (BMI).

DATA EXTRACTION

Two reviewers independently abstracted data on methodological quality, study characteristics, intervention components, and treatment effects.

DATA ANALYSIS

We conducted random-effects metaanalyses, quantified inconsistency using I(2), and conducted planned subgroup analyses for each examined outcome.

DATA SYNTHESIS

Regarding target behaviors, the pooled effect size for physical activity (22 comparisons; n = 9891 participants) was 0.12 [95% confidence interval (CI) = 0.04-0.20; I(2) = 63%], for sedentary activity (14 comparisons; n = 3003) was -0.29, (CI = -0.35 to -0.22; I(2) = 0%), for healthy dietary habits (14 comparisons, n = 5468) was 0.00 (CI = -0.20; 0.20; I(2) = 83%), and for unhealthy dietary habits (23 comparisons, n = 9578) was -0.20 (CI = -0.31 to -0.09; I(2) = 34%). The effect of these interventions on BMI (43 comparisons, n = 32,003) was trivial (-0.02; CI = -0.06-0.02; I(2) = 17%) compared with control. Trials with interventions lasting more than 6 months (vs. shorter trials) and trials with postintervention outcomes (vs. in-treatment outcomes) yielded marginally larger effects.

CONCLUSION

Pediatric obesity prevention programs caused small changes in target behaviors and no significant effect on BMI compared with control. Trials evaluating promising interventions applied over a long period, using responsive outcomes, with longer measurement timeframes are urgently needed.

Self-efficacy moderates the relation between declines in physical activity and perceived social support in high school girls

OBJECTIVE

To test whether self-efficacy for overcoming barriers to physical activity has direct, indirect (i.e., mediated), or moderating relations with naturally occurring change in perceived social support and declines in physical activity during high school.

METHODS

Latent growth modeling was used with measures completed in the 8th, 9th, and 12th grades by a cohort of 195 Black and White girls.

RESULTS

Self-efficacy was stable and moderated the relation between changes in physical activity and perceived social support. Girls who maintained a perception of strong social support had less of a decline in physical activity if they also had high self-efficacy. However, girls having high self-efficacy had a greater decline in physical activity if they perceived declines in social support.

CONCLUSIONS

Randomized controlled trials of physical activity interventions based on social cognitive theory should consider that the influence of girls' perceptions of social support on their physical activity may differ according to their efficacy beliefs about barriers to physical activity.

Lifestyle factors, body mass index, and lipid profile in adolescents

OBJECTIVE AND METHODS

A model specifying body mass index (BMI) as mediating the relationship between lifestyle factors (aerobic fitness determined by peak oxygen consumption; physical activity by 7-day physical activity recall; diet by 24 hr dietary recall), and lipid profile were tested in a sample of 205 adolescents (73% boys), who were on average at risk of overweight, aerobically unfit, and from ethnic minority groups.

RESULTS

In this well-fitting model, consuming a diet low in fat and cholesterol, and being aerobically fit predicted lower BMI, which together resulted in increases in high-density lipoprotein cholesterol and decreases in triglycerides and low-density lipoprotein cholesterol. Being physically active, predicted greater aerobic fitness.

CONCLUSIONS

In addition to furthering understanding of the interrelationships among predisposing, major, and conditional coronary heart disease risk factors in adolescents, these data suggest that improving diet and aerobic fitness will reduce BMI and result in a better lipid profile.

Evaluation of an extra-curricular school sport programme promoting lifestyle and lifetime activity for adolescents

The purpose of this study was to evaluate the impact of an extra-curricular school sport programme to promote physical activity among adolescents. One hundred and sixteen students (mean age 14.2 years, s = 0.5) were assigned to an intervention (n = 50) or comparison group (n = 66). The 8-week intervention involved structured exercise activities and information sessions. Four days of pedometer monitoring and time spent in non-organized physical activity and sedentary behaviours were measured at baseline and post-test. At baseline, participants were classified using steps per day as low-active (girls <11,000, boys <13,000) or active (girls > or = 11,000, boys > or = 13,000) and the effects of the intervention were assessed using these subgroups. Adolescents in the intervention group classified as low-active at baseline increased their step counts across the 8-week intervention (baseline: 7716 steps/day, s = 1751; post-test: 10,301 steps/day, s = 4410; P < 0.05) and accumulated significantly more steps (P < 0.05) than their peers in the comparison group (baseline: 8414 steps/day, s = 2460; post-test: 8248 steps/day, s = 3674; P = 0.879). The results of the present study provide further evidence that physical activity monitoring using pedometers is an effective strategy for increasing activity among low-active adolescents.