***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: OBJECTIVE To evaluate the impact of a school-based health behavior intervention known as Planet Health on obesity among boys and girls in grade s 6 to 8 . DESIGN R and omized , controlled field trial with 5 intervention and 5 control schools . Outcomes were assessed using preintervention ( fall 1995 ) and follow-up measures ( spring 1997 ) , including prevalence , incidence , and remission of obesity . PARTICIPANTS A group of 1295 ethnically diverse grade 6 and 7 students from public schools in 4 Massachusetts communities . INTERVENTION Students participated in a school-based interdisciplinary intervention over 2 school years . Planet Health sessions were included within existing curricula using classroom teachers in 4 major subjects and physical education . Sessions focused on decreasing television viewing , decreasing consumption of high-fat foods , increasing fruit and vegetable intake , and increasing moderate and vigorous physical activity . MAIN OUTCOME MEASURES Obesity was defined as a composite indicator based on both a body mass index and a triceps skinfold value greater than or equal to age- and sex-specific 85th percentiles . Because schools were r and omized , rather than students , the generalized estimating equation method was used to adjust for individual-level covariates under cluster r and omization . RESULTS The prevalence of obesity among girls in intervention schools was reduced compared with controls , controlling for baseline obesity ( odds ratio , 0.47 ; 95 % confidence interval , 0.24 - 0.93 ; P = .03 ) , with no differences found among boys . There was greater remission of obesity among intervention girls vs. control girls ( odds ratio , 2.16 ; 95 % confidence interval , 1.07 - 4.35 ; P = .04 ) . The intervention reduced television hours among both girls and boys , and increased fruit and vegetable consumption and result ed in a smaller increment in total energy intake among girls . Reductions in television viewing predicted obesity change and mediated the intervention effect . Among girls , each hour of reduction in television viewing predicted reduced obesity prevalence ( odds ratio , 0.85 ; 95 % confidence interval , 0.75 - 0.97 ; P = .02 ) . CONCLUSION Planet Health decreased obesity among female students , indicating a promising school-based approach to reducing obesity among youth CONTEXT Some observational studies have found an association between television viewing and child and adolescent adiposity .  OBJECTIVE To assess the effects of reducing television , videotape , and video game use on changes in adiposity , physical activity , and dietary intake . DESIGN R and omized controlled school-based trial conducted from September 1996 to April 1997 . SETTING Two sociodemographically and scholastically matched public elementary schools in San Jose , Calif. PARTICIPANTS Of 198 third- and fourth- grade students , who were given parental consent to participate , 192 students ( mean age , 8.9 years ) completed the study . INTERVENTION Children in 1 elementary school received an 18-lesson , 6-month classroom curriculum to reduce television , videotape , and video game use . MAIN OUTCOME MEASURES Changes in measures of height , weight , triceps skinfold thickness , waist and hip circumferences , and cardiorespiratory fitness ; self-reported media use , physical activity , and dietary behaviors ; and parental report of child and family behaviors . The primary outcome measure was body mass index , calculated as weight in kilograms divided by the square of height in meters . RESULTS Compared with controls , children in the intervention group had statistically significant relative decreases in body mass index ( intervention vs control change : 18.38 to 18.67 kg/m2 vs 18.10 to 18.81 kg/m2 , respectively ; adjusted difference -0.45 kg/m2 [ 95 % confidence interval [ CI ] , -0.73 to -0.17 ] ; P = .002 ) , triceps skinfold thickness ( intervention vs control change : 14.55 to 15.47 mm vs 13.97 to 16.46 mm , respectively ; adjusted difference , -1.47 mm [ 95 % CI , -2.41 to -0.54 ] ; P=.002 ) , waist circumference ( intervention vs control change : 60.48 to 63.57 cm vs 59.51 to 64.73 cm , respectively ; adjusted difference , -2.30 cm [ 95 % CI , -3.27 to -1.33 ] ; P<.001 ) , and waist-to-hip ratio ( intervention vs control change : 0.83 to 0.83 vs 0.82 to 0.84 , respectively ; adjusted difference , -0.02 [ 95 % CI , -0.03 to -0.01 ] ; P<.001 ) . Relative to controls , intervention group changes were accompanied by statistically significant decreases in children 's reported television viewing and meals eaten in front of the television . There were no statistically significant differences between groups for changes in high-fat food intake , moderate-to-vigorous physical activity , and cardiorespiratory fitness . CONCLUSIONS Reducing television , videotape , and video game use may be a promising , population -based approach to prevent childhood obesity BACKGROUND Sedentary behavior is associated with increased risk of chronic disease and sedentary behavior is increasing among adolescents . Data on changes in sedentary behavior in developing countries are limited . PURPOSE To describe 5-year longitudinal changes in nonschool sedentary hours among urban adolescents in Ho Chi Minh City , and to identify correlates with this change . METHODS This is a 5-year longitudinal cohort with systematic r and om sampling of 759 students from 18 junior high schools . All measures were taken annually between 2004 and 2009 .  Sedentary behavior  was assessed by self-report and accelerometry . Generalized linear latent and mixed models were used to analyze the data in 2011 . RESULTS Between 2004 and 2009 , self-reported time spent in nonschool sedentary behavior  increased from 498 to 603 minutes/day . In the 5th survey year , boys and girls ( aged 16 years ) were , respectively , 3.6 times ( 95 % CI=2.3 , 6.0 ) and 3.1 times ( 95 % CI= 1.8 , 5.0 ) more likely to spend ≥2 hours/day on screen time compared with baseline ( aged 12 years ) . Accelerometer data adjusted for wearing time revealed that boys and girls aged 16 years had , respectively , 78 minutes/day ( 95 % CI=48 , 104 ) and 69 minutes/day ( 95 % CI=34 , 95 ) more nonschool sedentary time than those at the first accelerometer assessment ( at age 13 years ) . Girls in the highest socioeconomic quartile spent an additional 90 minutes/day in sedentary behavior compared with girls in the lowest quartile ( 95 % CI=52 , 128 ) .  CONCLUSIONS Nonschool sedentary behavior  increased among Vietnamese adolescents with age . The largest increase was in recreational screen time ( 28 % ) , which would be the most obvious target for preventive health strategies PURPOSE To derive a regression equation that estimates metabolic equivalent ( MET ) from accelerometer counts , and to define thresholds of accelerometer counts that can be used to delineate sedentary , light , moderate , and vigorous activity in adolescent girls . METHODS Seventy-four healthy 8th grade girls , age 13 - 14 yr , were recruited from urban areas of Baltimore , MD , Minneapolis/St . Paul , MN , and Columbia , SC , to participate in the study .  Accelerometer and oxygen consumption (.-)VO(2 ) ) data for 10 activities that varied in intensity from sedentary ( e.g. , TV watching ) to vigorous ( e.g. , running ) were collected . While performing these activities , the girls wore two accelerometers , a heart rate monitor and a Cosmed K4b2 portable metabolic unit for measurement of (.-)VO(2 ) . A r and om-coefficients model was used to estimate the relationship between accelerometer counts and (.-)VO(2 ) . Activity thresholds were defined by minimizing the false positive and false negative classifications . RESULTS The activities provided a wide range in (.-)VO(2 ) ( 3 - 36 mL x kg x min ) with a correspondingly wide range in accelerometer counts ( 1- 3928 counts x 30 s ) . The regression line for MET score versus counts was MET = 2.01 + /- 0.00171 ( counts x 30 s ) ( mixed model R = 0.84 , SEE = 1.36 ) . A threshold of 1500 counts x 30 s defined the lower end of the moderate intensity ( approximately 4.6 METs ) range of physical activity . That cutpoint distinguished between slow and brisk walking , and gave the lowest number of false positive and false negative classifications . The threshold ranges for sedentary , light , moderate , and vigorous physical activity were found to be 0 - 50 , 51- 1499 , 1500 - 2600 , and > 2600 counts x 30 s , respectively . CONCLUSION The developed equation and these activity thresholds can be used for prediction of MET score from accelerometer counts and participation in various intensities of physical activity in adolescent girls BACKGROUND Obesity and poor physical fitness constitute a health problem affecting an increasing number of children . Causes include a pervasive " toxic " environment that facilitates increased caloric intake and reduced physical activity . An effective strategy for prevention and treatment of childhood obesity likely includes a collaborative effort in the school setting . OBJECTIVE To determine whether a school-based fitness program can improve body composition , cardiovascular fitness level , and insulin sensitivity in overweight children . DESIGN Fifty overweight middle school children with a body mass index ( BMI ) above the 95th percentile for age were r and omized to lifestyle-focused , fitness-oriented gym classes ( treatment group ) or st and ard gym classes ( control group ) for 9 months . Children underwent evaluation of  fasting insulin and glucose levels , body composition by means of  dual energy absorptiometry , and maximum oxygen consumption ( V0(2)max ) treadmill testing  at baseline ( before the school year ) and at end of the school year . SETTING S Rural middle school and an academic children 's hospital . MAIN OUTCOME MEASURES Baseline test results for cardiovascular fitness , body composition , and fasting insulin and glucose levels . RESULTS At baseline , there were no differences between groups before intervention ( values for age , 12 + /- 0.5 years [ all results , mean + /- SD ] ; BMI [ calculated as weight in kilograms divided by the square of height in meters ] , 31.0 + /- 3.7 ; percentage of body fat , 36.5 % + /- 4.6 % ; lean body mass , 41.4 + /- 8.6 kg ; and V0(2)max , 31.5 + /- 5.1 mL/kg per minute ) . Compared with the control group , the treatment group demonstrated a significantly greater loss of body fat ( loss , -4.1 % + /- 3.4 % vs -1.9 % + /- 2.3 % ; P = .04 ) , greater increase in cardiovascular fitness ( V0(2)max , 2.7 + /- 2.6 vs 0.4 + /- 3.3 mL/kg per minute ; P<.001 ) , and greater improvement in fasting insulin level ( insulin level , -5.1 + /- 5.2 vs 3.0 + /- 14.3 microIU/mL [ -35.4 + /- 36.1 vs 20.8 + /- 99.3 pmol/L ] ; P = .02 ) . CONCLUSIONS Children enrolled in fitness-oriented gym classes showed greater loss of body fat , increase in cardiovascular fitness , and improvement in fasting insulin levels than control subjects . The modification to the school physical education curriculum demonstrates that small but consistent changes in the amount of physical activity has beneficial effects on body composition , fitness , and insulin levels in children . Partnering with school districts should be a part of a public health approach to improving the health of overweight children OBJECTIVES : To assess the effects of simulated ostracism on children ’s physical activity behavior , time allocated to sedentary behavior , and liking of physical activity . METHODS : Nineteen children ( 11 boys , 8 girls ; age 11.7 ± 1.3 years ) completed 2 experimental sessions . During each session , children played a virtual ball-toss computer game ( Cyberball ) . In one session , children played Cyberball and experienced ostracism ; in the other session , they were exposed to the inclusion /control condition . The order of conditions was r and omized . After playing Cyberball , children were taken to a gymnasium where they had free-choice access to physical and sedentary activities for 30 minutes . Children could participate in the activities , in any pattern they chose , for the entire period . Physical activity during the free-choice period was assessed via accelerometery and sedentary time via observation . Finally , children reported their liking for the activity session via a visual analog scale . RESULTS : Children accumulated 22 % fewer ( P < .01 ) accelerometer counts and 41 % more ( P < .04 ) minutes of sedentary activity in the ostracized condition ( 8.9e+4 ± 4.5e+4 counts , 11.1 ± 9.3 minutes ) relative 
    Output:
    
Evidence was found for age being positively associated with total SB , and weight status and baseline assessment of screen time being positively associated with screen time ( at follow-up ) .
Evidence was also reported for the presence of safe places to cross roads and lengthening morning and lunch breaks being associated with less total SB .
However , since the relationship of many determinants with SB remains inconsistent , there is still a need for more longitudinal research on determinants of SB in youth