***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 The objective of this study was to test whether heart-rate feedback prompts increased physical activity ( PA ) in primary school students . METHODS A controlled trial with 210 9 - 11 year olds from subsidized Hong Kong Government primary schools was completed in December 2006 . Schools were r and omly assigned to one of three groups : Control ( CG ) ; Educational program ( EG ) ; No-educational program ( NEG ) . INTERVENTION In a short-term school-based intervention , heart-rate feedback was given either in combination with an educational program ( EG ) or in isolation ( NEG ) . Long-term retention was assessed in comparison to the control group after 6 months follow-up . MAIN OUTCOME MEASURES Physical activity and changes in attraction to PA . RESULTS In the short-term , heart-rate monitor feedback increased total daily PA by an average of 24 % ( p<0.001 ) and vigorous PA by 0.6 % ( p<0.05 ) . No change was found for moderate PA . Increases occurred regardless of involvement in the educational program , and in the absence of any change in attitudes towards PA . No long-term retention was apparent . CONCLUSIONS The findings from the study suggest that feedback from heart-rate monitors encourages low intensity PA , but when removed increases do not persist OBJECTIVE To verify the influence of programmed physical activity on body composition among adolescent students during 1 school year . METHODS The sample included 383 students ( age range : 10 to 15 years ) separated into two groups : 186 cases ( 96 male and 90 female ) and 197 controls ( 108 male and 89 female ) . This was an intervention study with pre- and post-test assessment s in which interventions consisted of programmed physical activity ; the control group had conventional school physical education .  Body composition was assessed by anthropometric measurements , body mass index ( BMI ) , body fat percentage and fat and lean body mass . RESULTS In the case group , subscapular skinfold thickness , BMI , body fat percentage and fat body mass remained stable ; there were significant reductions in tricipital skinfold thickness and in abdominal perimeter among girls and significant increases in arm , waist and calf perimeters and in lean body mass . In the control group , there were significant increases in BMI , tricipital skinfold thickness , abdominal perimeter and fat body mass among girls . At post-test , overweight and obesity significantly decreased among case group subjects , but not among controls . CONCLUSION Programmed physical activity result ed in improvement or maintenance of body composition parameters and in reduction of overweight and obesity in the intervention group 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 OBJECTIVES To determine whether a large-scale physical activity intervention could affect body composition in primary school students in Beijing , China . METHODS The study design was one-year cluster r and omized controlled trial of physical activity intervention ( 20 min of daily exercise in the classroom ) with an additional year of follow-up among 4 700 students aged 8 - 11 years at baseline . RESULTS After the one-year intervention , BMI increased by 0.56 kg/m(2 ) ( SD 1.15 ) in the intervention group and by 0.72 kg/m(2 ) ( SD 1.20 ) in the control group , with a mean difference of -0.15 kg/m(2 ) ( 95 % CI : -0.28 to -0.02 ) . BMI z score decreased by -0.05 ( SD 0.44 ) in the intervention group , but increased by 0.01 ( SD 0.46 ) in the control group , with a mean difference of -0.07 ( -0.13 to -0.01 ) . After another year of follow up , compared to the control group , children in the intervention group had significantly lower BMI ( -0.13 , -0.25 to -0.01 ) , BMI z score ( -0.05 , -0.10 to -0.01 ) , fat mass ( -0.27 kg , -0.53 to -0.02 ) and percent body fat ( -0.53 , -1.00 to -0.05 ) . The intervention had a more pronounced effect on weight , height , BMI , BMI z score , and body composition among obese children than among normal weight or overweight children . Compared to the control group , the intervention group had a significantly higher percentage of children who maintained or reduced their BMI z score at year 1 ( P=0.008 ) and year 2 ( P=0.04 ) . CONCLUSIONS These findings suggest that 20 min of daily moderate to vigorous physical activity during the school year is a feasible and effective way to prevent excessive gain of body weight , BMI , and body fatness in primary school students Regular physical activity is associated with a reduced risk of all-cause mortality , and mortality due to cardiovascular disease and cancer . Among adolescents , physical activity is associated with benefits in the prevention and control of emotional distress , and improvement of self-esteem . Countries in transitional epidemiological scenarios , such as Chile , need to develop effective strategies to improve physical activity as a way to face the epidemic of chronic diseases . The objective of this study was to evaluate the effects of a school-based physical activity program on physical fitness and mental health status of adolescents living in a low socioeconomic status area in Santiago , Chile . A quasi-experimental design was used to evaluate the effects of the program over one academic year . The study included 198 students aged 15 years old . Two ninth grade classes were r and omly selected as the  intervention group , with two classes of the same grade as controls . A social planning approach was used to develop the intervention . The program was design ed and implemented based on student preferences , teachers ' expertise and local re sources . Changes in physiological and mental health status were assessed . After the intervention , maximum oxygen capacity achieved a significant increase of 8.5 % in the intervention versus 1.8 % in the control group ( p < 0.0001 ) . Speed and jump performance scores improved significantly more in the intervention versus the control group ( p > 0.01 ) . Anxiety score decreased 13.7 % in the intervention group versus 2.8 % in the control group ( p < 0.01 ) , and self-esteem score increased 2.3 % in the intervention group and decreased 0.1 % in the control group after the end of the program ( p < 0.0001 ) . No significant change was observed in the depressive score . Student participation and compliance with the program was > 80 % . To conclude , a school-based program to improve physical activity in adolescents of low socioeconomic status , obtained a high level of participation and achieved significant benefits in terms of physical fitness and mental health status BACKGROUND With the aim of contributing to he Healthy Goal 2010 of reducing significantly the prevalence of childhood obesity we developed and implemented during 2003 and 2004 , a school-based obesity prevention intervention which included nutrition education and the promotion of physical activity . AIM To report the results of the intervention . MATERIAL AND METHODS The sample included 1760 children ( 1st to 7th grade ) from 3 elementary public schools in Casablanca ( experimental group ) and 671 from a similar school located in Quillota , a neighboring city ( control ) . Primary outcomes were body mass index ( BMI ) Z score , the mile and shuttle-run tests and obesity prevalence . We also compared changes in waist circumference and triceps skinfold between both groups . Effectiveness of the intervention was assessed by analyzing separately the group * age * time interaction for the first 3 outcomes ( follow-up-baseline ) , using a mixed model of covariance and by comparing variations in obesity prevalence between both groups . RESULTS There was a significant decline in BMI Z scores in experimental schools for both genders , but greater in boys ( p < 0.001 versus p = 0.0034 in girls ) , while in controls , BMI Z scores increased . Obesity prevalence declined significantly in experimental schools ; from 17 to 12.3 % and from 14.1 to 10.3 % in boys and girls respectively , while in the control group , it remained unchanged . Also , triceps skinfold in girls from Casablanca increased significantly less than that of control girls . CONCLUSION This intervention proved that it is possible to reduce significantly the prevalence of obesity in Chilean schoolchildren attending public elementary schools The aim of this study was to evaluate the impact of an intervention program on the patterns of physical activity in 8- to 10-year-old Mexican children from lower socioeconomic status . This study performed a r and omized controlled field trial in 498 children aged 8 - 10 years from 10 public schools of low socioeconomic status in Mexico City . Schools were r and omly assigned to intervention ( n = 5 ) or control ( n = 5 ) groups and followed up during 12 months . Physical and sedentary activities were assessed at the beginning of the program and after 6 and 12 months . At the end of follow-up , there was a significant increase in the performance of moderate physical activity ( MPA ) among children in intervention group who had not performed MPA at baseline any day of the week ( 40 % , P = 0.04 ) but not in the control group ( 8 % , P = not significant ) . The intervention group also showed a significant reduction in the proportion of children who spent more than 3 hours a day playing video games ( from 23 to 13 % , P = 0.01 ) , while control group did not show significant changes . Given these findings , we conclude that intervention was able to modify positively physical activity and reduce time spent on such sedentary activities as video games among those at highest risk studied children OBJECTIVE To determine whether an educational programme aim ed at discouraging students from drinking sugar-sweetened beverages could prevent excessive weight gain . DESIGN Forty-seven classes in twenty-two schools were r and omised as intervention or control . SUBJECTS Participants were 1140 , 9 - 12-year-old fourth grade rs ( 435 in the intervention group and 608 in the control group ) .  Sugar-sweetened beverages and juice intake were measured through one 24 h recall at baseline and another at the end of the trial . The main outcome was the change in BMI ( BMI = weight (kg)/height ( m2 ) ) , measured at the beginning and at the end of the school year . Intention-to-treat analysis was performed taking into account the cluster ( classes ) effect . RESULTS A statistically significant decrease in the daily consumption of carbonated drinks in the intervention compared to control ( mean difference = -56 ml ; 95 % CI -119 , -7 ml ) was followed by a non-significant overall reduction in BMI , P = 0.33 . However , among those students overweight at baseline , the intervention group showed greater BMI reduction ( -0.4 kg/m2 compared with -0.2 kg/ 
    Output:
    
School-based interventions have the potential to improve dietary and physical activity behavior and to prevent unhealthy body weights in low- and middle-income countries .