title: Bone mineral accrual and gain in skeletal width in pre-pubertal school children is independent of the mode of school transportation – one-year data from the prospective observational pediatric osteoporosis prevention (POP) study Diet, Screen Time, Physical Activity, and Childhood Overweight in the General Population and in High Risk Subgroups: Prospective Analyses in the PIAMA Birth Cohort The mode of school transportation in pre-pubertal children does not influence the accrual of bone mineral or the gain in bone size - two year prospective data from the paediatric osteoporosis preventive (POP) study Modifiable risk factors for overweight and obesity in children and adolescents from São Paulo, Brazil Prevalence of overweight, obesity, and associated risk factors among school children and adolescents in Tianjin, China Physical activity and clustered cardiovascular risk in children: a cross-sectional study (The European Youth Heart Study) Active transportation to school over 2 years in relation to weight status and physical activity. Determinants of sufficient daily activity in Australian primary school children. Physical activity and active commuting to elementary school. The Walking School Bus and Children's Physical Activity: A Pilot Cluster Randomized Controlled Trial Changes in physical activity from walking to school. Walking or bicycling to school and weight status among adolescents from Montería, Colombia.
abstract: Background Walking and cycling to school could be an important regular source of physical activity in growing children . The aim of this 12 months prospect i ve observational study was thus to evaluate the effect of self-transportation to school on bone mineral accrual and gain in bone width in pre-pubertal children , both traits independently contributing to bone strength . Methods Ninety-seven girls and 133 boys aged 7–9 years were recruited as a part of the Malmö Pediatric Osteoporosis Prevention ( POP ) Study in order to evaluate the influence of self-selected school transportation for the accrual of bone mineral and bone width .  Children who walked or cycled to school were compared with  children who went by bus or car . Bone mineral content ( BMC ) was measured by dual energy X-ray absorptiometry ( DXA ) in the lumbar spine ( L2–L4 ) , third lumbar vertebra ( L3 ) and hip , and bone width was calculated at L3 and femoral neck ( FN ) . Changes during the first 12 months were compared between the groups . Subjective duration of physical activity was estimated by a question naire and objective level of everyday physical activity at follow-up by accelerometers worn for four consecutive days . All children remained in Tanner stage 1 throughout the study . Comparisons were made by independent student 's t-tests between means , ANCOVA and Fisher 's exact tests . Results There were no differences in baseline or annual changes in BMC or bone width when the transportation groups were compared . No differences were detected in objective ly measured daily level of physical activity by accelerometer . All children reached above 60 minutes of moderate to intense daily physical activity per day , the international recommended level of daily physical activity according to the United Kingdom Expert Consensus Group . Conclusion The everyday physical activity in these pre-pubertal children seems to be so high that the school transportation contributes little to their total level of physical activity . As a result , the choice of school transportation seems not to influence the accrual of bone mineral or gain in bone size during a 12-month follow-up period Objective . To prospect ively identify behavioral risk factors for childhood overweight and to assess their relevance in high risk sub groups ( children of mothers with overweight or low education ) . Methods . In the PIAMA birth cohort ( n = 3963 ) , question naire data  were obtained at ages 5  and 7 on “ screen time ” , walking or cycling to school , playing outside , sports club membership , fast food consumption , snack consumption and soft drink consumption . Weight and height were measured at age 8 years . Results . Screen time , but none of the other hypothesized behavioral factors , was associated with overweight ( aOR 1.4 ( CI : 1.2–1.6 ) ) . The adjusted population attributable risk fraction for screen time > 1 hr/day was 10 % in the high risk and 17 % in the low risk sub groups . Conclusion . Reduction of screen time to < 1 hr/day could result in a reduction of overweight prevalence in the order of 2 percentage points in both high and low risks sub groups Background Walking and cycling to school are one source of regular physical activity . The aim of this two years observational study in pre-pubertal children was to evaluate if walking and cycling to school was associated with higher total amount of physical activity and larger gain in bone mineral content ( BMC ) and bone width than when going by car or bus . Methods 133 boys and 99 girls aged 7 - 9 years were recruited to the Malmö Prospect i ve Paediatric Osteoporosis Prevention ( POP ) study .  BMC ( g ) was measured by dual X-ray absorptiometry ( DXA ) in total body , lumbar spine ( L2-L4 ) and femoral neck ( FN ) at baseline and after 24 months . Bone width was measured in L2-L4 and FN . Skeletal changes in the 57 boys and 48 girls who consistently walked or cycled to school were compared with the 24 boys and 17 girls who consistently went by bus or car . All children remained in Tanner stage I. Level of everyday physical activity was estimated by accelerometers worn for four consecutive days and question naires . Comparisons were made by independent student 's t-tests between means and Fisher 's exact tests . Analysis of covariance ( ANCOVA ) was used to adjust for group differences in age at baseline , duration of organized physical activity , annual changes in length and BMC or bone width if there were differences in these traits at baseline . Results After the adjustments , there were no differences in the annual changes in BMC or bone width when comparing girls or boys who walked or cycled to school with those who went by car or bus . Furthermore , there were no differences in the levels of everyday physical activity objective ly measured by accelerometers and all children reached above the by the United Kingdom Expert Consensus Group recommended level of 60 minutes moderate to vigorous physical activity per day . Conclusion A physical active transportation to school for two years is in pre-pubertal children not associated with a higher accrual of BMC or bone width than a passive mode of transportation , possibly due to the fact that the everyday physical activity in these pre-pubertal children , independent of the mode of school transportation , was high Background Brazil is currently experiencing a nutrition transition : the displacement of traditional diets with foods high in saturated fat , sodium , and cholesterol and an increase in sedentary lifestyles . Despite these trends , our underst and ing of child obesity in Brazil is limited . Thus , the aims of this study were ( 1 ) to investigate the current prevalence of overweight and obesity in a large sample of children and adolescents living in São Paulo , Brazil , and ( 2 ) to identify the lifestyle behaviors associated with an increased risk of obesity in young Brazilians . Methods A total of 3,397 children and adolescents ( 1,596 male ) aged 7 - 18 years were r and omly selected from 22 schools in São Paulo , Brazil . Participants were classified as normal weight , overweight , or obese based on international age- and sex-specific body mass index thresholds . Selected sociodemographic , physical activity , and nutrition behaviors were assessed via question naire . Results Overall , 19.4 % of boys and 16.1 % of girls were overweight while 8.9 % and 4.3 % were obese . Two-way analysis of variance revealed that the prevalence of overweight and obesity was significantly higher in boys and in younger children when compared to girls and older children , respectively ( P < 0.05 for both ) . Logistic regression analysis revealed that overweight was associated with more computer usage , parental encouragement to be active , and light soft drink consumption after controlling for differences in sex , age , and parental education ( P < 0.05 for all ) . Conversely , overweight was associated with less active transport to school , eating before sleep , and consumption of breakfast , full-sugar soft drinks , fried food and confectionery ( P < 0.05 for all ) . Conclusions Our results show that obesity in São Paulo children and adolescents has reached a level equivalent to that seen in many developed countries . We have also identified three key modifiable factors related to obesity that may be appropriate targets for future intervention in Brazilian youth : transport mode to school , computer usage , and breakfast consumption To estimate the prevalence and determinants of overweight and obesity among school children and adolescents ( 7–18 years ) , a cross-sectional study was conducted in Tianjin City of Northeast China . Five primary and middle schools were selected using a multistage r and om cluster sampling . Anthropometric measurements were taken by the research team . Then , st and ardized question naires on socioeconomic status , diet and lifestyle , parental weight and height were sent to the parents to be completed together with their child . Overall , 3,140 students were screened for overweight and associated risk factors . Body mass index classification reference proposed by the Working Group on Obesity in China was used as a screening reference to calculate the prevalence of overweight in these groups . The prevalence of overweight and obesity was found to be 12.5 % and 15.7 % , respectively . Logistic regression analysis ( overweight compared with normal weight ) showed that , overweight in children was significantly associated with male gender , parental obesity , parental educational level , mother ’s history of gestational diabetes , high birth weight , less hours of physical activity per day , urban residence , motorized transportation , and eating food not prepared at home . After adjusting for parental obesity , the odds ratio of overweight children was increased by urban residence ( rural as a reference , 2.68 , 2.16–3.32 ) , positive gestational diabetes ( 2.76 , 1.37–4.50 ) , and fast-food/restaurant food service ( 2.03 , 1.34–3.07 ) . Children who walked to school and participated in outdoor activities were 54 % and 63 % less likely to be overweight respectively . Conclusions : The prevalence of overweight and obesity is high among school children and adolescents in Tianjin .  Changes in lifestyle , high socioeconomic status , parental obesity , mother ’s history of gestational diabetes , and high birth weight are among the highly associated risk factors of overweight . An educational approach about maintaining a healthy weight should be introduced much earlier to high-risk children , parents , and women of childbearing age BACKGROUND Atherosclerosis develops from early childhood ; physical activity could positively affect this process . This study 's aim was to assess the associations of objective ly measured physical activity with clustering of cardiovascular disease risk factors in children and derive guidelines on the basis of this analysis . METHODS We did a cross-sectional study of 1732 r and omly selected 9-year-old and 15-year-old school children from Denmark , Estonia , and Portugal . Risk factors included in the composite risk factor score ( mean of Z scores ) were systolic blood pressure , triglyceride , total cholesterol/HDL ratio , insulin resistance , sum of four skinfolds , and aerobic fitness . Individuals with a risk score above 1 SD of the composite variable were defined as being at risk . Physical activity was assessed by accelerometry . FINDINGS Odds ratios for having clustered risk for ascending quintiles of  physical activity  ( counts per min ; cpm ) were 3.29 ( 95 % CI 1.96 - 5.52 ) , 3.13 ( 1.87 - 5.25 ) , 2.51 ( 1.47 - 4.26 ) , and 2.03 ( 1.18 - 3.50 ) , respectively , compared with the most active quintile . The first to the third quintile of physical activity had a raised risk in all analyses . The mean time spent above 2000 cpm in the fourth quintile was 116 min per day in 9-year-old and 88 min per day in 15-year-old children . INTERPRETATION  Physical activity  levels should be higher than the current international guidelines of at least 1 h per day of physical activity of at least moderate intensity to prevent clustering of cardiovascular disease risk factors OBJECTIVE To prospect ively examine potential benefits of active commuting to school on measures of weight status and physical activity in a sample of youth . RESEARCH METHODS AND PROCEDURES A cohort of students from seven elementary schools was measured four times -- in the fall and spring of fourth grade ( N = 1083 ) and fifth grade ( N = 924 ) . Participants were classified as active ( walking , biking , or skateboarding to school almost every day for baseline analyses or at least 2 d/wk for analyses of consistent active commuting ) or non-active commuters to school . Accelerometers were used to measure physical activity . Height , weight , and skinfolds were objective ly assessed . RESULTS Boys who actively commuted to school had lower BMI ( p < 0.01 ) and skinfolds ( p < 0.05 ) than non-active commuters to school in the fourth grade . Active commuting to school over 2 years was not associated with BMI change or overweight status . DISCUSSION Walking and cycling to school may contribute to preventing excessive weight gain , or leaner children may walk or cycle to school AIMS Australian guidelines recommend that children participate in at least one hour of physical activity every day . We aim ed to measure physical activity  participation in a r and om sample of Australian primary school children and to determine the biological , behavioural , environmental and social influences associated with insufficient daily activity . METHOD We analysed the following cross-section data from a r and omly selected sample of children ( N=518 ) aged 5 to 12 years : age , gender , socioeconmic status ( SES ) indicators , family size , home play equipment availability , transport method to school , and estimated time per week in physical and sedentary activity . Logistic regression analysis was performed to determine variables that were associated with insufficient ( < 60 minutes ) daily activity . RESULTS Seventy-six children ( 15 % of the cohort ) failed to meet the minimum activity recommendations of 60 minutes of daily activity . These children were significantly less likely to walk or cycle to school ( adjusted odds ratio ( OR ) 0.43 ; 95 % CI=0.24 - 0.77 ) or participate in organised sports or activity ( OR 0.42 ; 95 % CI=0.28 - 0.64 ) and were more likely to spend in excess of 2 hours a day watching television of using a computer for entertainment ( OR 2.10 ( 1.16 - 3.78 ) . Age , gender , SES and family size were not significantly associated with insufficient activity . CONCLUSION There exists a significant proportion of the paediatric population who are insufficiently active . Interventions to encourage increased activity  in this sub-group may be successful if they seek to alter sedentary behaviour ( namely television use ) and method of transportation to and from school PURPOSE This study was conducted to determine if fifth- grade students who walked or bicycled to school on a regular basis were more physically active than those that did not . METHODS The sample consists of 219 fifth- grade students ( 10.3 + /- 0.6 yr , 44 % male , 58 % minority ) from eight r and omly selected urban and suburban elementary schools . Students wore an Acti-Graph physical activity monitor during the same week that they completed a daily survey to report their mode of transportation to and from school . Students were categorized on the number of reported active commuting trips , to and from school , per week ( regular;>or=5 ( N=11 ) , irregular ; 1 - 4 ( N=25 ) , nonactive ; 0 ( N=183 ) ) . RESULTS Compared with both other groups , regular active commuters accumulated 3 % more minutes of moderate-to-vigorous physical activity ( MVPA ; P=0.04 ) during weekdays . This weekday difference was because of regular active commuters accumulating 8.5 % more minutes of MVPA both before and after school ( P < or= 0.01 ) . No difference in physical activity was seen among groups during school or in the evening . Based on the mean number of minutes the students wore their monitors on weekdays ( 800 min.d ) , the 3 % difference translates into approximately 24 additional minutes of MVPA per day for the regular active commuters . CONCLUSION Walking to school was associated with approximately 24 additional minutes of MVPA per day in fifth- grade students . Additional observational and experimental research in larger , more diverse sample s is needed to further clarify the effects of active commuting to school on total daily physical activity and other health outcomes OBJECTIVE : To evaluate the impact of a “ walking school bus ” program on  children 's rates of active commuting to school and physical activity . METHODS : We conducted a pilot cluster r and omized controlled trial among 4th- grade rs from 8 schools in Houston , Texas ( N = 149 ) . R and om allocation to treatment or control conditions was at the school level . Study staff walked with children to and from school up to 5 days/week . Outcomes were measured the week before ( time 1 ) and during weeks 4 and 5 of the intervention ( time 2 ) . The main outcome was the weekly rate of active commuting , and a secondary outcome was moderate-to-vigorous physical activity . Covariates included sociodemographics , distance from home to school , neighborhood safety , child BMI z score , parent self-efficacy/ outcome expectations , and child self-efficacy for active commuting . A mixed-model repeated measures regression accounted for clustering by school , and stepwise procedures with backward elimination of nonsignificant covariates were used to identify significant predictors . RESULTS : Intervention children increased active commuting ( mean ± SD ) from 23.8 % ± 9.2 % ( time 1 ) to 54 % ± 9.2 % ( time 2 ) , whereas control subjects decreased from 40.2 % ± 8.9 % ( time 1 ) to 32.6 % ± 8.9 % ( time 2 ) ( P < .0001 ) . Intervention children increased their minutes of daily moderate-to-vigorous physical activity from 46.6 ± 4.5 ( time 1 ) to 48.8 ± 4.5 ( time 2 ) , whereas control children decreased from 46.1 ± 4.3 ( time 1 ) to 41.3 ± 4.3 ( time 2 ) ( P = .029 ) . CONCLUSIONS : The program improved children 's active commuting to school and daily moderate-to-vigorous physical activity Active commuting to school ( e.g. walking or bicycling ) has been suggested as a strategy to increase  children ’s physical activity 1 , 2 and a number of walk-to-school websites now exist . 3–5 Several observational studies have found positive associations between walking to school and physical activity 6–9 but they are unable to determine the causal direction . Adult-chaperoned walks to school ( i.e. , walking school bus1 , 5 ) have been evaluated 10–12 but no research was found that assessed objective ly measured changes in physical activity from walking to school . Walk-to-school programs can be a component of comprehensive school health plans , have particular relevance for school nurse/health staff and physical education faculty and can be adapted to suit the schools ’ physical and social environment . Therefore , we completed a small , short-term pilot and feasibility r and omized control trial to 1 ) test the feasibility of the walking school bus as an intervention strategy and 2 ) to identify any changes in physical activity from walking to school . A r and omized controlled trial design was used with all participants completing one week of baseline automobile commuting . Students were then r and omized , for the second week , to either a control group that continued to be driven to school or an intervention group that participated in the walking school bus .  Families were recruited from one elementary school ( Menlo Park , CA ) . Eighteen families responded and met the inclusion criteria : 1 ) student in 3rd–5th grade and 2 ) currently being driven to school at least four days/week . Six families declined to participate , due to time constraints ( n=4 ) , shared custody ( n=1 ) , and general concern ( n=1 ) . Therefore , 12 students were r and omized to a control ( CON  , n=6 ) or intervention ( WALK  , n=6 ) group . All students completed the study protocol as design ed . One student in the WALK group was excluded from analysis due to activity monitor malfunction , leaving five WALK and six CON students in the analysis sample . This study was approved by the Stanford University Administrative Panel on Human Subjects in Medical Research . This study was conducted during March and April of 2005 . The ActiGraph  physical activity monitor was used to measure physical activity . 13–15 One-minute data collection time intervals ( epochs ) were used for this study . An elastic belt with an attached monitor was fit to each student on the first day of the study ( always a weekend ) . Students were instructed to wear the monitor at all times for 14 consecutive days except when swimming , bathing , or sleeping . All students were instructed to maintain their normal activities during the baseline week . On the fifth day , families were notified of their group r and omization and , for the WALK group , the planned route and schedule . The morning commute for the CON group was not altered . A walking school bus , led by one study personnel , followed the safest route to school based on the location of the students ’ homes relative to each other and the school . Students walked at their normal pace but were encouraged to stay together as a group . A wagon , pulled by the study personnel , was used to transport backpacks and instruments . If a student lived more than 1.6 Km from the school , the parent/guardian dropped the student off at one of the other student ’s homes ( 1.1 Km from school ) and he/she walked the remainder of the trip . Raw accelerometer data were reduced to summary variables using a custom software program . 9 For analysis , accelerometer data were summarized for the total week and weekdays . Each weekday was also divided into four time blocks ; before- , during- , and after-school and evening . Average monitor counts·min−1 and the average percent of time spent in moderate-tovigorous physical activity ( % MVPA ) were calculated for each student using age-specific count cutoffs 16 and change scores ( intervention – baseline ) calculated . Between group comparisons used non-parametric Wilcoxon Rank Sum tests with a two-tailed alpha=0.05 . CON ( n=6 ) and WALK ( n=5 ) students were ( mean±SD ) 9.5±1.02 and 9.7±0.90 years old . The CON group had four boys ( all Caucasian ) and two girls ( 1 Caucasian , 1 Chinese ) . The WALK group had two boys and three girls ( all Caucasian ) . On average , CON and WALK students lived 1.3±0.68 and 0.9±0.46 Km from school . The time required to walk to school for the WALK students ranged from 10–36 minutes and was proportional to the distance traveled 0.4–1.1 Km ( mean , 0.8 Km ) ( Spearman r=0.95 ) . Compared to students in the CON group , WALK students significantly increased their counts·min-1 and % MVPA ( p≤0.02 ) before school ( Table 1 ) . This difference was even more pronounced when only looking at the General Commute Time ( GCT ) , defined as the 45 minutes before school ( p<0.01 ) . While there was no change for the CON group ( 12 min of MVPA ) , the WALK group added , on average , 14 minutes of MVPA during the GCT ( between group p=0.05 ) . No significant differences were detected for the other weekday periods . No significant between group differences were detected ( all p≥0.40 ) for the change in counts·min−1 or % MVPA averaged over all useable days or weekdays . Table 1 Average counts·min-1 and percent of time spent in MVPA by group by weekday time blocks , all days , and weekdays To our knowledge , this is the first experimental study to investigate the effect of walking to school on physical activity . The walking school bus did prove feasible in this small sample . Compared to students that were driven to school , those that walked to school increased their MVPA during the GCT by 14 minutes per day . Qualitative data collected at the end of the intervention indicated that the walking school bus was well liked . Parents noted that it was a , “ less stressful start to the day ” and another mentioned , “ She can do it ! And she enjoys walking . She even wanted to walk home ” . Students indicated that they enjoyed walking with others and one student noted that he , “ Did n't feel as tired in the morning compared to when I am driven to school ” . Two students indicated they did not like getting up earlier and none of the students liked the “ loud , embarrassing wagon ” . Five of the six students in the WALK group said they would continue to walk to school . In this experimental study we found no significant group differences for total daily or weekday physical activity or percent of time spent in MVPA . This was likely due to insufficient power to detect such differences , given the high variability of physical activity behavior and measurement error . The 14 minute increase in MVPA during the general commute time for the WALK students represents approximately 25 % of the recommended 60-minutes of MVPA per day . The promising results of this small experimental study justify larger walk to school experiments to examine whether walk to school interventions can impact total daily physical activity and MVPA , as well as other health and behavior outcomes . Additional community level benefits include less car congestion and emissions and improved neighborhood safety via more frequent social interactions with neighbors and greater community cohesion . Since walking to school will likely take longer than being driven , the morning routine may change to accommo date this . The child may need to get up earlier , potentially reducing the amount of time for sleeping and eating breakfast . Therefore , quality and quantity of sleep , consumption of breakfast and overall dietary behavior of students that walk to school should be considered . Lastly , such school- and community-based efforts should seek to engage school personnel and parent and community volunteers as walking school bus chaperones.17 The experiences from such programs can be incorporated into physical education and science curriculums as experiential learning opportunities ( e.g. , walkability audits ; car , bike , and pedestrian counts ; step or distance goals for active commuting , etc … ) BACKGROUND Active school transport ( AST ) is a recommended strategy to promote physical activity ( PA ) and prevent overweight ( OW ) in school-aged children . In many developing countries , such as Colombia , this association has not been well characterized . OBJECTIVE To determine the association between AST and weight status in a representative sample of adolescents from Montería , Colombia . METHODS Participants were 546 adolescents ( 278 boys ) aged 11 to 18 years old from 14 r and omly selected schools in Montería , Colombia in 2008 . The PA module of the Global School Health Survey ( GSHS-2007 ) was used to determine the prevalence of AST . To identify OW , participants were classified according to CDC 2000 criteria ( BMI ≥ 85th percentile ) . Association between AST and OW was determined by binomial logistic regression . RESULTS Odds ratios adjusted for age , sex , location of school , compliance with PA , and screen time recommendations showed that adolescents who reported AST had a significantly lower likelihood to be OW compared with adolescents who reported nonactive transportation ( OR = 0.5 , 95 % CI 0.3 - 0.8 , P < .05 ) . CONCLUSIONS These results support the importance of AST as a useful PA domain with potential implication s for overweight prevention , in rapidly developing setting s. Further epidemiologic and intervention studies addressing AST are needed in the region
target: These findings suggest that AST should be promoted to increase PA levels in children and adolescents and that cycling to/ from school is associated with increased cardiovascular fitness .
background: BACKGROUND The impact of  active school transport ( AST )  on daily physical activity ( PA ) levels , body composition and cardiovascular fitness remains unclear .